LittleFS：完整的嵌入式文件系统简介、移植教程

#include "lfs.h"
#include "w25qxx.h"

/**
* lfs与底层flash读数据接口
* @param c
* @param block 块编号
* @param off 块内偏移地址
* @param buffer 用于存储读取到的数据
* @param size 要读取的字节数
* @return
*/
static int lfs_deskio_read(const struct lfs_config *c, lfs_block_t block, lfs_off_t off, void *buffer, lfs_size_t size)
{
W25QXX_Read((uint8_t *)buffer, c->block_size * block + off, size);
return LFS_ERR_OK;
}

/**
* lfs与底层flash写数据接口
* @param c
* @param block 块编号
* @param off 块内偏移地址
* @param buffer 待写入的数据
* @param size 待写入数据的大小
* @return
*/
static int lfs_deskio_prog(const struct lfs_config *c, lfs_block_t block, lfs_off_t off, const void *buffer, lfs_size_t size)
{
W25QXX_Write_NoCheck((uint8_t *)buffer, c->block_size * block + off, size);
return LFS_ERR_OK;
}

/**
* lfs与底层flash擦除接口
* @param c
* @param block 块编号
* @return
*/
static int lfs_deskio_erase(const struct lfs_config *c, lfs_block_t block)
{
W25QXX_Erase_Sector(block);
return LFS_ERR_OK;
}

static int lfs_deskio_sync(const struct lfs_config *c)
{
return LFS_ERR_OK;
}


///
/// 静态内存使用方式必须设定这四个缓存
///
__align(4) static uint8_t read_buffer[16];
__align(4) static uint8_t prog_buffer[16];
__align(4) static uint8_t lookahead_buffer[16];

// lfs句柄
lfs_t lfs_w25qxx;

lfs_file_t lfs_file_w25qxx;

const struct lfs_config cfg =
{
// block device operations
.read = lfs_deskio_read,
.prog = lfs_deskio_prog,
.erase = lfs_deskio_erase,
.sync = lfs_deskio_sync,

// block device configuration
.read_size = 16,
.prog_size = 16,
.block_size = 4096,
.block_count = 128,
.cache_size = 16,
.lookahead_size = 16,
.block_cycles = 500,

//
// 使用静态内存必须设置这几个缓存
//
.read_buffer = read_buffer,
.prog_buffer = prog_buffer,
.lookahead_buffer = lookahead_buffer,
};

// entry point
void lfs_test(void)
{
// mount the filesystem
int err = lfs_mount(&lfs_w25qxx, &cfg);

// reformat if we can't mount the filesystem
// this should only happen on the first boot
if (err)
{
lfs_format(&lfs_w25qxx, &cfg);
lfs_mount(&lfs_w25qxx, &cfg);
}

// read current count
uint32_t boot_count = 0;
lfs_file_open(&lfs_w25qxx, &lfs_file_w25qxx, "boot_count", LFS_O_RDWR | LFS_O_CREAT);
lfs_file_read(&lfs_w25qxx, &lfs_file_w25qxx, &boot_count, sizeof(boot_count));

// update boot count
boot_count += 1;
lfs_file_rewind(&lfs_w25qxx, &lfs_file_w25qxx);
lfs_file_write(&lfs_w25qxx, &lfs_file_w25qxx, &boot_count, sizeof(boot_count));

// remember the storage is not updated until the file is closed successfully
lfs_file_close(&lfs_w25qxx, &lfs_file_w25qxx);

// release any resources we were using
lfs_unmount(&lfs_w25qxx);

// print the boot count
printf("boot_count: %d\n", boot_count);
}