Merged 1.0.5

1 files changed, 990 insertions, 0 deletions

diff --git a/libraries/Robot_Control/Fat16.cpp b/libraries/Robot_Control/Fat16.cpp
new file mode 100644
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--- /dev/null
+++ b/libraries/Robot_Control/Fat16.cpp
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+/* Arduino FAT16 Library
+ * Copyright (C) 2008 by William Greiman
+ *
+ * This file is part of the Arduino FAT16 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 Fat16 Library.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ */
+#include <avr/pgmspace.h>
+#if ARDUINO < 100
+#include <WProgram.h>
+#else  // ARDUINO
+#include <Arduino.h>
+#endif  // ARDUINO
+#include <Fat16.h>
+//-----------------------------------------------------------------------------
+// volume info
+uint8_t  Fat16::volumeInitialized_ = 0;  // true if FAT16 volume is valid
+uint8_t  Fat16::fatCount_;               // number of file allocation tables
+uint8_t  Fat16::blocksPerCluster_;       // must be power of 2
+uint16_t Fat16::rootDirEntryCount_;      // should be 512 for FAT16
+fat_t    Fat16::blocksPerFat_;           // number of blocks in one FAT
+fat_t    Fat16::clusterCount_;           // total clusters in volume
+uint32_t Fat16::fatStartBlock_;          // start of first FAT
+uint32_t Fat16::rootDirStartBlock_;      // start of root dir
+uint32_t Fat16::dataStartBlock_;         // start of data clusters
+//------------------------------------------------------------------------------
+// raw block cache
+SdCard *Fat16::rawDev_ = 0;             // class for block read and write
+uint32_t Fat16::cacheBlockNumber_ = 0XFFFFFFFF;  // init to invalid block number
+cache16_t  Fat16::cacheBuffer_;         // 512 byte cache for SdCard
+uint8_t  Fat16::cacheDirty_ = 0;        // cacheFlush() will write block if true
+uint32_t Fat16::cacheMirrorBlock_ = 0;  // mirror  block for second FAT
+//------------------------------------------------------------------------------
+// callback function for date/time
+void (*Fat16::dateTime_)(uint16_t* date, uint16_t* time) = NULL;
+
+#if ALLOW_DEPRECATED_FUNCTIONS
+void (*Fat16::oldDateTime_)(uint16_t& date, uint16_t& time) = NULL;  // NOLINT
+#endif  // ALLOW_DEPRECATED_FUNCTIONS
+//------------------------------------------------------------------------------
+// format 8.3 name for directory entry
+static uint8_t make83Name(const char* str, uint8_t* name) {
+  uint8_t c;
+  uint8_t n = 7;  // max index for part before dot
+  uint8_t i = 0;
+  // blank fill name and extension
+  while (i < 11) name[i++] = ' ';
+  i = 0;
+  while ((c = *str++) != '\0') {
+    if (c == '.') {
+      if (n == 10) return false;  // only one dot allowed
+      n = 10;  // max index for full 8.3 name
+      i = 8;   // place for extension
+    } else {
+      // illegal FAT characters
+      PGM_P p = PSTR("|<>^+=?/[];,*\"\\");
+      uint8_t b;
+      while ((b = pgm_read_byte(p++))) if (b == c) return false;
+      // check length and only allow ASCII printable characters
+      if (i > n || c < 0X21 || c > 0X7E) return false;
+      // only upper case allowed in 8.3 names - convert lower to upper
+      name[i++] = c < 'a' || c > 'z' ?  c : c + ('A' - 'a');
+    }
+  }
+  // must have a file name, extension is optional
+  return name[0] != ' ';
+}
+//==============================================================================
+// Fat16 member functions
+//------------------------------------------------------------------------------
+uint8_t Fat16::addCluster(void) {
+  // start search after last cluster of file or at cluster two in FAT
+  fat_t freeCluster = curCluster_ ? curCluster_ : 1;
+  for (fat_t i = 0; ; i++) {
+    // return no free clusters
+    if (i >= clusterCount_) return false;
+    // Fat has clusterCount + 2 entries
+    if (freeCluster > clusterCount_) freeCluster = 1;
+    freeCluster++;
+    fat_t value;
+    if (!fatGet(freeCluster, &value)) return false;
+    if (value == 0) break;
+  }
+  // mark cluster allocated
+  if (!fatPut(freeCluster, FAT16EOC)) return false;
+
