wio-e5 : initial port

arch/stm32/Adafruit_LittleFS_stm32/README.md

@@ -0,0 +1 @@
+This is LittleFS from Adafruit, stripped from things that makes it not compile with stm32 (refs to TinyUSB and free_rtos, mostly)

arch/stm32/Adafruit_LittleFS_stm32/library.properties

@@ -0,0 +1,10 @@
+name=Adafruit Little File System Libraries
+version=0.11.0
+author=Adafruit
+maintainer=Adafruit <info@adafruit.com>
+sentence=Arduino library for ARM Little File System
+paragraph=Arduino library for ARM Little File System
+category=Data Storage
+url=https://github.com/adafruit/Adafruit_nRF52_Arduino
+architectures=*
+includes=Adafruit_LittleFS.h

arch/stm32/Adafruit_LittleFS_stm32/src/Adafruit_LittleFS.cpp

@@ -0,0 +1,273 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2019 Ha Thach for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <Arduino.h>
+#include <string.h>
+#include "Adafruit_LittleFS.h"
+
+//#include <Adafruit_TinyUSB.h> // for Serial
+
+using namespace Adafruit_LittleFS_Namespace;
+
+#define memclr(buffer, size) memset(buffer, 0, size)
+#define varclr(_var) memclr(_var, sizeof(*(_var)))
+ 
+//--------------------------------------------------------------------+
+// Implementation
+//--------------------------------------------------------------------+
+
+Adafruit_LittleFS::Adafruit_LittleFS (void)
+  : Adafruit_LittleFS(NULL)
+{
+
+}
+
+Adafruit_LittleFS::Adafruit_LittleFS (struct lfs_config* cfg)
+{
+  varclr(&_lfs);
+  _lfs_cfg = cfg;
+  _mounted = false;
+// _mutex = xSemaphoreCreateMutexStatic(&this->_MutexStorageSpace);
+}
+
+Adafruit_LittleFS::~Adafruit_LittleFS ()
+{
+
+}
+
+// Initialize and mount the file system
+// Return true if mounted successfully else probably corrupted.
+// User should format the disk and try again
+bool Adafruit_LittleFS::begin (struct lfs_config * cfg)
+{
+  _lockFS();
+
+  bool ret;
+  // not a loop, just an quick way to short-circuit on error
+  do {
+    if (_mounted) { ret = true; break; }
+    if (cfg) { _lfs_cfg = cfg; }
+    if (nullptr == _lfs_cfg) { ret = false; break; }
+    // actually attempt to mount, and log error if one occurs
+    int err = lfs_mount(&_lfs, _lfs_cfg);
+    PRINT_LFS_ERR(err);
+    _mounted = (err == LFS_ERR_OK);
+    ret = _mounted;
+  } while(0);
+
+  _unlockFS();
+  return ret;
+}
+
+// Tear down and unmount file system
+void Adafruit_LittleFS::end(void)
+{
+  _lockFS();
+
+  if (_mounted)
+  {
+    _mounted = false;
+    int err = lfs_unmount(&_lfs);
+    PRINT_LFS_ERR(err);
+    (void)err;
+  }
+
+  _unlockFS();
+}
+
+bool Adafruit_LittleFS::format (void)
+{
+  _lockFS();
+
+  int err = LFS_ERR_OK;
+  bool attemptMount = _mounted;
+  // not a loop, just an quick way to short-circuit on error
+  do
+  {
+    // if already mounted: umount first -> format -> remount
+    if (_mounted)
+    {
+      _mounted = false;
+      err = lfs_unmount(&_lfs);
+      if ( LFS_ERR_OK != err) { PRINT_LFS_ERR(err); break; }
+    }
+    err = lfs_format(&_lfs, _lfs_cfg);
+    if ( LFS_ERR_OK != err ) { PRINT_LFS_ERR(err); break; }
+
+    if (attemptMount)
+    {
+      err = lfs_mount(&_lfs, _lfs_cfg);
+      if ( LFS_ERR_OK != err ) { PRINT_LFS_ERR(err); break; }
+      _mounted = true;
+    }
+    // success!
+  } while(0);
+
+  _unlockFS();
+  return LFS_ERR_OK == err;
+}
+
+// Open a file or folder
+Adafruit_LittleFS_Namespace::File Adafruit_LittleFS::open (char const *filepath, uint8_t mode)
+{
+  // No lock is required here ... the File() object will synchronize with the mutex provided
+  return Adafruit_LittleFS_Namespace::File(filepath, mode, *this);
+}
+
+// Check if file or folder exists
+bool Adafruit_LittleFS::exists (char const *filepath)
+{
+  struct lfs_info info;
+  _lockFS();
+
+  bool ret = (0 == lfs_stat(&_lfs, filepath, &info));
+
+  _unlockFS();
+  return ret;
+}
+
+
+// Create a directory, create intermediate parent if needed
+bool Adafruit_LittleFS::mkdir (char const *filepath)
+{
+  bool ret = true;
+  const char* slash = filepath;
+  if ( slash[0] == '/' ) slash++;    // skip root '/'
+
+  _lockFS();
+
+  // make intermediate parent directory(ies)
+  while ( NULL != (slash = strchr(slash, '/')) )
+  {
+    char parent[slash - filepath + 1] = { 0 };
+    memcpy(parent, filepath, slash - filepath);
+
+    int rc = lfs_mkdir(&_lfs, parent);
+    if ( rc != LFS_ERR_OK && rc != LFS_ERR_EXIST )
+    {
+      PRINT_LFS_ERR(rc);
+      ret = false;
+      break;
+    }
+    slash++;
+  }
+  // make the final requested directory
+  if (ret)
+  {
+    int rc = lfs_mkdir(&_lfs, filepath);
+    if ( rc != LFS_ERR_OK && rc != LFS_ERR_EXIST )
+    {
+      PRINT_LFS_ERR(rc);
+      ret = false;
+    }
+  }
+
+  _unlockFS();
+  return ret;
+}
+
+// Remove a file
+bool Adafruit_LittleFS::remove (char const *filepath)
+{
+  _lockFS();
+
+  int err = lfs_remove(&_lfs, filepath);
+  PRINT_LFS_ERR(err);
+
+  _unlockFS();
+  return LFS_ERR_OK == err;
+}
+
+// Rename a file
+bool Adafruit_LittleFS::rename (char const *oldfilepath, char const *newfilepath)
+{
+  _lockFS();
+
+  int err = lfs_rename(&_lfs, oldfilepath, newfilepath);
+  PRINT_LFS_ERR(err);
+
+  _unlockFS();
+  return LFS_ERR_OK == err;
+}
+
+// Remove a folder
+bool Adafruit_LittleFS::rmdir (char const *filepath)
+{
+  _lockFS();
+
+  int err = lfs_remove(&_lfs, filepath);
+  PRINT_LFS_ERR(err);
+
+  _unlockFS();
+  return LFS_ERR_OK == err;
+}
+
+// Remove a folder recursively
+bool Adafruit_LittleFS::rmdir_r (char const *filepath)
+{
+  /* adafruit: lfs is modified to remove non-empty folder,
+   According to below issue, comment these 2 line won't corrupt filesystem
+   at least when using LFS v1.  If moving to LFS v2, see tracked issue
+   to see if issues (such as the orphans in threaded linked list) are resolved.
+   https://github.com/ARMmbed/littlefs/issues/43
+   */
+  _lockFS();
+
+  int err = lfs_remove(&_lfs, filepath);
+  PRINT_LFS_ERR(err);
+
+  _unlockFS();
+  return LFS_ERR_OK == err;
+}
+
+//------------- Debug -------------//
+#if CFG_DEBUG
+
+const char* dbg_strerr_lfs (int32_t err)
+{
+  switch ( err )
+  {
+    case LFS_ERR_OK       : return "LFS_ERR_OK";
+    case LFS_ERR_IO       : return "LFS_ERR_IO";
+    case LFS_ERR_CORRUPT  : return "LFS_ERR_CORRUPT";
+    case LFS_ERR_NOENT    : return "LFS_ERR_NOENT";
+    case LFS_ERR_EXIST    : return "LFS_ERR_EXIST";
+    case LFS_ERR_NOTDIR   : return "LFS_ERR_NOTDIR";
+    case LFS_ERR_ISDIR    : return "LFS_ERR_ISDIR";
+    case LFS_ERR_NOTEMPTY : return "LFS_ERR_NOTEMPTY";
+    case LFS_ERR_BADF     : return "LFS_ERR_BADF";
+    case LFS_ERR_INVAL    : return "LFS_ERR_INVAL";
+    case LFS_ERR_NOSPC    : return "LFS_ERR_NOSPC";
+    case LFS_ERR_NOMEM    : return "LFS_ERR_NOMEM";
+
+    default:
+      static char errcode[10];
+      sprintf(errcode, "%ld", err);
+      return errcode;
+  }
+
+  return NULL;
+}
+
+#endif

arch/stm32/Adafruit_LittleFS_stm32/src/Adafruit_LittleFS.h

@@ -0,0 +1,102 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2019 Ha Thach for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef ADAFRUIT_LITTLEFS_H_
+#define ADAFRUIT_LITTLEFS_H_
+
+#include <Stream.h>
+
+// Internal Flash uses ARM Little FileSystem
+// https://github.com/ARMmbed/littlefs
+#include "littlefs/lfs.h"
+#include "Adafruit_LittleFS_File.h"
+//#include "rtos.h" // tied to FreeRTOS for serialization
+
+class Adafruit_LittleFS
+{
+  public:
+    Adafruit_LittleFS (void);
+    Adafruit_LittleFS (struct lfs_config* cfg);
+    virtual ~Adafruit_LittleFS ();
+
+    bool begin(struct lfs_config * cfg = NULL);
+    void end(void);
+
+    // Open the specified file/directory with the supplied mode (e.g. read or
+    // write, etc). Returns a File object for interacting with the file.
+    // Note that currently only one file can be open at a time.
+    Adafruit_LittleFS_Namespace::File open (char const *filename, uint8_t mode = Adafruit_LittleFS_Namespace::FILE_O_READ);
+
+    // Methods to determine if the requested file path exists.
+    bool exists (char const *filepath);
+
+    // Create the requested directory hierarchy--if intermediate directories
+    // do not exist they will be created.
+    bool mkdir (char const *filepath);
+
+    // Delete the file.
+    bool remove (char const *filepath);
+
+    // Rename the file.
+    bool rename (char const *oldfilepath, char const *newfilepath);
+
+    // Delete a folder (must be empty)
+    bool rmdir (char const *filepath);
+
+    // Delete a folder (recursively)
+    bool rmdir_r (char const *filepath);
+
+    // format file system
+    bool format (void);
+
+    /*------------------------------------------------------------------*/
+    /* INTERNAL USAGE ONLY
+     * Although declare as public, it is meant to be invoked by internal
+     * code. User should not call these directly
+     *------------------------------------------------------------------*/
+    lfs_t* _getFS   (void) { return &_lfs; }
+    void   _lockFS  (void) { }//xSemaphoreTake(_mutex,  portMAX_DELAY); }
+    void   _unlockFS(void) { }//xSemaphoreGive(_mutex); }
+
+  protected:
+    bool _mounted;
+    struct lfs_config* _lfs_cfg;
+    lfs_t _lfs;
+//    SemaphoreHandle_t _mutex;
+
+  private:
+//    StaticSemaphore_t _MutexStorageSpace;
+};
+
+#if !CFG_DEBUG
+  #define VERIFY_LFS(...)       _GET_3RD_ARG(__VA_ARGS__, VERIFY_ERR_2ARGS, VERIFY_ERR_1ARGS)(__VA_ARGS__, NULL)
+  #define PRINT_LFS_ERR(_err)
+#else
+  #define VERIFY_LFS(...)       _GET_3RD_ARG(__VA_ARGS__, VERIFY_ERR_2ARGS, VERIFY_ERR_1ARGS)(__VA_ARGS__, dbg_strerr_lfs)
+  #define PRINT_LFS_ERR(_err)   do { if (_err) { VERIFY_MESS((long int)_err, dbg_strerr_lfs); } } while(0) // LFS_ERR are of type int, VERIFY_MESS expects long_int
+
+  const char* dbg_strerr_lfs (int32_t err);
+#endif
+
+#endif /* ADAFRUIT_LITTLEFS_H_ */

arch/stm32/Adafruit_LittleFS_stm32/src/Adafruit_LittleFS_File.cpp

@@ -0,0 +1,420 @@
+/* 
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2019 Ha Thach for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <Arduino.h>
+#include "Adafruit_LittleFS.h"
+#include "littlefs/lfs.h"
+
+//--------------------------------------------------------------------+
+// MACRO TYPEDEF CONSTANT ENUM DECLARATION
+//--------------------------------------------------------------------+
+
+using namespace Adafruit_LittleFS_Namespace;
+
+File::File (Adafruit_LittleFS &fs)
+{
+  _fs = &fs;
+  _is_dir = false;
+  _name[0] = 0;
+  _name[LFS_NAME_MAX] = 0;
+  _dir_path = NULL;
+
+  _dir = NULL;
+  _file = NULL;
+}
+
+File::File (char const *filename, uint8_t mode, Adafruit_LittleFS &fs)
+ : File(fs)
+{
+  // public constructor calls public API open(), which will obtain the mutex
+  this->open(filename, mode);
+}
+
+bool File::_open_file (char const *filepath, uint8_t mode)
+{
+  int flags = (mode == FILE_O_READ) ? LFS_O_RDONLY :
+              (mode == FILE_O_WRITE) ? (LFS_O_RDWR | LFS_O_CREAT) : 0;
+
+  if ( flags )
+  {
+    _file = (lfs_file_t*) malloc(sizeof(lfs_file_t));
+    if (!_file) return false;
+
+    int rc = lfs_file_open(_fs->_getFS(), _file, filepath, flags);
+
+    if ( rc )
+    {
+      // failed to open
+      PRINT_LFS_ERR(rc);
+      // free memory
+      free(_file);
+      _file = NULL;
+      return false;
+    }
+
+    // move to end of file
+    if ( mode == FILE_O_WRITE ) lfs_file_seek(_fs->_getFS(), _file, 0, LFS_SEEK_END);
+
+    _is_dir = false;
+  }
+
+  return true;
+}
+
+bool File::_open_dir (char const *filepath)
+{
+  _dir = (lfs_dir_t*) malloc(sizeof(lfs_dir_t));
+  if (!_dir) return false;
+
+  int rc = lfs_dir_open(_fs->_getFS(), _dir, filepath);
+
+  if ( rc )
+  {
+    // failed to open
+    PRINT_LFS_ERR(rc);
+    // free memory
+    free(_dir);
+    _dir = NULL;
+    return false;
+  }
+
+  _is_dir = true;
+
+  _dir_path = (char*) malloc(strlen(filepath) + 1);
+  strcpy(_dir_path, filepath);
+
+  return true;
+}
+
+bool File::open (char const *filepath, uint8_t mode)
+{
+  bool ret = false;
+  _fs->_lockFS();
+
+  ret = this->_open(filepath, mode);
+
+  _fs->_unlockFS();
+  return ret;
+}
+
+bool File::_open (char const *filepath, uint8_t mode)
+{
+  bool ret = false;
+
+  // close if currently opened
+  if ( this->isOpen() ) _close();
+
+  struct lfs_info info;
+  int rc = lfs_stat(_fs->_getFS(), filepath, &info);
+
+  if ( LFS_ERR_OK == rc )
+  {
+    // file existed, open file or directory accordingly
+    ret = (info.type == LFS_TYPE_REG) ? _open_file(filepath, mode) : _open_dir(filepath);
+  }
+  else if ( LFS_ERR_NOENT == rc )
+  {
+    // file not existed, only proceed with FILE_O_WRITE mode
+    if ( mode == FILE_O_WRITE ) ret = _open_file(filepath, mode);
+  }
+  else
+  {
+    PRINT_LFS_ERR(rc);
+  }
+
+  // save bare file name
+  if (ret)
+  {
+    char const* splash = strrchr(filepath, '/');
+    strncpy(_name, splash ? (splash + 1) : filepath, LFS_NAME_MAX);
+  }
+  return ret;
+}
+
+size_t File::write (uint8_t ch)
+{
+  return write(&ch, 1);
+}
+
+size_t File::write (uint8_t const *buf, size_t size)
+{
+  lfs_ssize_t wrcount = 0;
+  _fs->_lockFS();
+
+  if (!this->_is_dir)
+  {
+    wrcount = lfs_file_write(_fs->_getFS(), _file, buf, size);
+    if (wrcount < 0)
+    {
+      wrcount = 0;
+    }
+  }
+
+  _fs->_unlockFS();
+  return wrcount;
+}
+
+int File::read (void)
+{
+  // this thin wrapper relies on called function to synchronize
+  int ret = -1;
+  uint8_t ch;
+  if (read(&ch, 1) > 0)
+  {
+    ret = static_cast<int>(ch);
+  }
+  return ret;
+}
+
+int File::read (void *buf, uint16_t nbyte)
+{
+  int ret = 0;
+  _fs->_lockFS();
+
+  if (!this->_is_dir)
+  {
+    ret = lfs_file_read(_fs->_getFS(), _file, buf, nbyte);
+  }
+
+  _fs->_unlockFS();
+  return ret;
+}
+
+int File::peek (void)
+{
+  int ret = -1;
+  _fs->_lockFS();
+
+  if (!this->_is_dir)
+  {
+    uint32_t pos = lfs_file_tell(_fs->_getFS(), _file);
+    uint8_t ch = 0;
+    if (lfs_file_read(_fs->_getFS(), _file, &ch, 1) > 0)
+    {
+      ret = static_cast<int>(ch);
+    }
+    (void) lfs_file_seek(_fs->_getFS(), _file, pos, LFS_SEEK_SET);
+  }
+
+  _fs->_unlockFS();
+  return ret;
+}
+
+int File::available (void)
+{
+  int ret = 0;
+  _fs->_lockFS();
+
+  if (!this->_is_dir)
+  {
+    uint32_t size = lfs_file_size(_fs->_getFS(), _file);
+    uint32_t pos  = lfs_file_tell(_fs->_getFS(), _file);
+    ret = size - pos;
+  }
+
+  _fs->_unlockFS();
+  return ret;
+}
+
+bool File::seek (uint32_t pos)
+{
+  bool ret = false;
+  _fs->_lockFS();
+
+  if (!this->_is_dir)
+  {
+    ret = lfs_file_seek(_fs->_getFS(), _file, pos, LFS_SEEK_SET) >= 0;
+  }
+
+  _fs->_unlockFS();
+  return ret;
+}
+
+uint32_t File::position (void)
+{
+  uint32_t ret = 0;
+  _fs->_lockFS();
+
+  if (!this->_is_dir)
+  {
+    ret = lfs_file_tell(_fs->_getFS(), _file);
+  }
+
+  _fs->_unlockFS();
+  return ret;
+}
+
+uint32_t File::size (void)
+{
+  uint32_t ret = 0;
+  _fs->_lockFS();
+
+  if (!this->_is_dir)
+  {
+    ret = lfs_file_size(_fs->_getFS(), _file);
+  }
+
+  _fs->_unlockFS();
+  return ret;
+}
+
+bool File::truncate (uint32_t pos)
+{
+  int32_t ret=LFS_ERR_ISDIR;
+  _fs->_lockFS();
+  if (!this->_is_dir)
+  {
+    ret = lfs_file_truncate(_fs->_getFS(), _file, pos);
+  }
+  _fs->_unlockFS();
+  return ( ret == 0 );
+}
+
+bool File::truncate (void)
+{
+  int32_t ret=LFS_ERR_ISDIR;
+  uint32_t pos;
+  _fs->_lockFS();
+  if (!this->_is_dir)
+  {
+    pos = lfs_file_tell(_fs->_getFS(), _file);
+    ret = lfs_file_truncate(_fs->_getFS(), _file, pos);
+  }
+  _fs->_unlockFS();
+  return ( ret == 0 );
+}
+
+void File::flush (void)
+{
+  _fs->_lockFS();
+
+  if (!this->_is_dir)
+  {
+    lfs_file_sync(_fs->_getFS(), _file);
+  }
+
+  _fs->_unlockFS();
+  return;
+}
+
+void File::close (void)
+{
+  _fs->_lockFS();
+  this->_close();
+  _fs->_unlockFS();
+}
+
+void File::_close(void)
+{
+  if ( this->isOpen() )
+  {
+    if ( this->_is_dir )
+    {
+      lfs_dir_close(_fs->_getFS(), _dir);
+      free(_dir);
+      _dir = NULL;
+
+      if ( this->_dir_path ) free(_dir_path);
+      _dir_path = NULL;
+    }
+    else
+    {
+      lfs_file_close(this->_fs->_getFS(), _file);
+      free(_file);
+      _file = NULL;
+    }
+  }
+}
+
+File::operator bool (void)
+{
+  return isOpen();
+}
+
+bool File::isOpen(void)
+{
+  return (_file != NULL) || (_dir != NULL);
+}
+
+// WARNING -- although marked as `const`, the values pointed
+//            to may change.  For example, if the same File
+//            object has `open()` called with a different
+//            file or directory name, this same pointer will
+//            suddenly (unexpectedly?) have different values.
+char const* File::name (void)
+{
+  return this->_name;
+}
+
+bool File::isDirectory (void)
+{
+  return this->_is_dir;
+}
+
+File File::openNextFile (uint8_t mode)
+{
+  _fs->_lockFS();
+
+  File ret(*_fs);
+  if (this->_is_dir)
+  {
+    struct lfs_info info;
+    int rc;
+
+    // lfs_dir_read returns 0 when reaching end of directory, 1 if found an entry
+    // Skip the "." and ".." entries ...
+    do
+    {
+      rc = lfs_dir_read(_fs->_getFS(), _dir, &info);
+    } while ( rc == 1 && (!strcmp(".", info.name) || !strcmp("..", info.name)) );
+
+    if ( rc == 1 )
+    {
+      // string cat name with current folder
+      char filepath[strlen(_dir_path) + 1 + strlen(info.name) + 1]; // potential for significant stack usage
+      strcpy(filepath, _dir_path);
+      if ( !(_dir_path[0] == '/' && _dir_path[1] == 0) ) strcat(filepath, "/");    // only add '/' if cwd is not root
+      strcat(filepath, info.name);
+
+      (void)ret._open(filepath, mode); // return value is ignored ... caller is expected to check isOpened()
+    }
+    else if ( rc < 0 )
+    {
+      PRINT_LFS_ERR(rc);
+    }
+  }
+  _fs->_unlockFS();
+  return ret;
+}
+
+void File::rewindDirectory (void)
+{
+  _fs->_lockFS();
+  if (this->_is_dir)
+  {
+    lfs_dir_rewind(_fs->_getFS(), _dir);
+  }
+  _fs->_unlockFS();
+}
+

