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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