gf_example_2.c 2.76 KB
``````/*
* GF-Complete: A Comprehensive Open Source Library for Galois Field Arithmetic
* James S. Plank, Ethan L. Miller, Kevin M. Greenan,
* Benjamin A. Arnold, John A. Burnum, Adam W. Disney, Allen C. McBride.
*
* gf_example_2.c
*
* Demonstrates using the procedures for examples in GF(2^w) for w <= 32.
*/

#include <stdio.h>
#include <getopt.h>
#include <stdint.h>
#include <string.h>
#include <stdlib.h>
#include <time.h>

#include "gf_complete.h"
#include "gf_rand.h"

void usage(char *s)
{
fprintf(stderr, "usage: gf_example_2 w - w must be between 1 and 32\n");
exit(1);
}

int main(int argc, char **argv)
{
uint32_t a, b, c;
uint8_t *r1, *r2;
uint16_t *r16 = NULL;
uint32_t *r32 = NULL;
int w, i;
gf_t gf;

if (argc != 2) usage(NULL);
w = atoi(argv[1]);
if (w <= 0 || w > 32) usage("Bad w");

/* Get two random numbers in a and b */

MOA_Seed(time(0));
a = MOA_Random_W(w, 0);
b = MOA_Random_W(w, 0);

/* Create the proper instance of the gf_t object using defaults: */

gf_init_easy(&gf, w);

/* And multiply a and b using the galois field: */

c = gf.multiply.w32(&gf, a, b);
printf("%u * %u = %u\n", a, b, c);

/* Divide the product by a and b */

printf("%u / %u = %u\n", c, a, gf.divide.w32(&gf, c, a));
printf("%u / %u = %u\n", c, b, gf.divide.w32(&gf, c, b));

/* If w is 4, 8, 16 or 32, do a very small region operation */

if (w == 4 || w == 8 || w == 16 || w == 32) {
r1 = (uint8_t *) malloc(16);
r2 = (uint8_t *) malloc(16);

if (w == 4 || w == 8) {
r1[0] = b;
for (i = 1; i < 16; i++) r1[i] = MOA_Random_W(8, 1);
} else if (w == 16) {
r16 = (uint16_t *) r1;
r16[0] = b;
for (i = 1; i < 8; i++) r16[i] = MOA_Random_W(16, 1);
} else {
r32 = (uint32_t *) r1;
r32[0] = b;
for (i = 1; i < 4; i++) r32[i] = MOA_Random_W(32, 1);
}

gf.multiply_region.w32(&gf, r1, r2, a, 16, 0);

printf("\nmultiply_region by 0x%x (%u)\n\n", a, a);
printf("R1 (the source):  ");
if (w == 4) {
for (i = 0; i < 16; i++) printf(" %x %x", r1[i] >> 4, r1[i] & 0xf);
} else if (w == 8) {
for (i = 0; i < 16; i++) printf(" %02x", r1[i]);
} else if (w == 16) {
for (i = 0; i < 8; i++) printf(" %04x", r16[i]);
} else if (w == 32) {
for (i = 0; i < 4; i++) printf(" %08x", r32[i]);
}
printf("\nR2 (the product): ");
if (w == 4) {
for (i = 0; i < 16; i++) printf(" %x %x", r2[i] >> 4, r2[i] & 0xf);
} else if (w == 8) {
for (i = 0; i < 16; i++) printf(" %02x", r2[i]);
} else if (w == 16) {
r16 = (uint16_t *) r2;
for (i = 0; i < 8; i++) printf(" %04x", r16[i]);
} else if (w == 32) {
r32 = (uint32_t *) r2;
for (i = 0; i < 4; i++) printf(" %08x", r32[i]);
}
printf("\n");
}
exit(0);
}
``````