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// msequence_generator_example.c
//
// This example demonstrates finding maximal-length sequence
// (m-sequence) generator polynomials of a certain length.
#include <stdio.h>
#include <stdlib.h>
#include <getopt.h>
#include "liquid.h"
void usage()
{
printf("msequence_generator_example [options]\n");
printf(" -h : print usage\n");
printf(" -d <degree> : degree of polynomial, default: 2\n");
}
int main(int argc, char *argv[])
{
unsigned int degree = 2;
// get options
int dopt;
while((dopt = getopt(argc,argv,"uhd:")) != EOF){
switch (dopt) {
case 'h': usage(); return 0;
case 'd': degree = atol(optarg); break;
default:
exit(-1);
}
}
unsigned int maxpoly = (1 << degree) - 1;
unsigned int expected_sum = ((maxpoly + 1) / 2) * maxpoly;
unsigned int i;
unsigned int poly;
for (poly = 0; poly <= maxpoly; ++poly) {
unsigned int g = (poly << 1) + 1;
msequence seq = msequence_create(degree, g, 1);
unsigned int sum = 0;
for (i = 0; i < maxpoly; ++i) {
sum += msequence_get_state(seq);
msequence_advance(seq);
}
if (sum == expected_sum) {
printf("degree %d poly: %#06x\n", degree, g);
}
msequence_destroy(seq);
}
return 0;
}
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