text: /*
   * spiffs_hydrogen.c
   *
   *  Created on: Jun 16, 2013
   *      Author: petera
   */
  
  #include "spiffs.h"
  #include "spiffs_nucleus.h"
  
  #if SPIFFS_FILEHDL_OFFSET
  #define SPIFFS_FH_OFFS(fs, fh)   ((fh) != 0 ? ((fh) + (fs)->cfg.fh_ix_offset) : 0)
  #define SPIFFS_FH_UNOFFS(fs, fh) ((fh) != 0 ? ((fh) - (fs)->cfg.fh_ix_offset) : 0)
  #else
  #define SPIFFS_FH_OFFS(fs, fh)   (fh)
  #define SPIFFS_FH_UNOFFS(fs, fh) (fh)
  #endif
  
  #if SPIFFS_CACHE == 1
  static s32_t spiffs_fflush_cache(spiffs *fs, spiffs_file fh);
  #endif
  
  #if SPIFFS_BUFFER_HELP
  u32_t SPIFFS_buffer_bytes_for_filedescs(spiffs *fs, u32_t num_descs)
  {
  	return num_descs * sizeof(spiffs_fd);
  }
  #if SPIFFS_CACHE
  u32_t SPIFFS_buffer_bytes_for_cache(spiffs *fs, u32_t num_pages)
  {
  	return sizeof(spiffs_cache) + num_pages * (sizeof(spiffs_cache_page) + SPIFFS_CFG_LOG_PAGE_SZ(fs));
  }
  #endif
  #endif
  
  u8_t SPIFFS_mounted(spiffs *fs)
  {
  	return SPIFFS_CHECK_MOUNT(fs);
  }
  
  s32_t SPIFFS_format(spiffs *fs)
  {
  	SPIFFS_API_CHECK_CFG(fs);
  	if (SPIFFS_CHECK_MOUNT(fs))
  	{
  		fs->err_code = SPIFFS_ERR_MOUNTED;
  		return -1;
  	}
  
  	s32_t res;
  	SPIFFS_LOCK(fs);
  
  	spiffs_block_ix bix = 0;
  	while (bix < fs->block_count)
  	{
  		fs->max_erase_count = 0;
  		res = spiffs_erase_block(fs, bix);
  		if (res != SPIFFS_OK)
  		{
  			res = SPIFFS_ERR_ERASE_FAIL;
  		}
  		SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  		bix++;
  	}
  
  	SPIFFS_UNLOCK(fs);
  
  	return 0;
  }
  
  s32_t SPIFFS_mount(spiffs *fs, spiffs_config *config, u8_t *work, u8_t *fd_space, u32_t fd_space_size, void *cache,
  		u32_t cache_size, spiffs_check_callback check_cb_f)
  {
  	void *user_data;
  	SPIFFS_LOCK(fs);
  	user_data = fs->user_data;
  	memset(fs, 0, sizeof(spiffs));
  	memcpy(&fs->cfg, config, sizeof(spiffs_config));
  	fs->user_data = user_data;
  	fs->block_count = SPIFFS_CFG_PHYS_SZ(fs) / SPIFFS_CFG_LOG_BLOCK_SZ(fs);
  	fs->work = &work[0];
  	fs->lu_work = &work[SPIFFS_CFG_LOG_PAGE_SZ(fs)];
  	memset(fd_space, 0, fd_space_size);
  	// align fd_space pointer to pointer size byte boundary, below is safe
  	u8_t ptr_size = sizeof(void*);
  #pragma GCC diagnostic push
  #pragma GCC diagnostic ignored "-Wpointer-to-int-cast"
  	u8_t addr_lsb = ((u8_t) fd_space) & (ptr_size - 1);
  #pragma GCC diagnostic pop
  	if (addr_lsb)
  	{
  		fd_space += (ptr_size - addr_lsb);
  		fd_space_size -= (ptr_size - addr_lsb);
  	}
  	fs->fd_space = fd_space;
  	fs->fd_count = (fd_space_size / sizeof(spiffs_fd));
  
  	// align cache pointer to 4 byte boundary, below is safe
  #pragma GCC diagnostic push
  #pragma GCC diagnostic ignored "-Wpointer-to-int-cast"
  	addr_lsb = ((u8_t) cache) & (ptr_size - 1);
  #pragma GCC diagnostic pop
  	if (addr_lsb)
  	{
  		u8_t *cache_8 = (u8_t *) cache;
  		cache_8 += (ptr_size - addr_lsb);
  		cache = cache_8;
  		cache_size -= (ptr_size - addr_lsb);
  	}
  	if (cache_size & (ptr_size - 1))
  	{
  		cache_size -= (cache_size & (ptr_size - 1));
  	}
  
  #if SPIFFS_CACHE
  	fs->cache = cache;
  	fs->cache_size = (cache_size > (SPIFFS_CFG_LOG_PAGE_SZ(fs) * 32)) ? SPIFFS_CFG_LOG_PAGE_SZ(fs) * 32 : cache_size;
  	spiffs_cache_init(fs);
  #endif
  
  	s32_t res;
  
