teensy-sdfat/SdFat/SdVolume.cpp

/* 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/>.
 */
#include <SdFat.h>
//------------------------------------------------------------------------------
#if !USE_MULTIPLE_CARDS
// raw block cache
uint8_t  SdVolume::m_fatCount;          // number of FATs on volume
uint32_t SdVolume::m_blocksPerFat;      // FAT size in blocks
cache_t  SdVolume::m_cacheBuffer;       // 512 byte cache for Sd2Card
uint32_t SdVolume::m_cacheBlockNumber;  // current block number
uint8_t  SdVolume::m_cacheStatus;       // status of cache block
#if USE_SEPARATE_FAT_CACHE
cache_t  SdVolume::m_cacheFatBuffer;       // 512 byte cache for FAT
uint32_t SdVolume::m_cacheFatBlockNumber;  // current Fat block number
uint8_t  SdVolume::m_cacheFatStatus;       // status of cache Fatblock
#endif  // USE_SEPARATE_FAT_CACHE
Sd2Card* SdVolume::m_sdCard;            // pointer to SD card object
#endif  // USE_MULTIPLE_CARDS
//------------------------------------------------------------------------------
// find a contiguous group of clusters
bool SdVolume::allocContiguous(uint32_t count, uint32_t* curCluster) {
  // start of group
  uint32_t bgnCluster;
  // end of group
  uint32_t endCluster;
  // last cluster of FAT
  uint32_t fatEnd = m_clusterCount + 1;

  // flag to save place to start next search
  bool setStart;

  // set search start cluster
  if (*curCluster) {
    // try to make file contiguous
    bgnCluster = *curCluster + 1;

    // don't save new start location
    setStart = false;
  } else {
    // start at likely place for free cluster
    bgnCluster = m_allocSearchStart;

    // save next search start if no holes.
    setStart = true;
  }
  // end of group
  endCluster = bgnCluster;

  // search the FAT for free clusters
  for (uint32_t n = 0;; n++, endCluster++) {
    // can't find space checked all clusters
    if (n >= m_clusterCount) {
      DBG_FAIL_MACRO;
      goto fail;
    }
    // past end - start from beginning of FAT
    if (endCluster > fatEnd) {
      bgnCluster = endCluster = 2;
    }
    uint32_t f;
    if (!fatGet(endCluster, &f)) {
      DBG_FAIL_MACRO;
      goto fail;
    }

    if (f != 0) {
      // don't update search start if unallocated clusters before endCluster.
      if (bgnCluster != endCluster) setStart = false;
      // cluster in use try next cluster as bgnCluster
      bgnCluster = endCluster + 1;
    } else if ((endCluster - bgnCluster + 1) == count) {
      // done - found space
      break;
    }
  }
  // remember possible next free cluster
  if (setStart) m_allocSearchStart = endCluster + 1;

  // mark end of chain
  if (!fatPutEOC(endCluster)) {
    DBG_FAIL_MACRO;
    goto fail;
  }
  // link clusters
  while (endCluster > bgnCluster) {
    if (!fatPut(endCluster - 1, endCluster)) {
      DBG_FAIL_MACRO;
      goto fail;
    }
    endCluster--;
  }
  if (*curCluster != 0) {
    // connect chains
    if (!fatPut(*curCluster, bgnCluster)) {
      DBG_FAIL_MACRO;
      goto fail;
    }
  }
  // return first cluster number to caller
  *curCluster = bgnCluster;
  return true;

