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/* Arduino SdFat Library
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 * Copyright (C) 2009 by William Greiman
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 *
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 * This file is part of the Arduino SdFat Library
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 *
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 * This Library is free software: you can redistribute it and/or modify
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 * it under the terms of the GNU General Public License as published by
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 * the Free Software Foundation, either version 3 of the License, or
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 * (at your option) any later version.
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 *
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 * This Library is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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 * GNU General Public License for more details.
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 *
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 * You should have received a copy of the GNU General Public License
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 * along with the Arduino SdFat Library.  If not, see
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 * <http://www.gnu.org/licenses/>.
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 */
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#ifndef FatStructs_h
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#define FatStructs_h
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/**
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 * \file
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 * FAT file structures
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 */
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/*
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 * mostly from Microsoft document fatgen103.doc
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 * http://www.microsoft.com/whdc/system/platform/firmware/fatgen.mspx
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 */
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//------------------------------------------------------------------------------
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/** Value for byte 510 of boot block or MBR */
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uint8_t const BOOTSIG0 = 0X55;
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/** Value for byte 511 of boot block or MBR */
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uint8_t const BOOTSIG1 = 0XAA;
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//------------------------------------------------------------------------------
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/**
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 * \struct partitionTable
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 * \brief MBR partition table entry
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 *
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 * A partition table entry for a MBR formatted storage device.
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 * The MBR partition table has four entries.
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 */
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struct partitionTable {
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          /**
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           * Boot Indicator . Indicates whether the volume is the active
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           * partition.  Legal values include: 0X00. Do not use for booting.
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           * 0X80 Active partition.
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           */
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  uint8_t  boot;
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          /**
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            * Head part of Cylinder-head-sector address of the first block in
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            * the partition. Legal values are 0-255. Only used in old PC BIOS.
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            */
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  uint8_t  beginHead;
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          /**
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           * Sector part of Cylinder-head-sector address of the first block in
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           * the partition. Legal values are 1-63. Only used in old PC BIOS.
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           */
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  unsigned beginSector : 6;
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           /** High bits cylinder for first block in partition. */
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  unsigned beginCylinderHigh : 2;
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          /**
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           * Combine beginCylinderLow with beginCylinderHigh. Legal values
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           * are 0-1023.  Only used in old PC BIOS.
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           */
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  uint8_t  beginCylinderLow;
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          /**
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           * Partition type. See defines that begin with PART_TYPE_ for
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           * some Microsoft partition types.
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           */
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  uint8_t  type;
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          /**
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           * head part of cylinder-head-sector address of the last sector in the
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           * partition.  Legal values are 0-255. Only used in old PC BIOS.
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           */
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  uint8_t  endHead;
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          /**
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           * Sector part of cylinder-head-sector address of the last sector in
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           * the partition.  Legal values are 1-63. Only used in old PC BIOS.
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           */
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  unsigned endSector : 6;
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           /** High bits of end cylinder */
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  unsigned endCylinderHigh : 2;
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          /**
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           * Combine endCylinderLow with endCylinderHigh. Legal values
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           * are 0-1023.  Only used in old PC BIOS.
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           */
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  uint8_t  endCylinderLow;
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           /** Logical block address of the first block in the partition. */
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  uint32_t firstSector;
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           /** Length of the partition, in blocks. */
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  uint32_t totalSectors;
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};
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/** Type name for partitionTable */
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typedef struct partitionTable part_t;
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//------------------------------------------------------------------------------
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/**
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 * \struct masterBootRecord
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 *
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 * \brief Master Boot Record
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 *
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 * The first block of a storage device that is formatted with a MBR.
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 */
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struct masterBootRecord {
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           /** Code Area for master boot program. */
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  uint8_t  codeArea[440];
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           /** Optional WindowsNT disk signature. May contain more boot code. */
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  uint32_t diskSignature;
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           /** Usually zero but may be more boot code. */
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  uint16_t usuallyZero;
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           /** Partition tables. */
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  part_t   part[4];
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           /** First MBR signature byte. Must be 0X55 */
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  uint8_t  mbrSig0;
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           /** Second MBR signature byte. Must be 0XAA */
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  uint8_t  mbrSig1;
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};
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/** Type name for masterBootRecord */
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typedef struct masterBootRecord mbr_t;
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//------------------------------------------------------------------------------
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/** 
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 * \struct biosParmBlock
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 *
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 * \brief BIOS parameter block
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 * 
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 *  The BIOS parameter block describes the physical layout of a FAT volume.