  #if SPIFFS_USE_MAGIC
  	res = SPIFFS_CHECK_MAGIC_POSSIBLE(fs) ? SPIFFS_OK : SPIFFS_ERR_MAGIC_NOT_POSSIBLE;
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  #endif
  
  	fs->config_magic = SPIFFS_CONFIG_MAGIC;
  
  	res = spiffs_obj_lu_scan(fs);
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  
  	SPIFFS_DBG("page index byte len:         %i\n", SPIFFS_CFG_LOG_PAGE_SZ(fs)); SPIFFS_DBG("object lookup pages:         %i\n", SPIFFS_OBJ_LOOKUP_PAGES(fs)); SPIFFS_DBG("page pages per block:        %i\n", SPIFFS_PAGES_PER_BLOCK(fs)); SPIFFS_DBG("page header length:          %i\n", sizeof(spiffs_page_header)); SPIFFS_DBG("object header index entries: %i\n", SPIFFS_OBJ_HDR_IX_LEN(fs)); SPIFFS_DBG("object index entries:        %i\n", SPIFFS_OBJ_IX_LEN(fs)); SPIFFS_DBG("available file descriptors:  %i\n", fs->fd_count); SPIFFS_DBG("free blocks:                 %i\n", fs->free_blocks);
  
  	fs->check_cb_f = check_cb_f;
  
  	fs->mounted = 1;
  
  	SPIFFS_UNLOCK(fs);
  
  	return 0;
  }
  
  void SPIFFS_unmount(spiffs *fs)
  {
  	if (!SPIFFS_CHECK_CFG(fs) || !SPIFFS_CHECK_MOUNT(fs))
  		return; SPIFFS_LOCK(fs);
  	u32_t i;
  	spiffs_fd *fds = (spiffs_fd *) fs->fd_space;
  	for (i = 0; i < fs->fd_count; i++)
  	{
  		spiffs_fd *cur_fd = &fds[i];
  		if (cur_fd->file_nbr != 0)
  		{
  #if SPIFFS_CACHE
  			(void) spiffs_fflush_cache(fs, cur_fd->file_nbr);
  #endif
  			spiffs_fd_return(fs, cur_fd->file_nbr);
  		}
  	}
  	fs->mounted = 0;
  
  	SPIFFS_UNLOCK(fs);
  }
  
  s32_t SPIFFS_errno(spiffs *fs)
  {
  	return fs->err_code;
  }
  
  void SPIFFS_clearerr(spiffs *fs)
  {
  	fs->err_code = SPIFFS_OK;
  }
  
  s32_t SPIFFS_creat(spiffs *fs, const char *path, spiffs_mode mode)
  {
  	(void) mode;
  	SPIFFS_API_CHECK_CFG(fs);
  	SPIFFS_API_CHECK_MOUNT(fs); SPIFFS_LOCK(fs);
  	spiffs_obj_id obj_id;
  	s32_t res;
  
  	res = spiffs_obj_lu_find_free_obj_id(fs, &obj_id, (const u8_t*) path);
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  	res = spiffs_object_create(fs, obj_id, (const u8_t*) path, SPIFFS_TYPE_FILE, 0);
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res); SPIFFS_UNLOCK(fs);
  	return 0;
  }
  
  spiffs_file SPIFFS_open(spiffs *fs, const char *path, spiffs_flags flags, spiffs_mode mode)
  {
  	(void) mode;
  	SPIFFS_API_CHECK_CFG(fs);
  	SPIFFS_API_CHECK_MOUNT(fs); SPIFFS_LOCK(fs);
  
  	spiffs_fd *fd;
  	spiffs_page_ix pix;
  
  	s32_t res = spiffs_fd_find_new(fs, &fd);
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  
  	res = spiffs_object_find_object_index_header_by_name(fs, (const u8_t*) path, &pix);
  	if ((flags & SPIFFS_CREAT) == 0)
  	{
  		if (res < SPIFFS_OK)
  		{
  			spiffs_fd_return(fs, fd->file_nbr);
  		}
  		SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  	}
  
  	if (res == SPIFFS_OK && (flags & (SPIFFS_CREAT | SPIFFS_EXCL)) == (SPIFFS_CREAT | SPIFFS_EXCL))
  	{
  		// creat and excl and file exists - fail
  		res = SPIFFS_ERR_FILE_EXISTS;
  		spiffs_fd_return(fs, fd->file_nbr);
  		SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  	}
  
  	if ((flags & SPIFFS_CREAT) && res == SPIFFS_ERR_NOT_FOUND)
  	{
  		spiffs_obj_id obj_id;
  		// no need to enter conflicting name here, already looked for it above
  		res = spiffs_obj_lu_find_free_obj_id(fs, &obj_id, 0);
  		if (res < SPIFFS_OK)
  		{
  			spiffs_fd_return(fs, fd->file_nbr);
  		}
  		SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  		res = spiffs_object_create(fs, obj_id, (const u8_t*) path, SPIFFS_TYPE_FILE, &pix);
  		if (res < SPIFFS_OK)
  		{
  			spiffs_fd_return(fs, fd->file_nbr);
  		}
  		SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  		flags &= ~SPIFFS_TRUNC;
  	}
  	else
  	{
  		if (res < SPIFFS_OK)
  		{
  			spiffs_fd_return(fs, fd->file_nbr);
  		}
  		SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  	}
  	res = spiffs_object_open_by_page(fs, pix, fd, flags, mode);
  	if (res < SPIFFS_OK)
  	{
  		spiffs_fd_return(fs, fd->file_nbr);
  	}
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  	if (flags & SPIFFS_TRUNC)
  	{
  		res = spiffs_object_truncate(fd, 0, 0);
  		if (res < SPIFFS_OK)
  		{
  			spiffs_fd_return(fs, fd->file_nbr);
  		}
  		SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  	}
  
  	fd->fdoffset = 0;
  