+  if (curCluster_ != 0) {
+    // link cluster to chain
+    if (!fatPut(curCluster_, freeCluster)) return false;
+  } else {
+    // first cluster of file so update directory entry
+    flags_ |= F_FILE_DIR_DIRTY;
+    firstCluster_ = freeCluster;
+  }
+  curCluster_ = freeCluster;
+  return true;
+}
+//------------------------------------------------------------------------------
+//
+dir_t* Fat16::cacheDirEntry(uint16_t index, uint8_t action) {
+  if (index >= rootDirEntryCount_) return NULL;
+  if (!cacheRawBlock(rootDirStartBlock_ + (index >> 4), action)) return NULL;
+  return &cacheBuffer_.dir[index & 0XF];
+}
+//------------------------------------------------------------------------------
+//
+uint8_t Fat16::cacheFlush(void) {
+  if (cacheDirty_) {
+    if (!rawDev_->writeBlock(cacheBlockNumber_, cacheBuffer_.data)) {
+      return false;
+    }
+    // mirror FAT tables
+    if (cacheMirrorBlock_) {
+      if (!rawDev_->writeBlock(cacheMirrorBlock_, cacheBuffer_.data)) {
+        return false;
+      }
+      cacheMirrorBlock_ = 0;
+    }
+    cacheDirty_ = 0;
+  }
+  return true;
+}
+//------------------------------------------------------------------------------
+//
+uint8_t Fat16::cacheRawBlock(uint32_t blockNumber, uint8_t action) {
+  if (cacheBlockNumber_ != blockNumber) {
+    if (!cacheFlush()) return false;
+    if (!rawDev_->readBlock(blockNumber, cacheBuffer_.data)) return false;
+    cacheBlockNumber_ = blockNumber;
+  }
+  cacheDirty_ |= action;
+  return true;
+}
+//------------------------------------------------------------------------------
+/**
+ *  Close a file and force cached data and directory information
+ *  to be written to the storage device.
+ *
+ * \return The value one, true, is returned for success and
+ * the value zero, false, is returned for failure.
+ * Reasons for failure include no file is open or an I/O error.
+ */
+uint8_t Fat16::close(void) {
+  if (!sync()) return false;
+  flags_ = 0;
+  return true;
+}
+//------------------------------------------------------------------------------
+/**
+ * Return a files directory entry
+ *
+ * \param[out] dir Location for return of the files directory entry.
+ *
+ * \return The value one, true, is returned for success and
+ * the value zero, false, is returned for failure.
+ */
+uint8_t Fat16::dirEntry(dir_t* dir) {
+  if (!sync()) return false;
+  dir_t* p = cacheDirEntry(dirEntryIndex_, CACHE_FOR_WRITE);
+  if (!p) return false;
+  memcpy(dir, p, sizeof(dir_t));
+  return true;
+}
+//------------------------------------------------------------------------------
+uint8_t Fat16::fatGet(fat_t cluster, fat_t* value) {
+  if (cluster > (clusterCount_ + 1)) return false;
+  uint32_t lba = fatStartBlock_ + (cluster >> 8);
+  if (lba != cacheBlockNumber_) {
+    if (!cacheRawBlock(lba)) return false;
+  }
+  *value = cacheBuffer_.fat[cluster & 0XFF];
+  return true;
+}
+//------------------------------------------------------------------------------
+uint8_t Fat16::fatPut(fat_t cluster, fat_t value) {
+  if (cluster < 2) return false;
+  if (cluster > (clusterCount_ + 1)) return false;
+  uint32_t lba = fatStartBlock_ + (cluster >> 8);
+  if (lba != cacheBlockNumber_) {
+    if (!cacheRawBlock(lba)) return false;
+  }
+  cacheBuffer_.fat[cluster & 0XFF] = value;
+  cacheSetDirty();
+  // mirror second FAT
+  if (fatCount_ > 1) cacheMirrorBlock_ = lba + blocksPerFat_;
+  return true;
+}
+//------------------------------------------------------------------------------
+// free a cluster chain
+uint8_t Fat16::freeChain(fat_t cluster) {
+  while (1) {
+    fat_t next;
+    if (!fatGet(cluster, &next)) return false;
+    if (!fatPut(cluster, 0)) return false;
+    if (isEOC(next)) return true;
+    cluster = next;
+  }
+}
+//------------------------------------------------------------------------------
+/**
+ *  Initialize a FAT16 volume.
+ *
+ * \param[in] dev The SdCard 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 FAT16 file system in the
+ * specified partition, a call to init() after a volume has
+ * been successful initialized or an I/O error.