arch/stm32/Adafruit_LittleFS_stm32/src/Adafruit_LittleFS_File.h

@@ -0,0 +1,108 @@
+/* 
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2019 Ha Thach for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef ADAFRUIT_LITTLEFS_FILE_H_
+#define ADAFRUIT_LITTLEFS_FILE_H_
+
+// Forward declaration
+class Adafruit_LittleFS;
+
+namespace Adafruit_LittleFS_Namespace
+{
+
+// avoid conflict with other FileSystem FILE_READ/FILE_WRITE
+enum
+{
+  FILE_O_READ = 0,
+  FILE_O_WRITE = 1,
+};
+
+class File : public Stream
+{
+  public:
+    File (Adafruit_LittleFS &fs);
+    File (char const *filename, uint8_t mode, Adafruit_LittleFS &fs);
+
+  public:
+
+    bool open (char const *filename, uint8_t mode);
+
+    //------------- Stream API -------------//
+    virtual size_t write (uint8_t ch);
+    virtual size_t write (uint8_t const *buf, size_t size);
+    size_t write(const char *str) {
+      if (str == NULL) return 0;
+      return write((const uint8_t *)str, strlen(str));
+    }
+    size_t write(const char *buffer, size_t size) {
+      return write((const uint8_t *)buffer, size);
+    }
+
+    virtual int read (void);
+    int read (void *buf, uint16_t nbyte);
+
+    virtual int peek (void);
+    virtual int available (void);
+    virtual void flush (void);
+
+    bool seek (uint32_t pos);
+    uint32_t position (void);
+    uint32_t size (void);
+
+    bool truncate (uint32_t pos);
+    bool truncate (void);
+
+    void close (void);
+
+    operator bool (void);
+
+    bool isOpen(void);
+    char const* name (void);
+
+    bool isDirectory (void);
+    File openNextFile (uint8_t mode = FILE_O_READ);
+    void rewindDirectory (void);
+
+  private:
+    Adafruit_LittleFS* _fs;
+
+    bool _is_dir;
+
+    union {
+        lfs_file_t* _file;
+        lfs_dir_t*  _dir;
+    };
+
+    char* _dir_path;
+    char  _name[LFS_NAME_MAX+1];
+
+    bool _open(char const *filepath, uint8_t mode);
+    bool _open_file(char const *filepath, uint8_t mode);
+    bool _open_dir (char const *filepath);
+    void _close(void);
+};
+
+}
+
+#endif /* ADAFRUIT_LITTLEFS_FILE_H_ */

arch/stm32/Adafruit_LittleFS_stm32/src/littlefs/LICENSE.md

@@ -0,0 +1,24 @@
+Copyright (c) 2017, Arm Limited. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without modification,
+are permitted provided that the following conditions are met:
+
+-  Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+-  Redistributions in binary form must reproduce the above copyright notice, this
+   list of conditions and the following disclaimer in the documentation and/or
+   other materials provided with the distribution.
+-  Neither the name of ARM nor the names of its contributors may be used to
+   endorse or promote products derived from this software without specific prior
+   written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
+ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

arch/stm32/Adafruit_LittleFS_stm32/src/littlefs/README.md

@@ -0,0 +1,177 @@
+## The little filesystem
+
+A little fail-safe filesystem designed for embedded systems.
+
+```
+   | | |     .---._____
+  .-----.   |          |
+--|o    |---| littlefs |
+--|     |---|          |
+  '-----'   '----------'
+   | | |
+```
+
+**Bounded RAM/ROM** - The littlefs is designed to work with a limited amount
+of memory. Recursion is avoided and dynamic memory is limited to configurable
+buffers that can be provided statically.
+
+**Power-loss resilient** - The littlefs is designed for systems that may have
+random power failures. The littlefs has strong copy-on-write guarantees and
+storage on disk is always kept in a valid state.
+
+**Wear leveling** - Since the most common form of embedded storage is erodible
+flash memories, littlefs provides a form of dynamic wear leveling for systems
+that can not fit a full flash translation layer.
+
+## Example
+
+Here's a simple example that updates a file named `boot_count` every time
+main runs. The program can be interrupted at any time without losing track
+of how many times it has been booted and without corrupting the filesystem:
+
+``` c
+#include "lfs.h"
+
+// variables used by the filesystem
+lfs_t lfs;
+lfs_file_t file;
+
+// configuration of the filesystem is provided by this struct
+const struct lfs_config cfg = {
+    // block device operations
+    .read  = user_provided_block_device_read,
+    .prog  = user_provided_block_device_prog,
+    .erase = user_provided_block_device_erase,
+    .sync  = user_provided_block_device_sync,
+
+    // block device configuration
+    .read_size = 16,
+    .prog_size = 16,
+    .block_size = 4096,
+    .block_count = 128,
+    .lookahead = 128,
+};
+
+// entry point
+int main(void) {
+    // mount the filesystem
+    int err = lfs_mount(&lfs, &cfg);
+
+    // reformat if we can't mount the filesystem
+    // this should only happen on the first boot
+    if (err) {
+        lfs_format(&lfs, &cfg);
+        lfs_mount(&lfs, &cfg);
+    }
+
+    // read current count
+    uint32_t boot_count = 0;
+    lfs_file_open(&lfs, &file, "boot_count", LFS_O_RDWR | LFS_O_CREAT);
+    lfs_file_read(&lfs, &file, &boot_count, sizeof(boot_count));
+
+    // update boot count
+    boot_count += 1;
+    lfs_file_rewind(&lfs, &file);
+    lfs_file_write(&lfs, &file, &boot_count, sizeof(boot_count));
+
+    // remember the storage is not updated until the file is closed successfully
+    lfs_file_close(&lfs, &file);
+
+    // release any resources we were using
+    lfs_unmount(&lfs);
+
+    // print the boot count
+    printf("boot_count: %d\n", boot_count);
+}
+```
+
+## Usage
+
+Detailed documentation (or at least as much detail as is currently available)
+can be found in the comments in [lfs.h](lfs.h).
+
+As you may have noticed, littlefs takes in a configuration structure that
+defines how the filesystem operates. The configuration struct provides the
+filesystem with the block device operations and dimensions, tweakable
+parameters that tradeoff memory usage for performance, and optional
+static buffers if the user wants to avoid dynamic memory.
+
+The state of the littlefs is stored in the `lfs_t` type which is left up
+to the user to allocate, allowing multiple filesystems to be in use
+simultaneously. With the `lfs_t` and configuration struct, a user can
+format a block device or mount the filesystem.
+
+Once mounted, the littlefs provides a full set of POSIX-like file and
+directory functions, with the deviation that the allocation of filesystem
+structures must be provided by the user.
+
+All POSIX operations, such as remove and rename, are atomic, even in event
+of power-loss. Additionally, no file updates are actually committed to the
+filesystem until sync or close is called on the file.
+
+## Other notes
+
+All littlefs have the potential to return a negative error code. The errors
+can be either one of those found in the `enum lfs_error` in [lfs.h](lfs.h),
+or an error returned by the user's block device operations.
+
+In the configuration struct, the `prog` and `erase` function provided by the
+user may return a `LFS_ERR_CORRUPT` error if the implementation already can
+detect corrupt blocks. However, the wear leveling does not depend on the return
+code of these functions, instead all data is read back and checked for
+integrity.
+
+If your storage caches writes, make sure that the provided `sync` function
+flushes all the data to memory and ensures that the next read fetches the data
+from memory, otherwise data integrity can not be guaranteed. If the `write`
+function does not perform caching, and therefore each `read` or `write` call
+hits the memory, the `sync` function can simply return 0.
+
+## Reference material
+
+[DESIGN.md](DESIGN.md) - DESIGN.md contains a fully detailed dive into how
+littlefs actually works. I would encourage you to read it since the
+solutions and tradeoffs at work here are quite interesting.
+
+[SPEC.md](SPEC.md) - SPEC.md contains the on-disk specification of littlefs
+with all the nitty-gritty details. Can be useful for developing tooling.
+
+## Testing
+
+The littlefs comes with a test suite designed to run on a PC using the
+[emulated block device](emubd/lfs_emubd.h) found in the emubd directory.
+The tests assume a Linux environment and can be started with make:
+
+``` bash
+make test
+```
+
+## License
+
+The littlefs is provided under the [BSD-3-Clause](https://spdx.org/licenses/BSD-3-Clause.html)
+license. See [LICENSE.md](LICENSE.md) for more information. Contributions to
+this project are accepted under the same license.
+
+Individual files contain the following tag instead of the full license text.
+
+    SPDX-License-Identifier:    BSD-3-Clause
+
+This enables machine processing of license information based on the SPDX
+License Identifiers that are here available: http://spdx.org/licenses/
+
+## Related projects
+
+[Mbed OS](https://github.com/ARMmbed/mbed-os/tree/master/features/filesystem/littlefs) -
+The easiest way to get started with littlefs is to jump into [Mbed](https://os.mbed.com/),
+which already has block device drivers for most forms of embedded storage. The
+littlefs is available in Mbed OS as the [LittleFileSystem](https://os.mbed.com/docs/latest/reference/littlefilesystem.html)
+class.
+
+[littlefs-fuse](https://github.com/geky/littlefs-fuse) - A [FUSE](https://github.com/libfuse/libfuse)
+wrapper for littlefs. The project allows you to mount littlefs directly on a
+Linux machine. Can be useful for debugging littlefs if you have an SD card
+handy.
+
+[littlefs-js](https://github.com/geky/littlefs-js) - A javascript wrapper for
+littlefs. I'm not sure why you would want this, but it is handy for demos.
+You can see it in action [here](http://littlefs.geky.net/demo.html).