  	SPIFFS_UNLOCK(fs);
  
  	return SPIFFS_FH_OFFS(fs, fd->file_nbr);
  }
  
  spiffs_file SPIFFS_open_by_dirent(spiffs *fs, struct spiffs_dirent *e, spiffs_flags flags, spiffs_mode mode)
  {
  	SPIFFS_API_CHECK_CFG(fs);
  	SPIFFS_API_CHECK_MOUNT(fs); SPIFFS_LOCK(fs);
  
  	spiffs_fd *fd;
  
  	s32_t res = spiffs_fd_find_new(fs, &fd);
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  
  	res = spiffs_object_open_by_page(fs, e->pix, fd, flags, mode);
  	if (res < SPIFFS_OK)
  	{
  		spiffs_fd_return(fs, fd->file_nbr);
  	}
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  	if (flags & SPIFFS_TRUNC)
  	{
  		res = spiffs_object_truncate(fd, 0, 0);
  		if (res < SPIFFS_OK)
  		{
  			spiffs_fd_return(fs, fd->file_nbr);
  		}
  		SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  	}
  
  	fd->fdoffset = 0;
  
  	SPIFFS_UNLOCK(fs);
  
  	return SPIFFS_FH_OFFS(fs, fd->file_nbr);
  }
  
  s32_t SPIFFS_read(spiffs *fs, spiffs_file fh, void *buf, s32_t len)
  {
  	SPIFFS_API_CHECK_CFG(fs);
  	SPIFFS_API_CHECK_MOUNT(fs); SPIFFS_LOCK(fs);
  
  	spiffs_fd *fd;
  	s32_t res;
  
  	fh = SPIFFS_FH_UNOFFS(fs, fh);
  	res = spiffs_fd_get(fs, fh, &fd);
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  
  	if ((fd->flags & SPIFFS_RDONLY) == 0)
  	{
  		res = SPIFFS_ERR_NOT_READABLE;
  		SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  	}
  
  	if (fd->size == SPIFFS_UNDEFINED_LEN && len > 0)
  	{
  		// special case for zero sized files
  		res = SPIFFS_ERR_END_OF_OBJECT;
  		SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  	}
  
  #if SPIFFS_CACHE_WR
  	spiffs_fflush_cache(fs, fh);
  #endif
  
  	if (fd->fdoffset + len >= fd->size)
  	{
  		// reading beyond file size
  		s32_t avail = fd->size - fd->fdoffset;
  		if (avail <= 0)
  		{
  			SPIFFS_API_CHECK_RES_UNLOCK(fs, SPIFFS_ERR_END_OF_OBJECT);
  		}
  		res = spiffs_object_read(fd, fd->fdoffset, avail, (u8_t*) buf);
  		if (res == SPIFFS_ERR_END_OF_OBJECT)
  		{
  			fd->fdoffset += avail;
  			SPIFFS_UNLOCK(fs);
  			return avail;
  		}
  		else
  		{
  			SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  			len = avail;
  		}
  	}
  	else
  	{
  		// reading within file size
  		res = spiffs_object_read(fd, fd->fdoffset, len, (u8_t*) buf);
  		SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  	}
  	fd->fdoffset += len;
  
  	SPIFFS_UNLOCK(fs);
  
  	return len;
  }
  
  static s32_t spiffs_hydro_write(spiffs *fs, spiffs_fd *fd, void *buf, u32_t offset, s32_t len)
  {
  	(void) fs;
  	s32_t res = SPIFFS_OK;
  	s32_t remaining = len;
  	if (fd->size != SPIFFS_UNDEFINED_LEN && offset < fd->size)
  	{
  		s32_t m_len = MIN((s32_t )(fd->size - offset), len);
  		res = spiffs_object_modify(fd, offset, (u8_t *) buf, m_len);
  		SPIFFS_CHECK_RES(res);
  		remaining -= m_len;
  		u8_t *buf_8 = (u8_t *) buf;
  		buf_8 += m_len;
  		buf = buf_8;
  		offset += m_len;
  	}
  	if (remaining > 0)
  	{
  		res = spiffs_object_append(fd, offset, (u8_t *) buf, remaining);
  		SPIFFS_CHECK_RES(res);
  	}
  	return len;
  
  }
  
  s32_t SPIFFS_write(spiffs *fs, spiffs_file fh, void *buf, s32_t len)
  {
  	SPIFFS_API_CHECK_CFG(fs);
  	SPIFFS_API_CHECK_MOUNT(fs); SPIFFS_LOCK(fs);
  
  	spiffs_fd *fd;
  	s32_t res;
  	u32_t offset;
  
  	fh = SPIFFS_FH_UNOFFS(fs, fh);
  	res = spiffs_fd_get(fs, fh, &fd);
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  
  	if ((fd->flags & SPIFFS_WRONLY) == 0)
  	{
  		res = SPIFFS_ERR_NOT_WRITABLE;
  		SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  	}
  
  	offset = fd->fdoffset;
  
  #if SPIFFS_CACHE_WR
  	if (fd->cache_page == 0)
  	{
  		// see if object id is associated with cache already
  		fd->cache_page = spiffs_cache_page_get_by_fd(fs, fd);
  	}
  #endif
  	if (fd->flags & SPIFFS_APPEND)
  	{
  		if (fd->size == SPIFFS_UNDEFINED_LEN)
  		{
  			offset = 0;
  		}
  		else
  		{
  			offset = fd->size;
  		}
  #if SPIFFS_CACHE_WR
  		if (fd->cache_page)
  		{
  			offset = MAX(offset, fd->cache_page->offset + fd->cache_page->size);
  		}
  #endif
  	}
  