 fail:
  return false;
}
//==============================================================================
// cache functions
#if USE_SEPARATE_FAT_CACHE
//------------------------------------------------------------------------------
cache_t* SdVolume::cacheFetch(uint32_t blockNumber, uint8_t options) {
  return cacheFetchData(blockNumber, options);
}
//------------------------------------------------------------------------------
cache_t* SdVolume::cacheFetchData(uint32_t blockNumber, uint8_t options) {
  if (m_cacheBlockNumber != blockNumber) {
    if (!cacheWriteData()) {
      DBG_FAIL_MACRO;
      goto fail;
    }
    if (!(options & CACHE_OPTION_NO_READ)) {
      if (!m_sdCard->readBlock(blockNumber, m_cacheBuffer.data)) {
        DBG_FAIL_MACRO;
        goto fail;
      }
    }
    m_cacheStatus = 0;
    m_cacheBlockNumber = blockNumber;
  }
  m_cacheStatus |= options & CACHE_STATUS_MASK;
  return &m_cacheBuffer;

 fail:
  return 0;
}
//------------------------------------------------------------------------------
cache_t* SdVolume::cacheFetchFat(uint32_t blockNumber, uint8_t options) {
  if (m_cacheFatBlockNumber != blockNumber) {
    if (!cacheWriteFat()) {
      DBG_FAIL_MACRO;
      goto fail;
    }
    if (!(options & CACHE_OPTION_NO_READ)) {
      if (!m_sdCard->readBlock(blockNumber, m_cacheFatBuffer.data)) {
        DBG_FAIL_MACRO;
        goto fail;
      }
    }
    m_cacheFatStatus = 0;
    m_cacheFatBlockNumber = blockNumber;
  }
  m_cacheFatStatus |= options & CACHE_STATUS_MASK;
  return &m_cacheFatBuffer;

 fail:
  return 0;
}
//------------------------------------------------------------------------------
bool SdVolume::cacheSync() {
  return cacheWriteData() && cacheWriteFat();
}
//------------------------------------------------------------------------------
bool SdVolume::cacheWriteData() {
  if (m_cacheStatus & CACHE_STATUS_DIRTY) {
    if (!m_sdCard->writeBlock(m_cacheBlockNumber, m_cacheBuffer.data)) {
      DBG_FAIL_MACRO;
      goto fail;
    }
    m_cacheStatus &= ~CACHE_STATUS_DIRTY;
  }
  return true;

 fail:
  return false;
}
//------------------------------------------------------------------------------
bool SdVolume::cacheWriteFat() {
  if (m_cacheFatStatus & CACHE_STATUS_DIRTY) {
    if (!m_sdCard->writeBlock(m_cacheFatBlockNumber, m_cacheFatBuffer.data)) {
      DBG_FAIL_MACRO;
      goto fail;
    }
    // mirror second FAT
    if (m_fatCount > 1) {
      uint32_t lbn = m_cacheFatBlockNumber + m_blocksPerFat;
      if (!m_sdCard->writeBlock(lbn, m_cacheFatBuffer.data)) {
        DBG_FAIL_MACRO;
        goto fail;
      }
    }
    m_cacheFatStatus &= ~CACHE_STATUS_DIRTY;
  }
  return true;

 fail:
  return false;
}
#else  // USE_SEPARATE_FAT_CACHE
//------------------------------------------------------------------------------
cache_t* SdVolume::cacheFetch(uint32_t blockNumber, uint8_t options) {
  if (m_cacheBlockNumber != blockNumber) {
    if (!cacheSync()) {
      DBG_FAIL_MACRO;
      goto fail;
    }
    if (!(options & CACHE_OPTION_NO_READ)) {
      if (!m_sdCard->readBlock(blockNumber, m_cacheBuffer.data)) {
        DBG_FAIL_MACRO;
        goto fail;
      }
    }
    m_cacheStatus = 0;
    m_cacheBlockNumber = blockNumber;
  }
  m_cacheStatus |= options & CACHE_STATUS_MASK;
  return &m_cacheBuffer;

