// FAT on-disk layout definitions shared by the FAT driver.

#pragma once

#include <stdint.h>

#pragma pack(push, 1)

typedef struct {
    uint8_t  Jump[3];
    char     OemId[8];
    uint16_t BytesPerSector;
    uint8_t  SectorsPerCluster;
    uint16_t ReservedSectors;
    uint8_t  NumFats;
    uint16_t RootEntryCount;
    uint16_t TotalSectors16;
    uint8_t  MediaType;
    uint16_t FatSize16;
    uint16_t SectorsPerTrack;
    uint16_t NumHeads;
    uint32_t HiddenSectors;
    uint32_t TotalSectors32;
    uint32_t FatSize32;
    uint16_t ExtFlags;
    uint16_t FsVersion;
    uint32_t RootCluster;
    uint16_t FsInfoSector;
    uint16_t BackupBootSector;
    uint8_t  Reserved[12];
    uint8_t  DriveNumber;
    uint8_t  Reserved1;
    uint8_t  BootSignature;
    uint32_t VolumeId;
    char     VolumeLabel[11];
    char     FsType[8];
} BPB;

typedef struct {
    char     Name[8];
    char     Ext[3];
    uint8_t  Attr;
    uint8_t  Reserved;
    uint8_t  CrtTimeTenth;
    uint16_t CrtTime;
    uint16_t CrtDate;
    uint16_t LastAccDate;
    uint16_t FirstClusterHi;
    uint16_t WrtTime;
    uint16_t WrtDate;
    uint16_t FirstClusterLo;
    uint32_t FileSize;
} DIRENT;

typedef struct {
    uint8_t  Order;
    uint16_t Name1[5];
    uint8_t  Attr;
    uint8_t  Type;
    uint8_t  Checksum;
    uint16_t Name2[6];
    uint16_t FirstCluster;
    uint16_t Name3[2];
} LFN_ENTRY;

#pragma pack(pop)

#define ATTR_VOLUME_ID   0x08
#define ATTR_DIRECTORY   0x10
#define ATTR_ARCHIVE     0x20
#define ATTR_LFN         0x0F
#define FAT_NTRES_BASE_LOWER 0x08u
#define FAT_NTRES_EXT_LOWER  0x10u
#define FAT_FREE       0x00000000u
#define FAT16_EOC      0x0000FFF8u
#define FAT16_EOC_MARK 0x0000FFFFu
#define FAT32_EOC      0x0FFFFFF8u
#define FAT32_EOC_MARK 0x0FFFFFFFu
#define FAT_FIXED_ROOT_CLUSTER 0xFFFFFFFEu

typedef enum FAT_VARIANT {
    FatVariantUnsupported = 0,
    FatVariant12,
    FatVariant16,
    FatVariant32,
} FAT_VARIANT;