arch/stm32/Adafruit_LittleFS_stm32/src/littlefs/lfs.c

@@ -0,0 +1,2585 @@
+/*
+ * The little filesystem
+ *
+ * Copyright (c) 2017, Arm Limited. All rights reserved.
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+#include "lfs.h"
+#include "lfs_util.h"
+
+#include <inttypes.h>
+
+
+/// Caching block device operations ///
+static int lfs_cache_read(lfs_t *lfs, lfs_cache_t *rcache,
+        const lfs_cache_t *pcache, lfs_block_t block,
+        lfs_off_t off, void *buffer, lfs_size_t size) {
+    uint8_t *data = buffer;
+    LFS_ASSERT(block < lfs->cfg->block_count);
+
+    while (size > 0) {
+        if (pcache && block == pcache->block && off >= pcache->off &&
+                off < pcache->off + lfs->cfg->prog_size) {
+            // is already in pcache?
+            lfs_size_t diff = lfs_min(size,
+                    lfs->cfg->prog_size - (off-pcache->off));
+            memcpy(data, &pcache->buffer[off-pcache->off], diff);
+
+            data += diff;
+            off += diff;
+            size -= diff;
+            continue;
+        }
+
+        if (block == rcache->block && off >= rcache->off &&
+                off < rcache->off + lfs->cfg->read_size) {
+            // is already in rcache?
+            lfs_size_t diff = lfs_min(size,
+                    lfs->cfg->read_size - (off-rcache->off));
+            memcpy(data, &rcache->buffer[off-rcache->off], diff);
+
+            data += diff;
+            off += diff;
+            size -= diff;
+            continue;
+        }
+
+        if (off % lfs->cfg->read_size == 0 && size >= lfs->cfg->read_size) {
+            // bypass cache?
+            lfs_size_t diff = size - (size % lfs->cfg->read_size);
+            int err = lfs->cfg->read(lfs->cfg, block, off, data, diff);
+            if (err) {
+                return err;
+            }
+
+            data += diff;
+            off += diff;
+            size -= diff;
+            continue;
+        }
+
+        // load to cache, first condition can no longer fail
+        rcache->block = block;
+        rcache->off = off - (off % lfs->cfg->read_size);
+        int err = lfs->cfg->read(lfs->cfg, rcache->block,
+                rcache->off, rcache->buffer, lfs->cfg->read_size);
+        if (err) {
+            return err;
+        }
+    }
+
+    return 0;
+}
+
+static int lfs_cache_cmp(lfs_t *lfs, lfs_cache_t *rcache,
+        const lfs_cache_t *pcache, lfs_block_t block,
+        lfs_off_t off, const void *buffer, lfs_size_t size) {
+    const uint8_t *data = buffer;
+
+    for (lfs_off_t i = 0; i < size; i++) {
+        uint8_t c;
+        int err = lfs_cache_read(lfs, rcache, pcache,
+                block, off+i, &c, 1);
+        if (err) {
+            return err;
+        }
+
+        if (c != data[i]) {
+            return false;
+        }
+    }
+
+    return true;
+}
+
+static int lfs_cache_crc(lfs_t *lfs, lfs_cache_t *rcache,
+        const lfs_cache_t *pcache, lfs_block_t block,
+        lfs_off_t off, lfs_size_t size, uint32_t *crc) {
+    for (lfs_off_t i = 0; i < size; i++) {
+        uint8_t c;
+        int err = lfs_cache_read(lfs, rcache, pcache,
+                block, off+i, &c, 1);
+        if (err) {
+            return err;
+        }
+
+        lfs_crc(crc, &c, 1);
+    }
+
+    return 0;
+}
+
+static inline void lfs_cache_drop(lfs_t *lfs, lfs_cache_t *rcache) {
+    // do not zero, cheaper if cache is readonly or only going to be
+    // written with identical data (during relocates)
+    (void)lfs;
+    rcache->block = 0xffffffff;
+}
+
+static inline void lfs_cache_zero(lfs_t *lfs, lfs_cache_t *pcache) {
+    // zero to avoid information leak
+    memset(pcache->buffer, 0xff, lfs->cfg->prog_size);
+    pcache->block = 0xffffffff;
+}
+
+static int lfs_cache_flush(lfs_t *lfs,
+        lfs_cache_t *pcache, lfs_cache_t *rcache) {
+    if (pcache->block != 0xffffffff) {
+        int err = lfs->cfg->prog(lfs->cfg, pcache->block,
+                pcache->off, pcache->buffer, lfs->cfg->prog_size);
+        if (err) {
+            return err;
+        }
+
+        if (rcache) {
+            int res = lfs_cache_cmp(lfs, rcache, NULL, pcache->block,
+                    pcache->off, pcache->buffer, lfs->cfg->prog_size);
+            if (res < 0) {
+                return res;
+            }
+
+            if (!res) {
+                return LFS_ERR_CORRUPT;
+            }
+        }
+
+        lfs_cache_zero(lfs, pcache);
+    }
+
+    return 0;
+}
+
+static int lfs_cache_prog(lfs_t *lfs, lfs_cache_t *pcache,
+        lfs_cache_t *rcache, lfs_block_t block,
+        lfs_off_t off, const void *buffer, lfs_size_t size) {
+    const uint8_t *data = buffer;
+    LFS_ASSERT(block < lfs->cfg->block_count);
+
+    while (size > 0) {
+        if (block == pcache->block && off >= pcache->off &&
+                off < pcache->off + lfs->cfg->prog_size) {
+            // is already in pcache?
+            lfs_size_t diff = lfs_min(size,
+                    lfs->cfg->prog_size - (off-pcache->off));
+            memcpy(&pcache->buffer[off-pcache->off], data, diff);
+
+            data += diff;
+            off += diff;
+            size -= diff;
+
+            if (off % lfs->cfg->prog_size == 0) {
+                // eagerly flush out pcache if we fill up
+                int err = lfs_cache_flush(lfs, pcache, rcache);
+                if (err) {
+                    return err;
+                }
+            }
+
+            continue;
+        }
+
+        // pcache must have been flushed, either by programming and
+        // entire block or manually flushing the pcache
+        LFS_ASSERT(pcache->block == 0xffffffff);
+
+        if (off % lfs->cfg->prog_size == 0 &&
+                size >= lfs->cfg->prog_size) {
+            // bypass pcache?
+            lfs_size_t diff = size - (size % lfs->cfg->prog_size);
+            int err = lfs->cfg->prog(lfs->cfg, block, off, data, diff);
+            if (err) {
+                return err;
+            }
+
+            if (rcache) {
+                int res = lfs_cache_cmp(lfs, rcache, NULL,
+                        block, off, data, diff);
+                if (res < 0) {
+                    return res;
+                }
+
+                if (!res) {
+                    return LFS_ERR_CORRUPT;
+                }
+            }
+
+            data += diff;
+            off += diff;
+            size -= diff;
+            continue;
+        }
+
+        // prepare pcache, first condition can no longer fail
+        pcache->block = block;
+        pcache->off = off - (off % lfs->cfg->prog_size);
+    }
+
+    return 0;
+}
+
+
+/// General lfs block device operations ///
+static int lfs_bd_read(lfs_t *lfs, lfs_block_t block,
+        lfs_off_t off, void *buffer, lfs_size_t size) {
+    // if we ever do more than writes to alternating pairs,
+    // this may need to consider pcache
+    return lfs_cache_read(lfs, &lfs->rcache, NULL,
+            block, off, buffer, size);
+}
+
+static int lfs_bd_prog(lfs_t *lfs, lfs_block_t block,
+        lfs_off_t off, const void *buffer, lfs_size_t size) {
+    return lfs_cache_prog(lfs, &lfs->pcache, NULL,
+            block, off, buffer, size);
+}
+
+static int lfs_bd_cmp(lfs_t *lfs, lfs_block_t block,
+        lfs_off_t off, const void *buffer, lfs_size_t size) {
+    return lfs_cache_cmp(lfs, &lfs->rcache, NULL, block, off, buffer, size);
+}
+
+static int lfs_bd_crc(lfs_t *lfs, lfs_block_t block,
+        lfs_off_t off, lfs_size_t size, uint32_t *crc) {
+    return lfs_cache_crc(lfs, &lfs->rcache, NULL, block, off, size, crc);
+}
+
+static int lfs_bd_erase(lfs_t *lfs, lfs_block_t block) {
+    return lfs->cfg->erase(lfs->cfg, block);
+}
+
+static int lfs_bd_sync(lfs_t *lfs) {
+    lfs_cache_drop(lfs, &lfs->rcache);
+
+    int err = lfs_cache_flush(lfs, &lfs->pcache, NULL);
+    if (err) {
+        return err;
+    }
+
+    return lfs->cfg->sync(lfs->cfg);
+}
+
+
+/// Internal operations predeclared here ///
+int lfs_traverse(lfs_t *lfs, int (*cb)(void*, lfs_block_t), void *data);
+static int lfs_pred(lfs_t *lfs, const lfs_block_t dir[2], lfs_dir_t *pdir);
+static int lfs_parent(lfs_t *lfs, const lfs_block_t dir[2],
+        lfs_dir_t *parent, lfs_entry_t *entry);
+static int lfs_moved(lfs_t *lfs, const void *e);
+static int lfs_relocate(lfs_t *lfs,
+        const lfs_block_t oldpair[2], const lfs_block_t newpair[2]);
+int lfs_deorphan(lfs_t *lfs);
+
+
+/// Block allocator ///
+static int lfs_alloc_lookahead(void *p, lfs_block_t block) {
+    lfs_t *lfs = p;
+
+    lfs_block_t off = ((block - lfs->free.off)
+            + lfs->cfg->block_count) % lfs->cfg->block_count;
+
+    if (off < lfs->free.size) {
+        lfs->free.buffer[off / 32] |= 1U << (off % 32);
+    }
+
+    return 0;
+}
+
+static int lfs_alloc(lfs_t *lfs, lfs_block_t *block) {
+    while (true) {
+        while (lfs->free.i != lfs->free.size) {
+            lfs_block_t off = lfs->free.i;
+            lfs->free.i += 1;
+            lfs->free.ack -= 1;
+
+            if (!(lfs->free.buffer[off / 32] & (1U << (off % 32)))) {
+                // found a free block
+                *block = (lfs->free.off + off) % lfs->cfg->block_count;
+
+                // eagerly find next off so an alloc ack can
+                // discredit old lookahead blocks
+                while (lfs->free.i != lfs->free.size &&
+                        (lfs->free.buffer[lfs->free.i / 32]
+                            & (1U << (lfs->free.i % 32)))) {
+                    lfs->free.i += 1;
+                    lfs->free.ack -= 1;
+                }
+
+                return 0;
+            }
+        }
+
+        // check if we have looked at all blocks since last ack
+        if (lfs->free.ack == 0) {
+            LFS_WARN("No more free space %" PRIu32,
+                    lfs->free.i + lfs->free.off);
+            return LFS_ERR_NOSPC;
+        }
+
+        lfs->free.off = (lfs->free.off + lfs->free.size)
+                % lfs->cfg->block_count;
+        lfs->free.size = lfs_min(lfs->cfg->lookahead, lfs->free.ack);
+        lfs->free.i = 0;
+
+        // find mask of free blocks from tree
+        memset(lfs->free.buffer, 0, lfs->cfg->lookahead/8);
+        int err = lfs_traverse(lfs, lfs_alloc_lookahead, lfs);
+        if (err) {
+            return err;
+        }
+    }
+}
+
+static void lfs_alloc_ack(lfs_t *lfs) {
+    lfs->free.ack = lfs->cfg->block_count;
+}
+
+
+/// Endian swapping functions ///
+static void lfs_dir_fromle32(struct lfs_disk_dir *d) {
+    d->rev     = lfs_fromle32(d->rev);
+    d->size    = lfs_fromle32(d->size);
+    d->tail[0] = lfs_fromle32(d->tail[0]);
+    d->tail[1] = lfs_fromle32(d->tail[1]);
+}
+
+static void lfs_dir_tole32(struct lfs_disk_dir *d) {
+    d->rev     = lfs_tole32(d->rev);
+    d->size    = lfs_tole32(d->size);
+    d->tail[0] = lfs_tole32(d->tail[0]);
+    d->tail[1] = lfs_tole32(d->tail[1]);
+}
+
+static void lfs_entry_fromle32(struct lfs_disk_entry *d) {
+    d->u.dir[0] = lfs_fromle32(d->u.dir[0]);
+    d->u.dir[1] = lfs_fromle32(d->u.dir[1]);
+}
+
+static void lfs_entry_tole32(struct lfs_disk_entry *d) {
+    d->u.dir[0] = lfs_tole32(d->u.dir[0]);
+    d->u.dir[1] = lfs_tole32(d->u.dir[1]);
+}
+
+static void lfs_superblock_fromle32(struct lfs_disk_superblock *d) {
+    d->root[0]     = lfs_fromle32(d->root[0]);
+    d->root[1]     = lfs_fromle32(d->root[1]);
+    d->block_size  = lfs_fromle32(d->block_size);
+    d->block_count = lfs_fromle32(d->block_count);
+    d->version     = lfs_fromle32(d->version);
+}
+
+static void lfs_superblock_tole32(struct lfs_disk_superblock *d) {
+    d->root[0]     = lfs_tole32(d->root[0]);
+    d->root[1]     = lfs_tole32(d->root[1]);
+    d->block_size  = lfs_tole32(d->block_size);
+    d->block_count = lfs_tole32(d->block_count);
+    d->version     = lfs_tole32(d->version);
+}
+
+
+/// Metadata pair and directory operations ///
+static inline void lfs_pairswap(lfs_block_t pair[2]) {
+    lfs_block_t t = pair[0];
+    pair[0] = pair[1];
+    pair[1] = t;
+}
+
+static inline bool lfs_pairisnull(const lfs_block_t pair[2]) {
+    return pair[0] == 0xffffffff || pair[1] == 0xffffffff;
+}
+
+static inline int lfs_paircmp(
+        const lfs_block_t paira[2],
+        const lfs_block_t pairb[2]) {
+    return !(paira[0] == pairb[0] || paira[1] == pairb[1] ||
+             paira[0] == pairb[1] || paira[1] == pairb[0]);
+}
+
+static inline bool lfs_pairsync(
+        const lfs_block_t paira[2],
+        const lfs_block_t pairb[2]) {
+    return (paira[0] == pairb[0] && paira[1] == pairb[1]) ||
+           (paira[0] == pairb[1] && paira[1] == pairb[0]);
+}
+
+static inline lfs_size_t lfs_entry_size(const lfs_entry_t *entry) {
+    return 4 + entry->d.elen + entry->d.alen + entry->d.nlen;
+}
+
+static int lfs_dir_alloc(lfs_t *lfs, lfs_dir_t *dir) {
+    // allocate pair of dir blocks
+    for (int i = 0; i < 2; i++) {
+        int err = lfs_alloc(lfs, &dir->pair[i]);
+        if (err) {
+            return err;
+        }
+    }
+
+    // rather than clobbering one of the blocks we just pretend
+    // the revision may be valid
+    int err = lfs_bd_read(lfs, dir->pair[0], 0, &dir->d.rev, 4);
+    if (err && err != LFS_ERR_CORRUPT) {
+        return err;
+    }
+
+    if (err != LFS_ERR_CORRUPT) {
+        dir->d.rev = lfs_fromle32(dir->d.rev);
+    }
+
+    // set defaults
+    dir->d.rev += 1;
+    dir->d.size = sizeof(dir->d)+4;
+    dir->d.tail[0] = 0xffffffff;
+    dir->d.tail[1] = 0xffffffff;
+    dir->off = sizeof(dir->d);
+
+    // don't write out yet, let caller take care of that
+    return 0;
+}
+
+static int lfs_dir_fetch(lfs_t *lfs,
+        lfs_dir_t *dir, const lfs_block_t pair[2]) {
+    // copy out pair, otherwise may be aliasing dir
+    const lfs_block_t tpair[2] = {pair[0], pair[1]};
+    bool valid = false;
+
+    // check both blocks for the most recent revision
+    for (int i = 0; i < 2; i++) {
+        struct lfs_disk_dir test;
+        int err = lfs_bd_read(lfs, tpair[i], 0, &test, sizeof(test));
+        lfs_dir_fromle32(&test);
+        if (err) {
+            if (err == LFS_ERR_CORRUPT) {
+                continue;
+            }
+            return err;
+        }
+
+        if (valid && lfs_scmp(test.rev, dir->d.rev) < 0) {
+            continue;
+        }
+
+        if ((0x7fffffff & test.size) < sizeof(test)+4 ||
+            (0x7fffffff & test.size) > lfs->cfg->block_size) {
+            continue;
+        }
+
+        uint32_t crc = 0xffffffff;
+        lfs_dir_tole32(&test);
+        lfs_crc(&crc, &test, sizeof(test));
+        lfs_dir_fromle32(&test);
+        err = lfs_bd_crc(lfs, tpair[i], sizeof(test),
+                (0x7fffffff & test.size) - sizeof(test), &crc);
+        if (err) {
+            if (err == LFS_ERR_CORRUPT) {
+                continue;
+            }
+            return err;
+        }
+
+        if (crc != 0) {
+            continue;
+        }
+
+        valid = true;
+
+        // setup dir in case it's valid
+        dir->pair[0] = tpair[(i+0) % 2];
+        dir->pair[1] = tpair[(i+1) % 2];
+        dir->off = sizeof(dir->d);
+        dir->d = test;
+    }
+
+    if (!valid) {
+        LFS_ERROR("Corrupted dir pair at %" PRIu32 " %" PRIu32 ,
+                tpair[0], tpair[1]);
+        return LFS_ERR_CORRUPT;
+    }
+
+    return 0;
+}
+
+struct lfs_region {
+    lfs_off_t oldoff;
+    lfs_size_t oldlen;
+    const void *newdata;
+    lfs_size_t newlen;
+};
+
+static int lfs_dir_commit(lfs_t *lfs, lfs_dir_t *dir,
+        const struct lfs_region *regions, int count) {
+    // increment revision count
+    dir->d.rev += 1;
+
+    // keep pairs in order such that pair[0] is most recent
+    lfs_pairswap(dir->pair);
+    for (int i = 0; i < count; i++) {
+        dir->d.size += regions[i].newlen - regions[i].oldlen;
+    }
+
+    const lfs_block_t oldpair[2] = {dir->pair[0], dir->pair[1]};
+    bool relocated = false;
+
+    while (true) {
+        if (true) {
+            int err = lfs_bd_erase(lfs, dir->pair[0]);
+            if (err) {
+                if (err == LFS_ERR_CORRUPT) {
+                    goto relocate;
+                }
+                return err;
+            }
+
+            uint32_t crc = 0xffffffff;
+            lfs_dir_tole32(&dir->d);
+            lfs_crc(&crc, &dir->d, sizeof(dir->d));
+            err = lfs_bd_prog(lfs, dir->pair[0], 0, &dir->d, sizeof(dir->d));
+            lfs_dir_fromle32(&dir->d);
+            if (err) {
+                if (err == LFS_ERR_CORRUPT) {
+                    goto relocate;
+                }
+                return err;
+            }
+
+            int i = 0;
+            lfs_off_t oldoff = sizeof(dir->d);
+            lfs_off_t newoff = sizeof(dir->d);
+            while (newoff < (0x7fffffff & dir->d.size)-4) {
+                if (i < count && regions[i].oldoff == oldoff) {
+                    lfs_crc(&crc, regions[i].newdata, regions[i].newlen);
+                    err = lfs_bd_prog(lfs, dir->pair[0],
+                            newoff, regions[i].newdata, regions[i].newlen);
+                    if (err) {
+                        if (err == LFS_ERR_CORRUPT) {
+                            goto relocate;
+                        }
+                        return err;
+                    }
+
+                    oldoff += regions[i].oldlen;
+                    newoff += regions[i].newlen;
+                    i += 1;
+                } else {
+                    uint8_t data;
+                    err = lfs_bd_read(lfs, oldpair[1], oldoff, &data, 1);
+                    if (err) {
+                        return err;
+                    }
+
+                    lfs_crc(&crc, &data, 1);
+                    err = lfs_bd_prog(lfs, dir->pair[0], newoff, &data, 1);
+                    if (err) {
+                        if (err == LFS_ERR_CORRUPT) {
+                            goto relocate;
+                        }
+                        return err;
+                    }
+
+                    oldoff += 1;
+                    newoff += 1;
+                }
+            }
+
+            crc = lfs_tole32(crc);
+            err = lfs_bd_prog(lfs, dir->pair[0], newoff, &crc, 4);
+            crc = lfs_fromle32(crc);
+            if (err) {
+                if (err == LFS_ERR_CORRUPT) {
+                    goto relocate;
+                }
+                return err;
