[136] | 1 | /* Arduino SdFat Library
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| 2 | * Copyright (C) 2009 by William Greiman
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| 3 | *
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| 4 | * This file is part of the Arduino SdFat Library
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| 5 | *
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| 6 | * This Library is free software: you can redistribute it and/or modify
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| 7 | * it under the terms of the GNU General Public License as published by
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| 8 | * the Free Software Foundation, either version 3 of the License, or
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| 9 | * (at your option) any later version.
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| 10 | *
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| 11 | * This Library is distributed in the hope that it will be useful,
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| 12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 14 | * GNU General Public License for more details.
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| 15 | *
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| 16 | * You should have received a copy of the GNU General Public License
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| 17 | * along with the Arduino SdFat Library. If not, see
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| 18 | * <http://www.gnu.org/licenses/>.
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| 19 | */
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| 20 | #include "SdFat.h"
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| 21 | //------------------------------------------------------------------------------
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| 22 | // raw block cache
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| 23 | // init cacheBlockNumber_to invalid SD block number
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| 24 | uint32_t SdVolume::cacheBlockNumber_ = 0XFFFFFFFF;
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| 25 | cache_t SdVolume::cacheBuffer_; // 512 byte cache for Sd2Card
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| 26 | Sd2Card* SdVolume::sdCard_; // pointer to SD card object
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| 27 | uint8_t SdVolume::cacheDirty_ = 0; // cacheFlush() will write block if true
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| 28 | uint32_t SdVolume::cacheMirrorBlock_ = 0; // mirror block for second FAT
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| 29 | //------------------------------------------------------------------------------
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| 30 | // find a contiguous group of clusters
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| 31 | uint8_t SdVolume::allocContiguous(uint32_t count, uint32_t* curCluster) {
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| 32 | // start of group
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| 33 | uint32_t bgnCluster;
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| 34 |
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| 35 | // flag to save place to start next search
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| 36 | uint8_t setStart;
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| 37 |
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| 38 | // set search start cluster
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| 39 | if (*curCluster) {
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| 40 | // try to make file contiguous
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| 41 | bgnCluster = *curCluster + 1;
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| 42 |
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| 43 | // don't save new start location
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| 44 | setStart = false;
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| 45 | } else {
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| 46 | // start at likely place for free cluster
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| 47 | bgnCluster = allocSearchStart_;
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| 48 |
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| 49 | // save next search start if one cluster
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| 50 | setStart = 1 == count;
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| 51 | }
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| 52 | // end of group
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| 53 | uint32_t endCluster = bgnCluster;
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| 54 |
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| 55 | // last cluster of FAT
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| 56 | uint32_t fatEnd = clusterCount_ + 1;
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| 57 |
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| 58 | // search the FAT for free clusters
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| 59 | for (uint32_t n = 0;; n++, endCluster++) {
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| 60 | // can't find space checked all clusters
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| 61 | if (n >= clusterCount_) return false;
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| 62 |
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| 63 | // past end - start from beginning of FAT
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| 64 | if (endCluster > fatEnd) {
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| 65 | bgnCluster = endCluster = 2;
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| 66 | }
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| 67 | uint32_t f;
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| 68 | if (!fatGet(endCluster, &f)) return false;
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| 69 |
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| 70 | if (f != 0) {
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| 71 | // cluster in use try next cluster as bgnCluster
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| 72 | bgnCluster = endCluster + 1;
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| 73 | } else if ((endCluster - bgnCluster + 1) == count) {
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| 74 | // done - found space
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| 75 | break;
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| 76 | }
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| 77 | }
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| 78 | // mark end of chain
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| 79 | if (!fatPutEOC(endCluster)) return false;
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| 80 |
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| 81 | // link clusters
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| 82 | while (endCluster > bgnCluster) {
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| 83 | if (!fatPut(endCluster - 1, endCluster)) return false;
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| 84 | endCluster--;
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| 85 | }
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| 86 | if (*curCluster != 0) {
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| 87 | // connect chains
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| 88 | if (!fatPut(*curCluster, bgnCluster)) return false;
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| 89 | }
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| 90 | // return first cluster number to caller
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| 91 | *curCluster = bgnCluster;
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| 92 |
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| 93 | // remember possible next free cluster
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| 94 | if (setStart) allocSearchStart_ = bgnCluster + 1;
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| 95 |
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| 96 | return true;
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| 97 | }
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| 98 | //------------------------------------------------------------------------------
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| 99 | uint8_t SdVolume::cacheFlush(void) {
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| 100 | if (cacheDirty_) {
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| 101 | if (!sdCard_->writeBlock(cacheBlockNumber_, cacheBuffer_.data)) {
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| 102 | return false;
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| 103 | }
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| 104 | // mirror FAT tables
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| 105 | if (cacheMirrorBlock_) {
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| 106 | if (!sdCard_->writeBlock(cacheMirrorBlock_, cacheBuffer_.data)) {
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| 107 | return false;
