403 lines
12 KiB
C++
403 lines
12 KiB
C++
/* 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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#include "SdFat.h"
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#include "SdVolume.h"
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//------------------------------------------------------------------------------
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#if !USE_MULTIPLE_CARDS
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// raw block cache
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uint32_t SdVolume::cacheBlockNumber_; // current block number
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cache_t SdVolume::cacheBuffer_; // 512 byte cache for Sd2Card
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Sd2Card* SdVolume::sdCard_; // pointer to SD card object
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bool SdVolume::cacheDirty_; // cacheFlush() will write block if true
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uint32_t SdVolume::cacheMirrorBlock_; // mirror block for second FAT
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#endif // USE_MULTIPLE_CARDS
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//------------------------------------------------------------------------------
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// find a contiguous group of clusters
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bool SdVolume::allocContiguous(uint32_t count, uint32_t* curCluster) {
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// start of group
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uint32_t bgnCluster;
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// end of group
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uint32_t endCluster;
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// last cluster of FAT
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uint32_t fatEnd = clusterCount_ + 1;
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// flag to save place to start next search
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bool setStart;
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// set search start cluster
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if (*curCluster) {
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// try to make file contiguous
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bgnCluster = *curCluster + 1;
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// don't save new start location
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setStart = false;
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} else {
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// start at likely place for free cluster
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bgnCluster = allocSearchStart_;
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// save next search start if one cluster
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setStart = count == 1;
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}
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// end of group
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endCluster = bgnCluster;
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// search the FAT for free clusters
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for (uint32_t n = 0;; n++, endCluster++) {
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// can't find space checked all clusters
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if (n >= clusterCount_) goto fail;
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// past end - start from beginning of FAT
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if (endCluster > fatEnd) {
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bgnCluster = endCluster = 2;
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}
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uint32_t f;
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if (!fatGet(endCluster, &f)) goto fail;
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if (f != 0) {
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// cluster in use try next cluster as bgnCluster
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bgnCluster = endCluster + 1;
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} else if ((endCluster - bgnCluster + 1) == count) {
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// done - found space
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break;
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}
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}
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// mark end of chain
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if (!fatPutEOC(endCluster)) goto fail;
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// link clusters
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while (endCluster > bgnCluster) {
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if (!fatPut(endCluster - 1, endCluster)) goto fail;
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endCluster--;
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}
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if (*curCluster != 0) {
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// connect chains
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if (!fatPut(*curCluster, bgnCluster)) goto fail;
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}
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// return first cluster number to caller
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*curCluster = bgnCluster;
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// remember possible next free cluster
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if (setStart) allocSearchStart_ = bgnCluster + 1;
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return true;
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fail:
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return false;
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}
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//------------------------------------------------------------------------------
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bool SdVolume::cacheFlush() {
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if (cacheDirty_) {
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if (!sdCard_->writeBlock(cacheBlockNumber_, cacheBuffer_.data)) {
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goto fail;
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}
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// mirror FAT tables
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if (cacheMirrorBlock_) {
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if (!sdCard_->writeBlock(cacheMirrorBlock_, cacheBuffer_.data)) {
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goto fail;
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}
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cacheMirrorBlock_ = 0;
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}
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cacheDirty_ = 0;
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}
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return true;
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fail:
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return false;
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}
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//------------------------------------------------------------------------------
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bool SdVolume::cacheRawBlock(uint32_t blockNumber, bool dirty) {
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if (cacheBlockNumber_ != blockNumber) {
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if (!cacheFlush()) goto fail;
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if (!sdCard_->readBlock(blockNumber, cacheBuffer_.data)) goto fail;
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cacheBlockNumber_ = blockNumber;
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}
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if (dirty) cacheDirty_ = true;
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return true;
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fail:
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return false;
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}
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//------------------------------------------------------------------------------
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// return the size in bytes of a cluster chain
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bool SdVolume::chainSize(uint32_t cluster, uint32_t* size) {
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uint32_t s = 0;
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do {
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if (!fatGet(cluster, &cluster)) goto fail;
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s += 512UL << clusterSizeShift_;
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} while (!isEOC(cluster));
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*size = s;
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return true;