  #if SPIFFS_CACHE_WR
  	if ((fd->flags & SPIFFS_DIRECT) == 0)
  	{
  		if (len < (s32_t) SPIFFS_CFG_LOG_PAGE_SZ(fs))
  		{
  			// small write, try to cache it
  			u8_t alloc_cpage = 1;
  			if (fd->cache_page)
  			{
  				// have a cached page for this fd already, check cache page boundaries
  				if (offset < fd->cache_page->offset || // writing before cache
  						offset > fd->cache_page->offset + fd->cache_page->size || // writing after cache
  						offset + len > fd->cache_page->offset + SPIFFS_CFG_LOG_PAGE_SZ(fs)) // writing beyond cache page
  				{
  					// boundary violation, write back cache first and allocate new
  					SPIFFS_CACHE_DBG("CACHE_WR_DUMP: dumping cache page %i for fd %i:%04x, boundary viol, offs:%i size:%i\n",
  							fd->cache_page->ix, fd->file_nbr, fd->obj_id, fd->cache_page->offset, fd->cache_page->size);
  					res = spiffs_hydro_write(fs, fd, spiffs_get_cache_page(fs, spiffs_get_cache(fs), fd->cache_page->ix),
  							fd->cache_page->offset, fd->cache_page->size);
  					spiffs_cache_fd_release(fs, fd->cache_page);
  					SPIFFS_API_CHECK_RES(fs, res);
  				}
  				else
  				{
  					// writing within cache
  					alloc_cpage = 0;
  				}
  			}
  
  			if (alloc_cpage)
  			{
  				fd->cache_page = spiffs_cache_page_allocate_by_fd(fs, fd);
  				if (fd->cache_page)
  				{
  					fd->cache_page->offset = offset;
  					fd->cache_page->size = 0;
  					SPIFFS_CACHE_DBG("CACHE_WR_ALLO: allocating cache page %i for fd %i:%04x\n",
  							fd->cache_page->ix, fd->file_nbr, fd->obj_id);
  				}
  			}
  
  			if (fd->cache_page)
  			{
  				u32_t offset_in_cpage = offset - fd->cache_page->offset;
  				SPIFFS_CACHE_DBG("CACHE_WR_WRITE: storing to cache page %i for fd %i:%04x, offs %i:%i len %i\n",
  						fd->cache_page->ix, fd->file_nbr, fd->obj_id,
  						offset, offset_in_cpage, len);
  				spiffs_cache *cache = spiffs_get_cache(fs);
  				u8_t *cpage_data = spiffs_get_cache_page(fs, cache, fd->cache_page->ix);
  				memcpy(&cpage_data[offset_in_cpage], buf, len);
  				fd->cache_page->size = MAX(fd->cache_page->size, offset_in_cpage + len);
  				fd->fdoffset += len;
  				SPIFFS_UNLOCK(fs);
  				return len;
  			}
  			else
  			{
  				res = spiffs_hydro_write(fs, fd, buf, offset, len);
  				SPIFFS_API_CHECK_RES(fs, res);
  				fd->fdoffset += len;
  				SPIFFS_UNLOCK(fs);
  				return res;
  			}
  		}
  		else
  		{
  			// big write, no need to cache it - but first check if there is a cached write already
  			if (fd->cache_page)
  			{
  				// write back cache first
  				SPIFFS_CACHE_DBG("CACHE_WR_DUMP: dumping cache page %i for fd %i:%04x, big write, offs:%i size:%i\n",
  						fd->cache_page->ix, fd->file_nbr, fd->obj_id, fd->cache_page->offset, fd->cache_page->size);
  				res = spiffs_hydro_write(fs, fd, spiffs_get_cache_page(fs, spiffs_get_cache(fs), fd->cache_page->ix),
  						fd->cache_page->offset, fd->cache_page->size);
  				spiffs_cache_fd_release(fs, fd->cache_page);
  				SPIFFS_API_CHECK_RES(fs, res);
  				res = spiffs_hydro_write(fs, fd, buf, offset, len);
  				SPIFFS_API_CHECK_RES(fs, res);
  			}
  		}
  	}
  #endif
  
  	res = spiffs_hydro_write(fs, fd, buf, offset, len);
  	SPIFFS_API_CHECK_RES(fs, res);
  	fd->fdoffset += len;
  
  	SPIFFS_UNLOCK(fs);
  
  	return res;
  }
  
  s32_t SPIFFS_lseek(spiffs *fs, spiffs_file fh, s32_t offs, int whence)
  {
  	SPIFFS_API_CHECK_CFG(fs);
  	SPIFFS_API_CHECK_MOUNT(fs); SPIFFS_LOCK(fs);
  
  	spiffs_fd *fd;
  	s32_t res;
  	fh = SPIFFS_FH_UNOFFS(fs, fh);
  	res = spiffs_fd_get(fs, fh, &fd);
  	SPIFFS_API_CHECK_RES(fs, res);
  
  #if SPIFFS_CACHE_WR
  	spiffs_fflush_cache(fs, fh);
  #endif
  
  	switch (whence)
  	{
  	case SPIFFS_SEEK_CUR:
  		offs = fd->fdoffset + offs;
  		break;
  	case SPIFFS_SEEK_END:
  		offs = (fd->size == SPIFFS_UNDEFINED_LEN ? 0 : fd->size) + offs;
  		break;
  	}
  
  	if ((offs > (s32_t) fd->size) && (SPIFFS_UNDEFINED_LEN != fd->size))
  	{
  		res = SPIFFS_ERR_END_OF_OBJECT;
  	}
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  
  	spiffs_span_ix data_spix = offs / SPIFFS_DATA_PAGE_SIZE(fs);
  	spiffs_span_ix objix_spix = SPIFFS_OBJ_IX_ENTRY_SPAN_IX(fs, data_spix);
  	if (fd->cursor_objix_spix != objix_spix)
  	{
  		spiffs_page_ix pix;
  		res = spiffs_obj_lu_find_id_and_span(fs, fd->obj_id | SPIFFS_OBJ_ID_IX_FLAG, objix_spix, 0, &pix);
  		SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  		fd->cursor_objix_spix = objix_spix;
  		fd->cursor_objix_pix = pix;
  	}
  	fd->fdoffset = offs;
  