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| 108 | }
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| 109 | cacheMirrorBlock_ = 0;
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| 110 | }
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| 111 | cacheDirty_ = 0;
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| 112 | }
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| 113 | return true;
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| 114 | }
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| 115 | //------------------------------------------------------------------------------
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| 116 | uint8_t SdVolume::cacheRawBlock(uint32_t blockNumber, uint8_t action) {
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| 117 | if (cacheBlockNumber_ != blockNumber) {
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| 118 | if (!cacheFlush()) return false;
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| 119 | if (!sdCard_->readBlock(blockNumber, cacheBuffer_.data)) return false;
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| 120 | cacheBlockNumber_ = blockNumber;
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| 121 | }
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| 122 | cacheDirty_ |= action;
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| 123 | return true;
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| 124 | }
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| 125 | //------------------------------------------------------------------------------
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| 126 | // cache a zero block for blockNumber
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| 127 | uint8_t SdVolume::cacheZeroBlock(uint32_t blockNumber) {
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| 128 | if (!cacheFlush()) return false;
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| 129 |
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| 130 | // loop take less flash than memset(cacheBuffer_.data, 0, 512);
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| 131 | for (uint16_t i = 0; i < 512; i++) {
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| 132 | cacheBuffer_.data[i] = 0;
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| 133 | }
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| 134 | cacheBlockNumber_ = blockNumber;
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| 135 | cacheSetDirty();
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| 136 | return true;
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| 137 | }
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| 138 | //------------------------------------------------------------------------------
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| 139 | // return the size in bytes of a cluster chain
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| 140 | uint8_t SdVolume::chainSize(uint32_t cluster, uint32_t* size) const {
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| 141 | uint32_t s = 0;
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| 142 | do {
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| 143 | if (!fatGet(cluster, &cluster)) return false;
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| 144 | s += 512UL << clusterSizeShift_;
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| 145 | } while (!isEOC(cluster));
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| 146 | *size = s;
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| 147 | return true;
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| 148 | }
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| 149 | //------------------------------------------------------------------------------
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| 150 | // Fetch a FAT entry
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| 151 | uint8_t SdVolume::fatGet(uint32_t cluster, uint32_t* value) const {
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| 152 | if (cluster > (clusterCount_ + 1)) return false;
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| 153 | uint32_t lba = fatStartBlock_;
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| 154 | lba += fatType_ == 16 ? cluster >> 8 : cluster >> 7;
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| 155 | if (lba != cacheBlockNumber_) {
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| 156 | if (!cacheRawBlock(lba, CACHE_FOR_READ)) return false;
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| 157 | }
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| 158 | if (fatType_ == 16) {
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| 159 | *value = cacheBuffer_.fat16[cluster & 0XFF];
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| 160 | } else {
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| 161 | *value = cacheBuffer_.fat32[cluster & 0X7F] & FAT32MASK;
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| 162 | }
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| 163 | return true;
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| 164 | }
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| 165 | //------------------------------------------------------------------------------
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| 166 | // Store a FAT entry
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| 167 | uint8_t SdVolume::fatPut(uint32_t cluster, uint32_t value) {
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| 168 | // error if reserved cluster
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| 169 | if (cluster < 2) return false;
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| 170 |
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| 171 | // error if not in FAT
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| 172 | if (cluster > (clusterCount_ + 1)) return false;
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| 173 |
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| 174 | // calculate block address for entry
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| 175 | uint32_t lba = fatStartBlock_;
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| 176 | lba += fatType_ == 16 ? cluster >> 8 : cluster >> 7;
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| 177 |
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| 178 | if (lba != cacheBlockNumber_) {
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| 179 | if (!cacheRawBlock(lba, CACHE_FOR_READ)) return false;
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| 180 | }
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| 181 | // store entry
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| 182 | if (fatType_ == 16) {
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| 183 | cacheBuffer_.fat16[cluster & 0XFF] = value;
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| 184 | } else {
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| 185 | cacheBuffer_.fat32[cluster & 0X7F] = value;
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| 186 | }
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| 187 | cacheSetDirty();
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| 188 |
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| 189 | // mirror second FAT
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| 190 | if (fatCount_ > 1) cacheMirrorBlock_ = lba + blocksPerFat_;
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| 191 | return true;
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| 192 | }
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| 193 | //------------------------------------------------------------------------------
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| 194 | // free a cluster chain
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| 195 | uint8_t SdVolume::freeChain(uint32_t cluster) {
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| 196 | // clear free cluster location
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| 197 | allocSearchStart_ = 2;
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| 198 |
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| 199 | do {
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| 200 | uint32_t next;
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| 201 | if (!fatGet(cluster, &next)) return false;
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| 202 |
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| 203 | // free cluster
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| 204 | if (!fatPut(cluster, 0)) return false;
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| 205 |
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| 206 | cluster = next;
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| 207 | } while (!isEOC(cluster));
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| 208 |
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| 209 | return true;
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| 210 | }
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| 211 | //------------------------------------------------------------------------------
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| 212 | /**
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| 213 | * Initialize a FAT volume.
