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39 lines
988 B
C
39 lines
988 B
C
/**
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* Copyright (c) 2020 Paul-Louis Ageneau
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at https://mozilla.org/MPL/2.0/.
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*/
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#include "crc32.h"
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#define CRC32_REVERSED_POLY 0xEDB88320
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#define CRC32_INIT 0xFFFFFFFF
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#define CRC32_XOR 0xFFFFFFFF
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static uint32_t crc32_byte(uint32_t crc) {
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for (int i = 0; i < 8; ++i)
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if (crc & 1)
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crc = (crc >> 1) ^ CRC32_REVERSED_POLY;
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else
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crc = (crc >> 1);
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return crc;
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}
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static uint32_t crc32_table(const uint8_t *p, size_t size, uint32_t *table) {
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uint32_t crc = CRC32_INIT;
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while (size--)
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crc = table[(uint8_t)(crc & 0xFF) ^ *p++] ^ (crc >> 8);
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return crc ^ CRC32_XOR;
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}
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JUICE_EXPORT uint32_t juice_crc32(const void *data, size_t size) {
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static uint32_t table[256] = {0};
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if (table[0] == 0)
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for (uint32_t i = 0; i < 256; ++i)
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table[i] = crc32_byte(i);
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return crc32_table(data, size, table);
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}
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