SdFatStructs.h

/* Arduino SdFat Library
 * Copyright (C) 2012 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 SdFatStructs_h
#define SdFatStructs_h
/**
 * \file
 * \brief 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;
/** Value for bootSignature field int FAT/FAT32 boot sector */
uint8_t const EXTENDED_BOOT_SIG = 0X29;
//------------------------------------------------------------------------------
/**
 * \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 Windows NT disk signature. May contain 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 fat_boot
 *
 * \brief Boot sector for a FAT12/FAT16 volume.
 *
 */
struct fat_boot {
         /**
          * The first three bytes of the boot sector must be valid,
          * executable x 86-based CPU instructions. This includes a
          * jump instruction that skips the next nonexecutable bytes.
          */
  uint8_t jump[3];
         /**
          * This is typically a string of characters that identifies
          * the operating system that formatted the volume.
          */
  char    oemId[8];
          /**
           * The size of a hardware sector. Valid decimal values for this
           * field are 512, 1024, 2048, and 4096. For most disks used in
           * the United States, the value of this field is 512.
           */
  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.  128 should be avoided.
           */
  uint8_t  sectorsPerCluster;
          /**
           * The number of sectors preceding the start of the first FAT,
           * including the boot sector. The value of this field is always 1.
           */
  uint16_t reservedSectorCount;
          /**
           * The number of copies of the FAT on the volume.
           * The value of this field is always 2.
           */
  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 nonzero.  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 (nonremovable) 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 sectorsPerTrack;
           /** 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 nonzero.
           */
  uint32_t totalSectors32;
           /**
            * Related to the BIOS physical drive number. Floppy drives are
            * identified as 0x00 and physical hard disks are identified as
            * 0x80, regardless of the number of physical disk drives.
            * Typically, this value is set prior to issuing an INT 13h BIOS
            * call to specify the device to access. The value is only
            * relevant if the device is a boot device.
            */
  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;
           /**
            * A random serial number created when formatting a disk,
            * which helps to distinguish between disks.
            * Usually generated by combining date and time.
            */
  uint32_t volumeSerialNumber;
           /**
            * A field once used to store the volume label. The volume label
            * is now stored as a special file in the root directory.
            */
  char     volumeLabel[11];
           /**
            * A field with a value of either FAT, FAT12 or FAT16,
            * depending on the disk format.
            */
  char     fileSystemType[8];
           /** X86 boot code */
  uint8_t  bootCode[448];
           /** must be 0X55 */
  uint8_t  bootSectorSig0;
           /** must be 0XAA */
  uint8_t  bootSectorSig1;
}__attribute__((packed));
/** Type name for FAT Boot Sector */
typedef struct fat_boot fat_boot_t;
//------------------------------------------------------------------------------
/**
 * \struct fat32_boot
 *
 * \brief Boot sector for a FAT32 volume.
 *
 */
struct fat32_boot {
         /**
          * The first three bytes of the boot sector must be valid,
          * executable x 86-based CPU instructions. This includes a
          * jump instruction that skips the next nonexecutable bytes.
          */
  uint8_t jump[3];
         /**
          * This is typically a string of characters that identifies
          * the operating system that formatted the volume.
          */
  char    oemId[8];
          /**
           * The size of a hardware sector. Valid decimal values for this
           * field are 512, 1024, 2048, and 4096. For most disks used in
           * the United States, the value of this field is 512.
           */
  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.  128 should be avoided.
           */
  uint8_t  sectorsPerCluster;
          /**
           * The number of sectors preceding the start of the first FAT,
           * including the boot sector. Must not be zero
           */
  uint16_t reservedSectorCount;
          /**
           * The number of copies of the FAT on the volume.
           * The value of this field is always 2.
           */
  uint8_t  fatCount;
          /**
           * FAT12/FAT16 only. For FAT32 volumes, this field must be set to 0.
           */
  uint16_t rootDirEntryCount;
          /**
           * For FAT32 volumes, this field must be 0.
           */
  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 (nonremovable) media. For removable media, 0xF0 is
           * frequently used. Legal values are 0xF0 or 0xF8-0xFF.