+ *
+ */
+uint8_t Fat16::init(SdCard* dev, uint8_t part) {
+  // error if invalid partition
+  if (part > 4) return false;
+  rawDev_ = dev;
+  uint32_t volumeStartBlock = 0;
+  // if part == 0 assume super floppy with FAT16 boot sector in block zero
+  // if part > 0 assume mbr volume with partition table
+  if (part) {
+    if (!cacheRawBlock(volumeStartBlock)) return false;
+    volumeStartBlock = cacheBuffer_.mbr.part[part - 1].firstSector;
+  }
+  if (!cacheRawBlock(volumeStartBlock)) return false;
+  // check boot block signature
+  if (cacheBuffer_.data[510] != BOOTSIG0 ||
+      cacheBuffer_.data[511] != BOOTSIG1) return false;
+  bpb_t* bpb = &cacheBuffer_.fbs.bpb;
+  fatCount_ = bpb->fatCount;
+  blocksPerCluster_ = bpb->sectorsPerCluster;
+  blocksPerFat_ = bpb->sectorsPerFat16;
+  rootDirEntryCount_ = bpb->rootDirEntryCount;
+  fatStartBlock_ = volumeStartBlock + bpb->reservedSectorCount;
+  rootDirStartBlock_ = fatStartBlock_ + bpb->fatCount*bpb->sectorsPerFat16;
+  dataStartBlock_ = rootDirStartBlock_
+                    + ((32*bpb->rootDirEntryCount + 511)/512);
+  uint32_t totalBlocks = bpb->totalSectors16 ?
+                               bpb->totalSectors16 : bpb->totalSectors32;
+  clusterCount_ = (totalBlocks - (dataStartBlock_ - volumeStartBlock))
+                  /bpb->sectorsPerCluster;
+  // verify valid FAT16 volume
+  if (bpb->bytesPerSector != 512       // only allow 512 byte blocks
+     || bpb->sectorsPerFat16 == 0      // zero for FAT32
+     || clusterCount_ < 4085           // FAT12 if true
+     || totalBlocks > 0X800000         // Max size for FAT16 volume
+     || bpb->reservedSectorCount == 0  // invalid volume
+     || bpb->fatCount == 0             // invalid volume
+     || bpb->sectorsPerFat16 < (clusterCount_ >> 8)  // invalid volume
+     || bpb->sectorsPerCluster == 0   // invalid volume
+        // power of 2 test
+     || bpb->sectorsPerCluster & (bpb->sectorsPerCluster - 1)) {
+    // not a usable FAT16 bpb
+    return false;
+  }
+  volumeInitialized_ = 1;
+  return true;
+}
+//------------------------------------------------------------------------------
+/** List directory contents to Serial.
+ *
+ * \param[in] flags The inclusive OR of
+ *
+ * LS_DATE - %Print file modification date
+ *
+ * LS_SIZE - %Print file size.
+ */
+void Fat16::ls(uint8_t flags) {
+  dir_t d;
+  for (uint16_t index = 0; readDir(&d, &index, DIR_ATT_VOLUME_ID); index++) {
+    // print file name with possible blank fill
+    printDirName(d, flags & (LS_DATE | LS_SIZE) ? 14 : 0);
+
+    // print modify date/time if requested
+    if (flags & LS_DATE) {
+       printFatDate(d.lastWriteDate);
+       Serial.write(' ');
+       printFatTime(d.lastWriteTime);
+    }
+
+    // print size if requested
+    if (DIR_IS_FILE(&d) && (flags & LS_SIZE)) {
+      Serial.write(' ');
+      Serial.print(d.fileSize);
+    }
+    Serial.println();
+  }
+}
+//------------------------------------------------------------------------------
+/**
+ * Open a file by file name.
+ *
+ * \note The file must be in the root directory and must have a DOS
+ * 8.3 name.
+ *
+ * \param[in] fileName A valid 8.3 DOS name for a file in the root directory.
+ *
+ * \param[in] oflag Values for \a oflag are constructed by a bitwise-inclusive
+ *  OR of flags from the following list
+ *
+ * O_READ - Open for reading.
+ *
+ * O_RDONLY - Same as O_READ.
+ *
+ * O_WRITE - Open for writing.
+ *
+ * O_WRONLY - Same as O_WRITE.
+ *
+ * O_RDWR - Open for reading and writing.
+ *
+ * O_APPEND - If set, the file offset shall be set to the end of the
+ * file prior to each write.
+ *
+ * O_CREAT - If the file exists, this flag has no effect except as noted
+ * under O_EXCL below. Otherwise, the file shall be created
+ *
+ * O_EXCL - If O_CREAT and O_EXCL are set, open() shall fail if the file exists.
+ *
+ * O_SYNC - Call sync() after each write.  This flag should not be used with
+ * write(uint8_t), write_P(PGM_P), writeln_P(PGM_P), or the Arduino Print class.
+ * These functions do character a time writes so sync() will be called
+ * after each byte.
+ *
+ * O_TRUNC - If the file exists and is a regular file, and the file is
+ * successfully opened and is not read only, its length shall be truncated to 0.
+ *
+ * \return The value one, true, is returned for success and
+ * the value zero, false, is returned for failure.
