mirror of https://github.com/bsnes-emu/bsnes.git
51 lines
971 B
C++
51 lines
971 B
C++
#pragma once
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#include <nall/hash/hash.hpp>
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namespace nall { namespace Hash {
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struct CRC16 : Hash {
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nallHash(CRC16)
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auto reset() -> void override {
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checksum = ~0;
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}
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auto input(uint8_t value) -> void override {
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checksum = (checksum >> 8) ^ table(checksum ^ value);
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}
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auto output() const -> vector<uint8_t> override {
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vector<uint8_t> result;
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for(auto n : rrange(2)) result.append(~checksum >> n * 8);
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return result;
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}
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auto value() const -> uint16_t {
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return ~checksum;
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}
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private:
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static auto table(uint8_t index) -> uint16_t {
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static uint16_t table[256] = {0};
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static bool initialized = false;
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if(!initialized) {
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initialized = true;
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for(auto index : range(256)) {
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uint16_t crc = index;
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for(auto bit : range(8)) {
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crc = (crc >> 1) ^ (crc & 1 ? 0x8408 : 0);
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}
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table[index] = crc;
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}
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}
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return table[index];
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}
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uint16_t checksum = 0;
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};
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}}
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