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