  	SPIFFS_UNLOCK(fs);
  
  	return offs;
  }
  
  s32_t SPIFFS_remove(spiffs *fs, const char *path)
  {
  	SPIFFS_API_CHECK_CFG(fs);
  	SPIFFS_API_CHECK_MOUNT(fs); SPIFFS_LOCK(fs);
  
  	spiffs_fd *fd;
  	spiffs_page_ix pix;
  	s32_t res;
  
  	res = spiffs_fd_find_new(fs, &fd);
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  
  	res = spiffs_object_find_object_index_header_by_name(fs, (const u8_t*) path, &pix);
  	if (res != SPIFFS_OK)
  	{
  		spiffs_fd_return(fs, fd->file_nbr);
  	}
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  
  	res = spiffs_object_open_by_page(fs, pix, fd, 0, 0);
  	if (res != SPIFFS_OK)
  	{
  		spiffs_fd_return(fs, fd->file_nbr);
  	}
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  
  	res = spiffs_object_truncate(fd, 0, 1);
  	if (res != SPIFFS_OK)
  	{
  		spiffs_fd_return(fs, fd->file_nbr);
  	}
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  
  	SPIFFS_UNLOCK(fs);
  	return 0;
  }
  
  s32_t SPIFFS_fremove(spiffs *fs, spiffs_file fh)
  {
  	SPIFFS_API_CHECK_CFG(fs);
  	SPIFFS_API_CHECK_MOUNT(fs); SPIFFS_LOCK(fs);
  
  	spiffs_fd *fd;
  	s32_t res;
  	fh = SPIFFS_FH_UNOFFS(fs, fh);
  	res = spiffs_fd_get(fs, fh, &fd);
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  
  	if ((fd->flags & SPIFFS_WRONLY) == 0)
  	{
  		res = SPIFFS_ERR_NOT_WRITABLE;
  		SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  	}
  
  #if SPIFFS_CACHE_WR
  	spiffs_cache_fd_release(fs, fd->cache_page);
  #endif
  
  	res = spiffs_object_truncate(fd, 0, 1);
  
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  
  	SPIFFS_UNLOCK(fs);
  
  	return 0;
  }
  
  static s32_t spiffs_stat_pix(spiffs *fs, spiffs_page_ix pix, spiffs_file fh, spiffs_stat *s)
  {
  	(void) fh;
  	spiffs_page_object_ix_header objix_hdr;
  	spiffs_obj_id obj_id;
  	s32_t res = _spiffs_rd(fs, SPIFFS_OP_T_OBJ_IX | SPIFFS_OP_C_READ, fh, SPIFFS_PAGE_TO_PADDR(fs, pix),
  			sizeof(spiffs_page_object_ix_header), (u8_t * )&objix_hdr);
  	SPIFFS_API_CHECK_RES(fs, res);
  
  	u32_t obj_id_addr = SPIFFS_BLOCK_TO_PADDR(fs, SPIFFS_BLOCK_FOR_PAGE(fs , pix)) +
  	SPIFFS_OBJ_LOOKUP_ENTRY_FOR_PAGE(fs, pix) * sizeof(spiffs_obj_id);
  	res = _spiffs_rd(fs, SPIFFS_OP_T_OBJ_LU | SPIFFS_OP_C_READ, fh, obj_id_addr, sizeof(spiffs_obj_id), (u8_t * )&obj_id);
  	SPIFFS_API_CHECK_RES(fs, res);
  
  	s->obj_id = obj_id;
  	s->type = objix_hdr.type;
  	s->size = objix_hdr.size == SPIFFS_UNDEFINED_LEN ? 0 : objix_hdr.size;
  	strncpy((char *) s->name, (char *) objix_hdr.name, SPIFFS_OBJ_NAME_LEN);
  
  	return res;
  }
  
  s32_t SPIFFS_stat(spiffs *fs, const char *path, spiffs_stat *s)
  {
  	SPIFFS_API_CHECK_CFG(fs);
  	SPIFFS_API_CHECK_MOUNT(fs); SPIFFS_LOCK(fs);
  
  	s32_t res;
  	spiffs_page_ix pix;
  
  	res = spiffs_object_find_object_index_header_by_name(fs, (const u8_t*) path, &pix);
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  
  	res = spiffs_stat_pix(fs, pix, 0, s);
  
  	SPIFFS_UNLOCK(fs);
  
  	return res;
  }
  
  s32_t SPIFFS_fstat(spiffs *fs, spiffs_file fh, spiffs_stat *s)
  {
  	SPIFFS_API_CHECK_CFG(fs);
  	SPIFFS_API_CHECK_MOUNT(fs); SPIFFS_LOCK(fs);
  
  	spiffs_fd *fd;
  	s32_t res;
  
  	fh = SPIFFS_FH_UNOFFS(fs, fh);
  	res = spiffs_fd_get(fs, fh, &fd);
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  
  #if SPIFFS_CACHE_WR
  	spiffs_fflush_cache(fs, fh);
  #endif
  
  	res = spiffs_stat_pix(fs, fd->objix_hdr_pix, fh, s);
  