           */
  uint8_t  mediaType;
          /**
           * 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 sectorsPerTrack;
           /** 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;
          /**
           * Contains the total number of sectors in the FAT32 volume.
           */
  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 nonzero, 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];
           /**
            * Related to the BIOS physical drive number. Floppy drives are
            * identified as 0x00 and physical hard disks are identified as
            * 0x80, regardless of the number of physical disk drives.
            * Typically, this value is set prior to issuing an INT 13h BIOS
            * call to specify the device to access. The value is only
            * relevant if the device is a boot device.
            */
  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;
           /**
            * A random serial number created when formatting a disk,
            * which helps to distinguish between disks.
            * Usually generated by combining date and time.
            */
  uint32_t volumeSerialNumber;
           /**
            * A field once used to store the volume label. The volume label
            * is now stored as a special file in the root directory.
            */
  char     volumeLabel[11];
           /**
            * A text field with a value of FAT32.
            */
  char     fileSystemType[8];
           /** X86 boot code */
  uint8_t  bootCode[420];
           /** must be 0X55 */
  uint8_t  bootSectorSig0;
           /** must be 0XAA */
  uint8_t  bootSectorSig1;
}__attribute__((packed));
/** Type name for FAT32 Boot Sector */
typedef struct fat32_boot fat32_boot_t;
//------------------------------------------------------------------------------
/** Lead signature for a FSINFO sector */
uint32_t const FSINFO_LEAD_SIG = 0x41615252;
/** Struct signature for a FSINFO sector */
uint32_t const FSINFO_STRUCT_SIG = 0x61417272;
/**
 * \struct fat32_fsinfo
 *
 * \brief FSINFO sector for a FAT32 volume.
 *
 */
struct fat32_fsinfo {
           /** must be 0X52, 0X52, 0X61, 0X41 */
  uint32_t  leadSignature;
           /** must be zero */
  uint8_t  reserved1[480];
           /** must be 0X72, 0X72, 0X41, 0X61 */
  uint32_t  structSignature;
          /**
           * Contains the last known free cluster count on the volume.
           * If the value is 0xFFFFFFFF, then the free count is unknown
           * and must be computed. Any other value can be used, but is
           * not necessarily correct. It should be range checked at least
           * to make sure it is <= volume cluster count.
           */
  uint32_t freeCount;
          /**
           * This is a hint for the FAT driver. It indicates the cluster
           * number at which the driver should start looking for free clusters.
           * If the value is 0xFFFFFFFF, then there is no hint and the driver
           * should start looking at cluster 2.
           */
  uint32_t nextFree;
           /** must be zero */
  uint8_t  reserved2[12];
           /** must be 0X00, 0X00, 0X55, 0XAA */
  uint8_t  tailSignature[4];
}__attribute__((packed));
/** Type name for FAT32 FSINFO Sector */
typedef struct fat32_fsinfo fat32_fsinfo_t;
//------------------------------------------------------------------------------
// End Of Chain values for FAT entries
/** FAT12 end of chain value used by Microsoft. */
uint16_t const FAT12EOC = 0XFFF;
/** Minimum value for FAT12 EOC.  Use to test for EOC. */
uint16_t const FAT12EOC_MIN = 0XFF8;
/** 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;
//------------------------------------------------------------------------------
/**
 * \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
 * \param[in] dir Pointer to a directory entry.
 *
 * \return true if the entry is for part of a long name else false.
 */
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
 * \param[in] dir Pointer to a directory entry.
 *
 * \return true if the entry is for a normal file else false.
 */
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
 * \param[in] dir Pointer to a directory entry.
 *
 * \return true if the entry is for a subdirectory else false.
 */
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
 * \param[in] dir Pointer to a directory entry.
 *
 * \return true if the entry is for a normal file or subdirectory else false.
 */
static inline uint8_t DIR_IS_FILE_OR_SUBDIR(const dir_t* dir) {
  return (dir->attributes & DIR_ATT_VOLUME_ID) == 0;
}
#endif  // SdFatStructs_h