]> git.zerfleddert.de Git - proxmark3-svn/blob - common/crc32.c
added new functions to `hf emv`
[proxmark3-svn] / common / crc32.c
1 #include <stdint.h>
2 #include <stddef.h>
3 #include "crc32.h"
4
5 #define htole32(x) (x)
6 #define CRC32_PRESET 0xFFFFFFFF
7
8
9 static void crc32_byte (uint32_t *crc, const uint8_t value);
10
11 static void crc32_byte (uint32_t *crc, const uint8_t value) {
12 /* x32 + x26 + x23 + x22 + x16 + x12 + x11 + x10 + x8 + x7 + x5 + x4 + x2 + x + 1 */
13 const uint32_t poly = 0xEDB88320;
14
15 *crc ^= value;
16 for (int current_bit = 7; current_bit >= 0; current_bit--) {
17 int bit_out = (*crc) & 0x00000001;
18 *crc >>= 1;
19 if (bit_out)
20 *crc ^= poly;
21 }
22 }
23
24 void crc32 (const uint8_t *data, const size_t len, uint8_t *crc) {
25 uint32_t desfire_crc = CRC32_PRESET;
26 for (size_t i = 0; i < len; i++) {
27 crc32_byte (&desfire_crc, data[i]);
28 }
29
30 *((uint32_t *)(crc)) = htole32 (desfire_crc);
31 }
32
33 void crc32_append (uint8_t *data, const size_t len) {
34 crc32 (data, len, data + len);
35 }
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