  	SPIFFS_UNLOCK(fs);
  
  	return res;
  }
  
  // Checks if there are any cached writes for the object id associated with
  // given filehandle. If so, these writes are flushed.
  #if SPIFFS_CACHE == 1
  static s32_t spiffs_fflush_cache(spiffs *fs, spiffs_file fh)
  {
  	(void) fs;
  	(void) fh;
  	s32_t res = SPIFFS_OK;
  #if SPIFFS_CACHE_WR
  
  	spiffs_fd *fd;
  	res = spiffs_fd_get(fs, fh, &fd);
  	SPIFFS_API_CHECK_RES(fs, res);
  
  	if ((fd->flags & SPIFFS_DIRECT) == 0)
  	{
  		if (fd->cache_page == 0)
  		{
  			// see if object id is associated with cache already
  			fd->cache_page = spiffs_cache_page_get_by_fd(fs, fd);
  		}
  		if (fd->cache_page)
  		{
  			SPIFFS_CACHE_DBG("CACHE_WR_DUMP: dumping cache page %i for fd %i:%04x, flush, offs:%i size:%i\n",
  					fd->cache_page->ix, fd->file_nbr, fd->obj_id, fd->cache_page->offset, fd->cache_page->size);
  			res = spiffs_hydro_write(fs, fd, spiffs_get_cache_page(fs, spiffs_get_cache(fs), fd->cache_page->ix),
  					fd->cache_page->offset, fd->cache_page->size);
  			if (res < SPIFFS_OK)
  			{
  				fs->err_code = res;
  			}
  			spiffs_cache_fd_release(fs, fd->cache_page);
  		}
  	}
  #endif
  
  	return res;
  }
  #endif
  
  s32_t SPIFFS_fflush(spiffs *fs, spiffs_file fh)
  {
  	(void) fh;
  	SPIFFS_API_CHECK_CFG(fs);
  	SPIFFS_API_CHECK_MOUNT(fs);
  	s32_t res = SPIFFS_OK;
  #if SPIFFS_CACHE_WR
  	SPIFFS_LOCK(fs);
  	fh = SPIFFS_FH_UNOFFS(fs, fh);
  	res = spiffs_fflush_cache(fs, fh);
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res); SPIFFS_UNLOCK(fs);
  #endif
  
  	return res;
  }
  
  s32_t SPIFFS_close(spiffs *fs, spiffs_file fh)
  {
  	SPIFFS_API_CHECK_CFG(fs);
  	SPIFFS_API_CHECK_MOUNT(fs);
  
  	s32_t res = SPIFFS_OK;
  	SPIFFS_LOCK(fs);
  
  	fh = SPIFFS_FH_UNOFFS(fs, fh);
  #if SPIFFS_CACHE
  	res = spiffs_fflush_cache(fs, fh);
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  #endif
  	res = spiffs_fd_return(fs, fh);
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  
  	SPIFFS_UNLOCK(fs);
  
  	return res;
  }
  
  s32_t SPIFFS_rename(spiffs *fs, const char *old, const char *new)
  {
  	SPIFFS_API_CHECK_CFG(fs);
  	SPIFFS_API_CHECK_MOUNT(fs); SPIFFS_LOCK(fs);
  
  	spiffs_page_ix pix_old, pix_dummy;
  	spiffs_fd *fd;
  
  	s32_t res = spiffs_object_find_object_index_header_by_name(fs, (const u8_t*) old, &pix_old);
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  
  	res = spiffs_object_find_object_index_header_by_name(fs, (const u8_t*) new, &pix_dummy);
  	if (res == SPIFFS_ERR_NOT_FOUND)
  	{
  		res = SPIFFS_OK;
  	}
  	else if (res == SPIFFS_OK)
  	{
  		res = SPIFFS_ERR_CONFLICTING_NAME;
  	}
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  
  	res = spiffs_fd_find_new(fs, &fd);
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  
  	res = spiffs_object_open_by_page(fs, pix_old, fd, 0, 0);
  	if (res != SPIFFS_OK)
  	{
  		spiffs_fd_return(fs, fd->file_nbr);
  	}
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  
  	res = spiffs_object_update_index_hdr(fs, fd, fd->obj_id, fd->objix_hdr_pix, 0, (const u8_t*) new, 0, &pix_dummy);
  
  	spiffs_fd_return(fs, fd->file_nbr);
  
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  
  	SPIFFS_UNLOCK(fs);
  
  	return res;
  }
  
  spiffs_DIR *SPIFFS_opendir(spiffs *fs, const char *name, spiffs_DIR *d)
  {
  	(void) name;
  
  	if (!SPIFFS_CHECK_CFG((fs)))
  	{
  		(fs)->err_code = SPIFFS_ERR_NOT_CONFIGURED;
  		return 0;
  	}
  
  	if (!SPIFFS_CHECK_MOUNT(fs))
  	{
  		fs->err_code = SPIFFS_ERR_NOT_MOUNTED;
  		return 0;
  	}
  
  	d->fs = fs;
  	d->block = 0;
  	d->entry = 0;
  	return d;
  }
  
  static s32_t spiffs_read_dir_v(spiffs *fs, spiffs_obj_id obj_id, spiffs_block_ix bix, int ix_entry, const void *user_const_p,
  		void *user_var_p)
  {
  	(void) user_const_p;
  	s32_t res;
  	spiffs_page_object_ix_header objix_hdr;
  	if (obj_id == SPIFFS_OBJ_ID_FREE || obj_id == SPIFFS_OBJ_ID_DELETED || (obj_id & SPIFFS_OBJ_ID_IX_FLAG) == 0)
  	{
  		return SPIFFS_VIS_COUNTINUE;
  	}
  
