mirror of
https://github.com/RfidResearchGroup/proxmark3.git
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51 lines
1.6 KiB
C
51 lines
1.6 KiB
C
//-----------------------------------------------------------------------------
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// Copyright (C) Proxmark3 contributors. See AUTHORS.md for details.
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// See LICENSE.txt for the text of the license.
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//-----------------------------------------------------------------------------
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#include "crc32.h"
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#define htole32(x) (x)
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#define CRC32_PRESET 0xFFFFFFFF
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static void crc32_byte(uint32_t *crc, const uint8_t value);
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static void crc32_byte(uint32_t *crc, const uint8_t value) {
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/* x32 + x26 + x23 + x22 + x16 + x12 + x11 + x10 + x8 + x7 + x5 + x4 + x2 + x + 1 */
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const uint32_t poly = 0xEDB88320;
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*crc ^= value;
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for (int current_bit = 7; current_bit >= 0; current_bit--) {
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int bit_out = (*crc) & 0x00000001;
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*crc >>= 1;
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if (bit_out)
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*crc ^= poly;
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}
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}
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void crc32_ex(const uint8_t *d, const size_t n, uint8_t *crc) {
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uint32_t c = CRC32_PRESET;
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for (size_t i = 0; i < n; i++) {
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crc32_byte(&c, d[i]);
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}
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crc[0] = (uint8_t) c;
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crc[1] = (uint8_t)(c >> 8);
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crc[2] = (uint8_t)(c >> 16);
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crc[3] = (uint8_t)(c >> 24);
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}
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void crc32_append(uint8_t *d, const size_t n) {
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crc32_ex(d, n, d + n);
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}
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