+ * Reasons for failure include the FAT volume has not been initialized,
+ * a file is already open, \a fileName is invalid, the file does not exist,
+ * is a directory, or can't be opened in the access mode specified by oflag.
+ */
+uint8_t Fat16::open(const char* fileName, uint8_t oflag) {
+  uint8_t dname[11];   // name formated for dir entry
+  int16_t empty = -1;  // index of empty slot
+  dir_t* p;            // pointer to cached dir entry
+
+  if (!volumeInitialized_ || isOpen()) return false;
+
+  // error if invalid name
+  if (!make83Name(fileName, dname)) return false;
+
+  for (uint16_t index = 0; index < rootDirEntryCount_; index++) {
+    if (!(p = cacheDirEntry(index))) return false;
+    if (p->name[0] == DIR_NAME_FREE || p->name[0] == DIR_NAME_DELETED) {
+      // remember first empty slot
+      if (empty < 0) empty = index;
+      // done if no entries follow
+      if (p->name[0] == DIR_NAME_FREE) break;
+    } else if (!memcmp(dname, p->name, 11)) {
+      // don't open existing file if O_CREAT and O_EXCL
+      if ((oflag & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL)) return false;
+
+      // open existing file
+      return open(index, oflag);
+    }
+  }
+  // error if directory is full
+  if (empty < 0) return false;
+
+  // only create file if O_CREAT and O_WRITE
+  if ((oflag & (O_CREAT | O_WRITE)) != (O_CREAT | O_WRITE)) return false;
+
+  if (!(p = cacheDirEntry(empty, CACHE_FOR_WRITE))) return false;
+
+  // initialize as empty file
+  memset(p, 0, sizeof(dir_t));
+  memcpy(p->name, dname, 11);
+
+  // set timestamps
+  if (dateTime_) {
+    // call user function
+    dateTime_(&p->creationDate, &p->creationTime);
+  } else {
+    // use default date/time
+    p->creationDate = FAT_DEFAULT_DATE;
+    p->creationTime = FAT_DEFAULT_TIME;
+  }
+  p->lastAccessDate = p->creationDate;
+  p->lastWriteDate = p->creationDate;
+  p->lastWriteTime = p->creationTime;
+
+  // insure created directory entry will be written to storage device
+  if (!cacheFlush()) return false;
+
+  // open entry
+  return open(empty, oflag);
+}
+//------------------------------------------------------------------------------
+/**
+ * Open a file by file index.
+ *
+ * \param[in] index The root directory index of the file to be opened.  See \link
+ *  Fat16::readDir() readDir()\endlink.
+ *
+ * \param[in] oflag  See \link Fat16::open(const char*, uint8_t)\endlink.
+ *
+ * \return The value one, true, is returned for success and
+ * the value zero, false, is returned for failure.
+ * Reasons for failure include the FAT volume has not been initialized,
+ * a file is already open, \a index is invalid or is not the index of a
+ * file or the file cannot be opened in the access mode specified by oflag.
+ */
+uint8_t Fat16::open(uint16_t index, uint8_t oflag) {
+  if (!volumeInitialized_ || isOpen()) return false;
+  if ((oflag & O_TRUNC) && !(oflag & O_WRITE)) return false;
+  dir_t* d = cacheDirEntry(index);
+  // if bad file index or I/O error
+  if (!d) return false;
+
+  // error if unused entry
+  if (d->name[0] == DIR_NAME_FREE || d->name[0] == DIR_NAME_DELETED) {
+    return false;
+  }
+  // error if long name, volume label or subdirectory
+  if ((d->attributes & (DIR_ATT_VOLUME_ID | DIR_ATT_DIRECTORY)) != 0) {
+    return false;
+  }
+  // don't allow write or truncate if read-only
+  if (d->attributes & DIR_ATT_READ_ONLY) {
+    if (oflag & (O_WRITE | O_TRUNC)) return false;
+  }
+
+  curCluster_ = 0;
+  curPosition_ = 0;
+  dirEntryIndex_ = index;
+  fileSize_ = d->fileSize;
+  firstCluster_ = d->firstClusterLow;
+  flags_ = oflag & (O_ACCMODE | O_SYNC | O_APPEND);
+
+  if (oflag & O_TRUNC ) return truncate(0);
+  return true;
+}
+//------------------------------------------------------------------------------
+/** %Print the name field of a directory entry in 8.3 format to Serial.
+ *
+ * \param[in] dir The directory structure containing the name.
+ * \param[in] width Blank fill name if length is less than \a width.