+            }
+
+            err = lfs_bd_sync(lfs);
+            if (err) {
+                if (err == LFS_ERR_CORRUPT) {
+                    goto relocate;
+                }
+                return err;
+            }
+
+            // successful commit, check checksum to make sure
+            uint32_t ncrc = 0xffffffff;
+            err = lfs_bd_crc(lfs, dir->pair[0], 0,
+                    (0x7fffffff & dir->d.size)-4, &ncrc);
+            if (err) {
+                return err;
+            }
+
+            if (ncrc != crc) {
+                goto relocate;
+            }
+        }
+
+        break;
+relocate:
+        //commit was corrupted
+        LFS_DEBUG("Bad block at %" PRIu32, dir->pair[0]);
+
+        // drop caches and prepare to relocate block
+        relocated = true;
+        lfs_cache_drop(lfs, &lfs->pcache);
+
+        // can't relocate superblock, filesystem is now frozen
+        if (lfs_paircmp(oldpair, (const lfs_block_t[2]){0, 1}) == 0) {
+            LFS_WARN("Superblock %" PRIu32 " has become unwritable",
+                    oldpair[0]);
+            return LFS_ERR_CORRUPT;
+        }
+
+        // relocate half of pair
+        int err = lfs_alloc(lfs, &dir->pair[0]);
+        if (err) {
+            return err;
+        }
+    }
+
+    if (relocated) {
+        // update references if we relocated
+        LFS_DEBUG("Relocating %" PRIu32 " %" PRIu32 " to %" PRIu32 " %" PRIu32,
+                oldpair[0], oldpair[1], dir->pair[0], dir->pair[1]);
+        int err = lfs_relocate(lfs, oldpair, dir->pair);
+        if (err) {
+            return err;
+        }
+    }
+
+    // shift over any directories that are affected
+    for (lfs_dir_t *d = lfs->dirs; d; d = d->next) {
+        if (lfs_paircmp(d->pair, dir->pair) == 0) {
+            d->pair[0] = dir->pair[0];
+            d->pair[1] = dir->pair[1];
+        }
+    }
+
+    return 0;
+}
+
+static int lfs_dir_update(lfs_t *lfs, lfs_dir_t *dir,
+        lfs_entry_t *entry, const void *data) {
+    lfs_entry_tole32(&entry->d);
+    int err = lfs_dir_commit(lfs, dir, (struct lfs_region[]){
+            {entry->off, sizeof(entry->d), &entry->d, sizeof(entry->d)},
+            {entry->off+sizeof(entry->d), entry->d.nlen, data, entry->d.nlen}
+        }, data ? 2 : 1);
+    lfs_entry_fromle32(&entry->d);
+    return err;
+}
+
+static int lfs_dir_append(lfs_t *lfs, lfs_dir_t *dir,
+        lfs_entry_t *entry, const void *data) {
+    // check if we fit, if top bit is set we do not and move on
+    while (true) {
+        if (dir->d.size + lfs_entry_size(entry) <= lfs->cfg->block_size) {
+            entry->off = dir->d.size - 4;
+
+            lfs_entry_tole32(&entry->d);
+            int err = lfs_dir_commit(lfs, dir, (struct lfs_region[]){
+                    {entry->off, 0, &entry->d, sizeof(entry->d)},
+                    {entry->off, 0, data, entry->d.nlen}
+                }, 2);
+            lfs_entry_fromle32(&entry->d);
+            return err;
+        }
+
+        // we need to allocate a new dir block
+        if (!(0x80000000 & dir->d.size)) {
+            lfs_dir_t olddir = *dir;
+            int err = lfs_dir_alloc(lfs, dir);
+            if (err) {
+                return err;
+            }
+
+            dir->d.tail[0] = olddir.d.tail[0];
+            dir->d.tail[1] = olddir.d.tail[1];
+            entry->off = dir->d.size - 4;
+            lfs_entry_tole32(&entry->d);
+            err = lfs_dir_commit(lfs, dir, (struct lfs_region[]){
+                    {entry->off, 0, &entry->d, sizeof(entry->d)},
+                    {entry->off, 0, data, entry->d.nlen}
+                }, 2);
+            lfs_entry_fromle32(&entry->d);
+            if (err) {
+                return err;
+            }
+
+            olddir.d.size |= 0x80000000;
+            olddir.d.tail[0] = dir->pair[0];
+            olddir.d.tail[1] = dir->pair[1];
+            return lfs_dir_commit(lfs, &olddir, NULL, 0);
+        }
+
+        int err = lfs_dir_fetch(lfs, dir, dir->d.tail);
+        if (err) {
+            return err;
+        }
+    }
+}
+
+static int lfs_dir_remove(lfs_t *lfs, lfs_dir_t *dir, lfs_entry_t *entry) {
+    // check if we should just drop the directory block
+    if ((dir->d.size & 0x7fffffff) == sizeof(dir->d)+4
+            + lfs_entry_size(entry)) {
+        lfs_dir_t pdir;
+        int res = lfs_pred(lfs, dir->pair, &pdir);
+        if (res < 0) {
+            return res;
+        }
+
+        if (pdir.d.size & 0x80000000) {
+            pdir.d.size &= dir->d.size | 0x7fffffff;
+            pdir.d.tail[0] = dir->d.tail[0];
+            pdir.d.tail[1] = dir->d.tail[1];
+            return lfs_dir_commit(lfs, &pdir, NULL, 0);
+        }
+    }
+
+    // shift out the entry
+    int err = lfs_dir_commit(lfs, dir, (struct lfs_region[]){
+            {entry->off, lfs_entry_size(entry), NULL, 0},
+        }, 1);
+    if (err) {
+        return err;
+    }
+
+    // shift over any files/directories that are affected
+    for (lfs_file_t *f = lfs->files; f; f = f->next) {
+        if (lfs_paircmp(f->pair, dir->pair) == 0) {
+            if (f->poff == entry->off) {
+                f->pair[0] = 0xffffffff;
+                f->pair[1] = 0xffffffff;
+            } else if (f->poff > entry->off) {
+                f->poff -= lfs_entry_size(entry);
+            }
+        }
+    }
+
+    for (lfs_dir_t *d = lfs->dirs; d; d = d->next) {
+        if (lfs_paircmp(d->pair, dir->pair) == 0) {
+            if (d->off > entry->off) {
+                d->off -= lfs_entry_size(entry);
+                d->pos -= lfs_entry_size(entry);
+            }
+        }
+    }
+
+    return 0;
+}
+
+static int lfs_dir_next(lfs_t *lfs, lfs_dir_t *dir, lfs_entry_t *entry) {
+    while (dir->off + sizeof(entry->d) > (0x7fffffff & dir->d.size)-4) {
+        if (!(0x80000000 & dir->d.size)) {
+            entry->off = dir->off;
+            return LFS_ERR_NOENT;
+        }
+
+        int err = lfs_dir_fetch(lfs, dir, dir->d.tail);
+        if (err) {
+            return err;
+        }
+
+        dir->off = sizeof(dir->d);
+        dir->pos += sizeof(dir->d) + 4;
+    }
+
+    int err = lfs_bd_read(lfs, dir->pair[0], dir->off,
+            &entry->d, sizeof(entry->d));
+    lfs_entry_fromle32(&entry->d);
+    if (err) {
+        return err;
+    }
+
+    entry->off = dir->off;
+    dir->off += lfs_entry_size(entry);
+    dir->pos += lfs_entry_size(entry);
+    return 0;
+}
+
+static int lfs_dir_find(lfs_t *lfs, lfs_dir_t *dir,
+        lfs_entry_t *entry, const char **path) {
+    const char *pathname = *path;
+    size_t pathlen;
+    entry->d.type = LFS_TYPE_DIR;
+    entry->d.elen = sizeof(entry->d) - 4;
+    entry->d.alen = 0;
+    entry->d.nlen = 0;
+    entry->d.u.dir[0] = lfs->root[0];
+    entry->d.u.dir[1] = lfs->root[1];
+
+    while (true) {
+nextname:
+        // skip slashes
+        pathname += strspn(pathname, "/");
+        pathlen = strcspn(pathname, "/");
+
+        // skip '.' and root '..'
+        if ((pathlen == 1 && memcmp(pathname, ".", 1) == 0) ||
+            (pathlen == 2 && memcmp(pathname, "..", 2) == 0)) {
+            pathname += pathlen;
+            goto nextname;
+        }
+
+        // skip if matched by '..' in name
+        const char *suffix = pathname + pathlen;
+        size_t sufflen;
+        int depth = 1;
+        while (true) {
+            suffix += strspn(suffix, "/");
+            sufflen = strcspn(suffix, "/");
+            if (sufflen == 0) {
+                break;
+            }
+
+            if (sufflen == 2 && memcmp(suffix, "..", 2) == 0) {
+                depth -= 1;
+                if (depth == 0) {
+                    pathname = suffix + sufflen;
+                    goto nextname;
+                }
+            } else {
+                depth += 1;
+            }
+
+            suffix += sufflen;
+        }
+
+        // found path
+        if (pathname[0] == '\0') {
+            return 0;
+        }
+
+        // update what we've found
+        *path = pathname;
+
+        // continue on if we hit a directory
+        if (entry->d.type != LFS_TYPE_DIR) {
+            return LFS_ERR_NOTDIR;
+        }
+
+        int err = lfs_dir_fetch(lfs, dir, entry->d.u.dir);
+        if (err) {
+            return err;
+        }
+
+        // find entry matching name
+        while (true) {
+            err = lfs_dir_next(lfs, dir, entry);
+            if (err) {
+                return err;
+            }
+
+            if (((0x7f & entry->d.type) != LFS_TYPE_REG &&
+                 (0x7f & entry->d.type) != LFS_TYPE_DIR) ||
+                entry->d.nlen != pathlen) {
+                continue;
+            }
+
+            int res = lfs_bd_cmp(lfs, dir->pair[0],
+                    entry->off + 4+entry->d.elen+entry->d.alen,
+                    pathname, pathlen);
+            if (res < 0) {
+                return res;
+            }
+
+            // found match
+            if (res) {
+                break;
+            }
+        }
+
+        // check that entry has not been moved
+        if (!lfs->moving && entry->d.type & 0x80) {
+            int moved = lfs_moved(lfs, &entry->d.u);
+            if (moved < 0 || moved) {
+                return (moved < 0) ? moved : LFS_ERR_NOENT;
+            }
+
+            entry->d.type &= ~0x80;
+        }
+
+        // to next name
+        pathname += pathlen;
+    }
+}
+
+
+/// Top level directory operations ///
+int lfs_mkdir(lfs_t *lfs, const char *path) {
+    // deorphan if we haven't yet, needed at most once after poweron
+    if (!lfs->deorphaned) {
+        int err = lfs_deorphan(lfs);
+        if (err) {
+            return err;
+        }
+    }
+
+    // fetch parent directory
+    lfs_dir_t cwd;
+    lfs_entry_t entry;
+    int err = lfs_dir_find(lfs, &cwd, &entry, &path);
+    if (err != LFS_ERR_NOENT || strchr(path, '/') != NULL) {
+        return err ? err : LFS_ERR_EXIST;
+    }
+
+    // build up new directory
+    lfs_alloc_ack(lfs);
+
+    lfs_dir_t dir;
+    err = lfs_dir_alloc(lfs, &dir);
+    if (err) {
+        return err;
+    }
+    dir.d.tail[0] = cwd.d.tail[0];
+    dir.d.tail[1] = cwd.d.tail[1];
+
+    err = lfs_dir_commit(lfs, &dir, NULL, 0);
+    if (err) {
+        return err;
+    }
+
+    entry.d.type = LFS_TYPE_DIR;
+    entry.d.elen = sizeof(entry.d) - 4;
+    entry.d.alen = 0;
+    entry.d.nlen = strlen(path);
+    entry.d.u.dir[0] = dir.pair[0];
+    entry.d.u.dir[1] = dir.pair[1];
+
+    cwd.d.tail[0] = dir.pair[0];
+    cwd.d.tail[1] = dir.pair[1];
+
+    err = lfs_dir_append(lfs, &cwd, &entry, path);
+    if (err) {
+        return err;
+    }
+
+    lfs_alloc_ack(lfs);
+    return 0;
+}
+
+int lfs_dir_open(lfs_t *lfs, lfs_dir_t *dir, const char *path) {
+    dir->pair[0] = lfs->root[0];
+    dir->pair[1] = lfs->root[1];
+
+    lfs_entry_t entry;
+    int err = lfs_dir_find(lfs, dir, &entry, &path);
+    if (err) {
+        return err;
+    } else if (entry.d.type != LFS_TYPE_DIR) {
+        return LFS_ERR_NOTDIR;
+    }
+
+    err = lfs_dir_fetch(lfs, dir, entry.d.u.dir);
+    if (err) {
+        return err;
+    }
+
+    // setup head dir
+    // special offset for '.' and '..'
+    dir->head[0] = dir->pair[0];
+    dir->head[1] = dir->pair[1];
+    dir->pos = sizeof(dir->d) - 2;
+    dir->off = sizeof(dir->d);
+
+    // add to list of directories
+    dir->next = lfs->dirs;
+    lfs->dirs = dir;
+
+    return 0;
+}
+
+int lfs_dir_close(lfs_t *lfs, lfs_dir_t *dir) {
+    // remove from list of directories
+    for (lfs_dir_t **p = &lfs->dirs; *p; p = &(*p)->next) {
+        if (*p == dir) {
+            *p = dir->next;
+            break;
+        }
+    }
+
+    return 0;
+}
+
+int lfs_dir_read(lfs_t *lfs, lfs_dir_t *dir, struct lfs_info *info) {
+    memset(info, 0, sizeof(*info));
+
+    // special offset for '.' and '..'
+    if (dir->pos == sizeof(dir->d) - 2) {
+        info->type = LFS_TYPE_DIR;
+        strcpy(info->name, ".");
+        dir->pos += 1;
+        return 1;
+    } else if (dir->pos == sizeof(dir->d) - 1) {
+        info->type = LFS_TYPE_DIR;
+        strcpy(info->name, "..");
+        dir->pos += 1;
+        return 1;
+    }
+
+    lfs_entry_t entry;
+    while (true) {
+        int err = lfs_dir_next(lfs, dir, &entry);
+        if (err) {
+            return (err == LFS_ERR_NOENT) ? 0 : err;
+        }
+
+        if ((0x7f & entry.d.type) != LFS_TYPE_REG &&
+            (0x7f & entry.d.type) != LFS_TYPE_DIR) {
+            continue;
+        }
+
+        // check that entry has not been moved
+        if (entry.d.type & 0x80) {
+            int moved = lfs_moved(lfs, &entry.d.u);
+            if (moved < 0) {
+                return moved;
+            }
+
+            if (moved) {
+                continue;
+            }
+
+            entry.d.type &= ~0x80;
+        }
+
+        break;
+    }
+
+    info->type = entry.d.type;
+    if (info->type == LFS_TYPE_REG) {
+        info->size = entry.d.u.file.size;
+    }
+
+    int err = lfs_bd_read(lfs, dir->pair[0],
+            entry.off + 4+entry.d.elen+entry.d.alen,
+            info->name, entry.d.nlen);
+    if (err) {
+        return err;
+    }
+
+    return 1;
+}
+
+int lfs_dir_seek(lfs_t *lfs, lfs_dir_t *dir, lfs_off_t off) {
+    // simply walk from head dir
+    int err = lfs_dir_rewind(lfs, dir);
+    if (err) {
+        return err;
+    }
+    dir->pos = off;
+
+    while (off > (0x7fffffff & dir->d.size)) {
+        off -= 0x7fffffff & dir->d.size;
+        if (!(0x80000000 & dir->d.size)) {
+            return LFS_ERR_INVAL;
+        }
+
+        err = lfs_dir_fetch(lfs, dir, dir->d.tail);
+        if (err) {
+            return err;
+        }
+    }
+
+    dir->off = off;
+    return 0;
+}
+
+lfs_soff_t lfs_dir_tell(lfs_t *lfs, lfs_dir_t *dir) {
+    (void)lfs;
+    return dir->pos;
+}
+
+int lfs_dir_rewind(lfs_t *lfs, lfs_dir_t *dir) {
+    // reload the head dir
+    int err = lfs_dir_fetch(lfs, dir, dir->head);
+    if (err) {
+        return err;
+    }
+
+    dir->pair[0] = dir->head[0];
+    dir->pair[1] = dir->head[1];
+    dir->pos = sizeof(dir->d) - 2;
+    dir->off = sizeof(dir->d);
+    return 0;
+}
+
+
+/// File index list operations ///
+static int lfs_ctz_index(lfs_t *lfs, lfs_off_t *off) {
+    lfs_off_t size = *off;
+    lfs_off_t b = lfs->cfg->block_size - 2*4;
+    lfs_off_t i = size / b;
+    if (i == 0) {
+        return 0;
+    }
+
+    i = (size - 4*(lfs_popc(i-1)+2)) / b;
+    *off = size - b*i - 4*lfs_popc(i);
+    return i;
+}
+
+static int lfs_ctz_find(lfs_t *lfs,
+        lfs_cache_t *rcache, const lfs_cache_t *pcache,
+        lfs_block_t head, lfs_size_t size,
+        lfs_size_t pos, lfs_block_t *block, lfs_off_t *off) {
+    if (size == 0) {
+        *block = 0xffffffff;
+        *off = 0;
+        return 0;
+    }
+
+    lfs_off_t current = lfs_ctz_index(lfs, &(lfs_off_t){size-1});
+    lfs_off_t target = lfs_ctz_index(lfs, &pos);
+
+    while (current > target) {
+        lfs_size_t skip = lfs_min(
+                lfs_npw2(current-target+1) - 1,
+                lfs_ctz(current));
+
+        int err = lfs_cache_read(lfs, rcache, pcache, head, 4*skip, &head, 4);
+        head = lfs_fromle32(head);
+        if (err) {
+            return err;
+        }
+
+        LFS_ASSERT(head >= 2 && head <= lfs->cfg->block_count);
+        current -= 1 << skip;
+    }
+
+    *block = head;
+    *off = pos;
+    return 0;
+}
+
+static int lfs_ctz_extend(lfs_t *lfs,
+        lfs_cache_t *rcache, lfs_cache_t *pcache,
+        lfs_block_t head, lfs_size_t size,
+        lfs_block_t *block, lfs_off_t *off) {
+    while (true) {
+        // go ahead and grab a block
+        lfs_block_t nblock;
+        int err = lfs_alloc(lfs, &nblock);
+        if (err) {
+            return err;
+        }
+        LFS_ASSERT(nblock >= 2 && nblock <= lfs->cfg->block_count);
+
+        if (true) {
+            err = lfs_bd_erase(lfs, nblock);
+            if (err) {
+                if (err == LFS_ERR_CORRUPT) {
+                    goto relocate;
+                }
+                return err;
+            }
+
+            if (size == 0) {
+                *block = nblock;
+                *off = 0;
+                return 0;
+            }
+
+            size -= 1;
+            lfs_off_t index = lfs_ctz_index(lfs, &size);
+            size += 1;
+
+            // just copy out the last block if it is incomplete
+            if (size != lfs->cfg->block_size) {
+                for (lfs_off_t i = 0; i < size; i++) {
+                    uint8_t data;
+                    err = lfs_cache_read(lfs, rcache, NULL,
+                            head, i, &data, 1);
+                    if (err) {
+                        return err;
+                    }
+
+                    err = lfs_cache_prog(lfs, pcache, rcache,
+                            nblock, i, &data, 1);
+                    if (err) {
+                        if (err == LFS_ERR_CORRUPT) {
+                            goto relocate;
+                        }
+                        return err;
+                    }
+                }
+
+                *block = nblock;
+                *off = size;
+                return 0;
+            }
+
+            // append block
+            index += 1;
+            lfs_size_t skips = lfs_ctz(index) + 1;
+
+            for (lfs_off_t i = 0; i < skips; i++) {
+                head = lfs_tole32(head);
+                err = lfs_cache_prog(lfs, pcache, rcache,
+                        nblock, 4*i, &head, 4);
+                head = lfs_fromle32(head);
+                if (err) {
+                    if (err == LFS_ERR_CORRUPT) {
+                        goto relocate;
+                    }
+                    return err;
+                }
+
+                if (i != skips-1) {
+                    err = lfs_cache_read(lfs, rcache, NULL,
+                            head, 4*i, &head, 4);
+                    head = lfs_fromle32(head);
+                    if (err) {
+                        return err;
+                    }
+                }
+
+                LFS_ASSERT(head >= 2 && head <= lfs->cfg->block_count);
+            }
+
+            *block = nblock;
+            *off = 4*skips;
+            return 0;
+        }
+
+relocate:
+        LFS_DEBUG("Bad block at %" PRIu32, nblock);
+
+        // just clear cache and try a new block