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| 214 | *
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| 215 | * \param[in] dev The SD card where the volume is located.
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| 216 | *
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| 217 | * \param[in] part The partition to be used. Legal values for \a part are
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| 218 | * 1-4 to use the corresponding partition on a device formatted with
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| 219 | * a MBR, Master Boot Record, or zero if the device is formatted as
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| 220 | * a super floppy with the FAT boot sector in block zero.
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| 221 | *
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| 222 | * \return The value one, true, is returned for success and
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| 223 | * the value zero, false, is returned for failure. Reasons for
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| 224 | * failure include not finding a valid partition, not finding a valid
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| 225 | * FAT file system in the specified partition or an I/O error.
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| 226 | */
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| 227 | uint8_t SdVolume::init(Sd2Card* dev, uint8_t part) {
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| 228 | uint32_t volumeStartBlock = 0;
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| 229 | sdCard_ = dev;
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| 230 | // if part == 0 assume super floppy with FAT boot sector in block zero
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| 231 | // if part > 0 assume mbr volume with partition table
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| 232 | if (part) {
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| 233 | if (part > 4)return false;
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| 234 | if (!cacheRawBlock(volumeStartBlock, CACHE_FOR_READ)) return false;
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| 235 | part_t* p = &cacheBuffer_.mbr.part[part-1];
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| 236 | if ((p->boot & 0X7F) !=0 ||
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| 237 | p->totalSectors < 100 ||
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| 238 | p->firstSector == 0) {
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| 239 | // not a valid partition
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| 240 | return false;
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| 241 | }
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| 242 | volumeStartBlock = p->firstSector;
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| 243 | }
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| 244 | if (!cacheRawBlock(volumeStartBlock, CACHE_FOR_READ)) return false;
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| 245 | bpb_t* bpb = &cacheBuffer_.fbs.bpb;
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| 246 | if (bpb->bytesPerSector != 512 ||
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| 247 | bpb->fatCount == 0 ||
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| 248 | bpb->reservedSectorCount == 0 ||
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| 249 | bpb->sectorsPerCluster == 0) {
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| 250 | // not valid FAT volume
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| 251 | return false;
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| 252 | }
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| 253 | fatCount_ = bpb->fatCount;
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| 254 | blocksPerCluster_ = bpb->sectorsPerCluster;
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| 255 |
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| 256 | // determine shift that is same as multiply by blocksPerCluster_
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| 257 | clusterSizeShift_ = 0;
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| 258 | while (blocksPerCluster_ != (1 << clusterSizeShift_)) {
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| 259 | // error if not power of 2
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| 260 | if (clusterSizeShift_++ > 7) return false;
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| 261 | }
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| 262 | blocksPerFat_ = bpb->sectorsPerFat16 ?
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| 263 | bpb->sectorsPerFat16 : bpb->sectorsPerFat32;
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| 264 |
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| 265 | fatStartBlock_ = volumeStartBlock + bpb->reservedSectorCount;
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| 266 |
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| 267 | // count for FAT16 zero for FAT32
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| 268 | rootDirEntryCount_ = bpb->rootDirEntryCount;
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| 269 |
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| 270 | // directory start for FAT16 dataStart for FAT32
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| 271 | rootDirStart_ = fatStartBlock_ + bpb->fatCount * blocksPerFat_;
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| 272 |
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| 273 | // data start for FAT16 and FAT32
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| 274 | dataStartBlock_ = rootDirStart_ + ((32 * bpb->rootDirEntryCount + 511)/512);
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| 275 |
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| 276 | // total blocks for FAT16 or FAT32
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| 277 | uint32_t totalBlocks = bpb->totalSectors16 ?
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| 278 | bpb->totalSectors16 : bpb->totalSectors32;
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| 279 | // total data blocks
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| 280 | clusterCount_ = totalBlocks - (dataStartBlock_ - volumeStartBlock);
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| 281 |
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| 282 | // divide by cluster size to get cluster count
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| 283 | clusterCount_ >>= clusterSizeShift_;
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| 284 |
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| 285 | // FAT type is determined by cluster count
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| 286 | if (clusterCount_ < 4085) {
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| 287 | fatType_ = 12;
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| 288 | } else if (clusterCount_ < 65525) {
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| 289 | fatType_ = 16;
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| 290 | } else {
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| 291 | rootDirStart_ = bpb->fat32RootCluster;
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| 292 | fatType_ = 32;
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| 293 | }
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| 294 | return true;
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| 295 | }
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