 fail:
  return 0;
}
//------------------------------------------------------------------------------
cache_t* SdVolume::cacheFetchFat(uint32_t blockNumber, uint8_t options) {
  return cacheFetch(blockNumber, options | CACHE_STATUS_FAT_BLOCK);
}
//------------------------------------------------------------------------------
bool SdVolume::cacheSync() {
  if (m_cacheStatus & CACHE_STATUS_DIRTY) {
    if (!m_sdCard->writeBlock(m_cacheBlockNumber, m_cacheBuffer.data)) {
      DBG_FAIL_MACRO;
      goto fail;
    }
    // mirror second FAT
    if ((m_cacheStatus & CACHE_STATUS_FAT_BLOCK) && m_fatCount > 1) {
      uint32_t lbn = m_cacheBlockNumber + m_blocksPerFat;
      if (!m_sdCard->writeBlock(lbn, m_cacheBuffer.data)) {
        DBG_FAIL_MACRO;
        goto fail;
      }
    }
    m_cacheStatus &= ~CACHE_STATUS_DIRTY;
  }
  return true;

 fail:
  return false;
}
//------------------------------------------------------------------------------
bool SdVolume::cacheWriteData() {
  return cacheSync();
}
#endif  // USE_SEPARATE_FAT_CACHE
//------------------------------------------------------------------------------
void SdVolume::cacheInvalidate() {
    m_cacheBlockNumber = 0XFFFFFFFF;
    m_cacheStatus = 0;
}
//==============================================================================
//------------------------------------------------------------------------------
uint32_t SdVolume::clusterStartBlock(uint32_t cluster) const {
  return m_dataStartBlock + ((cluster - 2) << m_clusterSizeShift);
}
//------------------------------------------------------------------------------
// Fetch a FAT entry
bool SdVolume::fatGet(uint32_t cluster, uint32_t* value) {
  uint32_t lba;
  cache_t* pc;
  // error if reserved cluster of beyond FAT
  if (cluster < 2  || cluster > (m_clusterCount + 1)) {
    DBG_FAIL_MACRO;
    goto fail;
  }
  if (FAT12_SUPPORT && m_fatType == 12) {
    uint16_t index = cluster;
    index += index >> 1;
    lba = m_fatStartBlock + (index >> 9);
    pc = cacheFetchFat(lba, CACHE_FOR_READ);
    if (!pc) {
      DBG_FAIL_MACRO;
      goto fail;
    }
    index &= 0X1FF;
    uint16_t tmp = pc->data[index];
    index++;
    if (index == 512) {
      pc = cacheFetchFat(lba + 1, CACHE_FOR_READ);
      if (!pc) {
        DBG_FAIL_MACRO;
        goto fail;
      }
      index = 0;
    }
    tmp |= pc->data[index] << 8;
    *value = cluster & 1 ? tmp >> 4 : tmp & 0XFFF;
    return true;
  }
  if (m_fatType == 16) {
    lba = m_fatStartBlock + (cluster >> 8);
  } else if (m_fatType == 32) {
    lba = m_fatStartBlock + (cluster >> 7);
  } else {
    DBG_FAIL_MACRO;
    goto fail;
  }
  pc = cacheFetchFat(lba, CACHE_FOR_READ);
  if (!pc) {
    DBG_FAIL_MACRO;
    goto fail;
  }
  if (m_fatType == 16) {
    *value = pc->fat16[cluster & 0XFF];
  } else {
    *value = pc->fat32[cluster & 0X7F] & FAT32MASK;
  }
  return true;

 fail:
  return false;
}
//------------------------------------------------------------------------------
// Store a FAT entry
bool SdVolume::fatPut(uint32_t cluster, uint32_t value) {
  uint32_t lba;
  cache_t* pc;
  // error if reserved cluster of beyond FAT
  if (cluster < 2 || cluster > (m_clusterCount + 1)) {
    DBG_FAIL_MACRO;
    goto fail;
  }
  if (FAT12_SUPPORT && m_fatType == 12) {
    uint16_t index = cluster;
    index += index >> 1;
    lba = m_fatStartBlock + (index >> 9);
    pc = cacheFetchFat(lba, CACHE_FOR_WRITE);
    if (!pc) {
      DBG_FAIL_MACRO;
      goto fail;
    }
    index &= 0X1FF;
    uint8_t tmp = value;
    if (cluster & 1) {
      tmp = (pc->data[index] & 0XF) | tmp << 4;
    }
    pc->data[index] = tmp;