  	spiffs_page_ix pix = SPIFFS_OBJ_LOOKUP_ENTRY_TO_PIX(fs, bix, ix_entry);
  	res = _spiffs_rd(fs, SPIFFS_OP_T_OBJ_LU2 | SPIFFS_OP_C_READ, 0, SPIFFS_PAGE_TO_PADDR(fs, pix),
  			sizeof(spiffs_page_object_ix_header), (u8_t * )&objix_hdr);
  	if (res != SPIFFS_OK)
  		return res;
  	if ((obj_id & SPIFFS_OBJ_ID_IX_FLAG) && objix_hdr.p_hdr.span_ix == 0
  			&& (objix_hdr.p_hdr.flags & (SPIFFS_PH_FLAG_DELET | SPIFFS_PH_FLAG_FINAL | SPIFFS_PH_FLAG_IXDELE))
  					== (SPIFFS_PH_FLAG_DELET | SPIFFS_PH_FLAG_IXDELE))
  	{
  		struct spiffs_dirent *e = (struct spiffs_dirent*) user_var_p;
  		e->obj_id = obj_id;
  		strcpy((char *) e->name, (char *) objix_hdr.name);
  		e->type = objix_hdr.type;
  		e->size = objix_hdr.size == SPIFFS_UNDEFINED_LEN ? 0 : objix_hdr.size;
  		e->pix = pix;
  		return SPIFFS_OK;
  	}
  
  	return SPIFFS_VIS_COUNTINUE;
  }
  
  struct spiffs_dirent *SPIFFS_readdir(spiffs_DIR *d, struct spiffs_dirent *e)
  {
  	if (!SPIFFS_CHECK_MOUNT(d->fs))
  	{
  		d->fs->err_code = SPIFFS_ERR_NOT_MOUNTED;
  		return 0;
  	} SPIFFS_LOCK(d->fs);
  
  	spiffs_block_ix bix;
  	int entry;
  	s32_t res;
  	struct spiffs_dirent *ret = 0;
  
  	res = spiffs_obj_lu_find_entry_visitor(d->fs, d->block, d->entry,
  	SPIFFS_VIS_NO_WRAP, 0, spiffs_read_dir_v, 0, e, &bix, &entry);
  	if (res == SPIFFS_OK)
  	{
  		d->block = bix;
  		d->entry = entry + 1;
  		ret = e;
  	}
  	else
  	{
  		d->fs->err_code = res;
  	} SPIFFS_UNLOCK(d->fs);
  	return ret;
  }
  
  s32_t SPIFFS_closedir(spiffs_DIR *d)
  {
  	SPIFFS_API_CHECK_CFG(d->fs);
  	SPIFFS_API_CHECK_MOUNT(d->fs);
  	return 0;
  }
  
  s32_t SPIFFS_check(spiffs *fs)
  {
  	s32_t res;
  	SPIFFS_API_CHECK_CFG(fs);
  	SPIFFS_API_CHECK_MOUNT(fs); SPIFFS_LOCK(fs);
  
  	res = spiffs_lookup_consistency_check(fs, 0);
  
  	res = spiffs_object_index_consistency_check(fs);
  
  	res = spiffs_page_consistency_check(fs);
  
  	res = spiffs_obj_lu_scan(fs);
  
  	SPIFFS_UNLOCK(fs);
  	return res;
  }
  
  s32_t SPIFFS_info(spiffs *fs, u32_t *total, u32_t *used)
  {
  	s32_t res = SPIFFS_OK;
  	SPIFFS_API_CHECK_CFG(fs);
  	SPIFFS_API_CHECK_MOUNT(fs); SPIFFS_LOCK(fs);
  
  	u32_t pages_per_block = SPIFFS_PAGES_PER_BLOCK(fs);
  	u32_t blocks = fs->block_count;
  	u32_t obj_lu_pages = SPIFFS_OBJ_LOOKUP_PAGES(fs);
  	u32_t data_page_size = SPIFFS_DATA_PAGE_SIZE(fs);
  	u32_t total_data_pages = (blocks - 2) * (pages_per_block - obj_lu_pages) + 1; // -2 for spare blocks, +1 for emergency page
  
  	if (total)
  	{
  		*total = total_data_pages * data_page_size;
  	}
  
  	if (used)
  	{
  		*used = fs->stats_p_allocated * data_page_size;
  	}
  
  	SPIFFS_UNLOCK(fs);
  	return res;
  }
  
  s32_t SPIFFS_gc_quick(spiffs *fs, u16_t max_free_pages)
  {
  	s32_t res;
  	SPIFFS_API_CHECK_CFG(fs);
  	SPIFFS_API_CHECK_MOUNT(fs); SPIFFS_LOCK(fs);
  
  	res = spiffs_gc_quick(fs, max_free_pages);
  
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res); SPIFFS_UNLOCK(fs);
  	return 0;
  }
  
  s32_t SPIFFS_gc(spiffs *fs, u32_t size)
  {
  	s32_t res;
  	SPIFFS_API_CHECK_CFG(fs);
  	SPIFFS_API_CHECK_MOUNT(fs); SPIFFS_LOCK(fs);
  
  	res = spiffs_gc_check(fs, size);
  
