diff options
Diffstat (limited to 'lib/decoding/fire_crc.c')
| -rw-r--r-- | lib/decoding/fire_crc.c | 163 |
1 files changed, 0 insertions, 163 deletions
diff --git a/lib/decoding/fire_crc.c b/lib/decoding/fire_crc.c deleted file mode 100644 index 5800517..0000000 --- a/lib/decoding/fire_crc.c +++ /dev/null @@ -1,163 +0,0 @@ -/* - The Hacker's Choice - http://www.thc.org - Part of THC's GSM SCANNER PROJECT -*/ - - -#include "fire_crc.h" -#include <stdio.h> -#include <string.h> - -#define REM(x, y) (x) % (y) - -static int FC_syndrome_shift(FC_CTX *ctx, unsigned int bit); - -static int -outit(int *data, int len) -{ - int i; - - for (i = 0; i < len; i++) - printf("%d ", data[i]); - printf("\n"); - return 0; -} - -int -FC_init(FC_CTX *ctx, unsigned int crc_size, unsigned int data_size) -{ - ctx->crc_size = crc_size; - ctx->data_size = data_size; - ctx->syn_start = 0; - - return 0; -} - -int -FC_check_crc(FC_CTX *ctx, unsigned char *input_bits, unsigned char *control_data) -{ - int j,error_count = 0, error_index = 0, success_flag = 0, syn_index = 0; - unsigned int i; - - ctx->syn_start = 0; - // reset the syndrome register - memset(ctx->syndrome_reg, 0, sizeof ctx->syndrome_reg); - - // shift in the data bits - for (i=0; i < ctx->data_size; i++) { - error_count = FC_syndrome_shift(ctx, input_bits[i]); - control_data[i] = input_bits[i]; - } - - // shift in the crc bits - for (i=0; i < ctx->crc_size; i++) { - error_count = FC_syndrome_shift(ctx, 1-input_bits[i+ctx->data_size]); - } - - // Find position of error burst - if (error_count == 0) { - error_index = 0; - } - else { - error_index = 1; - error_count = FC_syndrome_shift(ctx, 0); - error_index += 1; - while (error_index < (ctx->data_size + ctx->crc_size) ) { - error_count = FC_syndrome_shift(ctx, 0); - error_index += 1; - if ( error_count == 0 ) break; - } - } - - // Test for correctable errors - //printf("error_index %d\n",error_index); - if (error_index == 224) success_flag = 0; - else { - - // correct index depending on the position of the error - if (error_index == 0) syn_index = error_index; - else syn_index = error_index - 1; - - // error burst lies within data bits - if (error_index < 184) { - //printf("error < bit 184,%d\n",error_index); - j = error_index; - while ( j < (error_index+12) ) { - if (j < 184) { - control_data[j] = control_data[j] ^ - ctx->syndrome_reg[REM(ctx->syn_start+39-j+syn_index,40)]; - } - else break; - j = j + 1; - } - } - else if ( error_index > 212 ) { - //printf("error > bit 212,%d\n",error_index); - j = 0; - while ( j < (error_index - 212) ) { - control_data[j] = control_data[j] ^ - ctx->syndrome_reg[REM(ctx->syn_start+39-j-224+syn_index,40)]; - j = j + 1; - } - } - // for 183 < error_index < 213 error in parity alone so ignore - success_flag = 1; - } - return success_flag; -} - -static int -FC_syndrome_shift(FC_CTX *ctx, unsigned int bit) -{ - int error_count = 0; - unsigned int i; - - if (ctx->syn_start == 0) - ctx->syn_start = 39; - else ctx->syn_start -= 1; - - int temp_syndrome_reg[sizeof ctx->syndrome_reg]; - - memcpy(temp_syndrome_reg, ctx->syndrome_reg, sizeof temp_syndrome_reg); - - temp_syndrome_reg[REM(ctx->syn_start+3,40)] = - ctx->syndrome_reg[REM(ctx->syn_start+3,40)] ^ - ctx->syndrome_reg[ctx->syn_start]; - temp_syndrome_reg[REM(ctx->syn_start+17,40)] = - ctx->syndrome_reg[REM(ctx->syn_start+17,40)] ^ - ctx->syndrome_reg[ctx->syn_start]; - temp_syndrome_reg[REM(ctx->syn_start+23,40)] = - ctx->syndrome_reg[REM(ctx->syn_start+23,40)] ^ - ctx->syndrome_reg[ctx->syn_start]; - temp_syndrome_reg[REM(ctx->syn_start+26,40)] = - ctx->syndrome_reg[REM(ctx->syn_start+26,40)] ^ - ctx->syndrome_reg[ctx->syn_start]; - - temp_syndrome_reg[REM(ctx->syn_start+4,40)] = - ctx->syndrome_reg[REM(ctx->syn_start+4,40)] ^ bit; - temp_syndrome_reg[REM(ctx->syn_start+6,40)] = - ctx->syndrome_reg[REM(ctx->syn_start+6,40)] ^ bit; - temp_syndrome_reg[REM(ctx->syn_start+10,40)] = - ctx->syndrome_reg[REM(ctx->syn_start+10,40)] ^ bit; - temp_syndrome_reg[REM(ctx->syn_start+16,40)] = - ctx->syndrome_reg[REM(ctx->syn_start+16,40)] ^ bit; - temp_syndrome_reg[REM(ctx->syn_start+27,40)] = - ctx->syndrome_reg[REM(ctx->syn_start+27,40)] ^ bit; - temp_syndrome_reg[REM(ctx->syn_start+29,40)] = - ctx->syndrome_reg[REM(ctx->syn_start+29,40)] ^ bit; - temp_syndrome_reg[REM(ctx->syn_start+33,40)] = - ctx->syndrome_reg[REM(ctx->syn_start+33,40)] ^ bit; - temp_syndrome_reg[REM(ctx->syn_start+39,40)] = - ctx->syndrome_reg[REM(ctx->syn_start+39,40)] ^ bit; - - temp_syndrome_reg[ctx->syn_start] = ctx->syndrome_reg[ctx->syn_start] ^ bit; - - memcpy(ctx->syndrome_reg, temp_syndrome_reg, sizeof ctx->syndrome_reg); - - for (i = 0; i < 28; i++) { - error_count = error_count + ctx->syndrome_reg[REM(ctx->syn_start+i,40)]; - } - return error_count; -} - - |