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Corrects data prologue usage and off-by-one error in checksum placement.

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Thomas Harte 2018-04-28 23:17:06 -04:00
parent 45cf28e0eb
commit fabcb261dc
1 changed files with 8 additions and 8 deletions
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16
Storage/Disk/Encodings/AppleGCR.cpp
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@ -94,8 +94,8 @@ Storage::Disk::PCMSegment AppleGCR::header(uint8_t volume, uint8_t track, uint8_
segment.data[2] = header_prologue[2];
#define WriteFM(index, value) \
segment.data[index+0] = static_cast<uint8_t>((value >> 1) | 0xaa); \
segment.data[index+1] = static_cast<uint8_t>(value | 0xaa); \
segment.data[index+0] = static_cast<uint8_t>(((value) >> 1) | 0xaa); \
segment.data[index+1] = static_cast<uint8_t>((value) | 0xaa); \
WriteFM(3, volume);
WriteFM(5, track);
@ -138,9 +138,9 @@ Storage::Disk::PCMSegment AppleGCR::six_and_two_data(const uint8_t *source) {
segment.number_of_bits = static_cast<unsigned int>(segment.data.size() * 8);
// Add the prologue and epilogue.
segment.data[0] = header_prologue[0];
segment.data[1] = header_prologue[1];
segment.data[2] = header_prologue[2];
segment.data[0] = data_prologue[0];
segment.data[1] = data_prologue[1];
segment.data[2] = data_prologue[2];
segment.data[346] = epilogue[0];
segment.data[347] = epilogue[1];
@ -162,12 +162,12 @@ Storage::Disk::PCMSegment AppleGCR::six_and_two_data(const uint8_t *source) {
segment.data[3 + 85] = bit_shuffle[source[255]&3];
for(std::size_t c = 0; c < 256; ++c) {
segment.data[3 + 85 + c] = source[c] >> 2;
segment.data[3 + 85 + 1 + c] = source[c] >> 2;
}
// Exclusive OR each byte with the one before it.
segment.data[344] = segment.data[343];
std::size_t location = 343;
segment.data[345] = segment.data[344];
std::size_t location = 344;
while(location > 3) {
segment.data[location] ^= segment.data[location-1];
--location;