mirror of https://github.com/bsnes-emu/bsnes.git
285 lines
7.3 KiB
C++
285 lines
7.3 KiB
C++
//S-DD1 decompression algorithm implementation
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//original code written by Andreas Naive (public domain license)
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//bsnes port written by byuu
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//note: decompression module does not need to be serialized with bsnes
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//this is because decompression only runs during DMA, and bsnes will complete
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//any pending DMA transfers prior to serialization.
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//input manager
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auto SDD1::Decompressor::IM::init(uint offset_) -> void {
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offset = offset_;
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bitCount = 4;
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}
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auto SDD1::Decompressor::IM::getCodeWord(uint8 codeLength) -> uint8 {
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uint8 codeWord;
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uint8 compCount;
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codeWord = sdd1.mmcRead(offset) << bitCount;
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bitCount++;
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if(codeWord & 0x80) {
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codeWord |= sdd1.mmcRead(offset + 1) >> (9 - bitCount);
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bitCount += codeLength;
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}
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if(bitCount & 0x08) {
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offset++;
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bitCount &= 0x07;
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}
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return codeWord;
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}
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//golomb-code decoder
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const uint8 SDD1::Decompressor::GCD::runCount[] = {
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0x00, 0x00, 0x01, 0x00, 0x03, 0x01, 0x02, 0x00,
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0x07, 0x03, 0x05, 0x01, 0x06, 0x02, 0x04, 0x00,
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0x0f, 0x07, 0x0b, 0x03, 0x0d, 0x05, 0x09, 0x01,
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0x0e, 0x06, 0x0a, 0x02, 0x0c, 0x04, 0x08, 0x00,
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0x1f, 0x0f, 0x17, 0x07, 0x1b, 0x0b, 0x13, 0x03,
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0x1d, 0x0d, 0x15, 0x05, 0x19, 0x09, 0x11, 0x01,
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0x1e, 0x0e, 0x16, 0x06, 0x1a, 0x0a, 0x12, 0x02,
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0x1c, 0x0c, 0x14, 0x04, 0x18, 0x08, 0x10, 0x00,
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0x3f, 0x1f, 0x2f, 0x0f, 0x37, 0x17, 0x27, 0x07,
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0x3b, 0x1b, 0x2b, 0x0b, 0x33, 0x13, 0x23, 0x03,
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0x3d, 0x1d, 0x2d, 0x0d, 0x35, 0x15, 0x25, 0x05,
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0x39, 0x19, 0x29, 0x09, 0x31, 0x11, 0x21, 0x01,
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0x3e, 0x1e, 0x2e, 0x0e, 0x36, 0x16, 0x26, 0x06,
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0x3a, 0x1a, 0x2a, 0x0a, 0x32, 0x12, 0x22, 0x02,
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0x3c, 0x1c, 0x2c, 0x0c, 0x34, 0x14, 0x24, 0x04,
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0x38, 0x18, 0x28, 0x08, 0x30, 0x10, 0x20, 0x00,
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0x7f, 0x3f, 0x5f, 0x1f, 0x6f, 0x2f, 0x4f, 0x0f,
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0x77, 0x37, 0x57, 0x17, 0x67, 0x27, 0x47, 0x07,
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0x7b, 0x3b, 0x5b, 0x1b, 0x6b, 0x2b, 0x4b, 0x0b,
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0x73, 0x33, 0x53, 0x13, 0x63, 0x23, 0x43, 0x03,
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0x7d, 0x3d, 0x5d, 0x1d, 0x6d, 0x2d, 0x4d, 0x0d,
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0x75, 0x35, 0x55, 0x15, 0x65, 0x25, 0x45, 0x05,
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0x79, 0x39, 0x59, 0x19, 0x69, 0x29, 0x49, 0x09,
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0x71, 0x31, 0x51, 0x11, 0x61, 0x21, 0x41, 0x01,
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0x7e, 0x3e, 0x5e, 0x1e, 0x6e, 0x2e, 0x4e, 0x0e,
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0x76, 0x36, 0x56, 0x16, 0x66, 0x26, 0x46, 0x06,
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0x7a, 0x3a, 0x5a, 0x1a, 0x6a, 0x2a, 0x4a, 0x0a,
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0x72, 0x32, 0x52, 0x12, 0x62, 0x22, 0x42, 0x02,
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0x7c, 0x3c, 0x5c, 0x1c, 0x6c, 0x2c, 0x4c, 0x0c,
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0x74, 0x34, 0x54, 0x14, 0x64, 0x24, 0x44, 0x04,
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0x78, 0x38, 0x58, 0x18, 0x68, 0x28, 0x48, 0x08,
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0x70, 0x30, 0x50, 0x10, 0x60, 0x20, 0x40, 0x00,
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};
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auto SDD1::Decompressor::GCD::getRunCount(uint8 codeNumber, uint8& mpsCount, bool& lpsIndex) -> void {
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uint8 codeWord = self.im.getCodeWord(codeNumber);
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if(codeWord & 0x80) {
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lpsIndex = 1;
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mpsCount = runCount[codeWord >> (codeNumber ^ 0x07)];
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} else {
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mpsCount = 1 << codeNumber;
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}
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}
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//bits generator
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auto SDD1::Decompressor::BG::init() -> void {
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mpsCount = 0;
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lpsIndex = 0;