+ */
+void Fat16::printDirName(const dir_t& dir, uint8_t width) {
+  uint8_t w = 0;
+  for (uint8_t i = 0; i < 11; i++) {
+    if (dir.name[i] == ' ') continue;
+    if (i == 8) {
+      Serial.write('.');
+      w++;
+    }
+    Serial.write(dir.name[i]);
+    w++;
+  }
+  if (DIR_IS_SUBDIR(&dir)) {
+    Serial.write('/');
+    w++;
+  }
+  while (w < width) {
+    Serial.write(' ');
+    w++;
+  }
+}
+//------------------------------------------------------------------------------
+/** %Print a directory date field to Serial.
+ *
+ *  Format is yyyy-mm-dd.
+ *
+ * \param[in] fatDate The date field from a directory entry.
+ */
+void Fat16::printFatDate(uint16_t fatDate) {
+  Serial.print(FAT_YEAR(fatDate));
+  Serial.write('-');
+  printTwoDigits(FAT_MONTH(fatDate));
+  Serial.write('-');
+  printTwoDigits(FAT_DAY(fatDate));
+}
+//------------------------------------------------------------------------------
+/** %Print a directory time field to Serial.
+ *
+ * Format is hh:mm:ss.
+ *
+ * \param[in] fatTime The time field from a directory entry.
+ */
+void Fat16::printFatTime(uint16_t fatTime) {
+  printTwoDigits(FAT_HOUR(fatTime));
+  Serial.write(':');
+  printTwoDigits(FAT_MINUTE(fatTime));
+  Serial.write(':');
+  printTwoDigits(FAT_SECOND(fatTime));
+}
+
+//------------------------------------------------------------------------------
+/** %Print a value as two digits to Serial.
+ *
+ * \param[in] v Value to be printed, 0 <= \a v <= 99
+ */
+void Fat16::printTwoDigits(uint8_t v) {
+  char str[3];
+  str[0] = '0' + v/10;
+  str[1] = '0' + v % 10;
+  str[2] = 0;
+  Serial.print(str);
+}
+//------------------------------------------------------------------------------
+/**
+ * Read the next byte from a file.
+ *
+ * \return For success read returns the next byte in the file as an int.
+ * If an error occurs or end of file is reached -1 is returned.
+ */
+int16_t Fat16::read(void) {
+  uint8_t b;
+  return read(&b, 1) == 1 ? b : -1;
+}
+//------------------------------------------------------------------------------
+/**
+ * Read data from a file at starting at the current file position.
+ *
+ * \param[out] buf Pointer to the location that will receive the data.
+ *
+ * \param[in] nbyte Maximum number of bytes to read.
+ *
+ * \return For success read returns the number of bytes read.
+ * A value less than \a nbyte, including zero, may be returned
+ * if end of file is reached.
+ * If an error occurs, read returns -1.  Possible errors include
+ * read called before a file has been opened, the file has not been opened in
+ * read mode, a corrupt file system, or an I/O error.
+ */
+int16_t Fat16::read(void* buf, uint16_t nbyte) {
+  // convert void pointer to uin8_t pointer
+  uint8_t* dst = reinterpret_cast<uint8_t*>(buf);
+
+  // error if not open for read
+  if (!(flags_ & O_READ)) return -1;
+
+  // don't read beyond end of file
+  if ((curPosition_ + nbyte) > fileSize_) nbyte = fileSize_ - curPosition_;
+
+  // bytes left to read in loop
+  uint16_t nToRead = nbyte;
+  while (nToRead > 0) {
+    uint8_t blkOfCluster = blockOfCluster(curPosition_);
+    uint16_t blockOffset = cacheDataOffset(curPosition_);
+    if (blkOfCluster == 0 && blockOffset == 0) {
+      // start next cluster
+      if (curCluster_ == 0) {
+        curCluster_ = firstCluster_;
+      } else {
+        if (!fatGet(curCluster_, &curCluster_)) return -1;
+      }
+      // return error if bad cluster chain
+      if (curCluster_ < 2 || isEOC(curCluster_)) return -1;
+    }
+    // cache data block
+    if (!cacheRawBlock(dataBlockLba(curCluster_, blkOfCluster))) return -1;
+
+    // location of data in cache
+    uint8_t* src = cacheBuffer_.data + blockOffset;
+
+    // max number of byte available in block
+    uint16_t n = 512 - blockOffset;
+
+    // lesser of available and amount to read
+    if (n > nToRead) n = nToRead;
+
+    // copy data to caller
+    memcpy(dst, src, n);
+
+    curPosition_ += n;
+    dst += n;
+    nToRead -= n;
+  }
+  return nbyte;
+}
+//------------------------------------------------------------------------------
+/**
+ *  Read the next short, 8.3, directory entry.
+ *
+ *  Unused entries and entries for long names are skipped.
+ *
+ * \param[out] dir Location that will receive the entry.
+ *
+ * \param[in,out] index The search starts at \a index and \a index is
+ * updated with the root directory index of the found directory entry.
