mirror of https://github.com/bsnes-emu/bsnes.git
73 lines
1.9 KiB
C++
73 lines
1.9 KiB
C++
#pragma once
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#include <nall/decode/huffman.hpp>
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namespace nall::Decode {
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inline auto LZSA(array_view<uint8_t> input) -> vector<uint8_t> {
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vector<uint8_t> output;
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uint index = 0;
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uint size = 0;
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for(uint byte : range(8)) size |= *input++ << byte * 8;
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output.resize(size);
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auto load = [&]() -> vector<uint8_t> {
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uint size = 0;
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for(uint byte : range(8)) size |= *input++ << byte * 8;
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vector<uint8_t> buffer;
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buffer.reserve(size);
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while(size--) buffer.append(*input++);
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return buffer;
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};
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auto flags = Decode::Huffman(load());
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auto literals = Decode::Huffman(load());
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auto lengths = Decode::Huffman(load());
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auto offsets = Decode::Huffman(load());
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auto flagData = flags.data();
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uint byte = 0, bits = 0;
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auto flagRead = [&]() -> bool {
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if(bits == 0) bits = 8, byte = *flagData++;
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return byte >> --bits & 1;
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};
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auto literalData = literals.data();
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auto literalRead = [&]() -> uint8_t {
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return *literalData++;
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};
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auto lengthData = lengths.data();
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auto lengthRead = [&]() -> uint64_t {
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uint byte = *lengthData++, bytes = 1;
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while(!(byte & 1)) byte >>= 1, bytes++;
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uint length = byte >> 1, shift = 8 - bytes;
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while(--bytes) length |= *lengthData++ << shift, shift += 8;
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return length;
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};
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auto offsetData = offsets.data();
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auto offsetRead = [&]() -> uint {
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uint offset = 0;
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offset |= *offsetData++ << 0; if(index < 1 << 8) return offset;
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offset |= *offsetData++ << 8; if(index < 1 << 16) return offset;
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offset |= *offsetData++ << 16; if(index < 1 << 24) return offset;
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offset |= *offsetData++ << 24; return offset;
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};
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while(index < size) {
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if(!flagRead()) {
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output[index++] = literalRead();
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} else {
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uint length = lengthRead() + 6;
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uint offset = index - offsetRead();
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while(length--) output[index++] = output[offset++];
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}
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}
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return output;
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}
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}
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