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}
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auto SDD1::Decompressor::BG::getBit(bool& endOfRun) -> uint8 {
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if(!(mpsCount || lpsIndex)) self.gcd.getRunCount(codeNumber, mpsCount, lpsIndex);
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uint8 bit;
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if(mpsCount) {
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bit = 0;
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mpsCount--;
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} else {
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bit = 1;
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lpsIndex = 0;
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}
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endOfRun = !(mpsCount || lpsIndex);
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return bit;
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}
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//probability estimation module
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const SDD1::Decompressor::PEM::State SDD1::Decompressor::PEM::evolutionTable[33] = {
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{0, 25, 25},
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{0, 2, 1},
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{0, 3, 1},
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{0, 4, 2},
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{0, 5, 3},
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{1, 6, 4},
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{1, 7, 5},
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{1, 8, 6},
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{1, 9, 7},
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{2, 10, 8},
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{2, 11, 9},
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{2, 12, 10},
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{2, 13, 11},
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{3, 14, 12},
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{3, 15, 13},
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{3, 16, 14},
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{3, 17, 15},
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{4, 18, 16},
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{4, 19, 17},
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{5, 20, 18},
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{5, 21, 19},
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{6, 22, 20},
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{6, 23, 21},
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{7, 24, 22},
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{7, 24, 23},
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{0, 26, 1},
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{1, 27, 2},
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{2, 28, 4},
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{3, 29, 8},
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{4, 30, 12},
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{5, 31, 16},
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{6, 32, 18},
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{7, 24, 22},
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};
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auto SDD1::Decompressor::PEM::init() -> void {
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for(auto n : range(32)) {
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contextInfo[n].status = 0;
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contextInfo[n].mps = 0;
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}
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}
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auto SDD1::Decompressor::PEM::getBit(uint8 context) -> uint8 {
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ContextInfo& info = contextInfo[context];
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uint8 currentStatus = info.status;
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uint8 currentMps = info.mps;
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const State& s = SDD1::Decompressor::PEM::evolutionTable[currentStatus];
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uint8 bit;
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bool endOfRun;
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switch(s.codeNumber) {
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case 0: bit = self.bg0.getBit(endOfRun); break;
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case 1: bit = self.bg1.getBit(endOfRun); break;
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case 2: bit = self.bg2.getBit(endOfRun); break;
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case 3: bit = self.bg3.getBit(endOfRun); break;
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case 4: bit = self.bg4.getBit(endOfRun); break;
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case 5: bit = self.bg5.getBit(endOfRun); break;
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case 6: bit = self.bg6.getBit(endOfRun); break;
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case 7: bit = self.bg7.getBit(endOfRun); break;
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}
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if(endOfRun) {
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if(bit) {
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if(!(currentStatus & 0xfe)) info.mps ^= 0x01;
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info.status = s.nextIfLps;
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} else {
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info.status = s.nextIfMps;
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}
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}
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return bit ^ currentMps;
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}
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//context model
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auto SDD1::Decompressor::CM::init(uint offset) -> void {
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bitplanesInfo = sdd1.mmcRead(offset) & 0xc0;
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contextBitsInfo = sdd1.mmcRead(offset) & 0x30;
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bitNumber = 0;
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for(auto n : range(8)) previousBitplaneBits[n] = 0;