+ * If the entry is a file, it may be opened by calling
+ * \link Fat16::open(uint16_t, uint8_t) \endlink.
+ *
+ * \param[in] skip Skip entries that have these attributes. If \a skip
+ * is not specified, the default is to skip the volume label and directories.
+ *
+ * \return The value one, true, is returned for success and the value zero,
+ * false, is returned if an error occurs or the end of the root directory is
+ * reached.  On success, \a entry is set to the index of the found directory
+ * entry.
+ */
+uint8_t Fat16::readDir(dir_t* dir, uint16_t* index, uint8_t skip) {
+  dir_t* p;
+  for (uint16_t i = *index; ; i++) {
+    if (i >= rootDirEntryCount_) return false;
+    if (!(p = cacheDirEntry(i))) return false;
+
+    // done if beyond last used entry
+    if (p->name[0] == DIR_NAME_FREE) return false;
+
+    // skip deleted entry
+    if (p->name[0] == DIR_NAME_DELETED) continue;
+
+    // skip long names
+    if ((p->attributes & DIR_ATT_LONG_NAME_MASK) == DIR_ATT_LONG_NAME) continue;
+
+    // skip if attribute match
+    if (p->attributes & skip) continue;
+
+    // return found index
+    *index = i;
+    break;
+  }
+  memcpy(dir, p, sizeof(dir_t));
+  return true;
+}
+//------------------------------------------------------------------------------
+/**
+ * Remove a file.  The directory entry and all data for the file are deleted.
+ *
+ * \note This function should not be used to delete the 8.3 version of a
+ * file that has a long name. For example if a file has the long name
+ * "New Text Document.txt" you should not delete the 8.3 name "NEWTEX~1.TXT".
+ *
+ * \return The value one, true, is returned for success and
+ * the value zero, false, is returned for failure.
+ * Reasons for failure include the file is not open for write
+ * or an I/O error occurred.
+ */
+uint8_t Fat16::remove(void) {
+  // error if file is not open for write
+  if (!(flags_ & O_WRITE)) return false;
+  if (firstCluster_) {
+    if (!freeChain(firstCluster_)) return false;
+  }
+  dir_t* d = cacheDirEntry(dirEntryIndex_, CACHE_FOR_WRITE);
+  if (!d) return false;
+  d->name[0] = DIR_NAME_DELETED;
+  flags_ = 0;
+  return cacheFlush();
+}
+//------------------------------------------------------------------------------
+/**
+ * Remove a file.
+ *
+ * The directory entry and all data for the file are deleted.
+ *
+ * \param[in] fileName The name of the file to be removed.
+ *
+ * \note This function should not be used to delete the 8.3 version of a
+ * file that has a long name. For example if a file has the long name
+ * "New Text Document.txt" you should not delete the 8.3 name "NEWTEX~1.TXT".
+ *
+ * \return The value one, true, is returned for success and
+ * the value zero, false, is returned for failure.
+ * Reasons for failure include the file is read only, \a fileName is not found
+ * or an I/O error occurred.
+ */
+uint8_t Fat16::remove(const char* fileName) {
+  Fat16 file;
+  if (!file.open(fileName, O_WRITE)) return false;
+  return file.remove();
+}
+//------------------------------------------------------------------------------
+/**
+ * Sets the file's read/write position.
+ *
+ * \param[in] pos The new position in bytes from the beginning of the file.
+ *
+ * \return The value one, true, is returned for success and
+ * the value zero, false, is returned for failure.
+ */
+uint8_t Fat16::seekSet(uint32_t pos) {
+  // error if file not open or seek past end of file
+  if (!isOpen() || pos > fileSize_) return false;
+  if (pos == 0) {
+    // set position to start of file
+    curCluster_ = 0;
+    curPosition_ = 0;
+    return true;
+  }
+  fat_t n = ((pos - 1) >> 9)/blocksPerCluster_;
+  if (pos < curPosition_ || curPosition_ == 0) {
+    // must follow chain from first cluster
+    curCluster_ = firstCluster_;
+  } else {
+    // advance from curPosition
+    n -= ((curPosition_ - 1) >> 9)/blocksPerCluster_;
+  }
+  while (n--) {
+    if (!fatGet(curCluster_, &curCluster_)) return false;
+  }
+  curPosition_ = pos;
+  return true;
+}
+//------------------------------------------------------------------------------
+/**
+ *  The sync() call causes all modified data and directory fields
+ *  to be written to the storage device.
+ *
+ * \return The value one, true, is returned for success and
+ * the value zero, false, is returned for failure.
+ * Reasons for failure include a call to sync() before a file has been
+ * opened or an I/O error.
