mirror of https://github.com/bsnes-emu/bsnes.git
48 lines
884 B
C++
48 lines
884 B
C++
#pragma once
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//burrows-wheeler transform
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#include <nall/suffix-array.hpp>
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namespace nall::Decode {
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inline auto BWT(array_view<uint8_t> input) -> vector<uint8_t> {
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vector<uint8_t> output;
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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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uint I = 0;
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for(uint byte : range(8)) I |= *input++ << byte * 8;
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auto suffixes = SuffixArray(input);
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auto L = input;
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auto F = new uint8_t[size];
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for(uint offset : range(size)) F[offset] = L[suffixes[offset + 1]];
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uint64_t K[256] = {};
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auto C = new int[size];
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for(uint i : range(size)) {
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C[i] = K[L[i]];
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K[L[i]]++;
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}
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int M[256];
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memory::fill<int>(M, 256, -1);
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for(uint i : range(size)) {
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if(M[F[i]] == -1) M[F[i]] = i;
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}
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uint i = I;
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for(uint j : reverse(range(size))) {
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output[j] = L[i];
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i = C[i] + M[L[i]];
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}
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return output;
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}
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}
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