+        lfs_cache_drop(lfs, &lfs->pcache);
+    }
+}
+
+static int lfs_ctz_traverse(lfs_t *lfs,
+        lfs_cache_t *rcache, const lfs_cache_t *pcache,
+        lfs_block_t head, lfs_size_t size,
+        int (*cb)(void*, lfs_block_t), void *data) {
+    if (size == 0) {
+        return 0;
+    }
+
+    lfs_off_t index = lfs_ctz_index(lfs, &(lfs_off_t){size-1});
+
+    while (true) {
+        int err = cb(data, head);
+        if (err) {
+            return err;
+        }
+
+        if (index == 0) {
+            return 0;
+        }
+
+        lfs_block_t heads[2];
+        int count = 2 - (index & 1);
+        err = lfs_cache_read(lfs, rcache, pcache, head, 0, &heads, count*4);
+        heads[0] = lfs_fromle32(heads[0]);
+        heads[1] = lfs_fromle32(heads[1]);
+        if (err) {
+            return err;
+        }
+
+        for (int i = 0; i < count-1; i++) {
+            err = cb(data, heads[i]);
+            if (err) {
+                return err;
+            }
+        }
+
+        head = heads[count-1];
+        index -= count;
+    }
+}
+
+
+/// Top level file operations ///
+int lfs_file_opencfg(lfs_t *lfs, lfs_file_t *file,
+        const char *path, int flags,
+        const struct lfs_file_config *cfg) {
+    // deorphan if we haven't yet, needed at most once after poweron
+    if ((flags & 3) != LFS_O_RDONLY && !lfs->deorphaned) {
+        int err = lfs_deorphan(lfs);
+        if (err) {
+            return err;
+        }
+    }
+
+    // allocate entry for file if it doesn't exist
+    lfs_dir_t cwd;
+    lfs_entry_t entry;
+    int err = lfs_dir_find(lfs, &cwd, &entry, &path);
+    if (err && (err != LFS_ERR_NOENT || strchr(path, '/') != NULL)) {
+        return err;
+    }
+
+    if (err == LFS_ERR_NOENT) {
+        if (!(flags & LFS_O_CREAT)) {
+            return LFS_ERR_NOENT;
+        }
+
+        // create entry to remember name
+        entry.d.type = LFS_TYPE_REG;
+        entry.d.elen = sizeof(entry.d) - 4;
+        entry.d.alen = 0;
+        entry.d.nlen = strlen(path);
+        entry.d.u.file.head = 0xffffffff;
+        entry.d.u.file.size = 0;
+        err = lfs_dir_append(lfs, &cwd, &entry, path);
+        if (err) {
+            return err;
+        }
+    } else if (entry.d.type == LFS_TYPE_DIR) {
+        return LFS_ERR_ISDIR;
+    } else if (flags & LFS_O_EXCL) {
+        return LFS_ERR_EXIST;
+    }
+
+    // setup file struct
+    file->cfg = cfg;
+    file->pair[0] = cwd.pair[0];
+    file->pair[1] = cwd.pair[1];
+    file->poff = entry.off;
+    file->head = entry.d.u.file.head;
+    file->size = entry.d.u.file.size;
+    file->flags = flags;
+    file->pos = 0;
+
+    if (flags & LFS_O_TRUNC) {
+        if (file->size != 0) {
+            file->flags |= LFS_F_DIRTY;
+        }
+        file->head = 0xffffffff;
+        file->size = 0;
+    }
+
+    // allocate buffer if needed
+    file->cache.block = 0xffffffff;
+    if (file->cfg && file->cfg->buffer) {
+        file->cache.buffer = file->cfg->buffer;
+    } else if (lfs->cfg->file_buffer) {
+        if (lfs->files) {
+            // already in use
+            return LFS_ERR_NOMEM;
+        }
+        file->cache.buffer = lfs->cfg->file_buffer;
+    } else if ((file->flags & 3) == LFS_O_RDONLY) {
+        file->cache.buffer = lfs_malloc(lfs->cfg->read_size);
+        if (!file->cache.buffer) {
+            return LFS_ERR_NOMEM;
+        }
+    } else {
+        file->cache.buffer = lfs_malloc(lfs->cfg->prog_size);
+        if (!file->cache.buffer) {
+            return LFS_ERR_NOMEM;
+        }
+    }
+
+    // zero to avoid information leak
+    lfs_cache_drop(lfs, &file->cache);
+    if ((file->flags & 3) != LFS_O_RDONLY) {
+        lfs_cache_zero(lfs, &file->cache);
+    }
+
+    // add to list of files
+    file->next = lfs->files;
+    lfs->files = file;
+
+    return 0;
+}
+
+int lfs_file_open(lfs_t *lfs, lfs_file_t *file,
+        const char *path, int flags) {
+    return lfs_file_opencfg(lfs, file, path, flags, NULL);
+}
+
+int lfs_file_close(lfs_t *lfs, lfs_file_t *file) {
+    int err = lfs_file_sync(lfs, file);
+
+    // remove from list of files
+    for (lfs_file_t **p = &lfs->files; *p; p = &(*p)->next) {
+        if (*p == file) {
+            *p = file->next;
+            break;
+        }
+    }
+
+    // clean up memory
+    if (!(file->cfg && file->cfg->buffer) && !lfs->cfg->file_buffer) {
+        lfs_free(file->cache.buffer);
+    }
+
+    return err;
+}
+
+static int lfs_file_relocate(lfs_t *lfs, lfs_file_t *file) {
+relocate:
+    LFS_DEBUG("Bad block at %" PRIu32, file->block);
+
+    // just relocate what exists into new block
+    lfs_block_t nblock;
+    int err = lfs_alloc(lfs, &nblock);
+    if (err) {
+        return err;
+    }
+
+    err = lfs_bd_erase(lfs, nblock);
+    if (err) {
+        if (err == LFS_ERR_CORRUPT) {
+            goto relocate;
+        }
+        return err;
+    }
+
+    // either read from dirty cache or disk
+    for (lfs_off_t i = 0; i < file->off; i++) {
+        uint8_t data;
+        err = lfs_cache_read(lfs, &lfs->rcache, &file->cache,
+                file->block, i, &data, 1);
+        if (err) {
+            return err;
+        }
+
+        err = lfs_cache_prog(lfs, &lfs->pcache, &lfs->rcache,
+                nblock, i, &data, 1);
+        if (err) {
+            if (err == LFS_ERR_CORRUPT) {
+                goto relocate;
+            }
+            return err;
+        }
+    }
+
+    // copy over new state of file
+    memcpy(file->cache.buffer, lfs->pcache.buffer, lfs->cfg->prog_size);
+    file->cache.block = lfs->pcache.block;
+    file->cache.off = lfs->pcache.off;
+    lfs_cache_zero(lfs, &lfs->pcache);
+
+    file->block = nblock;
+    return 0;
+}
+
+static int lfs_file_flush(lfs_t *lfs, lfs_file_t *file) {
+    if (file->flags & LFS_F_READING) {
+        // just drop read cache
+        lfs_cache_drop(lfs, &file->cache);
+        file->flags &= ~LFS_F_READING;
+    }
+
+    if (file->flags & LFS_F_WRITING) {
+        lfs_off_t pos = file->pos;
+
+        // copy over anything after current branch
+        lfs_file_t orig = {
+            .head = file->head,
+            .size = file->size,
+            .flags = LFS_O_RDONLY,
+            .pos = file->pos,
+            .cache = lfs->rcache,
+        };
+        lfs_cache_drop(lfs, &lfs->rcache);
+
+        while (file->pos < file->size) {
+            // copy over a byte at a time, leave it up to caching
+            // to make this efficient
+            uint8_t data;
+            lfs_ssize_t res = lfs_file_read(lfs, &orig, &data, 1);
+            if (res < 0) {
+                return res;
+            }
+
+            res = lfs_file_write(lfs, file, &data, 1);
+            if (res < 0) {
+                return res;
+            }
+
+            // keep our reference to the rcache in sync
+            if (lfs->rcache.block != 0xffffffff) {
+                lfs_cache_drop(lfs, &orig.cache);
+                lfs_cache_drop(lfs, &lfs->rcache);
+            }
+        }
+
+        // write out what we have
+        while (true) {
+            int err = lfs_cache_flush(lfs, &file->cache, &lfs->rcache);
+            if (err) {
+                if (err == LFS_ERR_CORRUPT) {
+                    goto relocate;
+                }
+                return err;
+            }
+
+            break;
+relocate:
+            err = lfs_file_relocate(lfs, file);
+            if (err) {
+                return err;
+            }
+        }
+
+        // actual file updates
+        file->head = file->block;
+        file->size = file->pos;
+        file->flags &= ~LFS_F_WRITING;
+        file->flags |= LFS_F_DIRTY;
+
+        file->pos = pos;
+    }
+
+    return 0;
+}
+
+int lfs_file_sync(lfs_t *lfs, lfs_file_t *file) {
+    int err = lfs_file_flush(lfs, file);
+    if (err) {
+        return err;
+    }
+
+    if ((file->flags & LFS_F_DIRTY) &&
+            !(file->flags & LFS_F_ERRED) &&
+            !lfs_pairisnull(file->pair)) {
+        // update dir entry
+        lfs_dir_t cwd;
+        err = lfs_dir_fetch(lfs, &cwd, file->pair);
+        if (err) {
+            return err;
+        }
+
+        lfs_entry_t entry = {.off = file->poff};
+        err = lfs_bd_read(lfs, cwd.pair[0], entry.off,
+                &entry.d, sizeof(entry.d));
+        lfs_entry_fromle32(&entry.d);
+        if (err) {
+            return err;
+        }
+
+        LFS_ASSERT(entry.d.type == LFS_TYPE_REG);
+        entry.d.u.file.head = file->head;
+        entry.d.u.file.size = file->size;
+
+        err = lfs_dir_update(lfs, &cwd, &entry, NULL);
+        if (err) {
+            return err;
+        }
+
+        file->flags &= ~LFS_F_DIRTY;
+    }
+
+    return 0;
+}
+
+lfs_ssize_t lfs_file_read(lfs_t *lfs, lfs_file_t *file,
+        void *buffer, lfs_size_t size) {
+    uint8_t *data = buffer;
+    lfs_size_t nsize = size;
+
+    if ((file->flags & 3) == LFS_O_WRONLY) {
+        return LFS_ERR_BADF;
+    }
+
+    if (file->flags & LFS_F_WRITING) {
+        // flush out any writes
+        int err = lfs_file_flush(lfs, file);
+        if (err) {
+            return err;
+        }
+    }
+
+    if (file->pos >= file->size) {
+        // eof if past end
+        return 0;
+    }
+
+    size = lfs_min(size, file->size - file->pos);
+    nsize = size;
+
+    while (nsize > 0) {
+        // check if we need a new block
+        if (!(file->flags & LFS_F_READING) ||
+                file->off == lfs->cfg->block_size) {
+            int err = lfs_ctz_find(lfs, &file->cache, NULL,
+                    file->head, file->size,
+                    file->pos, &file->block, &file->off);
+            if (err) {
+                return err;
+            }
+
+            file->flags |= LFS_F_READING;
+        }
+
+        // read as much as we can in current block
+        lfs_size_t diff = lfs_min(nsize, lfs->cfg->block_size - file->off);
+        int err = lfs_cache_read(lfs, &file->cache, NULL,
+                file->block, file->off, data, diff);
+        if (err) {
+            return err;
+        }
+
+        file->pos += diff;
+        file->off += diff;
+        data += diff;
+        nsize -= diff;
+    }
+
+    return size;
+}
+
+lfs_ssize_t lfs_file_write(lfs_t *lfs, lfs_file_t *file,
+        const void *buffer, lfs_size_t size) {
+    const uint8_t *data = buffer;
+    lfs_size_t nsize = size;
+
+    if ((file->flags & 3) == LFS_O_RDONLY) {
+        return LFS_ERR_BADF;
+    }
+
+    if (file->flags & LFS_F_READING) {
+        // drop any reads
+        int err = lfs_file_flush(lfs, file);
+        if (err) {
+            return err;
+        }
+    }
+
+    if ((file->flags & LFS_O_APPEND) && file->pos < file->size) {
+        file->pos = file->size;
+    }
+
+    if (file->pos + size > LFS_FILE_MAX) {
+        // larger than file limit?
+        return LFS_ERR_FBIG;
+    }
+
+    if (!(file->flags & LFS_F_WRITING) && file->pos > file->size) {
+        // fill with zeros
+        lfs_off_t pos = file->pos;
+        file->pos = file->size;
+
+        while (file->pos < pos) {
+            lfs_ssize_t res = lfs_file_write(lfs, file, &(uint8_t){0}, 1);
+            if (res < 0) {
+                return res;
+            }
+        }
+    }
+
+    while (nsize > 0) {
+        // check if we need a new block
+        if (!(file->flags & LFS_F_WRITING) ||
+                file->off == lfs->cfg->block_size) {
+            if (!(file->flags & LFS_F_WRITING) && file->pos > 0) {
+                // find out which block we're extending from
+                int err = lfs_ctz_find(lfs, &file->cache, NULL,
+                        file->head, file->size,
+                        file->pos-1, &file->block, &file->off);
+                if (err) {
+                    file->flags |= LFS_F_ERRED;
+                    return err;
+                }
+
+                // mark cache as dirty since we may have read data into it
+                lfs_cache_zero(lfs, &file->cache);
+            }
+
+            // extend file with new blocks
+            lfs_alloc_ack(lfs);
+            int err = lfs_ctz_extend(lfs, &lfs->rcache, &file->cache,
+                    file->block, file->pos,
+                    &file->block, &file->off);
+            if (err) {
+                file->flags |= LFS_F_ERRED;
+                return err;
+            }
+
+            file->flags |= LFS_F_WRITING;
+        }
+
+        // program as much as we can in current block
+        lfs_size_t diff = lfs_min(nsize, lfs->cfg->block_size - file->off);
+        while (true) {
+            int err = lfs_cache_prog(lfs, &file->cache, &lfs->rcache,
+                    file->block, file->off, data, diff);
+            if (err) {
+                if (err == LFS_ERR_CORRUPT) {
+                    goto relocate;
+                }
+                file->flags |= LFS_F_ERRED;
+                return err;
+            }
+
+            break;
+relocate:
+            err = lfs_file_relocate(lfs, file);
+            if (err) {
+                file->flags |= LFS_F_ERRED;
+                return err;
+            }
+        }
+
+        file->pos += diff;
+        file->off += diff;
+        data += diff;
+        nsize -= diff;
+
+        lfs_alloc_ack(lfs);
+    }
+
+    file->flags &= ~LFS_F_ERRED;
+    return size;
+}
+
+lfs_soff_t lfs_file_seek(lfs_t *lfs, lfs_file_t *file,
+        lfs_soff_t off, int whence) {
+    // write out everything beforehand, may be noop if rdonly
+    int err = lfs_file_flush(lfs, file);
+    if (err) {
+        return err;
+    }
+
+    // find new pos
+    lfs_soff_t npos = file->pos;
+    if (whence == LFS_SEEK_SET) {
+        npos = off;
+    } else if (whence == LFS_SEEK_CUR) {
+        npos = file->pos + off;
+    } else if (whence == LFS_SEEK_END) {
+        npos = file->size + off;
+    }
+
+    if (npos < 0 || npos > LFS_FILE_MAX) {
+        // file position out of range
+        return LFS_ERR_INVAL;
+    }
+
+    // update pos
+    file->pos = npos;
+    return npos;
+}
+
+int lfs_file_truncate(lfs_t *lfs, lfs_file_t *file, lfs_off_t size) {
+    if ((file->flags & 3) == LFS_O_RDONLY) {
+        return LFS_ERR_BADF;
+    }
+
+    lfs_off_t oldsize = lfs_file_size(lfs, file);
+    if (size < oldsize) {
+        // need to flush since directly changing metadata
+        int err = lfs_file_flush(lfs, file);
+        if (err) {
+            return err;
+        }
+
+        // lookup new head in ctz skip list
+        err = lfs_ctz_find(lfs, &file->cache, NULL,
+                file->head, file->size,
+                size, &file->head, &(lfs_off_t){0});
+        if (err) {
+            return err;
+        }
+
+        file->size = size;
+        file->flags |= LFS_F_DIRTY;
+    } else if (size > oldsize) {
+        lfs_off_t pos = file->pos;
+
+        // flush+seek if not already at end
+        if (file->pos != oldsize) {
+            int err = lfs_file_seek(lfs, file, 0, LFS_SEEK_END);
+            if (err < 0) {
+                return err;
+            }
+        }
+
+        // fill with zeros
+        while (file->pos < size) {
+            lfs_ssize_t res = lfs_file_write(lfs, file, &(uint8_t){0}, 1);
+            if (res < 0) {
+                return res;
+            }
+        }
+
+        // restore pos
+        int err = lfs_file_seek(lfs, file, pos, LFS_SEEK_SET);
+        if (err < 0) {
+            return err;
+        }
+    }
+
+    return 0;
+}
+
+lfs_soff_t lfs_file_tell(lfs_t *lfs, lfs_file_t *file) {
+    (void)lfs;
+    return file->pos;
+}
+
+int lfs_file_rewind(lfs_t *lfs, lfs_file_t *file) {
+    lfs_soff_t res = lfs_file_seek(lfs, file, 0, LFS_SEEK_SET);
+    if (res < 0) {
+        return res;
+    }
+
+    return 0;
+}
+
+lfs_soff_t lfs_file_size(lfs_t *lfs, lfs_file_t *file) {
+    (void)lfs;
+    if (file->flags & LFS_F_WRITING) {
+        return lfs_max(file->pos, file->size);
+    } else {
+        return file->size;
+    }
+}
+
+
+/// General fs operations ///
+int lfs_stat(lfs_t *lfs, const char *path, struct lfs_info *info) {
+    lfs_dir_t cwd;
+    lfs_entry_t entry;
+    int err = lfs_dir_find(lfs, &cwd, &entry, &path);
+    if (err) {
+        return err;
+    }
+
+    memset(info, 0, sizeof(*info));
+    info->type = entry.d.type;
+    if (info->type == LFS_TYPE_REG) {
+        info->size = entry.d.u.file.size;
+    }
+
+    if (lfs_paircmp(entry.d.u.dir, lfs->root) == 0) {
+        strcpy(info->name, "/");
+    } else {
+        err = lfs_bd_read(lfs, cwd.pair[0],
+                entry.off + 4+entry.d.elen+entry.d.alen,
+                info->name, entry.d.nlen);
+        if (err) {
+            return err;
+        }
+    }
+
+    return 0;
+}
+
+int lfs_remove(lfs_t *lfs, const char *path) {
+    // deorphan if we haven't yet, needed at most once after poweron
+    if (!lfs->deorphaned) {
+        int err = lfs_deorphan(lfs);
+        if (err) {
+            return err;
+        }
+    }
+
+    lfs_dir_t cwd;
+    lfs_entry_t entry;
+    int err = lfs_dir_find(lfs, &cwd, &entry, &path);
+    if (err) {
+        return err;
+    }
+
+    lfs_dir_t dir;
+    if (entry.d.type == LFS_TYPE_DIR) {
+        // must be empty before removal, checking size
+        // without masking top bit checks for any case where
+        // dir is not empty
+        err = lfs_dir_fetch(lfs, &dir, entry.d.u.dir);
+        if (err) {
+            return err;
+        } /* else if (dir.d.size != sizeof(dir.d)+4) {
+            return LFS_ERR_NOTEMPTY;
+        }  adafruit: allow to remove non-empty folder,
+           According to below issue, comment these 2 line won't corrupt filesystem
+           https://github.com/ARMmbed/littlefs/issues/43 */
+    }
+
+    // remove the entry
+    err = lfs_dir_remove(lfs, &cwd, &entry);
+    if (err) {
+        return err;
+    }
+
+    // if we were a directory, find pred, replace tail
+    if (entry.d.type == LFS_TYPE_DIR) {
+        int res = lfs_pred(lfs, dir.pair, &cwd);
+        if (res < 0) {
+            return res;
+        }
+
+        LFS_ASSERT(res); // must have pred
+        cwd.d.tail[0] = dir.d.tail[0];
+        cwd.d.tail[1] = dir.d.tail[1];
+
+        err = lfs_dir_commit(lfs, &cwd, NULL, 0);
+        if (err) {
+            return err;
+        }
+    }
+
+    return 0;
+}
+
+int lfs_rename(lfs_t *lfs, const char *oldpath, const char *newpath) {