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fail:
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return false;
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}
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//------------------------------------------------------------------------------
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// Fetch a FAT entry
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bool SdVolume::fatGet(uint32_t cluster, uint32_t* value) {
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uint32_t lba;
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if (cluster > (clusterCount_ + 1)) goto fail;
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if (FAT12_SUPPORT && fatType_ == 12) {
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uint16_t index = cluster;
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index += index >> 1;
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lba = fatStartBlock_ + (index >> 9);
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if (!cacheRawBlock(lba, CACHE_FOR_READ)) goto fail;
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index &= 0X1FF;
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uint16_t tmp = cacheBuffer_.data[index];
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index++;
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if (index == 512) {
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if (!cacheRawBlock(lba + 1, CACHE_FOR_READ)) goto fail;
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index = 0;
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}
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tmp |= cacheBuffer_.data[index] << 8;
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*value = cluster & 1 ? tmp >> 4 : tmp & 0XFFF;
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return true;
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}
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if (fatType_ == 16) {
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lba = fatStartBlock_ + (cluster >> 8);
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} else if (fatType_ == 32) {
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lba = fatStartBlock_ + (cluster >> 7);
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} else {
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goto fail;
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}
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if (lba != cacheBlockNumber_) {
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if (!cacheRawBlock(lba, CACHE_FOR_READ)) goto fail;
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}
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if (fatType_ == 16) {
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*value = cacheBuffer_.fat16[cluster & 0XFF];
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} else {
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*value = cacheBuffer_.fat32[cluster & 0X7F] & FAT32MASK;
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}
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return true;
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fail:
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return false;
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}
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//------------------------------------------------------------------------------
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// Store a FAT entry
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bool SdVolume::fatPut(uint32_t cluster, uint32_t value) {
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uint32_t lba;
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// error if reserved cluster
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if (cluster < 2) goto fail;
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// error if not in FAT
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if (cluster > (clusterCount_ + 1)) goto fail;
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if (FAT12_SUPPORT && fatType_ == 12) {
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uint16_t index = cluster;
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index += index >> 1;
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lba = fatStartBlock_ + (index >> 9);
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if (!cacheRawBlock(lba, CACHE_FOR_WRITE)) goto fail;
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// mirror second FAT
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if (fatCount_ > 1) cacheMirrorBlock_ = lba + blocksPerFat_;
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index &= 0X1FF;
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uint8_t tmp = value;
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if (cluster & 1) {
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tmp = (cacheBuffer_.data[index] & 0XF) | tmp << 4;
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}
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cacheBuffer_.data[index] = tmp;
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index++;
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if (index == 512) {
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lba++;
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index = 0;
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if (!cacheRawBlock(lba, CACHE_FOR_WRITE)) goto fail;
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// mirror second FAT
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if (fatCount_ > 1) cacheMirrorBlock_ = lba + blocksPerFat_;
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}
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tmp = value >> 4;
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if (!(cluster & 1)) {
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tmp = ((cacheBuffer_.data[index] & 0XF0)) | tmp >> 4;
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}
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cacheBuffer_.data[index] = tmp;
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return true;
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}
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if (fatType_ == 16) {
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lba = fatStartBlock_ + (cluster >> 8);
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} else if (fatType_ == 32) {
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lba = fatStartBlock_ + (cluster >> 7);
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} else {
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goto fail;
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}
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if (!cacheRawBlock(lba, CACHE_FOR_WRITE)) goto fail;
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// store entry
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if (fatType_ == 16) {
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cacheBuffer_.fat16[cluster & 0XFF] = value;
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} else {
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cacheBuffer_.fat32[cluster & 0X7F] = value;
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}
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// mirror second FAT
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if (fatCount_ > 1) cacheMirrorBlock_ = lba + blocksPerFat_;
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return true;
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fail:
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return false;
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}
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//------------------------------------------------------------------------------
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// free a cluster chain
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bool SdVolume::freeChain(uint32_t cluster) {
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uint32_t next;
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// clear free cluster location
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allocSearchStart_ = 2;
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do {
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if (!fatGet(cluster, &next)) goto fail;
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// free cluster
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if (!fatPut(cluster, 0)) goto fail;
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cluster = next;
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} while (!isEOC(cluster));
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return true;
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fail:
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return false;
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}
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//------------------------------------------------------------------------------
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/** Volume free space in clusters.
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*
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* \return Count of free clusters for success or -1 if an error occurs.
