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99 lines
3.1 KiB
C
99 lines
3.1 KiB
C
//author: Victor Muñoz (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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typedef struct t_crc_ctx {
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unsigned int crc;
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unsigned int size;
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int reflect;
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unsigned int poly;
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unsigned int xout;
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} t_crc_ctx;
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void crc_init(t_crc_ctx *ctx, unsigned int crc, unsigned int size, int reflect, unsigned int poly, unsigned int 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(t_crc_ctx *ctx, unsigned char *data, unsigned int sz) {
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unsigned int 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) for (j=0; j<4; j++) if(((d>>j)^(d>>(7-j)))&1) d^=(1<<j)^(1<<(7-j));
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crc^=d<<(ctx->size-8);
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for(j=0; j<8; j++) crc=((crc>>(ctx->size-1))&1?ctx->poly:0)^(crc<<1);
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}
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ctx->crc=crc;
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}
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static void crc_final(t_crc_ctx *ctx, unsigned int *r) {
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unsigned int crc;
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int i;
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crc=ctx->crc;
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crc&=((((unsigned int)1<<(ctx->size-1))-1)<<1)|1;
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if(ctx->reflect) for(i=0; i<(ctx->size>>1); i++)
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if(((crc>>i)^(crc>>(ctx->size-1-i)))&1) crc^=((unsigned int)1<<i)^((unsigned int)1<<(ctx->size-1-i));
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*r=crc^ctx->xout;
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}
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enum CRC_PRESETS {
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CRC_32=0,
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CRC_16,
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CRC_32_ECMA_267,
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CRC_32C,
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CRC_24,
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CRC_16_CITT,
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CRC_16_USB,
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CRC_16_HDLC,
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CRC_15_CAN,
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CRC_8_SMBUS
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};
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t_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(t_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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#if 1
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#include <stdio.h>
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int main() {
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int i;
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unsigned int r;
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t_crc_ctx crc32;
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for(i=CRC_32; i<=CRC_8_SMBUS; i++) {
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crc_init_preset(&crc32, (enum CRC_PRESETS)i);
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crc_update(&crc32, (unsigned char *)"123456789", 9);
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crc_final(&crc32, &r);
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printf("%08x\n", r);
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}
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return 0;
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}
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#endif
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