+    // deorphan if we haven't yet, needed at most once after poweron
+    if (!lfs->deorphaned) {
+        int err = lfs_deorphan(lfs);
+        if (err) {
+            return err;
+        }
+    }
+
+    // find old entry
+    lfs_dir_t oldcwd;
+    lfs_entry_t oldentry;
+    int err = lfs_dir_find(lfs, &oldcwd, &oldentry, &(const char *){oldpath});
+    if (err) {
+        return err;
+    }
+
+    // mark as moving
+    oldentry.d.type |= 0x80;
+    err = lfs_dir_update(lfs, &oldcwd, &oldentry, NULL);
+    if (err) {
+        return err;
+    }
+
+    // allocate new entry
+    lfs_dir_t newcwd;
+    lfs_entry_t preventry;
+    err = lfs_dir_find(lfs, &newcwd, &preventry, &newpath);
+    if (err && (err != LFS_ERR_NOENT || strchr(newpath, '/') != NULL)) {
+        return err;
+    }
+
+    // must have same type
+    bool prevexists = (err != LFS_ERR_NOENT);
+    if (prevexists && preventry.d.type != (0x7f & oldentry.d.type)) {
+        return LFS_ERR_ISDIR;
+    }
+
+    lfs_dir_t dir;
+    if (prevexists && preventry.d.type == LFS_TYPE_DIR) {
+        // must be empty before removal, checking size
+        // without masking top bit checks for any case where
+        // dir is not empty
+        err = lfs_dir_fetch(lfs, &dir, preventry.d.u.dir);
+        if (err) {
+            return err;
+          } else if (dir.d.size != sizeof(dir.d)+4) {
+            return LFS_ERR_NOTEMPTY;
+          }
+    }
+
+    // move to new location
+    lfs_entry_t newentry = preventry;
+    newentry.d = oldentry.d;
+    newentry.d.type &= ~0x80;
+    newentry.d.nlen = strlen(newpath);
+
+    if (prevexists) {
+        err = lfs_dir_update(lfs, &newcwd, &newentry, newpath);
+        if (err) {
+            return err;
+        }
+    } else {
+        err = lfs_dir_append(lfs, &newcwd, &newentry, newpath);
+        if (err) {
+            return err;
+        }
+    }
+
+    // fetch old pair again in case dir block changed
+    lfs->moving = true;
+    err = lfs_dir_find(lfs, &oldcwd, &oldentry, &oldpath);
+    if (err) {
+        return err;
+    }
+    lfs->moving = false;
+
+    // remove old entry
+    err = lfs_dir_remove(lfs, &oldcwd, &oldentry);
+    if (err) {
+        return err;
+    }
+
+    // if we were a directory, find pred, replace tail
+    if (prevexists && preventry.d.type == LFS_TYPE_DIR) {
+        int res = lfs_pred(lfs, dir.pair, &newcwd);
+        if (res < 0) {
+            return res;
+        }
+
+        LFS_ASSERT(res); // must have pred
+        newcwd.d.tail[0] = dir.d.tail[0];
+        newcwd.d.tail[1] = dir.d.tail[1];
+
+        err = lfs_dir_commit(lfs, &newcwd, NULL, 0);
+        if (err) {
+            return err;
+        }
+    }
+
+    return 0;
+}
+
+
+/// Filesystem operations ///
+static void lfs_deinit(lfs_t *lfs) {
+    // free allocated memory
+    if (!lfs->cfg->read_buffer) {
+        lfs_free(lfs->rcache.buffer);
+    }
+
+    if (!lfs->cfg->prog_buffer) {
+        lfs_free(lfs->pcache.buffer);
+    }
+
+    if (!lfs->cfg->lookahead_buffer) {
+        lfs_free(lfs->free.buffer);
+    }
+}
+
+static int lfs_init(lfs_t *lfs, const struct lfs_config *cfg) {
+    lfs->cfg = cfg;
+
+    // setup read cache
+    if (lfs->cfg->read_buffer) {
+        lfs->rcache.buffer = lfs->cfg->read_buffer;
+    } else {
+        lfs->rcache.buffer = lfs_malloc(lfs->cfg->read_size);
+        if (!lfs->rcache.buffer) {
+            goto cleanup;
+        }
+    }
+
+    // setup program cache
+    if (lfs->cfg->prog_buffer) {
+        lfs->pcache.buffer = lfs->cfg->prog_buffer;
+    } else {
+        lfs->pcache.buffer = lfs_malloc(lfs->cfg->prog_size);
+        if (!lfs->pcache.buffer) {
+            goto cleanup;
+        }
+    }
+
+    // zero to avoid information leaks
+    lfs_cache_zero(lfs, &lfs->pcache);
+    lfs_cache_drop(lfs, &lfs->rcache);
+
+    // setup lookahead, round down to nearest 32-bits
+    LFS_ASSERT(lfs->cfg->lookahead % 32 == 0);
+    LFS_ASSERT(lfs->cfg->lookahead > 0);
+    if (lfs->cfg->lookahead_buffer) {
+        lfs->free.buffer = lfs->cfg->lookahead_buffer;
+    } else {
+        lfs->free.buffer = lfs_malloc(lfs->cfg->lookahead/8);
+        if (!lfs->free.buffer) {
+            goto cleanup;
+        }
+    }
+
+    // check that program and read sizes are multiples of the block size
+    LFS_ASSERT(lfs->cfg->prog_size % lfs->cfg->read_size == 0);
+    LFS_ASSERT(lfs->cfg->block_size % lfs->cfg->prog_size == 0);
+
+    // check that the block size is large enough to fit ctz pointers
+    LFS_ASSERT(4*lfs_npw2(0xffffffff / (lfs->cfg->block_size-2*4))
+            <= lfs->cfg->block_size);
+
+    // setup default state
+    lfs->root[0] = 0xffffffff;
+    lfs->root[1] = 0xffffffff;
+    lfs->files = NULL;
+    lfs->dirs = NULL;
+    lfs->deorphaned = false;
+    lfs->moving = false;
+
+    return 0;
+
+cleanup:
+    lfs_deinit(lfs);
+    return LFS_ERR_NOMEM;
+}
+
+int lfs_format(lfs_t *lfs, const struct lfs_config *cfg) {
+    int err = 0;
+    if (true) {
+        err = lfs_init(lfs, cfg);
+        if (err) {
+            return err;
+        }
+
+        // create free lookahead
+        memset(lfs->free.buffer, 0, lfs->cfg->lookahead/8);
+        lfs->free.off = 0;
+        lfs->free.size = lfs_min(lfs->cfg->lookahead, lfs->cfg->block_count);
+        lfs->free.i = 0;
+        lfs_alloc_ack(lfs);
+
+        // create superblock dir
+        lfs_dir_t superdir;
+        err = lfs_dir_alloc(lfs, &superdir);
+        if (err) {
+            goto cleanup;
+        }
+
+        // write root directory
+        lfs_dir_t root;
+        err = lfs_dir_alloc(lfs, &root);
+        if (err) {
+            goto cleanup;
+        }
+
+        err = lfs_dir_commit(lfs, &root, NULL, 0);
+        if (err) {
+            goto cleanup;
+        }
+
+        lfs->root[0] = root.pair[0];
+        lfs->root[1] = root.pair[1];
+
+        // write superblocks
+        lfs_superblock_t superblock = {
+            .off = sizeof(superdir.d),
+            .d.type = LFS_TYPE_SUPERBLOCK,
+            .d.elen = sizeof(superblock.d) - sizeof(superblock.d.magic) - 4,
+            .d.nlen = sizeof(superblock.d.magic),
+            .d.version = LFS_DISK_VERSION,
+            .d.magic = {"littlefs"},
+            .d.block_size  = lfs->cfg->block_size,
+            .d.block_count = lfs->cfg->block_count,
+            .d.root = {lfs->root[0], lfs->root[1]},
+        };
+        superdir.d.tail[0] = root.pair[0];
+        superdir.d.tail[1] = root.pair[1];
+        superdir.d.size = sizeof(superdir.d) + sizeof(superblock.d) + 4;
+
+        // write both pairs to be safe
+        lfs_superblock_tole32(&superblock.d);
+        bool valid = false;
+        for (int i = 0; i < 2; i++) {
+            err = lfs_dir_commit(lfs, &superdir, (struct lfs_region[]){
+                    {sizeof(superdir.d), sizeof(superblock.d),
+                     &superblock.d, sizeof(superblock.d)}
+                }, 1);
+            if (err && err != LFS_ERR_CORRUPT) {
+                goto cleanup;
+            }
+
+            valid = valid || !err;
+        }
+
+        if (!valid) {
+            err = LFS_ERR_CORRUPT;
+            goto cleanup;
+        }
+
+        // sanity check that fetch works
+        err = lfs_dir_fetch(lfs, &superdir, (const lfs_block_t[2]){0, 1});
+        if (err) {
+            goto cleanup;
+        }
+
+        lfs_alloc_ack(lfs);
+    }
+
+cleanup:
+    lfs_deinit(lfs);
+    return err;
+}
+
+int lfs_mount(lfs_t *lfs, const struct lfs_config *cfg) {
+    int err = 0;
+    if (true) {
+        err = lfs_init(lfs, cfg);
+        if (err) {
+            return err;
+        }
+
+        // setup free lookahead
+        lfs->free.off = 0;
+        lfs->free.size = 0;
+        lfs->free.i = 0;
+        lfs_alloc_ack(lfs);
+
+        // load superblock
+        lfs_dir_t dir;
+        lfs_superblock_t superblock;
+        err = lfs_dir_fetch(lfs, &dir, (const lfs_block_t[2]){0, 1});
+        if (err && err != LFS_ERR_CORRUPT) {
+            goto cleanup;
+        }
+
+        if (!err) {
+            err = lfs_bd_read(lfs, dir.pair[0], sizeof(dir.d),
+                    &superblock.d, sizeof(superblock.d));
+            lfs_superblock_fromle32(&superblock.d);
+            if (err) {
+                goto cleanup;
+            }
+
+            lfs->root[0] = superblock.d.root[0];
+            lfs->root[1] = superblock.d.root[1];
+        }
+
+        if (err || memcmp(superblock.d.magic, "littlefs", 8) != 0) {
+            LFS_ERROR("Invalid superblock at %d %d", 0, 1);
+            err = LFS_ERR_CORRUPT;
+            goto cleanup;
+        }
+
+        uint16_t major_version = (0xffff & (superblock.d.version >> 16));
+        uint16_t minor_version = (0xffff & (superblock.d.version >>  0));
+        if ((major_version != LFS_DISK_VERSION_MAJOR ||
+             minor_version > LFS_DISK_VERSION_MINOR)) {
+            LFS_ERROR("Invalid version %d.%d", major_version, minor_version);
+            err = LFS_ERR_INVAL;
+            goto cleanup;
+        }
+
+        return 0;
+    }
+
+cleanup:
+
+    lfs_deinit(lfs);
+    return err;
+}
+
+int lfs_unmount(lfs_t *lfs) {
+    lfs_deinit(lfs);
+    return 0;
+}
+
+
+/// Littlefs specific operations ///
+int lfs_traverse(lfs_t *lfs, int (*cb)(void*, lfs_block_t), void *data) {
+    if (lfs_pairisnull(lfs->root)) {
+        return 0;
+    }
+
+    // iterate over metadata pairs
+    lfs_dir_t dir;
+    lfs_entry_t entry;
+    lfs_block_t cwd[2] = {0, 1};
+
+    while (true) {
+        for (int i = 0; i < 2; i++) {
+            int err = cb(data, cwd[i]);
+            if (err) {
+                return err;
+            }
+        }
+
+        int err = lfs_dir_fetch(lfs, &dir, cwd);
+        if (err) {
+            return err;
+        }
+
+        // iterate over contents
+        while (dir.off + sizeof(entry.d) <= (0x7fffffff & dir.d.size)-4) {
+            err = lfs_bd_read(lfs, dir.pair[0], dir.off,
+                    &entry.d, sizeof(entry.d));
+            lfs_entry_fromle32(&entry.d);
+            if (err) {
+                return err;
+            }
+
+            dir.off += lfs_entry_size(&entry);
+            if ((0x70 & entry.d.type) == (0x70 & LFS_TYPE_REG)) {
+                err = lfs_ctz_traverse(lfs, &lfs->rcache, NULL,
+                        entry.d.u.file.head, entry.d.u.file.size, cb, data);
+                if (err) {
+                    return err;
+                }
+            }
+        }
+
+        cwd[0] = dir.d.tail[0];
+        cwd[1] = dir.d.tail[1];
+
+        if (lfs_pairisnull(cwd)) {
+            break;
+        }
+    }
+
+    // iterate over any open files
+    for (lfs_file_t *f = lfs->files; f; f = f->next) {
+        if (f->flags & LFS_F_DIRTY) {
+            int err = lfs_ctz_traverse(lfs, &lfs->rcache, &f->cache,
+                    f->head, f->size, cb, data);
+            if (err) {
+                return err;
+            }
+        }
+
+        if (f->flags & LFS_F_WRITING) {
+            int err = lfs_ctz_traverse(lfs, &lfs->rcache, &f->cache,
+                    f->block, f->pos, cb, data);
+            if (err) {
+                return err;
+            }
+        }
+    }
+
+    return 0;
+}
+
+static int lfs_pred(lfs_t *lfs, const lfs_block_t dir[2], lfs_dir_t *pdir) {
+    if (lfs_pairisnull(lfs->root)) {
+        return 0;
+    }
+
+    // iterate over all directory directory entries
+    int err = lfs_dir_fetch(lfs, pdir, (const lfs_block_t[2]){0, 1});
+    if (err) {
+        return err;
+    }
+
+    while (!lfs_pairisnull(pdir->d.tail)) {
+        if (lfs_paircmp(pdir->d.tail, dir) == 0) {
+            return true;
+        }
+
+        err = lfs_dir_fetch(lfs, pdir, pdir->d.tail);
+        if (err) {
+            return err;
+        }
+    }
+
+    return false;
+}
+
+static int lfs_parent(lfs_t *lfs, const lfs_block_t dir[2],
+        lfs_dir_t *parent, lfs_entry_t *entry) {
+    if (lfs_pairisnull(lfs->root)) {
+        return 0;
+    }
+
+    parent->d.tail[0] = 0;
+    parent->d.tail[1] = 1;
+
+    // iterate over all directory directory entries
+    while (!lfs_pairisnull(parent->d.tail)) {
+        int err = lfs_dir_fetch(lfs, parent, parent->d.tail);
+        if (err) {
+            return err;
+        }
+
+        while (true) {
+            err = lfs_dir_next(lfs, parent, entry);
+            if (err && err != LFS_ERR_NOENT) {
+                return err;
+            }
+
+            if (err == LFS_ERR_NOENT) {
+                break;
+            }
+
+            if (((0x70 & entry->d.type) == (0x70 & LFS_TYPE_DIR)) &&
+                 lfs_paircmp(entry->d.u.dir, dir) == 0) {
+                return true;
+            }
+        }
+    }
+
+    return false;
+}
+
+static int lfs_moved(lfs_t *lfs, const void *e) {
+    if (lfs_pairisnull(lfs->root)) {
+        return 0;
+    }
+
+    // skip superblock
+    lfs_dir_t cwd;
+    int err = lfs_dir_fetch(lfs, &cwd, (const lfs_block_t[2]){0, 1});
+    if (err) {
+        return err;
+    }
+
+    // iterate over all directory directory entries
+    lfs_entry_t entry;
+    while (!lfs_pairisnull(cwd.d.tail)) {
+        err = lfs_dir_fetch(lfs, &cwd, cwd.d.tail);
+        if (err) {
+            return err;
+        }
+
+        while (true) {
+            err = lfs_dir_next(lfs, &cwd, &entry);
+            if (err && err != LFS_ERR_NOENT) {
+                return err;
+            }
+
+            if (err == LFS_ERR_NOENT) {
+                break;
+            }
+
+            if (!(0x80 & entry.d.type) &&
+                 memcmp(&entry.d.u, e, sizeof(entry.d.u)) == 0) {
+                return true;
+            }
+        }
+    }
+
+    return false;
+}
+
+static int lfs_relocate(lfs_t *lfs,
+        const lfs_block_t oldpair[2], const lfs_block_t newpair[2]) {
+    // find parent
+    lfs_dir_t parent;
+    lfs_entry_t entry;
+    int res = lfs_parent(lfs, oldpair, &parent, &entry);
+    if (res < 0) {
+        return res;
+    }
+
+    if (res) {
+        // update disk, this creates a desync
+        entry.d.u.dir[0] = newpair[0];
+        entry.d.u.dir[1] = newpair[1];
+
+        int err = lfs_dir_update(lfs, &parent, &entry, NULL);
+        if (err) {
+            return err;
+        }
+
+        // update internal root
+        if (lfs_paircmp(oldpair, lfs->root) == 0) {
+            LFS_DEBUG("Relocating root %" PRIu32 " %" PRIu32,
+                    newpair[0], newpair[1]);
+            lfs->root[0] = newpair[0];
+            lfs->root[1] = newpair[1];
+        }
+
+        // clean up bad block, which should now be a desync
+        return lfs_deorphan(lfs);
+    }
+
+    // find pred
+    res = lfs_pred(lfs, oldpair, &parent);
+    if (res < 0) {
+        return res;
+    }
+
+    if (res) {
+        // just replace bad pair, no desync can occur
+        parent.d.tail[0] = newpair[0];
+        parent.d.tail[1] = newpair[1];
+
+        return lfs_dir_commit(lfs, &parent, NULL, 0);
+    }
+
+    // couldn't find dir, must be new
+    return 0;
+}
+
+int lfs_deorphan(lfs_t *lfs) {
+    lfs->deorphaned = true;
+
+    if (lfs_pairisnull(lfs->root)) {
+        return 0;
+    }
+
+    lfs_dir_t pdir = {.d.size = 0x80000000};
+    lfs_dir_t cwd = {.d.tail[0] = 0, .d.tail[1] = 1};
+
+    // iterate over all directory directory entries
+    for (lfs_size_t i = 0; i < lfs->cfg->block_count; i++) {
+        if (lfs_pairisnull(cwd.d.tail)) {
+            return 0;
+        }
+
+        int err = lfs_dir_fetch(lfs, &cwd, cwd.d.tail);
+        if (err) {
+            return err;
+        }
+
+        // check head blocks for orphans
+        if (!(0x80000000 & pdir.d.size)) {
+            // check if we have a parent
+            lfs_dir_t parent;
+            lfs_entry_t entry;
+            int res = lfs_parent(lfs, pdir.d.tail, &parent, &entry);
+            if (res < 0) {
+                return res;
+            }
+
+            if (!res) {
+                // we are an orphan
+                LFS_DEBUG("Found orphan %" PRIu32 " %" PRIu32,
+                        pdir.d.tail[0], pdir.d.tail[1]);
+
+                pdir.d.tail[0] = cwd.d.tail[0];
+                pdir.d.tail[1] = cwd.d.tail[1];
+
+                err = lfs_dir_commit(lfs, &pdir, NULL, 0);
+                if (err) {
+                    return err;
+                }
+
+                return 0;
+            }
+
+            if (!lfs_pairsync(entry.d.u.dir, pdir.d.tail)) {
+                // we have desynced
+                LFS_DEBUG("Found desync %" PRIu32 " %" PRIu32,
+                        entry.d.u.dir[0], entry.d.u.dir[1]);
+
+                pdir.d.tail[0] = entry.d.u.dir[0];
+                pdir.d.tail[1] = entry.d.u.dir[1];
+
+                err = lfs_dir_commit(lfs, &pdir, NULL, 0);
+                if (err) {
+                    return err;
+                }
+
+                return 0;
+            }
+        }
+
+        // check entries for moves
+        lfs_entry_t entry;
+        while (true) {
+            err = lfs_dir_next(lfs, &cwd, &entry);
+            if (err && err != LFS_ERR_NOENT) {
+                return err;
+            }
+
+            if (err == LFS_ERR_NOENT) {
+                break;
+            }
+
+            // found moved entry
+            if (entry.d.type & 0x80) {
+                int moved = lfs_moved(lfs, &entry.d.u);
+                if (moved < 0) {
+                    return moved;
+                }
+
+                if (moved) {
+                    LFS_DEBUG("Found move %" PRIu32 " %" PRIu32,
+                            entry.d.u.dir[0], entry.d.u.dir[1]);
+                    err = lfs_dir_remove(lfs, &cwd, &entry);
+                    if (err) {
+                        return err;
+                    }
+                } else {
+                    LFS_DEBUG("Found partial move %" PRIu32 " %" PRIu32,
+                            entry.d.u.dir[0], entry.d.u.dir[1]);
+                    entry.d.type &= ~0x80;
+                    err = lfs_dir_update(lfs, &cwd, &entry, NULL);
+                    if (err) {
+                        return err;
+                    }
+                }
+            }
+        }
+
+        memcpy(&pdir, &cwd, sizeof(pdir));
+    }
+
+    // If we reached here, we have more directory pairs than blocks in the
+    // filesystem... So something must be horribly wrong
+    return LFS_ERR_CORRUPT;
+}