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 */
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struct biosParmBlock {
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          /**
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           * Count of bytes per sector. This value may take on only the
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           * following values: 512, 1024, 2048 or 4096
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           */
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  uint16_t bytesPerSector;
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          /**
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           * Number of sectors per allocation unit. This value must be a
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           * power of 2 that is greater than 0. The legal values are
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           * 1, 2, 4, 8, 16, 32, 64, and 128.
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           */
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  uint8_t  sectorsPerCluster;
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          /**
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           * Number of sectors before the first FAT.
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           * This value must not be zero.
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           */
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  uint16_t reservedSectorCount;
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          /** The count of FAT data structures on the volume. This field should
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           *  always contain the value 2 for any FAT volume of any type.
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           */
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  uint8_t  fatCount;
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          /**
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          * For FAT12 and FAT16 volumes, this field contains the count of
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          * 32-byte directory entries in the root directory. For FAT32 volumes,
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          * this field must be set to 0. For FAT12 and FAT16 volumes, this
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          * value should always specify a count that when multiplied by 32
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          * results in a multiple of bytesPerSector.  FAT16 volumes should
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          * use the value 512.
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          */
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  uint16_t rootDirEntryCount;
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          /**
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           * This field is the old 16-bit total count of sectors on the volume.
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           * This count includes the count of all sectors in all four regions
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           * of the volume. This field can be 0; if it is 0, then totalSectors32
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           * must be non-zero.  For FAT32 volumes, this field must be 0. For
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           * FAT12 and FAT16 volumes, this field contains the sector count, and
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           * totalSectors32 is 0 if the total sector count fits
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           * (is less than 0x10000).
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           */
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  uint16_t totalSectors16;
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          /**
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           * This dates back to the old MS-DOS 1.x media determination and is
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           * no longer usually used for anything.  0xF8 is the standard value
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           * for fixed (non-removable) media. For removable media, 0xF0 is
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           * frequently used. Legal values are 0xF0 or 0xF8-0xFF.
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           */
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  uint8_t  mediaType;
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          /**
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           * Count of sectors occupied by one FAT on FAT12/FAT16 volumes.
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           * On FAT32 volumes this field must be 0, and sectorsPerFat32
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           * contains the FAT size count.
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           */
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  uint16_t sectorsPerFat16;
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           /** Sectors per track for interrupt 0x13. Not used otherwise. */
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  uint16_t sectorsPerTrtack;
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           /** Number of heads for interrupt 0x13.  Not used otherwise. */
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  uint16_t headCount;
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          /**
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           * Count of hidden sectors preceding the partition that contains this
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           * FAT volume. This field is generally only relevant for media
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           *  visible on interrupt 0x13.
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           */
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  uint32_t hidddenSectors;
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          /**
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           * This field is the new 32-bit total count of sectors on the volume.
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           * This count includes the count of all sectors in all four regions
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           * of the volume.  This field can be 0; if it is 0, then
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           * totalSectors16 must be non-zero.
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           */
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  uint32_t totalSectors32;
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          /**
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           * Count of sectors occupied by one FAT on FAT32 volumes.
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           */
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  uint32_t sectorsPerFat32;
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          /**
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           * This field is only defined for FAT32 media and does not exist on
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           * FAT12 and FAT16 media.
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           * Bits 0-3 -- Zero-based number of active FAT.
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           *             Only valid if mirroring is disabled.
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           * Bits 4-6 -- Reserved.
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           * Bit 7        -- 0 means the FAT is mirrored at runtime into all FATs.
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                 *        -- 1 means only one FAT is active; it is the one referenced in bits 0-3.
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           * Bits 8-15         -- Reserved.
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           */
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  uint16_t fat32Flags;
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          /**
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           * FAT32 version. High byte is major revision number.
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           * Low byte is minor revision number. Only 0.0 define.
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           */
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  uint16_t fat32Version;
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          /**
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           * Cluster number of the first cluster of the root directory for FAT32.
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           * This usually 2 but not required to be 2.
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           */
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  uint32_t fat32RootCluster;
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          /**
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           * Sector number of FSINFO structure in the reserved area of the
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           * FAT32 volume. Usually 1.