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*/
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int32_t SdVolume::freeClusterCount() {
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uint32_t free = 0;
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uint16_t n;
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uint32_t todo = clusterCount_ + 2;
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if (fatType_ == 16) {
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n = 256;
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} else if (fatType_ == 32) {
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n = 128;
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} else {
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// put FAT12 here
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return -1;
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}
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for (uint32_t lba = fatStartBlock_; todo; todo -= n, lba++) {
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if (!cacheRawBlock(lba, CACHE_FOR_READ)) return -1;
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if (todo < n) n = todo;
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if (fatType_ == 16) {
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for (uint16_t i = 0; i < n; i++) {
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if (cacheBuffer_.fat16[i] == 0) free++;
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}
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} else {
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for (uint16_t i = 0; i < n; i++) {
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if (cacheBuffer_.fat32[i] == 0) free++;
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}
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}
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}
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return free;
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}
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//------------------------------------------------------------------------------
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/** Initialize a FAT volume.
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*
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* \param[in] dev The SD card where the volume is located.
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*
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* \param[in] part The partition to be used. Legal values for \a part are
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* 1-4 to use the corresponding partition on a device formatted with
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* a MBR, Master Boot Record, or zero if the device is formatted as
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* a super floppy with the FAT boot sector in block zero.
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*
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* \return The value one, true, is returned for success and
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* the value zero, false, is returned for failure. Reasons for
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* failure include not finding a valid partition, not finding a valid
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* FAT file system in the specified partition or an I/O error.
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*/
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bool SdVolume::init(Sd2Card* dev, uint8_t part) {
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uint32_t totalBlocks;
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uint32_t volumeStartBlock = 0;
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fat32_boot_t* fbs;
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sdCard_ = dev;
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fatType_ = 0;
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allocSearchStart_ = 2;
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cacheDirty_ = 0; // cacheFlush() will write block if true
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cacheMirrorBlock_ = 0;
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cacheBlockNumber_ = 0XFFFFFFFF;
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// if part == 0 assume super floppy with FAT boot sector in block zero
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// if part > 0 assume mbr volume with partition table
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if (part) {
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if (part > 4)goto fail;
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if (!cacheRawBlock(volumeStartBlock, CACHE_FOR_READ)) goto fail;
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part_t* p = &cacheBuffer_.mbr.part[part-1];
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if ((p->boot & 0X7F) !=0 ||
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p->totalSectors < 100 ||
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p->firstSector == 0) {
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// not a valid partition
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goto fail;
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}
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volumeStartBlock = p->firstSector;
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}
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if (!cacheRawBlock(volumeStartBlock, CACHE_FOR_READ)) goto fail;
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fbs = &cacheBuffer_.fbs32;
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if (fbs->bytesPerSector != 512 ||
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fbs->fatCount == 0 ||
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fbs->reservedSectorCount == 0 ||
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fbs->sectorsPerCluster == 0) {
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// not valid FAT volume
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goto fail;
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}
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fatCount_ = fbs->fatCount;
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blocksPerCluster_ = fbs->sectorsPerCluster;
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// determine shift that is same as multiply by blocksPerCluster_
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clusterSizeShift_ = 0;
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while (blocksPerCluster_ != (1 << clusterSizeShift_)) {
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// error if not power of 2
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if (clusterSizeShift_++ > 7) goto fail;
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}
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blocksPerFat_ = fbs->sectorsPerFat16 ?
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fbs->sectorsPerFat16 : fbs->sectorsPerFat32;
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fatStartBlock_ = volumeStartBlock + fbs->reservedSectorCount;
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// count for FAT16 zero for FAT32
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rootDirEntryCount_ = fbs->rootDirEntryCount;
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// directory start for FAT16 dataStart for FAT32
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rootDirStart_ = fatStartBlock_ + fbs->fatCount * blocksPerFat_;
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// data start for FAT16 and FAT32
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dataStartBlock_ = rootDirStart_ + ((32 * fbs->rootDirEntryCount + 511)/512);
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// total blocks for FAT16 or FAT32
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totalBlocks = fbs->totalSectors16 ?
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fbs->totalSectors16 : fbs->totalSectors32;
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// total data blocks
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clusterCount_ = totalBlocks - (dataStartBlock_ - volumeStartBlock);
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// divide by cluster size to get cluster count
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clusterCount_ >>= clusterSizeShift_;
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// FAT type is determined by cluster count
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if (clusterCount_ < 4085) {
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fatType_ = 12;
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if (!FAT12_SUPPORT) goto fail;
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} else if (clusterCount_ < 65525) {
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fatType_ = 16;
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} else {
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rootDirStart_ = fbs->fat32RootCluster;
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fatType_ = 32;
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}
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return true;
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fail:
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return false;
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}
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