//------------------------------------------------------------------------------
// Store a FAT entry
uint8_t SdVolume::fatPut(uint32_t cluster, uint32_t value) {
// error if reserved cluster
if (cluster < 2)
return false;
// error if not in FAT
if (cluster > (clusterCount_ + 1))
return false;
// calculate block address for entry
uint32_t lba = fatStartBlock_;
lba += fatType_ == 16 ? cluster >> 8 : cluster >> 7;
if (lba != cacheBlockNumber_)
{
if (!cacheRawBlock(lba, CACHE_FOR_READ)) return false;
}
// store entry
if (fatType_ == 16)
{
cacheBuffer_.fat16[cluster & 0XFF] = value;
}
else
{
cacheBuffer_.fat32[cluster & 0X7F] = value;
}
cacheSetDirty();
// mirror second FAT
if (fatCount_ > 1)
cacheMirrorBlock_ = lba + blocksPerFat_;
return true;
}
//------------------------------------------------------------------------------
// cache a zero block for blockNumber
uint8_t SdVolume::cacheZeroBlock(uint32_t blockNumber) {
if (!cacheFlush()) return false;
// loop take less flash than memset(cacheBuffer_.data, 0, 512);
for (uint16_t i = 0; i < 512; i++) {
cacheBuffer_.data[i] = 0;
}
cacheBlockNumber_ = blockNumber;
cacheSetDirty();
return true;
}
