用于嵌入式设备的文件系统

#include "partition.h" #include "fat16.h" #include <stdlib.h> #include <string.h> #include "sd_file_time.h" /* 簇未使用 */ #define FAT16_CLUSTER_FREE 0x0000 /* 预留簇标记最小值 */ #define FAT16_CLUSTER_RESERVED_MIN 0xfff0 /* 预留簇标记最大值 */ #define FAT16_CLUSTER_RESERVED_MAX 0xfff6 /*坏簇*/ #define FAT16_CLUSTER_BAD 0xfff7 /*结束簇最小值*/ #define FAT16_CLUSTER_LAST_MIN 0xfff8 /*结束簇最大值，通常使用这个值*/ #define FAT16_CLUSTER_LAST_MAX 0xffff /*文件已经被标记删除*/ #define FAT16_DIRENTRY_DELETED 0xe5 /*??标记含义不清*/ #define FAT16_DIRENTRY_LFNLAST (1 << 6) /*??标记含义不清*/ #define FAT16_DIRENTRY_LFNSEQMASK ((1 << 6) - 1) /*用来传参数的的临时结构*/ struct fat16_read_callback_arg { uint16_t entry_cur; uint16_t entry_num; uint32_t entry_offset; uint8_t byte_count; }; /*读分区引导扇区*/ static uint8_t fat16_read_header(fat16_filesystem* fs); /*从根目录读一个目录项*/ static uint8_t fat16_read_root_dir_entry(const fat16_filesystem* fs, uint16_t entry_num, fat16_dir_entry* dir_entry); /*从一个子目录中读取一个目录项*/ static uint8_t fat16_read_sub_dir_entry(const fat16_filesystem* fs, uint16_t entry_num, const fat16_dir_entry* parent, struct fat16_dir_entry_struct* dir_entry); static uint8_t fat16_dir_entry_seek_callback(uint8_t* buffer, uint32_t offset, void* p); static uint8_t fat16_dir_entry_read_callback(uint8_t* buffer, uint32_t offset, void* p); static uint8_t fat16_interpret_dir_entry(fat16_dir_entry* dir_entry, const uint8_t* raw_entry); /*取出下一簇号*/ static uint16_t fat16_get_next_cluster(const fat16_filesystem* fs, uint16_t cluster_num); /*在簇链尾部增加一个新的簇*/ static uint16_t fat16_append_cluster(const fat16_filesystem* fs, uint16_t cluster_num); /*将簇释放以供后面使用*/ static uint8_t fat16_free_cluster(fat16_filesystem* fs, uint16_t cluster_num); /*写一个目录项到磁盘*/ uint8_t fat16_write_dir_entry(fat16_filesystem* fs, const fat16_dir_entry* dir_entry); /** 打开FAT16文件系统 输入参数 partition 分区句柄 返回： 0失败，1 成功 */ uint8_t fat16_open(fat16_filesystem * fat16_to_open, partition_base_info* partition) { if(!partition ||!partition->device_write ) return 0; if(!fat16_to_open) return 0; memset(fat16_to_open, 0, sizeof(*fat16_to_open)); fat16_to_open->ptr_partition = partition; if(!fat16_read_header(fat16_to_open)) { return 0; } return 1; } /** 特定分区文件系统 输入参数 fs 特定分区文件系统 */ void fat16_close(fat16_filesystem * fs) { if(!fs) return; memset(fs,0x00,sizeof(fs)); } /*读分区引导扇区*/ uint8_t fat16_read_header(fat16_filesystem* fs) { uint8_t buffer[25]; partition_base_info* partition; fat16_header* header; uint32_t partition_offset; uint16_t bytes_per_sector; uint8_t sectors_per_cluster ; uint16_t reserved_sectors ; uint8_t fat_copies ; uint16_t max_root_entries; uint16_t sectors_per_fat ; uint32_t sector_count ; if(!fs || !fs->ptr_partition) return 0; partition = fs->ptr_partition; header = &fs->header; if(partition->type != PARTITION_TYPE_FAT16 && partition->type != PARTITION_TYPE_FAT16_LBA) return 0; partition_offset = partition->offset * 512; if(!partition->device_read(partition_offset + 0x0b, buffer, sizeof(buffer))) return 0; memset(header, 0, sizeof(*header)); bytes_per_sector = ((uint16_t) buffer[0x00]) | ((uint16_t) buffer[0x01] << 