    index++;
    if (index == 512) {
      lba++;
      index = 0;
      pc = cacheFetchFat(lba, CACHE_FOR_WRITE);
      if (!pc) {
        DBG_FAIL_MACRO;
        goto fail;
      }
    }
    tmp = value >> 4;
    if (!(cluster & 1)) {
      tmp = ((pc->data[index] & 0XF0)) | tmp >> 4;
    }
    pc->data[index] = tmp;
    return true;
  }
  if (m_fatType == 16) {
    lba = m_fatStartBlock + (cluster >> 8);
  } else if (m_fatType == 32) {
    lba = m_fatStartBlock + (cluster >> 7);
  } else {
    DBG_FAIL_MACRO;
    goto fail;
  }
  pc = cacheFetchFat(lba, CACHE_FOR_WRITE);
  if (!pc) {
    DBG_FAIL_MACRO;
    goto fail;
  }
  // store entry
  if (m_fatType == 16) {
    pc->fat16[cluster & 0XFF] = value;
  } else {
    pc->fat32[cluster & 0X7F] = value;
  }
  return true;

 fail:
  return false;
}
//------------------------------------------------------------------------------
// free a cluster chain
bool SdVolume::freeChain(uint32_t cluster) {
  uint32_t next;

  do {
    if (!fatGet(cluster, &next)) {
      DBG_FAIL_MACRO;
      goto fail;
    }
    // free cluster
    if (!fatPut(cluster, 0)) {
      DBG_FAIL_MACRO;
      goto fail;
    }
    if (cluster < m_allocSearchStart) m_allocSearchStart = cluster;
    cluster = next;
  } while (!isEOC(cluster));

  return true;

 fail:
  return false;
}
//------------------------------------------------------------------------------
/** Volume free space in clusters.
 *
 * \return Count of free clusters for success or -1 if an error occurs.
 */
int32_t SdVolume::freeClusterCount() {
  uint32_t free = 0;
  uint32_t lba;
  uint32_t todo = m_clusterCount + 2;
  uint16_t n;

  if (FAT12_SUPPORT && m_fatType == 12) {
    for (unsigned i = 2; i < todo; i++) {
      uint32_t c;
      if (!fatGet(i, &c)) {
        DBG_FAIL_MACRO;
        goto fail;
      }
      if (c == 0) free++;
    }
  } else if (m_fatType == 16 || m_fatType == 32) {
    lba = m_fatStartBlock;
    while (todo) {
      cache_t* pc = cacheFetchFat(lba++, CACHE_FOR_READ);
      if (!pc) {
        DBG_FAIL_MACRO;
        goto fail;
      }
      n = m_fatType == 16 ? 256 : 128;
      if (todo < n) n = todo;
      if (m_fatType == 16) {
        for (uint16_t i = 0; i < n; i++) {
          if (pc->fat16[i] == 0) free++;
        }
      } else {
        for (uint16_t i = 0; i < n; i++) {
          if (pc->fat32[i] == 0) free++;
        }
      }
      todo -= n;
    }
  } else {
    // invalid FAT type
    DBG_FAIL_MACRO;
    goto fail;
  }
  return free;

