57 lines
1.2 KiB
C++
57 lines
1.2 KiB
C++
#pragma once
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namespace nall::Encode {
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template<u32 S = 1, u32 M = 4 / S> //S = word size; M = match length
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inline auto RLE(array_view<u8> input) -> vector<u8> {
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vector<u8> output;
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for(u32 byte : range(8)) output.append(input.size() >> byte * 8);
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u32 base = 0;
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u32 skip = 0;
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auto load = [&](u32 offset) -> u8 {
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return input(offset);
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};
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auto read = [&](u32 offset) -> u64 {
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u64 value = 0;
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for(u32 byte : range(S)) value |= load(offset + byte) << byte * 8;
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return value;
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};
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auto write = [&](u64 value) -> void {
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for(u32 byte : range(S)) output.append(value >> byte * 8);
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};
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auto flush = [&] {
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output.append(skip - 1);
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do {
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write(read(base));
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base += S;
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} while(--skip);
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};
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while(base + S * skip < input.size()) {
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u32 same = 1;
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for(u32 offset = base + S * (skip + 1); offset < input.size(); offset += S) {
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if(read(offset) != read(base + S * skip)) break;
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if(++same == 127 + M) break;
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}
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if(same < M) {
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if(++skip == 128) flush();
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} else {
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if(skip) flush();
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output.append(128 | same - M);
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write(read(base));
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base += S * same;
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}
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}
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if(skip) flush();
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return output;
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}
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}
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