arch/stm32/Adafruit_LittleFS_stm32/src/littlefs/lfs.h

@@ -0,0 +1,501 @@
+/*
+ * The little filesystem
+ *
+ * Copyright (c) 2017, Arm Limited. All rights reserved.
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+#ifndef LFS_H
+#define LFS_H
+
+#include <stdint.h>
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+
+/// Version info ///
+
+// Software library version
+// Major (top-nibble), incremented on backwards incompatible changes
+// Minor (bottom-nibble), incremented on feature additions
+#define LFS_VERSION 0x00010007
+#define LFS_VERSION_MAJOR (0xffff & (LFS_VERSION >> 16))
+#define LFS_VERSION_MINOR (0xffff & (LFS_VERSION >>  0))
+
+// Version of On-disk data structures
+// Major (top-nibble), incremented on backwards incompatible changes
+// Minor (bottom-nibble), incremented on feature additions
+#define LFS_DISK_VERSION 0x00010001
+#define LFS_DISK_VERSION_MAJOR (0xffff & (LFS_DISK_VERSION >> 16))
+#define LFS_DISK_VERSION_MINOR (0xffff & (LFS_DISK_VERSION >>  0))
+
+
+/// Definitions ///
+
+// Type definitions
+typedef uint32_t lfs_size_t;
+typedef uint32_t lfs_off_t;
+
+typedef int32_t  lfs_ssize_t;
+typedef int32_t  lfs_soff_t;
+
+typedef uint32_t lfs_block_t;
+
+// Max name size in bytes
+#ifndef LFS_NAME_MAX
+#define LFS_NAME_MAX 255
+#endif
+
+// Max file size in bytes
+#ifndef LFS_FILE_MAX
+#define LFS_FILE_MAX 2147483647
+#endif
+
+// Possible error codes, these are negative to allow
+// valid positive return values
+enum lfs_error {
+    LFS_ERR_OK       = 0,    // No error
+    LFS_ERR_IO       = -5,   // Error during device operation
+    LFS_ERR_CORRUPT  = -52,  // Corrupted
+    LFS_ERR_NOENT    = -2,   // No directory entry
+    LFS_ERR_EXIST    = -17,  // Entry already exists
+    LFS_ERR_NOTDIR   = -20,  // Entry is not a dir
+    LFS_ERR_ISDIR    = -21,  // Entry is a dir
+    LFS_ERR_NOTEMPTY = -39,  // Dir is not empty
+    LFS_ERR_BADF     = -9,   // Bad file number
+    LFS_ERR_FBIG     = -27,  // File too large
+    LFS_ERR_INVAL    = -22,  // Invalid parameter
+    LFS_ERR_NOSPC    = -28,  // No space left on device
+    LFS_ERR_NOMEM    = -12,  // No more memory available
+};
+
+// File types
+enum lfs_type {
+    LFS_TYPE_REG        = 0x11,
+    LFS_TYPE_DIR        = 0x22,
+    LFS_TYPE_SUPERBLOCK = 0x2e,
+};
+
+// File open flags
+enum lfs_open_flags {
+    // open flags
+    LFS_O_RDONLY = 1,        // Open a file as read only
+    LFS_O_WRONLY = 2,        // Open a file as write only
+    LFS_O_RDWR   = 3,        // Open a file as read and write
+    LFS_O_CREAT  = 0x0100,   // Create a file if it does not exist
+    LFS_O_EXCL   = 0x0200,   // Fail if a file already exists
+    LFS_O_TRUNC  = 0x0400,   // Truncate the existing file to zero size
+    LFS_O_APPEND = 0x0800,   // Move to end of file on every write
+
+    // internally used flags
+    LFS_F_DIRTY   = 0x10000, // File does not match storage
+    LFS_F_WRITING = 0x20000, // File has been written since last flush
+    LFS_F_READING = 0x40000, // File has been read since last flush
+    LFS_F_ERRED   = 0x80000, // An error occured during write
+};
+
+// File seek flags
+enum lfs_whence_flags {
+    LFS_SEEK_SET = 0,   // Seek relative to an absolute position
+    LFS_SEEK_CUR = 1,   // Seek relative to the current file position
+    LFS_SEEK_END = 2,   // Seek relative to the end of the file
+};
+
+
+// Configuration provided during initialization of the littlefs
+struct lfs_config {
+    // Opaque user provided context that can be used to pass
+    // information to the block device operations
+    void *context;
+
+    // Read a region in a block. Negative error codes are propogated
+    // to the user.
+    int (*read)(const struct lfs_config *c, lfs_block_t block,
+            lfs_off_t off, void *buffer, lfs_size_t size);
+
+    // Program a region in a block. The block must have previously
+    // been erased. Negative error codes are propogated to the user.
+    // May return LFS_ERR_CORRUPT if the block should be considered bad.
+    int (*prog)(const struct lfs_config *c, lfs_block_t block,
+            lfs_off_t off, const void *buffer, lfs_size_t size);
+
+    // Erase a block. A block must be erased before being programmed.
+    // The state of an erased block is undefined. Negative error codes
+    // are propogated to the user.
+    // May return LFS_ERR_CORRUPT if the block should be considered bad.
+    int (*erase)(const struct lfs_config *c, lfs_block_t block);
+
+    // Sync the state of the underlying block device. Negative error codes
+    // are propogated to the user.
+    int (*sync)(const struct lfs_config *c);
+
+    // Minimum size of a block read. This determines the size of read buffers.
+    // This may be larger than the physical read size to improve performance
+    // by caching more of the block device.
+    lfs_size_t read_size;
+
+    // Minimum size of a block program. This determines the size of program
+    // buffers. This may be larger than the physical program size to improve
+    // performance by caching more of the block device.
+    // Must be a multiple of the read size.
+    lfs_size_t prog_size;
+
+    // Size of an erasable block. This does not impact ram consumption and
+    // may be larger than the physical erase size. However, this should be
+    // kept small as each file currently takes up an entire block.
+    // Must be a multiple of the program size.
+    lfs_size_t block_size;
+
+    // Number of erasable blocks on the device.
+    lfs_size_t block_count;
+
+    // Number of blocks to lookahead during block allocation. A larger
+    // lookahead reduces the number of passes required to allocate a block.
+    // The lookahead buffer requires only 1 bit per block so it can be quite
+    // large with little ram impact. Should be a multiple of 32.
+    lfs_size_t lookahead;
+
+    // Optional, statically allocated read buffer. Must be read sized.
+    void *read_buffer;
+
+    // Optional, statically allocated program buffer. Must be program sized.
+    void *prog_buffer;
+
+    // Optional, statically allocated lookahead buffer. Must be 1 bit per
+    // lookahead block.
+    void *lookahead_buffer;
+
+    // Optional, statically allocated buffer for files. Must be program sized.
+    // If enabled, only one file may be opened at a time.
+    void *file_buffer;
+};
+
+// Optional configuration provided during lfs_file_opencfg
+struct lfs_file_config {
+    // Optional, statically allocated buffer for files. Must be program sized.
+    // If NULL, malloc will be used by default.
+    void *buffer;
+};
+
+// File info structure
+struct lfs_info {
+    // Type of the file, either LFS_TYPE_REG or LFS_TYPE_DIR
+    uint8_t type;
+
+    // Size of the file, only valid for REG files
+    lfs_size_t size;
+
+    // Name of the file stored as a null-terminated string
+    char name[LFS_NAME_MAX+1];
+};
+
+
+/// littlefs data structures ///
+typedef struct lfs_entry {
+    lfs_off_t off;
+
+    struct lfs_disk_entry {
+        uint8_t type;
+        uint8_t elen;
+        uint8_t alen;
+        uint8_t nlen;
+        union {
+            struct {
+                lfs_block_t head;
+                lfs_size_t size;
+            } file;
+            lfs_block_t dir[2];
+        } u;
+    } d;
+} lfs_entry_t;
+
+typedef struct lfs_cache {
+    lfs_block_t block;
+    lfs_off_t off;
+    uint8_t *buffer;
+} lfs_cache_t;
+
+typedef struct lfs_file {
+    struct lfs_file *next;
+    lfs_block_t pair[2];
+    lfs_off_t poff;
+
+    lfs_block_t head;
+    lfs_size_t size;
+
+    const struct lfs_file_config *cfg;
+    uint32_t flags;
+    lfs_off_t pos;
+    lfs_block_t block;
+    lfs_off_t off;
+    lfs_cache_t cache;
+} lfs_file_t;
+
+typedef struct lfs_dir {
+    struct lfs_dir *next;
+    lfs_block_t pair[2];
+    lfs_off_t off;
+
+    lfs_block_t head[2];
+    lfs_off_t pos;
+
+    struct lfs_disk_dir {
+        uint32_t rev;
+        lfs_size_t size;
+        lfs_block_t tail[2];
+    } d;
+} lfs_dir_t;
+
+typedef struct lfs_superblock {
+    lfs_off_t off;
+
+    struct lfs_disk_superblock {
+        uint8_t type;
+        uint8_t elen;
+        uint8_t alen;
+        uint8_t nlen;
+        lfs_block_t root[2];
+        uint32_t block_size;
+        uint32_t block_count;
+        uint32_t version;
+        char magic[8];
+    } d;
+} lfs_superblock_t;
+
+typedef struct lfs_free {
+    lfs_block_t off;
+    lfs_block_t size;
+    lfs_block_t i;
+    lfs_block_t ack;
+    uint32_t *buffer;
+} lfs_free_t;
+
+// The littlefs type
+typedef struct lfs {
+    const struct lfs_config *cfg;
+
+    lfs_block_t root[2];
+    lfs_file_t *files;
+    lfs_dir_t *dirs;
+
+    lfs_cache_t rcache;
+    lfs_cache_t pcache;
+
+    lfs_free_t free;
+    bool deorphaned;
+    bool moving;
+} lfs_t;
+
+
+/// Filesystem functions ///
+
+// Format a block device with the littlefs
+//
+// Requires a littlefs object and config struct. This clobbers the littlefs
+// object, and does not leave the filesystem mounted. The config struct must
+// be zeroed for defaults and backwards compatibility.
+//
+// Returns a negative error code on failure.
+int lfs_format(lfs_t *lfs, const struct lfs_config *config);
+
+// Mounts a littlefs
+//
+// Requires a littlefs object and config struct. Multiple filesystems
+// may be mounted simultaneously with multiple littlefs objects. Both
+// lfs and config must be allocated while mounted. The config struct must
+// be zeroed for defaults and backwards compatibility.
+//
+// Returns a negative error code on failure.
+int lfs_mount(lfs_t *lfs, const struct lfs_config *config);
+
+// Unmounts a littlefs
+//
+// Does nothing besides releasing any allocated resources.
+// Returns a negative error code on failure.
+int lfs_unmount(lfs_t *lfs);
+
+/// General operations ///
+
+// Removes a file or directory
+//
+// If removing a directory, the directory must be empty.
+// Returns a negative error code on failure.
+int lfs_remove(lfs_t *lfs, const char *path);
+
+// Rename or move a file or directory
+//
+// If the destination exists, it must match the source in type.
+// If the destination is a directory, the directory must be empty.
+//
+// Returns a negative error code on failure.
+int lfs_rename(lfs_t *lfs, const char *oldpath, const char *newpath);
+
+// Find info about a file or directory
+//
+// Fills out the info structure, based on the specified file or directory.
+// Returns a negative error code on failure.
+int lfs_stat(lfs_t *lfs, const char *path, struct lfs_info *info);
+
+
+/// File operations ///
+
+// Open a file
+//
+// The mode that the file is opened in is determined by the flags, which
+// are values from the enum lfs_open_flags that are bitwise-ored together.
+//
+// Returns a negative error code on failure.
+int lfs_file_open(lfs_t *lfs, lfs_file_t *file,
+        const char *path, int flags);
+
+// Open a file with extra configuration
+//
+// The mode that the file is opened in is determined by the flags, which
+// are values from the enum lfs_open_flags that are bitwise-ored together.
+//
+// The config struct provides additional config options per file as described
+// above. The config struct must be allocated while the file is open, and the
+// config struct must be zeroed for defaults and backwards compatibility.
+//
+// Returns a negative error code on failure.
+int lfs_file_opencfg(lfs_t *lfs, lfs_file_t *file,
+        const char *path, int flags,
+        const struct lfs_file_config *config);
+
+// Close a file
+//
+// Any pending writes are written out to storage as though
+// sync had been called and releases any allocated resources.
+//
+// Returns a negative error code on failure.
+int lfs_file_close(lfs_t *lfs, lfs_file_t *file);
+
+// Synchronize a file on storage
+//
+// Any pending writes are written out to storage.
+// Returns a negative error code on failure.
+int lfs_file_sync(lfs_t *lfs, lfs_file_t *file);
+
+// Read data from file
+//
+// Takes a buffer and size indicating where to store the read data.
+// Returns the number of bytes read, or a negative error code on failure.
+lfs_ssize_t lfs_file_read(lfs_t *lfs, lfs_file_t *file,
+        void *buffer, lfs_size_t size);
+
+// Write data to file
+//
+// Takes a buffer and size indicating the data to write. The file will not
+// actually be updated on the storage until either sync or close is called.
+//
+// Returns the number of bytes written, or a negative error code on failure.
+lfs_ssize_t lfs_file_write(lfs_t *lfs, lfs_file_t *file,
+        const void *buffer, lfs_size_t size);
+
+// Change the position of the file
+//
+// The change in position is determined by the offset and whence flag.
+// Returns the old position of the file, or a negative error code on failure.
+lfs_soff_t lfs_file_seek(lfs_t *lfs, lfs_file_t *file,
+        lfs_soff_t off, int whence);
+
+// Truncates the size of the file to the specified size
+//
+// Returns a negative error code on failure.
+int lfs_file_truncate(lfs_t *lfs, lfs_file_t *file, lfs_off_t size);
+
+// Return the position of the file
+//
+// Equivalent to lfs_file_seek(lfs, file, 0, LFS_SEEK_CUR)
+// Returns the position of the file, or a negative error code on failure.
+lfs_soff_t lfs_file_tell(lfs_t *lfs, lfs_file_t *file);
+
+// Change the position of the file to the beginning of the file
+//
+// Equivalent to lfs_file_seek(lfs, file, 0, LFS_SEEK_CUR)
+// Returns a negative error code on failure.
+int lfs_file_rewind(lfs_t *lfs, lfs_file_t *file);
+
+// Return the size of the file
+//
+// Similar to lfs_file_seek(lfs, file, 0, LFS_SEEK_END)
+// Returns the size of the file, or a negative error code on failure.
+lfs_soff_t lfs_file_size(lfs_t *lfs, lfs_file_t *file);
+
+
+/// Directory operations ///
+
+// Create a directory
+//
+// Returns a negative error code on failure.
+int lfs_mkdir(lfs_t *lfs, const char *path);
+
+// Open a directory
+//
+// Once open a directory can be used with read to iterate over files.
+// Returns a negative error code on failure.
+int lfs_dir_open(lfs_t *lfs, lfs_dir_t *dir, const char *path);
+
+// Close a directory
+//
+// Releases any allocated resources.
+// Returns a negative error code on failure.
+int lfs_dir_close(lfs_t *lfs, lfs_dir_t *dir);
+
+// Read an entry in the directory
+//
+// Fills out the info structure, based on the specified file or directory.
+// Returns a negative error code on failure.
+int lfs_dir_read(lfs_t *lfs, lfs_dir_t *dir, struct lfs_info *info);
+
+// Change the position of the directory
+//
+// The new off must be a value previous returned from tell and specifies
+// an absolute offset in the directory seek.
+//
+// Returns a negative error code on failure.
+int lfs_dir_seek(lfs_t *lfs, lfs_dir_t *dir, lfs_off_t off);
+
+// Return the position of the directory
+//
+// The returned offset is only meant to be consumed by seek and may not make
+// sense, but does indicate the current position in the directory iteration.
+//
+// Returns the position of the directory, or a negative error code on failure.
+lfs_soff_t lfs_dir_tell(lfs_t *lfs, lfs_dir_t *dir);
+
+// Change the position of the directory to the beginning of the directory
+//
+// Returns a negative error code on failure.
+int lfs_dir_rewind(lfs_t *lfs, lfs_dir_t *dir);
+
+
+/// Miscellaneous littlefs specific operations ///
+
+// Traverse through all blocks in use by the filesystem
+//
+// The provided callback will be called with each block address that is
+// currently in use by the filesystem. This can be used to determine which
+// blocks are in use or how much of the storage is available.
+//
+// Returns a negative error code on failure.
+int lfs_traverse(lfs_t *lfs, int (*cb)(void*, lfs_block_t), void *data);
+
+// Prunes any recoverable errors that may have occured in the filesystem
+//
+// Not needed to be called by user unless an operation is interrupted
+// but the filesystem is still mounted. This is already called on first
+// allocation.
+//
+// Returns a negative error code on failure.
+int lfs_deorphan(lfs_t *lfs);
+
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif

arch/stm32/Adafruit_LittleFS_stm32/src/littlefs/lfs_util.c

@@ -0,0 +1,31 @@
+/*
+ * lfs util functions
+ *
+ * Copyright (c) 2017, Arm Limited. All rights reserved.
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+#include "lfs_util.h"
+
+// Only compile if user does not provide custom config
+#ifndef LFS_CONFIG
+
+
+// Software CRC implementation with small lookup table
+void lfs_crc(uint32_t *restrict crc, const void *buffer, size_t size) {
+    static const uint32_t rtable[16] = {
+        0x00000000, 0x1db71064, 0x3b6e20c8, 0x26d930ac,
+        0x76dc4190, 0x6b6b51f4, 0x4db26158, 0x5005713c,
+        0xedb88320, 0xf00f9344, 0xd6d6a3e8, 0xcb61b38c,
+        0x9b64c2b0, 0x86d3d2d4, 0xa00ae278, 0xbdbdf21c,
+    };
+
+    const uint8_t *data = buffer;
+
+    for (size_t i = 0; i < size; i++) {
+        *crc = (*crc >> 4) ^ rtable[(*crc ^ (data[i] >> 0)) & 0xf];
+        *crc = (*crc >> 4) ^ rtable[(*crc ^ (data[i] >> 4)) & 0xf];
+    }
+}
+
+
+#endif

arch/stm32/Adafruit_LittleFS_stm32/src/littlefs/lfs_util.h

@@ -0,0 +1,197 @@
+/*
+ * lfs utility functions
+ *
+ * Copyright (c) 2017, Arm Limited. All rights reserved.
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+#ifndef LFS_UTIL_H
+#define LFS_UTIL_H
+
+// Users can override lfs_util.h with their own configuration by defining
+// LFS_CONFIG as a header file to include (-DLFS_CONFIG=lfs_config.h).
+//
+// If LFS_CONFIG is used, none of the default utils will be emitted and must be
+// provided by the config file. To start I would suggest copying lfs_util.h and
+// modifying as needed.
+#ifdef LFS_CONFIG
+#define LFS_STRINGIZE(x) LFS_STRINGIZE2(x)
+#define LFS_STRINGIZE2(x) #x
+#include LFS_STRINGIZE(LFS_CONFIG)
+#else
+
+// System includes
+#include <stdint.h>
+#include <stdbool.h>
+#include <string.h>
+
+#ifndef LFS_NO_MALLOC
+#include <stdlib.h>
+#endif
+#ifndef LFS_NO_ASSERT
+#include <assert.h>
+#endif
+
+#if !CFG_DEBUG
+#define LFS_NO_DEBUG
+#define LFS_NO_WARN
+#define LFS_NO_ERROR
+#endif
+
+#if !defined(LFS_NO_DEBUG) || !defined(LFS_NO_WARN) || !defined(LFS_NO_ERROR)
+#include <stdio.h>
+#endif
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+
+// Macros, may be replaced by system specific wrappers. Arguments to these
+// macros must not have side-effects as the macros can be removed for a smaller
+// code footprint
+
+// Logging functions
+#ifndef LFS_NO_DEBUG
+#define LFS_DEBUG(fmt, ...) \
+    printf("lfs debug:%d: " fmt "\n", __LINE__, __VA_ARGS__)
+#else
+#define LFS_DEBUG(fmt, ...)
+#endif
+
+#ifndef LFS_NO_WARN
+#define LFS_WARN(fmt, ...) \
+    printf("lfs warn:%d: " fmt "\n", __LINE__, __VA_ARGS__)
+#else
+#define LFS_WARN(fmt, ...)
+#endif
+
+#ifndef LFS_NO_ERROR
+#define LFS_ERROR(fmt, ...) \
+    printf("lfs error:%d: " fmt "\n", __LINE__, __VA_ARGS__)
+#else
+#define LFS_ERROR(fmt, ...)
+#endif
+
+// Runtime assertions
+#ifndef LFS_NO_ASSERT
+#define LFS_ASSERT(test) assert(test)
+#else
+#define LFS_ASSERT(test)
+#endif
+
+
+// Builtin functions, these may be replaced by more efficient
+// toolchain-specific implementations. LFS_NO_INTRINSICS falls back to a more
+// expensive basic C implementation for debugging purposes
+
+// Min/max functions for unsigned 32-bit numbers
+static inline uint32_t lfs_max(uint32_t a, uint32_t b) {
+    return (a > b) ? a : b;
+}
+
+static inline uint32_t lfs_min(uint32_t a, uint32_t b) {
+    return (a < b) ? a : b;
+}
+
+// Find the next smallest power of 2 less than or equal to a
+static inline uint32_t lfs_npw2(uint32_t a) {
+#if !defined(LFS_NO_INTRINSICS) && (defined(__GNUC__) || defined(__CC_ARM))
+    return 32 - __builtin_clz(a-1);
+#else
+    uint32_t r = 0;
+    uint32_t s;
+    a -= 1;
+    s = (a > 0xffff) << 4; a >>= s; r |= s;
+    s = (a > 0xff  ) << 3; a >>= s; r |= s;
+    s = (a > 0xf   ) << 2; a >>= s; r |= s;
+    s = (a > 0x3   ) << 1; a >>= s; r |= s;
+    return (r | (a >> 1)) + 1;
+#endif
+}
+
+// Count the number of trailing binary zeros in a
+// lfs_ctz(0) may be undefined
+static inline uint32_t lfs_ctz(uint32_t a) {
+#if !defined(LFS_NO_INTRINSICS) && defined(__GNUC__)
+    return __builtin_ctz(a);
+#else
+    return lfs_npw2((a & -a) + 1) - 1;
+#endif
+}
+
+// Count the number of binary ones in a
+static inline uint32_t lfs_popc(uint32_t a) {
+#if !defined(LFS_NO_INTRINSICS) && (defined(__GNUC__) || defined(__CC_ARM))
+    return __builtin_popcount(a);
+#else
+    a = a - ((a >> 1) & 0x55555555);
+    a = (a & 0x33333333) + ((a >> 2) & 0x33333333);
+    return (((a + (a >> 4)) & 0xf0f0f0f) * 0x1010101) >> 24;
+#endif
+}
+
+// Find the sequence comparison of a and b, this is the distance
+// between a and b ignoring overflow
+static inline int lfs_scmp(uint32_t a, uint32_t b) {
+    return (int)(unsigned)(a - b);
+}
+
+// Convert from 32-bit little-endian to native order
+static inline uint32_t lfs_fromle32(uint32_t a) {
+#if !defined(LFS_NO_INTRINSICS) && ( \
+    (defined(  BYTE_ORDER  ) &&   BYTE_ORDER   ==   ORDER_LITTLE_ENDIAN  ) || \
+    (defined(__BYTE_ORDER  ) && __BYTE_ORDER   == __ORDER_LITTLE_ENDIAN  ) || \
+    (defined(__BYTE_ORDER__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__))
+    return a;
+#elif !defined(LFS_NO_INTRINSICS) && ( \
+    (defined(  BYTE_ORDER  ) &&   BYTE_ORDER   ==   ORDER_BIG_ENDIAN  ) || \
+    (defined(__BYTE_ORDER  ) && __BYTE_ORDER   == __ORDER_BIG_ENDIAN  ) || \
+    (defined(__BYTE_ORDER__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__))
+    return __builtin_bswap32(a);
+#else
+    return (((uint8_t*)&a)[0] <<  0) |
+           (((uint8_t*)&a)[1] <<  8) |
+           (((uint8_t*)&a)[2] << 16) |
+           (((uint8_t*)&a)[3] << 24);
+#endif
+}
+
+// Convert to 32-bit little-endian from native order
+static inline uint32_t lfs_tole32(uint32_t a) {
+    return lfs_fromle32(a);
+}
+
+// Calculate CRC-32 with polynomial = 0x04c11db7
+void lfs_crc(uint32_t *crc, const void *buffer, size_t size);
+
+// Allocate memory, only used if buffers are not provided to littlefs
+static inline void *lfs_malloc(size_t size) {
+#ifndef LFS_NO_MALLOC
+    //extern void *pvPortMalloc( size_t xWantedSize );
+    //return pvPortMalloc(size);
+    return malloc(size);
+#else
+    (void)size;
+    return NULL;
+#endif
+}
+
+// Deallocate memory, only used if buffers are not provided to littlefs
+static inline void lfs_free(void *p) {
+#ifndef LFS_NO_MALLOC
+    //extern void vPortFree( void *pv );
+    //vPortFree(p);
+    free(p);
+#else
+    (void)p;
+#endif
+}
+
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif
+#endif

arch/stm32/build_hex.py

@@ -0,0 +1,10 @@
+Import("env")
+
+# Make custom HEX from ELF
+env.AddPostAction(
+    "$BUILD_DIR/${PROGNAME}.elf",
+    env.VerboseAction(" ".join([
+        "$OBJCOPY", "-O", "ihex", "-R", ".eeprom",
+        '"$BUILD_DIR/${PROGNAME}.elf"', '"$BUILD_DIR/${PROGNAME}.hex"'
+    ]), "Building $BUILD_DIR/${PROGNAME}.hex")
+)

examples/companion_radio/main.cpp

@@ -1,7 +1,7 @@
 #include <Arduino.h>   // needed for PlatformIO
 #include <Mesh.h>
 
-#if defined(NRF52_PLATFORM)
+#if defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
   #include <InternalFileSystem.h>
 #elif defined(RP2040_PLATFORM)
   #include <LittleFS.h>
@@ -291,7 +291,7 @@ class MyMesh : public BaseChatMesh {
   }
 
   void saveContacts() {
-#if defined(NRF52_PLATFORM)
+#if defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
     File file = _fs->open("/contacts3", FILE_O_WRITE);
     if (file) { file.seek(0); file.truncate(); }
 #elif defined(RP2040_PLATFORM)
@@ -356,7 +356,7 @@ class MyMesh : public BaseChatMesh {
   }
 
   void saveChannels() {
-  #if defined(NRF52_PLATFORM)
+  #if defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
     File file = _fs->open("/channels2", FILE_O_WRITE);
     if (file) { file.seek(0); file.truncate(); }
   #elif defined(RP2040_PLATFORM)
@@ -413,7 +413,7 @@ class MyMesh : public BaseChatMesh {
     mesh::Utils::toHex(fname, key, key_len);
     sprintf(path, "/bl/%s", fname);
 
