/* Arduino SdFat Library
   Copyright (C) 2009 by William Greiman

   This file is part of the Arduino SdFat Library

   This Library is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with the Arduino SdFat Library.  If not, see
   <http://www.gnu.org/licenses/>.
*/
#ifndef FatStructs_h
#define FatStructs_h
/**
   \file
   FAT file structures
*/
/*
   mostly from Microsoft document fatgen103.doc
   http://www.microsoft.com/whdc/system/platform/firmware/fatgen.mspx
*/
//------------------------------------------------------------------------------
/** Value for byte 510 of boot block or MBR */
uint8_t const BOOTSIG0 = 0X55;
/** Value for byte 511 of boot block or MBR */
uint8_t const BOOTSIG1 = 0XAA;
//------------------------------------------------------------------------------
/**
   \struct partitionTable
   \brief MBR partition table entry

   A partition table entry for a MBR formatted storage device.
   The MBR partition table has four entries.
*/
struct partitionTable {
  /**
     Boot Indicator . Indicates whether the volume is the active
     partition.  Legal values include: 0X00. Do not use for booting.
     0X80 Active partition.
  */
  uint8_t  boot;
  /**
      Head part of Cylinder-head-sector address of the first block in
      the partition. Legal values are 0-255. Only used in old PC BIOS.
  */
  uint8_t  beginHead;
  /**
     Sector part of Cylinder-head-sector address of the first block in
     the partition. Legal values are 1-63. Only used in old PC BIOS.
  */
  unsigned beginSector : 6;
  /** High bits cylinder for first block in partition. */
  unsigned beginCylinderHigh : 2;
  /**
     Combine beginCylinderLow with beginCylinderHigh. Legal values
     are 0-1023.  Only used in old PC BIOS.
  */
  uint8_t  beginCylinderLow;
  /**
     Partition type. See defines that begin with PART_TYPE_ for
     some Microsoft partition types.
  */
  uint8_t  type;
  /**
     head part of cylinder-head-sector address of the last sector in the
     partition.  Legal values are 0-255. Only used in old PC BIOS.
  */
  uint8_t  endHead;
  /**
     Sector part of cylinder-head-sector address of the last sector in
     the partition.  Legal values are 1-63. Only used in old PC BIOS.
  */
  unsigned endSector : 6;
  /** High bits of end cylinder */
  unsigned endCylinderHigh : 2;
  /**
     Combine endCylinderLow with endCylinderHigh. Legal values
     are 0-1023.  Only used in old PC BIOS.
  */
  uint8_t  endCylinderLow;
  /** Logical block address of the first block in the partition. */
  uint32_t firstSector;
  /** Length of the partition, in blocks. */
  uint32_t totalSectors;
} __attribute__((packed));
/** Type name for partitionTable */
typedef struct partitionTable part_t;
//------------------------------------------------------------------------------
/**
   \struct masterBootRecord

   \brief Master Boot Record

   The first block of a storage device that is formatted with a MBR.
*/
struct masterBootRecord {
  /** Code Area for master boot program. */
  uint8_t  codeArea[440];
  /** Optional WindowsNT disk signature. May contain more boot code. */
  uint32_t diskSignature;
  /** Usually zero but may be more boot code. */
  uint16_t usuallyZero;
  /** Partition tables. */
  part_t   part[4];
  /** First MBR signature byte. Must be 0X55 */
  uint8_t  mbrSig0;
  /** Second MBR signature byte. Must be 0XAA */
  uint8_t  mbrSig1;
} __attribute__((packed));
/** Type name for masterBootRecord */
typedef struct masterBootRecord mbr_t;
//------------------------------------------------------------------------------
/**
   \struct biosParmBlock

