1 files changed, 295 insertions, 0 deletions
diff --git a/libraries/SD/utility/SdVolume.cpp b/libraries/SD/utility/SdVolume.cpp
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+++ b/libraries/SD/utility/SdVolume.cpp
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+/* 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/>.
+ */
+#include <SdFat.h>
+//------------------------------------------------------------------------------
+// raw block cache
+// init cacheBlockNumber_to invalid SD block number
+uint32_t SdVolume::cacheBlockNumber_ = 0XFFFFFFFF;
+cache_t  SdVolume::cacheBuffer_;     // 512 byte cache for Sd2Card
+Sd2Card* SdVolume::sdCard_;          // pointer to SD card object
+uint8_t  SdVolume::cacheDirty_ = 0;  // cacheFlush() will write block if true
+uint32_t SdVolume::cacheMirrorBlock_ = 0;  // mirror  block for second FAT
+//------------------------------------------------------------------------------
+// find a contiguous group of clusters
+uint8_t SdVolume::allocContiguous(uint32_t count, uint32_t* curCluster) {
+  // start of group
+  uint32_t bgnCluster;
+
+  // flag to save place to start next search
+  uint8_t 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 = allocSearchStart_;
+
+    // save next search start if one cluster
+    setStart = 1 == count;
+  }
+  // end of group
+  uint32_t endCluster = bgnCluster;
+
+  // last cluster of FAT
+  uint32_t fatEnd = clusterCount_ + 1;
+
+  // search the FAT for free clusters
+  for (uint32_t n = 0;; n++, endCluster++) {
+    // can't find space checked all clusters
+    if (n >= clusterCount_) return false;
+
+    // past end - start from beginning of FAT
+    if (endCluster > fatEnd) {
+      bgnCluster = endCluster = 2;
+    }
+    uint32_t f;
+    if (!fatGet(endCluster, &f)) return false;
+
+    if (f != 0) {
+      // cluster in use try next cluster as bgnCluster
+      bgnCluster = endCluster + 1;
+    } else if ((endCluster - bgnCluster + 1) == count) {
+      // done - found space
+      break;
+    }
+  }
+  // mark end of chain
+  if (!fatPutEOC(endCluster)) return false;
+
+  // link clusters
+  while (endCluster > bgnCluster) {
+    if (!fatPut(endCluster - 1, endCluster)) return false;
+    endCluster--;
+  }
+  if (*curCluster != 0) {
+    // connect chains
+    if (!fatPut(*curCluster, bgnCluster)) return false;
+  }
+  // return first cluster number to caller
+  *curCluster = bgnCluster;
+
+  // remember possible next free cluster
+  if (setStart) allocSearchStart_ = bgnCluster + 1;
+
+  return true;
+}
+//------------------------------------------------------------------------------
+uint8_t SdVolume::cacheFlush(void) {
+  if (cacheDirty_) {
+    if (!sdCard_->writeBlock(cacheBlockNumber_, cacheBuffer_.data)) {
+      return false;
+    }
+    // mirror FAT tables
+    if (cacheMirrorBlock_) {
+      if (!sdCard_->writeBlock(cacheMirrorBlock_, cacheBuffer_.data)) {
+        return false;
+      }
+      cacheMirrorBlock_ = 0;
+    }
+    cacheDirty_ = 0;
+  }
+  return true;
+}
+//------------------------------------------------------------------------------
+uint8_t SdVolume::cacheRawBlock(uint32_t blockNumber, uint8_t action) {
+  if (cacheBlockNumber_ != blockNumber) {
+    if (!cacheFlush()) return false;
+    if (!sdCard_->readBlock(blockNumber, cacheBuffer_.data)) return false;
+    cacheBlockNumber_ = blockNumber;
+  }
+  cacheDirty_ |= action;
+  return true;
+}
+//------------------------------------------------------------------------------
+// cache a zero block for blockNumber
+uint8_t SdVolume::cacheZeroBlock(uint32_t blockNumber) {
+  if (!cacheFlush()) return false;
+
+  // loop take less flash than memset(cacheBuffer_.data, 0, 512);
+  for (uint16_t i = 0; i < 512; i++) {
+    cacheBuffer_.data[i] = 0;
+  }
+  cacheBlockNumber_ = blockNumber;
+  cacheSetDirty();
+  return true;
+}
+//------------------------------------------------------------------------------
+// return the size in bytes of a cluster chain
+uint8_t SdVolume::chainSize(uint32_t cluster, uint32_t* size) const {
+  uint32_t s = 0;
+  do {
+    if (!fatGet(cluster, &cluster)) return false;
+    s += 512UL << clusterSizeShift_;
+  } while (!isEOC(cluster));
+  *size = s;
+  return true;