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           */
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  uint16_t fat32FSInfo;
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          /**
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           * If non-zero, indicates the sector number in the reserved area
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           * of the volume of a copy of the boot record. Usually 6.
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           * No value other than 6 is recommended.
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           */
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  uint16_t fat32BackBootBlock;
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          /**
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           * Reserved for future expansion. Code that formats FAT32 volumes
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           * should always set all of the bytes of this field to 0.
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           */
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  uint8_t  fat32Reserved[12];
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};
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/** Type name for biosParmBlock */
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typedef struct biosParmBlock bpb_t;
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//------------------------------------------------------------------------------
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/**
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 * \struct fat32BootSector
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 *
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 * \brief Boot sector for a FAT16 or FAT32 volume.
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 * 
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 */  
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struct fat32BootSector {
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           /** X86 jmp to boot program */
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  uint8_t  jmpToBootCode[3];
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           /** informational only - don't depend on it */
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  char     oemName[8];
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           /** BIOS Parameter Block */
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  bpb_t    bpb;
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           /** for int0x13 use value 0X80 for hard drive */
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  uint8_t  driveNumber;
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           /** used by Windows NT - should be zero for FAT */
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  uint8_t  reserved1;
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           /** 0X29 if next three fields are valid */
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  uint8_t  bootSignature;
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           /** usually generated by combining date and time */
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  uint32_t volumeSerialNumber;
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           /** should match volume label in root dir */
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  char     volumeLabel[11];
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           /** informational only - don't depend on it */
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  char     fileSystemType[8];
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           /** X86 boot code */
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  uint8_t  bootCode[420];
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           /** must be 0X55 */
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  uint8_t  bootSectorSig0;
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           /** must be 0XAA */
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  uint8_t  bootSectorSig1;
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};
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//------------------------------------------------------------------------------
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// End Of Chain values for FAT entries
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/** FAT16 end of chain value used by Microsoft. */
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uint16_t const FAT16EOC = 0XFFFF;
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/** Minimum value for FAT16 EOC.  Use to test for EOC. */
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uint16_t const FAT16EOC_MIN = 0XFFF8;
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/** FAT32 end of chain value used by Microsoft. */
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uint32_t const FAT32EOC = 0X0FFFFFFF;
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/** Minimum value for FAT32 EOC.  Use to test for EOC. */
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uint32_t const FAT32EOC_MIN = 0X0FFFFFF8;
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/** Mask a for FAT32 entry. Entries are 28 bits. */
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uint32_t const FAT32MASK = 0X0FFFFFFF;
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/** Type name for fat32BootSector */
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typedef struct fat32BootSector fbs_t;
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//------------------------------------------------------------------------------
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/**
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 * \struct directoryEntry
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 * \brief FAT short directory entry
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 *
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 * Short means short 8.3 name, not the entry size.
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 *  
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 * Date Format. A FAT directory entry date stamp is a 16-bit field that is 
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 * basically a date relative to the MS-DOS epoch of 01/01/1980. Here is the
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 * format (bit 0 is the LSB of the 16-bit word, bit 15 is the MSB of the 
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 * 16-bit word):
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 *   
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 * Bits 9-15: Count of years from 1980, valid value range 0-127 
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 * inclusive (1980-2107).
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 *   
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 * Bits 5-8: Month of year, 1 = January, valid value range 1-12 inclusive.
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 *
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 * Bits 0-4: Day of month, valid value range 1-31 inclusive.
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 *
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 * Time Format. A FAT directory entry time stamp is a 16-bit field that has
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 * a granularity of 2 seconds. Here is the format (bit 0 is the LSB of the 
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 * 16-bit word, bit 15 is the MSB of the 16-bit word).
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 *   
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 * Bits 11-15: Hours, valid value range 0-23 inclusive.
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 * 
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 * Bits 5-10: Minutes, valid value range 0-59 inclusive.
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 *      
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 * Bits 0-4: 2-second count, valid value range 0-29 inclusive (0 - 58 seconds).
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 *   
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 * The valid time range is from Midnight 00:00:00 to 23:59:58.
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 */
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struct directoryEntry {
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           /**
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            * Short 8.3 name.
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            * The first eight bytes contain the file name with blank fill.
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            * The last three bytes contain the file extension with blank fill.
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            */
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  uint8_t  name[11];
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          /** Entry attributes.