+ */
+uint8_t Fat16::sync(void) {
+  if (flags_ & F_FILE_DIR_DIRTY) {
+    // cache directory entry
+    dir_t* d = cacheDirEntry(dirEntryIndex_, CACHE_FOR_WRITE);
+    if (!d) return false;
+
+    // update file size and first cluster
+    d->fileSize = fileSize_;
+    d->firstClusterLow = firstCluster_;
+
+    // set modify time if user supplied a callback date/time function
+    if (dateTime_) {
+      dateTime_(&d->lastWriteDate, &d->lastWriteTime);
+      d->lastAccessDate = d->lastWriteDate;
+    }
+    flags_ &= ~F_FILE_DIR_DIRTY;
+  }
+  return cacheFlush();
+}
+//------------------------------------------------------------------------------
+/**
+ * The timestamp() call sets a file's timestamps in its directory entry.
+ *
+ * \param[in] flags Values for \a flags are constructed by a bitwise-inclusive
+ * OR of flags from the following list
+ *
+ * T_ACCESS - Set the file's last access date.
+ *
+ * T_CREATE - Set the file's creation date and time.
+ *
+ * T_WRITE - Set the file's last write/modification date and time.
+ *
+ * \param[in] year Valid range 1980 - 2107 inclusive.
+ *
+ * \param[in] month Valid range 1 - 12 inclusive.
+ *
+ * \param[in] day Valid range 1 - 31 inclusive.
+ *
+ * \param[in] hour Valid range 0 - 23 inclusive.
+ *
+ * \param[in] minute Valid range 0 - 59 inclusive.
+ *
+ * \param[in] second Valid range 0 - 59 inclusive
+ *
+ * \note It is possible to set an invalid date since there is no check for
+ * the number of days in a month.
+ *
+ * \return The value one, true, is returned for success and
+ * the value zero, false, is returned for failure.
+ */
+uint8_t Fat16::timestamp(uint8_t flags, uint16_t year, uint8_t month,
+         uint8_t day, uint8_t hour, uint8_t minute, uint8_t second) {
+  if (!isOpen()
+    || year < 1980
+    || year > 2107
+    || month < 1
+    || month > 12
+    || day < 1
+    || day > 31
+    || hour > 23
+    || minute > 59
+    || second > 59) {
+      return false;
+  }
+  dir_t* d = cacheDirEntry(dirEntryIndex_, CACHE_FOR_WRITE);
+  if (!d) return false;
+  uint16_t dirDate = FAT_DATE(year, month, day);
+  uint16_t dirTime = FAT_TIME(hour, minute, second);
+  if (flags & T_ACCESS) {
+    d->lastAccessDate = dirDate;
+  }
+  if (flags & T_CREATE) {
+    d->creationDate = dirDate;
+    d->creationTime = dirTime;
+    // seems to be units of 1/100 second not 1/10 as Microsoft standard states
+    d->creationTimeTenths = second & 1 ? 100 : 0;
+  }
+  if (flags & T_WRITE) {
+    d->lastWriteDate = dirDate;
+    d->lastWriteTime = dirTime;
+  }
+  cacheSetDirty();
+  return sync();
+}
+//------------------------------------------------------------------------------
+/**
+ * Truncate a file to a specified length.  The current file position
+ * will be maintained if it is less than or equal to \a length otherwise
+ * it will be set to end of file.
+ *
+ * \param[in] length The desired length for the file.
+ *
+ * \return The value one, true, is returned for success and
+ * the value zero, false, is returned for failure.
+ * Reasons for failure include file is read only, file is a directory,
+ * \a length is greater than the current file size or an I/O error occurs.
+ */
+uint8_t Fat16::truncate(uint32_t length) {
+  // error if file is not open for write
+  if (!(flags_ & O_WRITE)) return false;
+
+  if (length > fileSize_) return false;
+
+  // fileSize and length are zero - nothing to do
+  if (fileSize_ == 0) return true;
+  uint32_t newPos = curPosition_ > length ? length : curPosition_;
+  if (length == 0) {
+    // free all clusters
+    if (!freeChain(firstCluster_)) return false;
+    curCluster_ = firstCluster_ = 0;
+  } else {
+    fat_t toFree;
+    if (!seekSet(length)) return false;
+    if (!fatGet(curCluster_, &toFree)) return false;
+    if (!isEOC(toFree)) {
+      // free extra clusters
+      if (!fatPut(curCluster_, FAT16EOC)) return false;
+      if (!freeChain(toFree)) return false;
+    }
+  }
+  fileSize_ = length;
+  flags_ |= F_FILE_DIR_DIRTY;
+  if (!sync()) return false;
+  return seekSet(newPos);
+}
+//------------------------------------------------------------------------------
+/**
+ * Write data at the current position of an open file.
+ *
+ * \note Data is moved to the cache but may not be written to the
+ * storage device until sync() is called.
+ *
+ * \param[in] buf Pointer to the location of the data to be written.