   \brief BIOS parameter block

    The BIOS parameter block describes the physical layout of a FAT volume.
*/
struct biosParmBlock {
  /**
     Count of bytes per sector. This value may take on only the
     following values: 512, 1024, 2048 or 4096
  */
  uint16_t bytesPerSector;
  /**
     Number of sectors per allocation unit. This value must be a
     power of 2 that is greater than 0. The legal values are
     1, 2, 4, 8, 16, 32, 64, and 128.
  */
  uint8_t  sectorsPerCluster;
  /**
     Number of sectors before the first FAT.
     This value must not be zero.
  */
  uint16_t reservedSectorCount;
  /** The count of FAT data structures on the volume. This field should
      always contain the value 2 for any FAT volume of any type.
  */
  uint8_t  fatCount;
  /**
    For FAT12 and FAT16 volumes, this field contains the count of
    32-byte directory entries in the root directory. For FAT32 volumes,
    this field must be set to 0. For FAT12 and FAT16 volumes, this
    value should always specify a count that when multiplied by 32
    results in a multiple of bytesPerSector.  FAT16 volumes should
    use the value 512.
  */
  uint16_t rootDirEntryCount;
  /**
     This field is the old 16-bit total count of sectors on the volume.
     This count includes the count of all sectors in all four regions
     of the volume. This field can be 0; if it is 0, then totalSectors32
     must be non-zero.  For FAT32 volumes, this field must be 0. For
     FAT12 and FAT16 volumes, this field contains the sector count, and
     totalSectors32 is 0 if the total sector count fits
     (is less than 0x10000).
  */
  uint16_t totalSectors16;
  /**
     This dates back to the old MS-DOS 1.x media determination and is
     no longer usually used for anything.  0xF8 is the standard value
     for fixed (non-removable) media. For removable media, 0xF0 is
     frequently used. Legal values are 0xF0 or 0xF8-0xFF.
  */
  uint8_t  mediaType;
  /**
     Count of sectors occupied by one FAT on FAT12/FAT16 volumes.
     On FAT32 volumes this field must be 0, and sectorsPerFat32
     contains the FAT size count.
  */
  uint16_t sectorsPerFat16;
  /** Sectors per track for interrupt 0x13. Not used otherwise. */
  uint16_t sectorsPerTrtack;
  /** Number of heads for interrupt 0x13.  Not used otherwise. */
  uint16_t headCount;
  /**
     Count of hidden sectors preceding the partition that contains this
     FAT volume. This field is generally only relevant for media
      visible on interrupt 0x13.
  */
  uint32_t hidddenSectors;
  /**
     This field is the new 32-bit total count of sectors on the volume.
     This count includes the count of all sectors in all four regions
     of the volume.  This field can be 0; if it is 0, then
     totalSectors16 must be non-zero.
  */
  uint32_t totalSectors32;
  /**
     Count of sectors occupied by one FAT on FAT32 volumes.
  */
  uint32_t sectorsPerFat32;
  /**
     This field is only defined for FAT32 media and does not exist on
     FAT12 and FAT16 media.
     Bits 0-3 -- Zero-based number of active FAT.
                 Only valid if mirroring is disabled.
     Bits 4-6 -- Reserved.
     Bit 7	-- 0 means the FAT is mirrored at runtime into all FATs.
            -- 1 means only one FAT is active; it is the one referenced in bits 0-3.
     Bits 8-15 	-- Reserved.
  */
  uint16_t fat32Flags;
  /**
     FAT32 version. High byte is major revision number.
     Low byte is minor revision number. Only 0.0 define.
  */
  uint16_t fat32Version;
  /**
     Cluster number of the first cluster of the root directory for FAT32.
     This usually 2 but not required to be 2.
  */
  uint32_t fat32RootCluster;
  /**
     Sector number of FSINFO structure in the reserved area of the
     FAT32 volume. Usually 1.
  */
  uint16_t fat32FSInfo;
  /**
     If non-zero, indicates the sector number in the reserved area
     of the volume of a copy of the boot record. Usually 6.
     No value other than 6 is recommended.
  */
  uint16_t fat32BackBootBlock;
  /**
     Reserved for future expansion. Code that formats FAT32 volumes
     should always set all of the bytes of this field to 0.
  */
  uint8_t  fat32Reserved[12];
} __attribute__((packed));
/** Type name for biosParmBlock */
typedef struct biosParmBlock bpb_t;
//------------------------------------------------------------------------------
/**
   \struct fat32BootSector

   \brief Boot sector for a FAT16 or FAT32 volume.

