fat32_struct.h

#ifndef NYUFILE_FAT32_STRUCT_H
#define NYUFILE_FAT32_STRUCT_H

#define INDEX(i, j, length) ((i) * (length) + (j))

#pragma pack(push, 1)
typedef struct BootEntry {
    unsigned char BS_jmpBoot[3]; // Assembly instruction to jump to boot code
    unsigned char BS_OEMName[8]; // OEM Name in ASCII
    unsigned short BPB_BytsPerSec; // Bytes per sector. Allowed values include 512, 1024, 2048, and 4096
    unsigned char BPB_SecPerClus; // Sectors per cluster (data unit). Allowed values are powers of 2, but the cluster size must be 32KB or smaller
    unsigned short BPB_RsvdSecCnt; // Size in sectors of the reserved area
    unsigned char BPB_NumFATs; // Number of FATs
    unsigned short BPB_RootEntCnt; // Maximum number of files in the root directory for FAT12 and FAT16. This is 0 for FAT32
    unsigned short BPB_TotSec16; // 16-bit value of number of sectors in file system
    unsigned char BPB_Media; // Media type
    unsigned short BPB_FATSz16; // 16-bit size in sectors of each FAT for FAT12 and FAT16. For FAT32, this field is 0
    unsigned short BPB_SecPerTrk; // Sectors per track of storage device
    unsigned short BPB_NumHeads; // Number of heads in storage device
    unsigned int BPB_HiddSec; // Number of sectors before the start of partition
    unsigned int BPB_TotSec32; // 32-bit value of number of sectors in file system. Either this value or the 16-bit value above must be 0
    unsigned int BPB_FATSz32; // 32-bit size in sectors of one FAT
    unsigned short BPB_ExtFlags; // A flag for FAT
    unsigned short BPB_FSVer; // The major and minor version number
    unsigned int BPB_RootClus; // Cluster where the root directory can be found
    unsigned short BPB_FSInfo; // Sector where FSINFO structure can be found
    unsigned short BPB_BkBootSec; // Sector where backup copy of boot sector is located
    unsigned char BPB_Reserved[12]; // Reserved
    unsigned char BS_DrvNum; // BIOS INT13h drive number
    unsigned char BS_Reserved1; // Not used
    unsigned char BS_BootSig; // Extended boot signature to identify if the next three values are valid
    unsigned int BS_VolID; // Volume serial number
    unsigned char BS_VolLab[11]; // Volume label in ASCII. User defines when creating the file system
    unsigned char BS_FilSysType[8]; // File system type label in ASCII
} BootEntry;
#pragma pack(pop)

#pragma pack(push, 1)
typedef struct DirEntry {
    unsigned char DIR_Name[11]; // File name
    unsigned char DIR_Attr; // File attributes
    unsigned char DIR_NTRes; // Reserved
    unsigned char DIR_CrtTimeTenth; // Created time (tenths of second)
    unsigned short DIR_CrtTime; // Created time (hours, minutes, seconds)
    unsigned short DIR_CrtDate; // Created day
    unsigned short DIR_LstAccDate; // Accessed day
    unsigned short DIR_FstClusHI; // High 2 bytes of the first cluster address
    unsigned short DIR_WrtTime; // Written time (hours, minutes, seconds
    unsigned short DIR_WrtDate; // Written day
    unsigned short DIR_FstClusLO; // Low 2 bytes of the first cluster address
    unsigned int DIR_FileSize; // File size in bytes. (0 for directories)
} DirEntry;
#pragma pack(pop)

#endif