8); sectors_per_cluster = buffer[0x02]; reserved_sectors = ((uint16_t) buffer[0x03]) | ((uint16_t) buffer[0x04] << 8); fat_copies = buffer[0x05]; max_root_entries = ((uint16_t) buffer[0x06]) | ((uint16_t) buffer[0x07] << 8); sectors_per_fat = ((uint16_t) buffer[0x0b]) | ((uint16_t) buffer[0x0c] << 8); sector_count = ((uint32_t) buffer[0x15]) | ((uint32_t) buffer[0x16] << 8) | ((uint32_t) buffer[0x17] << 16) | ((uint32_t) buffer[0x18] << 24); /*分区的大小字节数*/ header->size = sector_count * bytes_per_sector; /*fat表的相对于物理扇区的偏移地址*/ header->fat_offset = partition_offset + (uint32_t) reserved_sectors * bytes_per_sector; /*fat表占用的字节数 = fat表所占扇区数* 每扇区字节数 */ header->fat_size = (uint32_t) sectors_per_fat * bytes_per_sector; /*每扇区字节数*/ header->sector_size = bytes_per_sector; /*每簇字节数*/ header->cluster_size = (uint16_t) bytes_per_sector * sectors_per_cluster; /*根目录的偏移地址*/ header->root_dir_offset = header->fat_offset + (uint32_t) fat_copies * sectors_per_fat * bytes_per_sector; /*数据区第1个簇的偏移地址*/ header->cluster_zero_offset = /* jump to root directory entries */ header->root_dir_offset + /* skip root directory entries */ (uint32_t) max_root_entries * 32; return 1; } /*从根目录读一个目录项 输入参数 fs 特定分区文件系统句柄 输入参数 entry_num 目录项的索引号 输出参数 dir_entry 用来填写目录项的缓冲区 返回值 0 : 失败 , 1 成功 */ uint8_t fat16_read_root_dir_entry(const fat16_filesystem* fs, uint16_t entry_num, fat16_dir_entry* dir_entry) { /*我们读根目录的入口 */ const fat16_header* header = &fs->header; device_read_interval_t device_read_interval ; uint8_t buffer[32]; /* 跳到第n个项 */ struct fat16_read_callback_arg arg; if(!fs || !dir_entry) return 0; device_read_interval = fs->ptr_partition->device_read_interval; memset(&arg, 0, sizeof(arg)); arg.entry_num = entry_num; if(!device_read_interval(header->root_dir_offset, buffer, sizeof(buffer), header->cluster_zero_offset - header->root_dir_offset, fat16_dir_entry_seek_callback, &arg) || arg.entry_offset == 0 ) return 0; /* read entry */ memset(dir_entry, 0, sizeof(*dir_entry)); if(!device_read_interval(arg.entry_offset, buffer, sizeof(buffer), arg.byte_count, fat16_dir_entry_read_callback, dir_entry)) return 0; return dir_entry->long_name[0] != '\0' ? 1 : 0; } /** 从一个给定的父目录中读目录项（这个父目录不是根目录） 从根目录中读子目录用的是另外一个函数fat16_read_root_dir_entry 输入参数 fs 特定分区文件系统 输入参数 entry_num 目录的索引值 输入参数 parent 父目录的句柄 输出参数 dir_entry 填写目录项的缓冲区 返回值 0 失败, 1 成功 */ uint8_t fat16_read_sub_dir_entry(const fat16_filesystem * fs, uint16_t entry_num, const fat16_dir_entry* parent, struct fat16_dir_entry_struct* dir_entry) { /* 循环 这个目录所有的簇 */ uint8_t buffer[32]; uint32_t cluster_offset; uint16_t cluster_size = fs->header.cluster_size; uint16_t cluster_num = parent->cluster; struct fat16_read_callback_arg arg; if(!fs || !parent || !dir_entry) return 0; /* 我们是在一个父目录，并且准备在他的目录表中搜索 */ if(!(parent->attributes & FAT16_ATTRIB_DIR)) return 0; while(1) { /* 计算新簇的偏移量 */ cluster_offset = fs->header.cluster_zero_offset + (uint32_t) (cluster_num - 2) * cluster_size; /* 跳到第n个目录项 */ memset(&arg, 0, sizeof(arg)); arg.entry_num = entry_num; if(!fs->ptr_partition->device_read_interval(cluster_offset, buffer, sizeof(buffer), c