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switch(bitplanesInfo) {
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case 0x00: currentBitplane = 1; break;
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case 0x40: currentBitplane = 7; break;
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case 0x80: currentBitplane = 3; break;
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}
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}
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auto SDD1::Decompressor::CM::getBit() -> uint8 {
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switch(bitplanesInfo) {
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case 0x00:
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currentBitplane ^= 0x01;
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break;
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case 0x40:
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currentBitplane ^= 0x01;
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if(!(bitNumber & 0x7f)) currentBitplane = ((currentBitplane + 2) & 0x07);
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break;
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case 0x80:
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currentBitplane ^= 0x01;
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if(!(bitNumber & 0x7f)) currentBitplane ^= 0x02;
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break;
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case 0xc0:
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currentBitplane = bitNumber & 0x07;
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break;
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}
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uint16& contextBits = previousBitplaneBits[currentBitplane];
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uint8 currentContext = (currentBitplane & 0x01) << 4;
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switch(contextBitsInfo) {
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case 0x00: currentContext |= ((contextBits & 0x01c0) >> 5) | (contextBits & 0x0001); break;
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case 0x10: currentContext |= ((contextBits & 0x0180) >> 5) | (contextBits & 0x0001); break;
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case 0x20: currentContext |= ((contextBits & 0x00c0) >> 5) | (contextBits & 0x0001); break;
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case 0x30: currentContext |= ((contextBits & 0x0180) >> 5) | (contextBits & 0x0003); break;
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}
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uint8 bit = self.pem.getBit(currentContext);
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contextBits <<= 1;
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contextBits |= bit;
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bitNumber++;
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return bit;
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}
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//output logic
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auto SDD1::Decompressor::OL::init(uint offset) -> void {
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bitplanesInfo = sdd1.mmcRead(offset) & 0xc0;
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r0 = 0x01;
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}
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auto SDD1::Decompressor::OL::decompress() -> uint8 {
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switch(bitplanesInfo) {
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case 0x00: case 0x40: case 0x80:
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if(r0 == 0) {
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r0 = ~r0;
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return r2;
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}
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for(r0 = 0x80, r1 = 0, r2 = 0; r0; r0 >>= 1) {
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if(self.cm.getBit()) r1 |= r0;
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if(self.cm.getBit()) r2 |= r0;
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}
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return r1;
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case 0xc0:
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for(r0 = 0x01, r1 = 0; r0; r0 <<= 1) {
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if(self.cm.getBit()) r1 |= r0;
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}
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return r1;
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}
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}
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//core
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SDD1::Decompressor::Decompressor():
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im(*this), gcd(*this),
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bg0(*this, 0), bg1(*this, 1), bg2(*this, 2), bg3(*this, 3),
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bg4(*this, 4), bg5(*this, 5), bg6(*this, 6), bg7(*this, 7),
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pem(*this), cm(*this), ol(*this) {
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}
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auto SDD1::Decompressor::init(uint offset) -> void {
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im.init(offset);
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bg0.init();
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bg1.init();
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bg2.init();
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bg3.init();
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bg4.init();
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bg5.init();
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bg6.init();
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bg7.init();
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pem.init();
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cm.init(offset);
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ol.init(offset);
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}
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auto SDD1::Decompressor::read() -> uint8 {
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return ol.decompress();
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}
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