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89 lines
2.7 KiB
C
89 lines
2.7 KiB
C
//author: Victor Mu~noz (vmunoz@ingenieria-inversa.cl
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//license: the very same than radare, blah, blah
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//some definitions and test cases borrowed from http://www.nightmare.com/~ryb/code/CrcMoose.py (Ray Burr)
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#include <r_hash.h>
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void crc_init (R_CRC_CTX *ctx, ut32 crc, ut32 size, int reflect, ut32 poly, ut32 xout) {
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ctx->crc = crc;
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ctx->size = size;
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ctx->reflect = reflect;
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ctx->poly = poly;
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ctx->xout = xout;
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}
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void crc_update (R_CRC_CTX *ctx, const ut8 *data, ut32 sz) {
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ut32 crc, d;
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int i, j;
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crc = ctx->crc;
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for (i = 0; i < sz; i++) {
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d = data[i];
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if (ctx->reflect) {
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for (j = 0; j < 4; j++) {
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if (((d >> j) ^ (d >> (7 - j))) & 1) {
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d ^= (1 << j) ^ (1 << (7 - j));
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}
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}
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}
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crc ^= d << (ctx->size - 8);
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for (j = 0; j < 8; j++) {
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crc = ((crc >> (ctx->size - 1)) & 1? ctx->poly: 0) ^ (crc << 1);
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}
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}
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ctx->crc = crc;
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}
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static void crc_final (R_CRC_CTX *ctx, ut32 *r) {
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ut32 crc;
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int i;
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crc = ctx->crc;
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crc &= ((((ut32) 1 << (ctx->size - 1)) - 1) << 1) | 1;
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if (ctx->reflect) {
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for (i = 0; i < (ctx->size >> 1); i++) {
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if (((crc >> i) ^ (crc >> (ctx->size - 1 - i))) & 1) {
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crc ^= ((ut32) 1 << i) ^ ((ut32) 1 << (ctx->size - 1 - i));
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}
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}
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}
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*r = crc ^ ctx->xout;
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}
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R_CRC_CTX crc_presets[] = {
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{ 0xFFFFFFFF, 32, 1, 0x04C11DB7, 0xFFFFFFFF }, //CRC-32, test vector for "1234567892: cbf43926
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{ 0x0000 , 16, 1, 0x8005 , 0x0000 }, //CRC-16-IBM, test vector for "1234567892: bb3d
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{ 0x00000000, 32, 0, 0x80000011, 0x00000000 }, //CRC-32-ECMA-267 (EDC for DVD sectors), test vector for "1234567892: b27ce117
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{ 0xFFFFFFFF, 32, 1, 0x1EDC6F41, 0xFFFFFFFF }, //CRC-32C, test vector for "1234567892: e3069283
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{ 0xB704CE , 24, 0, 0x864CFB , 0x000000 }, //CRC-24, test vector for "1234567892: 21cf02
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{ 0xFFFF , 16, 0, 0x1021 , 0x0000 }, //CRC-16-CITT, test vector for "1234567892: 29b1
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{ 0xFFFF , 16, 1, 0x8005 , 0xFFFF }, //CRC-16-USB, test vector for "1234567892: b4c8
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{ 0xFFFF , 16, 1, 0x1021 , 0xFFFF }, //CRC-HDLC, test vector for "1234567892: 906e
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{ 0x0000 , 15, 0, 0x4599 , 0x0000 }, //CRC-15-CAN, test vector for "1234567892: 059e
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{ 0x00 , 8, 0, 0x07 , 0x00 }, //CRC-8-SMBUS, test vector for "1234567892: f4
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};
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void crc_init_preset (R_CRC_CTX *ctx, enum CRC_PRESETS preset) {
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ctx->crc = crc_presets[preset].crc;
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ctx->size = crc_presets[preset].size;
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ctx->reflect = crc_presets[preset].reflect;
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ctx->poly = crc_presets[preset].poly;
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ctx->xout = crc_presets[preset].xout;
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}
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ut32 r_hash_crc_preset (const ut8 *data, ut32 size, enum CRC_PRESETS preset) {
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if (!data || !size || preset >= CRC_PRESET_SIZE) {
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return 0;
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}
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ut32 r;
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R_CRC_CTX crc32;
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crc_init_preset (&crc32, preset);
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crc_update (&crc32, data, size);
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crc_final (&crc32, &r);
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return r;
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}
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