30 lines
674 B
C++
30 lines
674 B
C++
#pragma once
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#include <stdint.h>
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#define DEFAULT_POLY 0x973afb51
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template <uint32_t polynomial = DEFAULT_POLY> struct CRC32Table {
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constexpr CRC32Table() : table() {
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for (uint32_t i = 0; i < 256; i++) {
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uint32_t c = i;
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for (auto j = 0; j < 8; j++) {
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if (c & 1) {
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c = polynomial ^ (c >> 1);
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} else {
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c >>= 1;
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}
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}
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table[i] = c;
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}
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}
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uint32_t table[256];
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uint32_t computeCRC32(uint32_t initial, const uint8_t *buf, int len) {
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uint32_t c = initial ^ 0xFFFFFFFF;
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for (auto i = 0; i < len; ++i) {
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c = table[(c ^ buf[i]) & 0xFF] ^ (c >> 8);
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}
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return c ^ 0xFFFFFFFF;
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}
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};
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