*/
struct fat32BootSector {
  /** X86 jmp to boot program */
  uint8_t  jmpToBootCode[3];
  /** informational only - don't depend on it */
  char     oemName[8];
  /** BIOS Parameter Block */
  bpb_t    bpb;
  /** for int0x13 use value 0X80 for hard drive */
  uint8_t  driveNumber;
  /** used by Windows NT - should be zero for FAT */
  uint8_t  reserved1;
  /** 0X29 if next three fields are valid */
  uint8_t  bootSignature;
  /** usually generated by combining date and time */
  uint32_t volumeSerialNumber;
  /** should match volume label in root dir */
  char     volumeLabel[11];
  /** informational only - don't depend on it */
  char     fileSystemType[8];
  /** X86 boot code */
  uint8_t  bootCode[420];
  /** must be 0X55 */
  uint8_t  bootSectorSig0;
  /** must be 0XAA */
  uint8_t  bootSectorSig1;
} __attribute__((packed));
//------------------------------------------------------------------------------
// End Of Chain values for FAT entries
/** FAT16 end of chain value used by Microsoft. */
uint16_t const FAT16EOC = 0XFFFF;
/** Minimum value for FAT16 EOC.  Use to test for EOC. */
uint16_t const FAT16EOC_MIN = 0XFFF8;
/** FAT32 end of chain value used by Microsoft. */
uint32_t const FAT32EOC = 0X0FFFFFFF;
/** Minimum value for FAT32 EOC.  Use to test for EOC. */
uint32_t const FAT32EOC_MIN = 0X0FFFFFF8;
/** Mask a for FAT32 entry. Entries are 28 bits. */
uint32_t const FAT32MASK = 0X0FFFFFFF;

/** Type name for fat32BootSector */
typedef struct fat32BootSector fbs_t;
//------------------------------------------------------------------------------
/**
   \struct directoryEntry
   \brief FAT short directory entry

   Short means short 8.3 name, not the entry size.

   Date Format. A FAT directory entry date stamp is a 16-bit field that is
   basically a date relative to the MS-DOS epoch of 01/01/1980. Here is the
   format (bit 0 is the LSB of the 16-bit word, bit 15 is the MSB of the
   16-bit word):

   Bits 9-15: Count of years from 1980, valid value range 0-127
   inclusive (1980-2107).

   Bits 5-8: Month of year, 1 = January, valid value range 1-12 inclusive.

   Bits 0-4: Day of month, valid value range 1-31 inclusive.

   Time Format. A FAT directory entry time stamp is a 16-bit field that has
   a granularity of 2 seconds. Here is the format (bit 0 is the LSB of the
   16-bit word, bit 15 is the MSB of the 16-bit word).

   Bits 11-15: Hours, valid value range 0-23 inclusive.

   Bits 5-10: Minutes, valid value range 0-59 inclusive.

   Bits 0-4: 2-second count, valid value range 0-29 inclusive (0 - 58 seconds).

   The valid time range is from Midnight 00:00:00 to 23:59:58.
*/
struct directoryEntry {
  /**
     Short 8.3 name.
     The first eight bytes contain the file name with blank fill.
     The last three bytes contain the file extension with blank fill.
  */
  uint8_t  name[11];
  /** Entry attributes.