 fail:
  return -1;
}
//------------------------------------------------------------------------------
/** Initialize a FAT volume.
 *
 * \param[in] dev The SD card where the volume is located.
 *
 * \param[in] part The partition to be used.  Legal values for \a part are
 * 1-4 to use the corresponding partition on a device formatted with
 * a MBR, Master Boot Record, or zero if the device is formatted as
 * a super floppy with the FAT boot sector in block zero.
 *
 * \return The value one, true, is returned for success and
 * the value zero, false, is returned for failure.  Reasons for
 * failure include not finding a valid partition, not finding a valid
 * FAT file system in the specified partition or an I/O error.
 */
bool SdVolume::init(Sd2Card* dev, uint8_t part) {
  uint8_t tmp;
  uint32_t totalBlocks;
  uint32_t volumeStartBlock = 0;
  fat32_boot_t* fbs;
  cache_t* pc;
  m_sdCard = dev;
  m_fatType = 0;
  m_allocSearchStart = 2;
  m_cacheStatus = 0;  // cacheSync() will write block if true
  m_cacheBlockNumber = 0XFFFFFFFF;
#if USE_SEPARATE_FAT_CACHE
  m_cacheFatStatus = 0;  // cacheSync() will write block if true
  m_cacheFatBlockNumber = 0XFFFFFFFF;
#endif  // USE_SEPARATE_FAT_CACHE
  // if part == 0 assume super floppy with FAT boot sector in block zero
  // if part > 0 assume mbr volume with partition table
  if (part) {
    if (part > 4) {
      DBG_FAIL_MACRO;
      goto fail;
    }
    pc = cacheFetch(volumeStartBlock, CACHE_FOR_READ);
    if (!pc) {
      DBG_FAIL_MACRO;
      goto fail;
    }
    part_t* p = &pc->mbr.part[part-1];
    if ((p->boot & 0X7F) != 0 || p->firstSector == 0) {
      // not a valid partition
      DBG_FAIL_MACRO;
      goto fail;
    }
    volumeStartBlock = p->firstSector;
  }
  pc = cacheFetch(volumeStartBlock, CACHE_FOR_READ);
  if (!pc) {
    DBG_FAIL_MACRO;
    goto fail;
  }
  fbs = &(pc->fbs32);
  if (fbs->bytesPerSector != 512 ||
    fbs->fatCount == 0 ||
    fbs->reservedSectorCount == 0) {
       // not valid FAT volume
      DBG_FAIL_MACRO;
      goto fail;
  }
  m_fatCount = fbs->fatCount;
  m_blocksPerCluster = fbs->sectorsPerCluster;

  m_clusterBlockMask = m_blocksPerCluster - 1;

  // determine shift that is same as multiply by m_blocksPerCluster
  m_clusterSizeShift = 0;
  for (tmp = 1; m_blocksPerCluster != tmp; m_clusterSizeShift++) {
    tmp <<= 1;
    if (tmp == 0) {
      DBG_FAIL_MACRO;
      goto fail;
    }
  }

  m_blocksPerFat = fbs->sectorsPerFat16 ?
                    fbs->sectorsPerFat16 : fbs->sectorsPerFat32;

  m_fatStartBlock = volumeStartBlock + fbs->reservedSectorCount;

  // count for FAT16 zero for FAT32
  m_rootDirEntryCount = fbs->rootDirEntryCount;

  // directory start for FAT16 dataStart for FAT32
  m_rootDirStart = m_fatStartBlock + fbs->fatCount * m_blocksPerFat;

  // data start for FAT16 and FAT32
  m_dataStartBlock = m_rootDirStart + ((32 * fbs->rootDirEntryCount + 511)/512);

  // total blocks for FAT16 or FAT32
  totalBlocks = fbs->totalSectors16 ?
                           fbs->totalSectors16 : fbs->totalSectors32;
  // total data blocks
  m_clusterCount = totalBlocks - (m_dataStartBlock - volumeStartBlock);

  // divide by cluster size to get cluster count
  m_clusterCount >>= m_clusterSizeShift;

  // FAT type is determined by cluster count
  if (m_clusterCount < 4085) {
    m_fatType = 12;
    if (!FAT12_SUPPORT) {
      DBG_FAIL_MACRO;
      goto fail;
    }
  } else if (m_clusterCount < 65525) {
    m_fatType = 16;
  } else {
    m_rootDirStart = fbs->fat32RootCluster;
    m_fatType = 32;
  }
  return true;

 fail:
  return false;
}