Phat: FAT filesystem API

语言 Language

简体中文 | Chinglish

Overview

Phat is a FAT filesystem API designed for embedded systems and cross-platform development.

• Support MBR/GPT partition table
• Support no partition table (use the whole disk as a partition)
• Basic implementation for FAT12/16/32.
  • Iterate through directory
  • Open file(with creation or readonly)
  • Read file
  • Write file
  • Seek file
  • Delete file
  • Create directory
  • Remove directory
  • Rename
  • Move
  • Initialize a disk to MBR/GPT
  • Create partitions in a MBR/GPT disk
  • MakeFS: Format a partition to FAT12/16/32
• Debugging on Windows by accessing a virtual drive.
• Support for multiple partitions.
• No dynamic memory allocation is used (except the Windows debug code).
• Filenames and directories are encoded in UTF-16.
• The default code page is 437 (OEM United States).
• Includes an LRU (Least Recently Used) sector cache.
• No limitations on the length of any pathes (Only limits the filename/dirname length <= 255)

Usage

First, review BSP_phat.c and BSP_phat.h. These files provide the low-level driver implementation that allows the PHAT API to access the storage device.

You need to implement the following functions, NOTE: a block is a 512-byte sector

typedef int PhatBool_t;
PhatBool_t BSP_OpenDevice(void *userdata);
PhatBool_t BSP_CloseDevice(void *userdata);
PhatBool_t BSP_ReadSector(void *buffer, LBA_t LBA, size_t num_blocks, void *userdata);
PhatBool_t BSP_WriteSector(void *buffer, LBA_t LBA, size_t num_blocks, void *userdata);
LBA_t BSP_GetDeviceCapacity(void *userdata);

A default implementation is provided for the STM32H750 microcontroller to read/write via SDMMC1 when compiling with GCC or ARMCC.

If _WIN32 is defined, the default implementation uses CreateFileW() to open test.vhd. The virtual hard disk will be automatically created. After the test code exits, it will be automatically mounted to the system, meaning you'll notice that an additional drive appears. You can check this drive to observe whether the file system is functioning properly.

All you need is BSP_phat.c, BSP_phat.h, phat.c, phat.h. Add these files into your project.

Example

#include <stdio.h>
#include <stdlib.h>

#include "phat.h"

Phat_t phat;

void Error_Handler()
{
	exit(1);
}

#define V(x) if (x != PhatState_OK) Error_Handler()
#define V_(x) do {PhatState s = x; if (s != PhatState_OK) fprintf(stderr, #x ": %s\n", Phat_StateToString(s));} while (0)

int main(int argc, char**argv)
{
	PhatState res = PhatState_OK;
	Phat_DirInfo_t dir_info = { 0 };
	Phat_FileInfo_t file_info = { 0 };
	uint32_t file_size;
	char *file_buf = NULL;

	V(Phat_Init(&phat));
	V(Phat_Mount(&phat, 0));

	printf("==== Root directory files ====\n");
	V(Phat_OpenDir(&phat, L"", &dir_info));
	for (;;)
	{
		res = Phat_NextDirItem(&dir_info);
		if (res != PhatState_OK) break;
		if (dir_info.attributes & ATTRIB_DIRECTORY)
			printf("Dir:  %S\n", dir_info.LFN_name);
		else
			printf("File: %S\n", dir_info.LFN_name);
	}
	Phat_CloseDir(&dir_info);

	printf("==== Files in `TestPhat` directory ====\n");
	V_(Phat_OpenDir(&phat, L"TestPhat", &dir_info));
	for (;;)
	{
		res = Phat_NextDirItem(&dir_info);
		if (res != PhatState_OK) break;
		if (dir_info.attributes & ATTRIB_DIRECTORY)
			printf("Dir:  %S\n", dir_info.LFN_name);
		else
			printf("File: %S\n", dir_info.LFN_name);
	}
	Phat_CloseDir(&dir_info);

	V_(Phat_CreateDirectory(&phat, L"TestPhatMkDir"));
	V_(Phat_RemoveDirectory(&phat, L"TestPhatMkDir"));

	V_(Phat_OpenFile(&phat, L"TestPhat/The Biography of John Wok.txt", 1, &file_info));
	Phat_GetFileSize(&file_info, &file_size);
	file_buf = calloc(file_size + 1, 1);
	if (!file_buf) goto FailExit;
	V_(Phat_ReadFile(&file_info, file_buf, file_size, NULL));
	Phat_CloseFile(&file_info);
	printf("File contents:\n%s\n", file_buf);
	free(file_buf);

FailExit:
	V_(Phat_Unmount(&phat));
	V_(Phat_DeInit(&phat));
	return 0;
}