104 lines
2.5 KiB
C
104 lines
2.5 KiB
C
/*
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* gf_example_2.c
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*
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* Demonstrates using the procedures for examples in GF(2^w) for w <= 32.
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*/
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#include <stdio.h>
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#include <getopt.h>
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#include <stdint.h>
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#include <string.h>
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#include <stdlib.h>
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#include <time.h>
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#include "gf_complete.h"
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#include "gf_rand.h"
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void usage(char *s)
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{
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fprintf(stderr, "usage: gf_example_2 w - w must be between 1 and 32\n");
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exit(1);
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}
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int main(int argc, char **argv)
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{
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uint32_t a, b, c;
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uint8_t *r1, *r2;
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uint16_t *r16;
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uint32_t *r32;
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int w, i;
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gf_t gf;
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if (argc != 2) usage(NULL);
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w = atoi(argv[1]);
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if (w <= 0 || w > 32) usage("Bad w");
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/* Get two random numbers in a and b */
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MOA_Seed(time(0));
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a = MOA_Random_W(w, 0);
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b = MOA_Random_W(w, 0);
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/* Create the proper instance of the gf_t object using defaults: */
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gf_init_easy(&gf, w);
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/* And multiply a and b using the galois field: */
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c = gf.multiply.w32(&gf, a, b);
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printf("%u * %u = %u\n", a, b, c);
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/* Divide the product by a and b */
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printf("%u / %u = %u\n", c, a, gf.divide.w32(&gf, c, a));
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printf("%u / %u = %u\n", c, b, gf.divide.w32(&gf, c, b));
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/* If w is 4, 8, 16 or 32, do a very small region operation */
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if (w == 4 || w == 8 || w == 16 || w == 32) {
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r1 = (uint8_t *) malloc(16);
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r2 = (uint8_t *) malloc(16);
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if (w == 4 || w == 8) {
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r1[0] = b;
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for (i = 1; i < 16; i++) r1[i] = MOA_Random_W(8, 1);
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} else if (w == 16) {
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r16 = (uint16_t *) r1;
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r16[0] = b;
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for (i = 1; i < 8; i++) r16[i] = MOA_Random_W(16, 1);
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} else {
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r32 = (uint32_t *) r1;
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r32[0] = b;
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for (i = 1; i < 4; i++) r32[i] = MOA_Random_W(32, 1);
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}
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gf.multiply_region.w32(&gf, r1, r2, a, 16, 0);
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printf("\nmultiply_region by 0x%x (%u)\n\n", a, a);
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printf("R1 (the source): ");
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if (w == 4) {
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for (i = 0; i < 16; i++) printf(" %x %x", r1[i] >> 4, r1[i] & 0xf);
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} else if (w == 8) {
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for (i = 0; i < 16; i++) printf(" %02x", r1[i]);
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} else if (w == 16) {
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for (i = 0; i < 8; i++) printf(" %04x", r16[i]);
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} else if (w == 32) {
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for (i = 0; i < 4; i++) printf(" %08x", r32[i]);
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}
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printf("\nR2 (the product): ");
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if (w == 4) {
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for (i = 0; i < 16; i++) printf(" %x %x", r2[i] >> 4, r2[i] & 0xf);
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} else if (w == 8) {
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for (i = 0; i < 16; i++) printf(" %02x", r2[i]);
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} else if (w == 16) {
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r16 = (uint16_t *) r2;
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for (i = 0; i < 8; i++) printf(" %04x", r16[i]);
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} else if (w == 32) {
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r32 = (uint32_t *) r2;
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for (i = 0; i < 4; i++) printf(" %08x", r32[i]);
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}
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printf("\n");
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}
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exit(0);
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}
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