bsnes/nall/decode/huffman.hpp

37 lines
804 B
C++

#pragma once
namespace nall { namespace Decode {
inline auto Huffman(array_view<uint8_t> input) -> vector<uint8_t> {
vector<uint8_t> output;
uint size = 0;
for(uint byte : range(8)) size |= *input++ << byte * 8;
output.reserve(size);
uint byte = 0, bits = 0;
auto read = [&]() -> bool {
if(bits == 0) bits = 8, byte = *input++;
return byte >> --bits & 1;
};
uint nodes[256][2] = {};
for(uint offset : range(256)) {
for(uint index : range(9)) nodes[offset][0] = nodes[offset][0] << 1 | read();
for(uint index : range(9)) nodes[offset][1] = nodes[offset][1] << 1 | read();
}
uint node = 511;
while(output.size() < size) {
node = nodes[node - 256][read()];
if(node < 256) {
output.append(node);
node = 511;
}
}
return output;
}
}}