     The upper two bits of the attribute byte are reserved and should
     always be set to 0 when a file is created and never modified or
     looked at after that.  See defines that begin with DIR_ATT_.
  */
  uint8_t  attributes;
  /**
     Reserved for use by Windows NT. Set value to 0 when a file is
     created and never modify or look at it after that.
  */
  uint8_t  reservedNT;
  /**
     The granularity of the seconds part of creationTime is 2 seconds
     so this field is a count of tenths of a second and its valid
     value range is 0-199 inclusive. (WHG note - seems to be hundredths)
  */
  uint8_t  creationTimeTenths;
  /** Time file was created. */
  uint16_t creationTime;
  /** Date file was created. */
  uint16_t creationDate;
  /**
     Last access date. Note that there is no last access time, only
     a date.  This is the date of last read or write. In the case of
     a write, this should be set to the same date as lastWriteDate.
  */
  uint16_t lastAccessDate;
  /**
     High word of this entry's first cluster number (always 0 for a
     FAT12 or FAT16 volume).
  */
  uint16_t firstClusterHigh;
  /** Time of last write. File creation is considered a write. */
  uint16_t lastWriteTime;
  /** Date of last write. File creation is considered a write. */
  uint16_t lastWriteDate;
  /** Low word of this entry's first cluster number. */
  uint16_t firstClusterLow;
  /** 32-bit unsigned holding this file's size in bytes. */
  uint32_t fileSize;
} __attribute__((packed));
//------------------------------------------------------------------------------
// Definitions for directory entries
//
/** Type name for directoryEntry */
typedef struct directoryEntry dir_t;
/** escape for name[0] = 0XE5 */
uint8_t const DIR_NAME_0XE5 = 0X05;
/** name[0] value for entry that is free after being "deleted" */
uint8_t const DIR_NAME_DELETED = 0XE5;
/** name[0] value for entry that is free and no allocated entries follow */
uint8_t const DIR_NAME_FREE = 0X00;
/** file is read-only */
uint8_t const DIR_ATT_READ_ONLY = 0X01;
/** File should hidden in directory listings */
uint8_t const DIR_ATT_HIDDEN = 0X02;
/** Entry is for a system file */
uint8_t const DIR_ATT_SYSTEM = 0X04;
/** Directory entry contains the volume label */
uint8_t const DIR_ATT_VOLUME_ID = 0X08;
/** Entry is for a directory */
uint8_t const DIR_ATT_DIRECTORY = 0X10;
/** Old DOS archive bit for backup support */
uint8_t const DIR_ATT_ARCHIVE = 0X20;
/** Test value for long name entry.  Test is
  (d->attributes & DIR_ATT_LONG_NAME_MASK) == DIR_ATT_LONG_NAME. */
uint8_t const DIR_ATT_LONG_NAME = 0X0F;
/** Test mask for long name entry */
uint8_t const DIR_ATT_LONG_NAME_MASK = 0X3F;
/** defined attribute bits */
uint8_t const DIR_ATT_DEFINED_BITS = 0X3F;
/** Directory entry is part of a long name */
static inline uint8_t DIR_IS_LONG_NAME(const dir_t* dir) {
  return (dir->attributes & DIR_ATT_LONG_NAME_MASK) == DIR_ATT_LONG_NAME;
}
/** Mask for file/subdirectory tests */
uint8_t const DIR_ATT_FILE_TYPE_MASK = (DIR_ATT_VOLUME_ID | DIR_ATT_DIRECTORY);
/** Directory entry is for a file */
static inline uint8_t DIR_IS_FILE(const dir_t* dir) {
  return (dir->attributes & DIR_ATT_FILE_TYPE_MASK) == 0;
}
/** Directory entry is for a subdirectory */
static inline uint8_t DIR_IS_SUBDIR(const dir_t* dir) {
  return (dir->attributes & DIR_ATT_FILE_TYPE_MASK) == DIR_ATT_DIRECTORY;
}
/** Directory entry is for a file or subdirectory */
static inline uint8_t DIR_IS_FILE_OR_SUBDIR(const dir_t* dir) {
  return (dir->attributes & DIR_ATT_VOLUME_ID) == 0;
}
#endif  // FatStructs_h