+ *
+ * \param[in] nbyte Number of bytes to write.
+ *
+ * \return For success write() returns the number of bytes written, always
+ * \a nbyte.  If an error occurs, write() returns -1.  Possible errors include
+ * write() is called before a file has been opened, the file has not been opened
+ * for write, device is full, a corrupt file system or an I/O error.
+ *
+ */
+int16_t Fat16::write(const void* buf, uint16_t nbyte) {
+  uint16_t nToWrite = nbyte;
+  const uint8_t* src = reinterpret_cast<const uint8_t*>(buf);
+
+  // error if file is not open for write
+  if (!(flags_ & O_WRITE)) goto writeErrorReturn;
+
+  // go to end of file if O_APPEND
+  if ((flags_ & O_APPEND) && curPosition_ != fileSize_) {
+    if (!seekEnd()) goto writeErrorReturn;
+  }
+  while (nToWrite > 0) {
+    uint8_t blkOfCluster = blockOfCluster(curPosition_);
+    uint16_t blockOffset = cacheDataOffset(curPosition_);
+    if (blkOfCluster == 0 && blockOffset == 0) {
+      // start of new cluster
+      if (curCluster_ == 0) {
+        if (firstCluster_ == 0) {
+          // allocate first cluster of file
+          if (!addCluster()) goto writeErrorReturn;
+        } else {
+          curCluster_ = firstCluster_;
+        }
+      } else {
+        fat_t next;
+        if (!fatGet(curCluster_, &next)) goto writeErrorReturn;
+        if (isEOC(next)) {
+          // add cluster if at end of chain
+          if (!addCluster()) goto writeErrorReturn;
+        } else {
+          curCluster_ = next;
+        }
+      }
+    }
+    uint32_t lba = dataBlockLba(curCluster_, blkOfCluster);
+    if (blockOffset == 0 && curPosition_ >= fileSize_) {
+      // start of new block don't need to read into cache
+      if (!cacheFlush()) goto writeErrorReturn;
+      cacheBlockNumber_ = lba;
+      cacheSetDirty();
+    } else {
+      // rewrite part of block
+      if (!cacheRawBlock(lba, CACHE_FOR_WRITE)) return -1;
+    }
+    uint8_t* dst = cacheBuffer_.data + blockOffset;
+
+    // max space in block
+    uint16_t n = 512 - blockOffset;
+
+    // lesser of space and amount to write
+    if (n > nToWrite) n = nToWrite;
+
+    // copy data to cache
+    memcpy(dst, src, n);
+
+    curPosition_ += n;
+    nToWrite -= n;
+    src += n;
+  }
+  if (curPosition_ > fileSize_) {
+    // update fileSize and insure sync will update dir entry
+    fileSize_ = curPosition_;
+    flags_ |= F_FILE_DIR_DIRTY;
+  } else if (dateTime_ && nbyte) {
+    // insure sync will update modified date and time
+    flags_ |= F_FILE_DIR_DIRTY;
+  }
+
+  if (flags_ & O_SYNC) {
+    if (!sync()) goto writeErrorReturn;
+  }
+  return nbyte;
+
+ writeErrorReturn:
+  writeError = true;
+  return -1;
+}
+//------------------------------------------------------------------------------
+/**
+ * Write a byte to a file. Required by the Arduino Print class.
+ *
+ *  Use Fat16::writeError to check for errors.
+ */
+#if ARDUINO < 100
+void Fat16::write(uint8_t b) {
+  write(&b, 1);
+}
+#else  // ARDUINO < 100
+size_t Fat16::write(uint8_t b) {
+  return write(&b, 1) == 1 ? 1 : 0;
+}
+#endif  // ARDUINO < 100
+//------------------------------------------------------------------------------
+/**
+ * Write a string to a file. Used by the Arduino Print class.
+ *
+ * Use Fat16::writeError to check for errors.
+ */
+#if ARDUINO < 100
+void Fat16::write(const char* str) {
+  write(str, strlen(str));
+}
+#else  // ARDUINO < 100
+int16_t Fat16::write(const char* str) {
+  return write(str, strlen(str));
+}
+#endif  // ARDUINO < 100
+//------------------------------------------------------------------------------
+/**
+ * Write a PROGMEM string to a file.
+ *
+ * Use Fat16::writeError to check for errors.
+ */
+void Fat16::write_P(PGM_P str) {
+  for (uint8_t c; (c = pgm_read_byte(str)); str++) write(c);
+}
+//------------------------------------------------------------------------------
+/**
+ * Write a PROGMEM string followed by CR/LF to a file.
+ *
+ * Use Fat16::writeError to check for errors.
+ */
+void Fat16::writeln_P(PGM_P str) {
+  write_P(str);
+  println();
+}