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#include "stdio.h"
#include "stdint.h"
#include "string.h"
#include "../libv27/scrambler.h"
static int show_bin(uint8_t *data1, uint8_t *data2, int len)
{
int i, j, error = 0;;
uint8_t bit1, bit2;
for (i = 0; i < len; i++) {
printf(".");
for (j = 0; j < 8; j++) {
bit1 = (data1[i] >> j) & 1;
bit2 = (data2[i] >> j) & 1;
if (bit1 == bit2)
printf("%d", bit1);
else {
printf("X");
error++;
}
}
}
printf("\n");
return error;
}
static int check_repetition(uint8_t *data, int len, int repeat, int start)
{
int i;
uint8_t b1, b2;
for (i = start; i < (len * 8 - repeat); i++) {
b1 = (data[i >> 3] >> (i & 7)) & 1;
b2 = (data[(i+repeat) >> 3] >> ((i+repeat) & 7)) & 1;
if (b1 != b2)
return i - start + repeat;
}
return 0;
}
int main(void)
{
v27scrambler_t scram, descram;
char message[] = "Jolly Roger~~~~";
int len = strlen(message);
uint8_t data[len];
int ret;
printf("Message: %s\n", message);
memcpy(data, message, len);
show_bin(data, (uint8_t *)message, len);
v27_scrambler_init(&scram, 1, 0);
v27_scrambler_block(&scram, data, len);
printf("Scrambled:\n");
show_bin(data, data, len);
v27_scrambler_init(&descram, 1, 1);
v27_scrambler_block(&descram, data, len);
printf("Descramble without corruption?\n");
ret = show_bin(data, (uint8_t *)message, len);
if (ret) {
printf("Descrambling failed!\n");
return 1;
}
printf("Yes!\n");
printf("\n");
v27_scrambler_init(&scram, 1, 0);
v27_scrambler_block(&scram, data, len);
data[0] = 'B';
data[1] = 'U';
data[2] = 'G';
v27_scrambler_init(&descram, 1, 1);
v27_scrambler_block(&descram, data, len);
printf("Descramble with 3 bytes corruption: (should fix itself after 4 bytes)\n");
show_bin(data, (uint8_t *)message, len);
printf("\n");
printf("Descramble a scrambled sequence of 8 bit repetitions with V.27: 01111110\n");
memset(data, 0x7e, len);
v27_scrambler_init(&descram, 0, 1);
v27_scrambler_block(&descram, data, len);
show_bin(data, (uint8_t *)data, len);
/* note at position 6 we have no more change towards 8 bit offset */
ret = check_repetition(data, len, 8, 6);
if (ret) {
printf("Theres is a change of repetition after %d bits after start %d, please fix!\n", ret, 6);
return 1;
}
printf("Repetition not detected, good!\n");
printf("\n");
printf("Descramble a scrambled sequence of 8 bit repetitions with V.27bis/ter: 01111110\n");
memset(data, 0x7e, len);
v27_scrambler_init(&descram, 1, 1);
v27_scrambler_block(&descram, data, len);
show_bin(data, (uint8_t *)data, len);
/* note at position 6 we have no more change towards 8 bit offset */
ret = check_repetition(data, len, 8, 6);
if (ret != 34) {
printf("Theres is NO change of repetition after 34 bits, but after %d bits, which should not happen!\n", ret);
return 1;
}
printf("Repetition detected after %d bits from start %d, good!\n", ret, 6);
return 0;
}
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