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Initial commit of project!

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A.M. Rowsell 2024-07-14 08:51:06 -04:00
commit 62e13b6cb0
Signed by: amr
GPG key ID: 0B6E2D8375CF79A9
4 changed files with 138 additions and 0 deletions
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#include <stdlib.h>
#include <stdio.h>
#include <inttypes.h>
#include <stddef.h>
// x^16 + x^15 + x^13 + x^1 + 1 -- D4 LFSR
// 0, 7, 12, 14 works for 16-bits
// 1, 12, 14, 15 works for 16-bits
// 16,14,13,11
// 0, 12, 14, 15 works for 15-bits
// 31, 9, 7, 6, 3, 2
// 29, 28, 25, 24, 22, 0
// 0x8000019F
void createGnuplot(int tap1, int tap2, int tap3, int tap4) {
char buf[1] = " ";
FILE *template = fopen("plottemplate", "r");
FILE *plotout = fopen("plot", "w");
if(template == NULL || plotout == NULL) {
return;
}
while(1) {
*buf = fgetc(template);
if (*buf == EOF) {
fflush(plotout);
break;
}
if(*buf == '$') {
fprintf(plotout, "%d, %d, %d, %d", tap1, tap2, tap3, tap4);
} else {
fputc(*buf, plotout);
}
}
fclose(template);
fclose(plotout);
return;
}
int main(int argc, char **argv) {
uint16_t startState = 0x0005;
uint16_t lfsr = startState;
uint16_t bit;
uint32_t count = 0;
char *c;
int tap1, tap2, tap3, tap4;
if(argc == 5) {
tap1 = strtol(argv[1], NULL, 10);
tap2 = strtol(argv[2], NULL, 10);
tap3 = strtol(argv[3], NULL, 10);
tap4 = strtol(argv[4], NULL, 10);
} else {
tap1 = 15;
tap2 = 4;
tap3 = 2;
tap4 = 1;
}
//printf("Initial state: %0x\n", lfsr);
do {
bit = ((lfsr >> tap1) ^ (lfsr >> tap2) ^ (lfsr >> tap3) ^ (lfsr >> tap4));
lfsr = (lfsr >> 1) | (bit << 15);
count++;
//count % 100000000 == 0 ? printf("0x%08x\t%032b\n", lfsr, lfsr) : 0; // comment this line for speed check
printf("%d\n", lfsr);
// *c = scanf("%s");
} while(lfsr != startState && count < 70000); //while(lfsr != startState);
//printf("Final count: %u\n", count);
createGnuplot(tap1, tap2, tap3, tap4);
return 0;
}