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           *
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           * The upper two bits of the attribute byte are reserved and should
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           * always be set to 0 when a file is created and never modified or
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           * looked at after that.  See defines that begin with DIR_ATT_.
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           */
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  uint8_t  attributes;
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          /**
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           * Reserved for use by Windows NT. Set value to 0 when a file is
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           * created and never modify or look at it after that.
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           */
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  uint8_t  reservedNT;
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          /**
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           * The granularity of the seconds part of creationTime is 2 seconds
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           * so this field is a count of tenths of a second and its valid
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           * value range is 0-199 inclusive. (WHG note - seems to be hundredths)
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           */
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  uint8_t  creationTimeTenths;
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           /** Time file was created. */
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  uint16_t creationTime;
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           /** Date file was created. */
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  uint16_t creationDate;
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          /**
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           * Last access date. Note that there is no last access time, only
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           * a date.  This is the date of last read or write. In the case of
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           * a write, this should be set to the same date as lastWriteDate.
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           */
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  uint16_t lastAccessDate;
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          /**
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           * High word of this entry's first cluster number (always 0 for a
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           * FAT12 or FAT16 volume).
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           */
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  uint16_t firstClusterHigh;
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           /** Time of last write. File creation is considered a write. */
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  uint16_t lastWriteTime;
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           /** Date of last write. File creation is considered a write. */
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  uint16_t lastWriteDate;
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           /** Low word of this entry's first cluster number. */
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  uint16_t firstClusterLow;
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           /** 32-bit unsigned holding this file's size in bytes. */
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  uint32_t fileSize;
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};
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//------------------------------------------------------------------------------
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// Definitions for directory entries
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//
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/** Type name for directoryEntry */
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typedef struct directoryEntry dir_t;
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/** escape for name[0] = 0XE5 */
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uint8_t const DIR_NAME_0XE5 = 0X05;
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/** name[0] value for entry that is free after being "deleted" */
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uint8_t const DIR_NAME_DELETED = 0XE5;
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/** name[0] value for entry that is free and no allocated entries follow */
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uint8_t const DIR_NAME_FREE = 0X00;
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/** file is read-only */
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uint8_t const DIR_ATT_READ_ONLY = 0X01;
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/** File should hidden in directory listings */
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uint8_t const DIR_ATT_HIDDEN = 0X02;
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/** Entry is for a system file */
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uint8_t const DIR_ATT_SYSTEM = 0X04;
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/** Directory entry contains the volume label */
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uint8_t const DIR_ATT_VOLUME_ID = 0X08;
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/** Entry is for a directory */
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uint8_t const DIR_ATT_DIRECTORY = 0X10;
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/** Old DOS archive bit for backup support */
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uint8_t const DIR_ATT_ARCHIVE = 0X20;
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/** Test value for long name entry.  Test is
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  (d->attributes & DIR_ATT_LONG_NAME_MASK) == DIR_ATT_LONG_NAME. */
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uint8_t const DIR_ATT_LONG_NAME = 0X0F;
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/** Test mask for long name entry */
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uint8_t const DIR_ATT_LONG_NAME_MASK = 0X3F;
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/** defined attribute bits */
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uint8_t const DIR_ATT_DEFINED_BITS = 0X3F;
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/** Directory entry is part of a long name */
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static inline uint8_t DIR_IS_LONG_NAME(const dir_t* dir) {
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  return (dir->attributes & DIR_ATT_LONG_NAME_MASK) == DIR_ATT_LONG_NAME;
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}
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/** Mask for file/subdirectory tests */
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uint8_t const DIR_ATT_FILE_TYPE_MASK = (DIR_ATT_VOLUME_ID | DIR_ATT_DIRECTORY);
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/** Directory entry is for a file */
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static inline uint8_t DIR_IS_FILE(const dir_t* dir) {
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  return (dir->attributes & DIR_ATT_FILE_TYPE_MASK) == 0;
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}
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/** Directory entry is for a subdirectory */
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static inline uint8_t DIR_IS_SUBDIR(const dir_t* dir) {
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  return (dir->attributes & DIR_ATT_FILE_TYPE_MASK) == DIR_ATT_DIRECTORY;
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}
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/** Directory entry is for a file or subdirectory */
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static inline uint8_t DIR_IS_FILE_OR_SUBDIR(const dir_t* dir) {
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  return (dir->attributes & DIR_ATT_VOLUME_ID) == 0;
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}
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#endif  // FatStructs_h