-  #if defined(NRF52_PLATFORM)
+  #if defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
     File f = _fs->open(path, FILE_O_WRITE);
     if (f) { f.seek(0); f.truncate(); }
   #elif defined(RP2040_PLATFORM)
@@ -866,7 +866,7 @@ public:
 
     BaseChatMesh::begin();
 
-  #if defined(NRF52_PLATFORM)
+  #if defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
     _identity_store = new IdentityStore(fs, "");
   #elif defined(RP2040_PLATFORM)
     _identity_store = new IdentityStore(fs, "/identity");
@@ -933,7 +933,7 @@ public:
   }
 
   void savePrefs() {
-#if defined(NRF52_PLATFORM)
+#if defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
     File file = _fs->open("/new_prefs", FILE_O_WRITE);
     if (file) { file.seek(0); file.truncate(); }
 #elif defined(RP2040_PLATFORM)
@@ -1621,6 +1621,9 @@ public:
     #include <helpers/ArduinoSerialInterface.h>
     ArduinoSerialInterface serial_interface;
   #endif
+#elif defined(STM32_PLATFORM)
+  #include <helpers/ArduinoSerialInterface.h>
+  ArduinoSerialInterface serial_interface;
 #else
   #error "need to define a serial interface"
 #endif
@@ -1654,7 +1657,7 @@ void setup() {
 
   fast_rng.begin(radio_get_rng_seed());
 
-#if defined(NRF52_PLATFORM)
+#if defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
   InternalFS.begin();
   the_mesh.begin(InternalFS,
     #ifdef HAS_UI

examples/simple_repeater/main.cpp

@@ -1,7 +1,7 @@
 #include <Arduino.h>   // needed for PlatformIO
 #include <Mesh.h>
 
-#if defined(NRF52_PLATFORM)
+#if defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
   #include <InternalFileSystem.h>
 #elif defined(RP2040_PLATFORM)
   #include <LittleFS.h>
@@ -230,7 +230,7 @@ class MyMesh : public mesh::Mesh, public CommonCLICallbacks {
   }
 
   File openAppend(const char* fname) {
-  #if defined(NRF52_PLATFORM)
+  #if defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
     return _fs->open(fname, FILE_O_WRITE);
   #elif defined(RP2040_PLATFORM)
     return _fs->open(fname, "a");
@@ -597,7 +597,7 @@ public:
   }
 
   bool formatFileSystem() override {
-#if defined(NRF52_PLATFORM)
+#if defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
     return InternalFS.format();
 #elif defined(RP2040_PLATFORM)
     return LittleFS.format();
@@ -738,7 +738,7 @@ void setup() {
   fast_rng.begin(radio_get_rng_seed());
 
   FILESYSTEM* fs;
-#if defined(NRF52_PLATFORM)
+#if defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
   InternalFS.begin();
   fs = &InternalFS;
   IdentityStore store(InternalFS, "");

platformio.ini

@@ -69,3 +69,18 @@ lib_deps =
 extends = arduino_base
 build_flags = ${arduino_base.build_flags}
   -D RP2040_PLATFORM
+
+; ----------------- STM32 ----------------------
+
+[stm32_base]
+extends = arduino_base
+platform = platformio/ststm32@19.1.0
+platform_packages = platformio/framework-arduinoststm32@https://github.com/stm32duino/Arduino_Core_STM32/archive/2.10.1.zip
+extra_scripts = post:arch/stm32/build_hex.py
+build_flags = ${arduino_base.build_flags}
+  -D STM32_PLATFORM
+  -I src/helpers/stm32
+build_src_filter = ${arduino_base.build_src_filter}
+  +<helpers/stm32>
+lib_deps = ${arduino_base.lib_deps}
+  file://arch/stm32/Adafruit_LittleFS_stm32

src/helpers/CommonCLI.cpp

@@ -73,7 +73,7 @@ void CommonCLI::loadPrefsInt(FILESYSTEM* fs, const char* filename) {
 }
 
 void CommonCLI::savePrefs(FILESYSTEM* fs) {
-#if defined(NRF52_PLATFORM)
+#if defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
   File file = fs->open("/com_prefs", FILE_O_WRITE);
   if (file) { file.seek(0); file.truncate(); }
 #elif defined(RP2040_PLATFORM)

src/helpers/CustomSTM32WLx.h

@@ -0,0 +1,17 @@
+#pragma once
+
+#include <RadioLib.h>
+
+#define SX126X_IRQ_HEADER_VALID                     0b0000010000  //  4     4     valid LoRa header received
+#define SX126X_IRQ_PREAMBLE_DETECTED           0x04
+
+class CustomSTM32WLx : public STM32WLx {
+  public:
+    CustomSTM32WLx(STM32WLx_Module *mod) : STM32WLx(mod) { }
+
+    bool isReceiving() {
+      uint16_t irq = getIrqFlags();
+      bool detected = (irq & SX126X_IRQ_HEADER_VALID) || (irq & SX126X_IRQ_PREAMBLE_DETECTED);
+      return detected;
+    }
+};

src/helpers/CustomSTM32WLxWrapper.h

@@ -0,0 +1,30 @@
+#pragma once
+
+#include "CustomSTM32WLx.h"
+#include "RadioLibWrappers.h"
+#include <math.h>
+
+class CustomSTM32WLxWrapper : public RadioLibWrapper {
+public:
+  CustomSTM32WLxWrapper(CustomSTM32WLx& radio, mesh::MainBoard& board) : RadioLibWrapper(radio, board) { }
+  bool isReceiving() override { 
+    if (((CustomSTM32WLx *)_radio)->isReceiving()) return true;
+
+    idle();  // put sx126x into standby
+    // do some basic CAD (blocks for ~12780 micros (on SF 10)!)
+    bool activity = (((CustomSTM32WLx *)_radio)->scanChannel() == RADIOLIB_LORA_DETECTED);
+    if (activity) {
+      startRecv();
+    } else {
+      idle();
+    }
+    return activity;
+  }
+  float getLastRSSI() const override { return ((CustomSTM32WLx *)_radio)->getRSSI(); }
+  float getLastSNR() const override { return ((CustomSTM32WLx *)_radio)->getSNR(); }
+
+  float packetScore(float snr, int packet_len) override {
+    int sf = ((CustomSTM32WLx *)_radio)->spreadingFactor;
+    return packetScoreInt(snr, sf, packet_len);
+  }
+};

src/helpers/IdentityStore.cpp

@@ -46,7 +46,7 @@ bool IdentityStore::save(const char *name, const mesh::LocalIdentity& id) {
   char filename[40];
   sprintf(filename, "%s/%s.id", _dir, name);
 
-#if defined(NRF52_PLATFORM)
+#if defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
   File file = _fs->open(filename, FILE_O_WRITE);
   if (file) { file.seek(0); file.truncate(); }
 #elif defined(RP2040_PLATFORM)
@@ -68,7 +68,7 @@ bool IdentityStore::save(const char *name, const mesh::LocalIdentity& id, const
   char filename[40];
   sprintf(filename, "%s/%s.id", _dir, name);
 
-#if defined(NRF52_PLATFORM)
+#if defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
   File file = _fs->open(filename, FILE_O_WRITE);
   if (file) { file.seek(0); file.truncate(); }
 #elif defined(RP2040_PLATFORM)

src/helpers/IdentityStore.h

@@ -3,7 +3,7 @@
 #if defined(ESP32) || defined(RP2040_PLATFORM)
   #include <FS.h>
   #define FILESYSTEM  fs::FS
-#elif defined(NRF52_PLATFORM)
+#elif defined(NRF52_PLATFORM) || defined(STM32_PLATFORM)
   #include <Adafruit_LittleFS.h>
   #define FILESYSTEM  Adafruit_LittleFS
 

src/helpers/stm32/InternalFileSystem.cpp

@@ -0,0 +1,139 @@
+/*
+ * The MIT License (MIT)
+ *  
+ * Copyright (c) 2019 hathach for Adafruit Industries
+ *  
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *  
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *  
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */ 
+    
+#include <Arduino.h>
+#include "InternalFileSystem.h"
+
+//--------------------------------------------------------------------+
+// LFS Disk IO
+//--------------------------------------------------------------------+
+static int _internal_flash_read(const struct lfs_config *c, lfs_block_t block, lfs_off_t off, void *buffer, lfs_size_t size)
+{    
+    if (!buffer || !size) return LFS_ERR_INVAL;
+    lfs_block_t address = LFS_FLASH_ADDR_BASE + (block * FLASH_PAGE_SIZE + off);
+    memcpy(buffer, (void *)address, size);
+    return LFS_ERR_OK;
+}    
+
+// Program a region in a block. The block must have previously
+// been erased. Negative error codes are propogated to the user.
+// May return LFS_ERR_CORRUPT if the block should be considered bad.
+static int _internal_flash_prog(const struct lfs_config *c, lfs_block_t block, lfs_off_t off, const void *buffer, lfs_size_t size)
+{    
+    HAL_StatusTypeDef hal_rc = HAL_OK;
+    lfs_block_t addr = LFS_FLASH_ADDR_BASE + (block * FLASH_PAGE_SIZE + off);
+    uint64_t *bufp = (uint64_t *) buffer;
+     
+    if (HAL_FLASH_Unlock() != HAL_OK) return LFS_ERR_IO;
+    for (uint32_t i = 0; i < size/8; i++) {
+        if ((addr < LFS_FLASH_ADDR_BASE) || (addr > FLASH_END_ADDR)) {
+            HAL_FLASH_Lock();
+            return LFS_ERR_INVAL;
+        }
+        hal_rc = HAL_FLASH_Program(FLASH_TYPEPROGRAM_DOUBLEWORD, addr, *bufp);
+        addr += 8;
+        bufp += 1;
+    }
+    if (HAL_FLASH_Lock() != HAL_OK) return LFS_ERR_IO;
+     
+    return hal_rc == HAL_OK ? LFS_ERR_OK : LFS_ERR_IO;
+}    
+
+// Erase a block. A block must be erased before being programmed.
+// The state of an erased block is undefined. Negative error codes
+// are propogated to the user.
+// May return LFS_ERR_CORRUPT if the block should be considered bad.
+static int _internal_flash_erase(const struct lfs_config *c, lfs_block_t block)
+{   
+    HAL_StatusTypeDef hal_rc;
+    lfs_block_t address = LFS_FLASH_ADDR_BASE + (block * FLASH_PAGE_SIZE);
+    uint32_t pageError = 0;
+    FLASH_EraseInitTypeDef EraseInitStruct = {
+        .TypeErase = FLASH_TYPEERASE_PAGES, 
+        .Page = 0, 
+        .NbPages = 1
+    };
+    
+    if ((address < LFS_FLASH_ADDR_BASE) || (address > FLASH_END_ADDR)) {
+        return LFS_ERR_INVAL;
+    }
+    EraseInitStruct.Page = (address - FLASH_BASE) / FLASH_PAGE_SIZE;
+    HAL_FLASH_Unlock();
+    hal_rc = HAL_FLASHEx_Erase(&EraseInitStruct, &pageError);
+    HAL_FLASH_Lock();
+
+    return hal_rc == HAL_OK ? LFS_ERR_OK : LFS_ERR_IO; 
+}   
+
+// Sync the state of the underlying block device. Negative error codes
+// are propogated to the user.
+static int _internal_flash_sync(const struct lfs_config *c)
+{    
+    return LFS_ERR_OK; // don't need sync
+}    
+
+struct lfs_config _InternalFSConfig = {
+    .context = NULL, 
+    .read = _internal_flash_read,
+    .prog = _internal_flash_prog,
+    .erase = _internal_flash_erase,
+    .sync = _internal_flash_sync,
+
+    .read_size = LFS_BLOCK_SIZE,
+    .prog_size = LFS_BLOCK_SIZE,
+    .block_size = LFS_BLOCK_SIZE,
+    .block_count = LFS_FLASH_TOTAL_SIZE / LFS_BLOCK_SIZE,
+    .lookahead = 128,
+
+    .read_buffer = NULL,
+    .prog_buffer = NULL,
+    .lookahead_buffer = NULL,
+    .file_buffer = NULL
+};
+
+InternalFileSystem InternalFS;
+
+//--------------------------------------------------------------------+
+//
+//--------------------------------------------------------------------+
+
+InternalFileSystem::InternalFileSystem(void)
+  : Adafruit_LittleFS(&_InternalFSConfig)
+{
+
+}
+
+bool InternalFileSystem::begin(void)
+{
+  // failed to mount, erase all sector then format and mount again
+  if ( !Adafruit_LittleFS::begin() )
+  {
+    // lfs format
+    this->format();
+    // mount again if still failed, give up
+    if ( !Adafruit_LittleFS::begin() ) return false;
+  }
+
+  return true;
+}

src/helpers/stm32/InternalFileSystem.h

@@ -0,0 +1,48 @@
+/* 
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2019 hathach for Adafruit Industries
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+ #ifndef INTERNALFILESYSTEM_H_
+ #define INTERNALFILESYSTEM_H_
+ 
+ #include "Adafruit_LittleFS.h"
+ 
+#ifndef LFS_FLASH_TOTAL_SIZE /* Flash size can be configured in platformio.ini */
+  #define LFS_FLASH_TOTAL_SIZE (16 * 2048) /* defaults to 32k flash */
+#endif
+#define LFS_BLOCK_SIZE (2048)
+#define LFS_FLASH_ADDR_BASE (FLASH_END_ADDR - LFS_FLASH_TOTAL_SIZE + 1)
+    
+ class InternalFileSystem : public Adafruit_LittleFS
+ {
+   public:
+     InternalFileSystem(void);
+ 
+     // overwrite to also perform low level format (sector erase of whole flash region)
+     bool begin(void);
+ };
+ 
+ extern InternalFileSystem InternalFS;
+ 
+ #endif /* INTERNALFILESYSTEM_H_ */
+ 

src/helpers/stm32/STM32Board.h

@@ -0,0 +1,29 @@
+#pragma once
+
+#include <MeshCore.h>
+#include <Arduino.h>
+
+class STM32Board : public mesh::MainBoard {
+protected:
+  uint8_t startup_reason;
+
+public:
+  void begin() {
+    startup_reason = BD_STARTUP_NORMAL;
+  }
+
+  uint8_t getStartupReason() const override { return startup_reason; }
+
+  uint16_t getBattMilliVolts() override {
+    return 0;  // not supported
+  }
+
+  const char* getManufacturerName() const override {
+    return "Generic STM32";
+  }
+
+  void reboot() override {
+  }
+
+  bool startOTAUpdate(const char* id, char reply[]) override { return false; };
+};

variants/wio-e5/platformio.ini

@@ -0,0 +1,31 @@
+[lora_e5]
+extends = stm32_base
+board = lora_e5_dev_board
+board_upload.maximum_size = 229376 ; 32kb for FS
+build_flags = ${stm32_base.build_flags}
+  -D RADIO_CLASS=CustomSTM32WLx
+  -D WRAPPER_CLASS=CustomSTM32WLxWrapper
+  -D SPI_INTERFACES_COUNT=0
+  -I variants/wio-e5
+build_src_filter = ${stm32_base.build_src_filter}
+  +<../variants/wio-e5>
+
+[env:wio-e5-repeater]
+extends = lora_e5
+build_flags = ${lora_e5.build_flags}
+  -D LORA_TX_POWER=20
+  -D ADVERT_NAME='"WIO-E5 Repeater"'
+  -D ADMIN_PASSWORD='"password"'
+build_src_filter = ${lora_e5.build_src_filter}
+  +<../examples/simple_repeater/main.cpp>
+
+[env:wio-e5_companion_radio_usb]
+extends = lora_e5
+build_flags = ${lora_e5.build_flags}
+  -D LORA_TX_POWER=20
+  -D MAX_CONTACTS=100
+  -D MAX_GROUP_CHANNELS=8
+build_src_filter = ${lora_e5.build_src_filter}
+  +<../examples/companion_radio/*.cpp>
+lib_deps = ${lora_e5.lib_deps}
+  densaugeo/base64 @ ~1.4.0

variants/wio-e5/target.cpp

@@ -0,0 +1,69 @@
+#include <Arduino.h>
+#include "target.h"
+#include <helpers/ArduinoHelpers.h>
+
+STM32Board board;
+
+RADIO_CLASS radio = new STM32WLx_Module();
+
+WRAPPER_CLASS radio_driver(radio, board);
+
+static const uint32_t rfswitch_pins[] = {PA4,  PA5,  RADIOLIB_NC, RADIOLIB_NC, RADIOLIB_NC};
+static const Module::RfSwitchMode_t rfswitch_table[] = {
+  {STM32WLx::MODE_IDLE,  {LOW,  LOW}},
+  {STM32WLx::MODE_RX,    {HIGH, LOW}},
+  {STM32WLx::MODE_TX_HP, {LOW, HIGH}},  // for LoRa-E5 mini
+//  {STM32WLx::MODE_TX_LP, {HIGH, HIGH}},   // for LoRa-E5-LE mini
+  END_OF_MODE_TABLE,
+};
+
+VolatileRTCClock rtc_clock;
+SensorManager sensors;
+
+#ifndef LORA_CR
+  #define LORA_CR      5
+#endif
+
+bool radio_init() {
+//  rtc_clock.begin(Wire);
+  
+// #ifdef SX126X_DIO3_TCXO_VOLTAGE
+//   float tcxo = SX126X_DIO3_TCXO_VOLTAGE;
+// #else
+//   float tcxo = 1.6f;
+// #endif
+
+  radio.setRfSwitchTable(rfswitch_pins, rfswitch_table);
+
+  int status = radio.begin(LORA_FREQ, LORA_BW, LORA_SF, LORA_CR, RADIOLIB_SX126X_SYNC_WORD_PRIVATE, LORA_TX_POWER, 8, 1.7, 0);
+
+  if (status != RADIOLIB_ERR_NONE) {
+    Serial.print("ERROR: radio init failed: ");
+    Serial.println(status);
+    return false;  // fail
+  }
+  
+  radio.setCRC(1);
+  
+  return true;  // success
+}
+
+uint32_t radio_get_rng_seed() {
+  return radio.random(0x7FFFFFFF);
+}
+
+void radio_set_params(float freq, float bw, uint8_t sf, uint8_t cr) {
+  radio.setFrequency(freq);
+  radio.setSpreadingFactor(sf);
+  radio.setBandwidth(bw);
+  radio.setCodingRate(cr);
+}
+
+void radio_set_tx_power(uint8_t dbm) {
+  radio.setOutputPower(dbm);
+}
+
+mesh::LocalIdentity radio_new_identity() {
+  RadioNoiseListener rng(radio);
+  return mesh::LocalIdentity(&rng);  // create new random identity
+}

variants/wio-e5/target.h

@@ -0,0 +1,20 @@
+#pragma once
+
+#define RADIOLIB_STATIC_ONLY 1
+#include <RadioLib.h>
+#include <helpers/RadioLibWrappers.h>
+#include <helpers/stm32/STM32Board.h>
+#include <helpers/CustomSTM32WLxWrapper.h>
+#include <helpers/ArduinoHelpers.h>
+#include <helpers/SensorManager.h>
+
+extern STM32Board board;
+extern WRAPPER_CLASS radio_driver;
+extern VolatileRTCClock rtc_clock;
+extern SensorManager sensors;
+
+bool radio_init();
+uint32_t radio_get_rng_seed();
+void radio_set_params(float freq, float bw, uint8_t sf, uint8_t cr);
+void radio_set_tx_power(uint8_t dbm);
+mesh::LocalIdentity radio_new_identity();

variants/wio-e5/variant.h

@@ -0,0 +1,10 @@
+#pragma once
+
+// UART Definitions
+#ifndef SERIAL_UART_INSTANCE
+  #define SERIAL_UART_INSTANCE  101
+#endif
+
+#include <variant_LORA_E5_MINI.h>
+
+#undef RNG