+}
+//------------------------------------------------------------------------------
+// Fetch a FAT entry
+uint8_t SdVolume::fatGet(uint32_t cluster, uint32_t* value) const {
+  if (cluster > (clusterCount_ + 1)) return false;
+  uint32_t lba = fatStartBlock_;
+  lba += fatType_ == 16 ? cluster >> 8 : cluster >> 7;
+  if (lba != cacheBlockNumber_) {
+    if (!cacheRawBlock(lba, CACHE_FOR_READ)) return false;
+  }
+  if (fatType_ == 16) {
+    *value = cacheBuffer_.fat16[cluster & 0XFF];
+  } else {
+    *value = cacheBuffer_.fat32[cluster & 0X7F] & FAT32MASK;
+  }
+  return true;
+}
+//------------------------------------------------------------------------------
+// Store a FAT entry
+uint8_t SdVolume::fatPut(uint32_t cluster, uint32_t value) {
+  // error if reserved cluster
+  if (cluster < 2) return false;
+
+  // error if not in FAT
+  if (cluster > (clusterCount_ + 1)) return false;
+
+  // calculate block address for entry
+  uint32_t lba = fatStartBlock_;
+  lba += fatType_ == 16 ? cluster >> 8 : cluster >> 7;
+
+  if (lba != cacheBlockNumber_) {
+    if (!cacheRawBlock(lba, CACHE_FOR_READ)) return false;
+  }
+  // store entry
+  if (fatType_ == 16) {
+    cacheBuffer_.fat16[cluster & 0XFF] = value;
+  } else {
+    cacheBuffer_.fat32[cluster & 0X7F] = value;
+  }
+  cacheSetDirty();
+
+  // mirror second FAT
+  if (fatCount_ > 1) cacheMirrorBlock_ = lba + blocksPerFat_;
+  return true;
+}
+//------------------------------------------------------------------------------
+// free a cluster chain
+uint8_t SdVolume::freeChain(uint32_t cluster) {
+  // clear free cluster location
+  allocSearchStart_ = 2;
+
+  do {
+    uint32_t next;
+    if (!fatGet(cluster, &next)) return false;
+
+    // free cluster
+    if (!fatPut(cluster, 0)) return false;
+
+    cluster = next;
+  } while (!isEOC(cluster));
+
+  return true;
+}
+//------------------------------------------------------------------------------
+/**
+ * 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.
+ */
+uint8_t SdVolume::init(Sd2Card* dev, uint8_t part) {
+  uint32_t volumeStartBlock = 0;
+  sdCard_ = dev;
+  // 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)return false;
+    if (!cacheRawBlock(volumeStartBlock, CACHE_FOR_READ)) return false;
+    part_t* p = &cacheBuffer_.mbr.part[part-1];
+    if ((p->boot & 0X7F) !=0  ||
+      p->totalSectors < 100 ||
+      p->firstSector == 0) {
+      // not a valid partition
+      return false;
+    }
+    volumeStartBlock = p->firstSector;
+  }
+  if (!cacheRawBlock(volumeStartBlock, CACHE_FOR_READ)) return false;
+  bpb_t* bpb = &cacheBuffer_.fbs.bpb;
+  if (bpb->bytesPerSector != 512 ||
+    bpb->fatCount == 0 ||
+    bpb->reservedSectorCount == 0 ||
+    bpb->sectorsPerCluster == 0) {
+       // not valid FAT volume
+      return false;
+  }
+  fatCount_ = bpb->fatCount;
+  blocksPerCluster_ = bpb->sectorsPerCluster;
+
+  // determine shift that is same as multiply by blocksPerCluster_
+  clusterSizeShift_ = 0;
+  while (blocksPerCluster_ != (1 << clusterSizeShift_)) {
+    // error if not power of 2
+    if (clusterSizeShift_++ > 7) return false;
+  }
+  blocksPerFat_ = bpb->sectorsPerFat16 ?
+                    bpb->sectorsPerFat16 : bpb->sectorsPerFat32;
+
+  fatStartBlock_ = volumeStartBlock + bpb->reservedSectorCount;
+
+  // count for FAT16 zero for FAT32
+  rootDirEntryCount_ = bpb->rootDirEntryCount;
+
+  // directory start for FAT16 dataStart for FAT32
+  rootDirStart_ = fatStartBlock_ + bpb->fatCount * blocksPerFat_;
+
+  // data start for FAT16 and FAT32
+  dataStartBlock_ = rootDirStart_ + ((32 * bpb->rootDirEntryCount + 511)/512);
+
+  // total blocks for FAT16 or FAT32
+  uint32_t totalBlocks = bpb->totalSectors16 ?
+                           bpb->totalSectors16 : bpb->totalSectors32;
+  // total data blocks
+  clusterCount_ = totalBlocks - (dataStartBlock_ - volumeStartBlock);
+
+  // divide by cluster size to get cluster count
+  clusterCount_ >>= clusterSizeShift_;
+
+  // FAT type is determined by cluster count
+  if (clusterCount_ < 4085) {
+    fatType_ = 12;
+  } else if (clusterCount_ < 65525) {
+    fatType_ = 16;
+  } else {
+    rootDirStart_ = bpb->fat32RootCluster;
+    fatType_ = 32;
+  }
+  return true;
+}