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res); SPIFFS_UNLOCK(fs);
  	return 0;
  }
  
  s32_t SPIFFS_eof(spiffs *fs, spiffs_file fh)
  {
  	s32_t res;
  	SPIFFS_API_CHECK_CFG(fs);
  	SPIFFS_API_CHECK_MOUNT(fs); SPIFFS_LOCK(fs);
  
  	fh = SPIFFS_FH_UNOFFS(fs, fh);
  
  	spiffs_fd *fd;
  	res = spiffs_fd_get(fs, fh, &fd);
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  
  #if SPIFFS_CACHE_WR
  	res = spiffs_fflush_cache(fs, fh);
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  #endif
  
  	res = (fd->fdoffset == fd->size);
  
  	SPIFFS_UNLOCK(fs);
  	return res;
  }
  
  s32_t SPIFFS_tell(spiffs *fs, spiffs_file fh)
  {
  	s32_t res;
  	SPIFFS_API_CHECK_CFG(fs);
  	SPIFFS_API_CHECK_MOUNT(fs); SPIFFS_LOCK(fs);
  
  	fh = SPIFFS_FH_UNOFFS(fs, fh);
  
  	spiffs_fd *fd;
  	res = spiffs_fd_get(fs, fh, &fd);
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  
  #if SPIFFS_CACHE_WR
  	res = spiffs_fflush_cache(fs, fh);
  	SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
  #endif
  
  	res = fd->fdoffset;
  
  	SPIFFS_UNLOCK(fs);
  	return res;
  }
  
  #if SPIFFS_TEST_VISUALISATION
  s32_t SPIFFS_vis(spiffs *fs)
  {
  	s32_t res = SPIFFS_OK;
  	SPIFFS_API_CHECK_CFG(fs);
  	SPIFFS_API_CHECK_MOUNT(fs); SPIFFS_LOCK(fs);
  
  	int entries_per_page = (SPIFFS_CFG_LOG_PAGE_SZ(fs) / sizeof(spiffs_obj_id));
  	spiffs_obj_id *obj_lu_buf = (spiffs_obj_id *) fs->lu_work;
  	spiffs_block_ix bix = 0;
  
  	while (bix < fs->block_count)
  	{
  		// check each object lookup page
  		int obj_lookup_page = 0;
  		int cur_entry = 0;
  
  		while (res == SPIFFS_OK && obj_lookup_page < (int) SPIFFS_OBJ_LOOKUP_PAGES(fs))
  		{
  			int entry_offset = obj_lookup_page * entries_per_page;
  			res = _spiffs_rd(fs, SPIFFS_OP_T_OBJ_LU | SPIFFS_OP_C_READ, 0,
  					bix * SPIFFS_CFG_LOG_BLOCK_SZ(fs) + SPIFFS_PAGE_TO_PADDR(fs, obj_lookup_page), SPIFFS_CFG_LOG_PAGE_SZ(fs),
  					fs->lu_work);
  			// check each entry
  			while (res == SPIFFS_OK && cur_entry - entry_offset < entries_per_page
  					&& cur_entry < (int) (SPIFFS_PAGES_PER_BLOCK(fs) - SPIFFS_OBJ_LOOKUP_PAGES(fs)))
  			{
  				spiffs_obj_id obj_id = obj_lu_buf[cur_entry - entry_offset];
  				if (cur_entry == 0)
  				{
  					spiffs_printf("%4i ", bix);
  				}
  				else if ((cur_entry & 0x3f) == 0)
  				{
  					spiffs_printf("     ");
  				}
  				if (obj_id == SPIFFS_OBJ_ID_FREE)
  				{
  					spiffs_printf(SPIFFS_TEST_VIS_FREE_STR);
  				}
  				else if (obj_id == SPIFFS_OBJ_ID_DELETED)
  				{
  					spiffs_printf(SPIFFS_TEST_VIS_DELE_STR);
  				}
  				else if (obj_id & SPIFFS_OBJ_ID_IX_FLAG)
  				{
  					spiffs_printf(SPIFFS_TEST_VIS_INDX_STR(obj_id));
  				}
  				else
  				{
  					spiffs_printf(SPIFFS_TEST_VIS_DATA_STR(obj_id));
  				}
  				cur_entry++;
  				if ((cur_entry & 0x3f) == 0)
  				{
  					spiffs_printf("\n");
  				}
  			} // per entry
  			obj_lookup_page++;
  		} // per object lookup page
  
  		spiffs_obj_id erase_count;
  		res = _spiffs_rd(fs, SPIFFS_OP_C_READ | SPIFFS_OP_T_OBJ_LU2, 0, SPIFFS_ERASE_COUNT_PADDR(fs, bix), sizeof(spiffs_obj_id),
  				(u8_t * )&erase_count);
  		SPIFFS_CHECK_RES(res);
  
  		if (erase_count != (spiffs_obj_id) -1)
  		{
  			spiffs_printf("\tera_cnt: %i\n", erase_count);
  		}
  		else
  		{
  			spiffs_printf("\tera_cnt: N/A\n");
  		}
  
  		bix++;
  	} // per block
  #pragma GCC diagnostic push
  #pragma GCC diagnostic ignored "-Wformat"
  
  	spiffs_printf("era_cnt_max: %i\n", fs->max_erase_count);
  	spiffs_printf("last_errno:  %i\n", fs->err_code);
  	spiffs_printf("blocks:      %i\n", fs->block_count);
  	spiffs_printf("free_blocks: %i\n", fs->free_blocks);
  	spiffs_printf("page_alloc:  %i\n", fs->stats_p_allocated);
  	spiffs_printf("page_delet:  %i\n", fs->stats_p_deleted);
  	u32_t total, used;
  	SPIFFS_info(fs, &total, &used);
  	spiffs_printf("used:        %i of %i\n", used, total);
  
  #pragma GCC diagnostic pop
  
  	SPIFFS_UNLOCK(fs);
  	return res;
  }
  #endif
  