gf_rand.c 1.7 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_rand.c -- Random number generator.
*/

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include "gf_rand.h"

/* Lifted the "Mother of All" random number generator from http://www.agner.org/random/ */

static uint32_t MOA_X[5];

uint32_t MOA_Random_32() {
uint64_t sum;
sum = (uint64_t)2111111111UL * (uint64_t)MOA_X[3] +
(uint64_t)1492 * (uint64_t)(MOA_X[2]) +
(uint64_t)1776 * (uint64_t)(MOA_X[1]) +
(uint64_t)5115 * (uint64_t)(MOA_X[0]) +
(uint64_t)MOA_X[4];
MOA_X[3] = MOA_X[2];  MOA_X[2] = MOA_X[1];  MOA_X[1] = MOA_X[0];
MOA_X[4] = (uint32_t)(sum >> 32);
MOA_X[0] = (uint32_t)sum;
return MOA_X[0];
}

uint64_t MOA_Random_64() {
uint64_t sum;

sum = MOA_Random_32();
sum <<= 32;
sum |= MOA_Random_32();
return sum;
}

void MOA_Random_128(uint64_t *x) {
x[0] = MOA_Random_64();
x[1] = MOA_Random_64();
return;
}

uint32_t MOA_Random_W(int w, int zero_ok)
{
uint32_t b;

do {
b = MOA_Random_32();
if (w == 31) b &= 0x7fffffff;
if (w < 31)  b %= (1 << w);
} while (!zero_ok && b == 0);
return b;
}

void MOA_Seed(uint32_t seed) {
int i;
uint32_t s = seed;
for (i = 0; i < 5; i++) {
s = s * 29943829 - 1;
MOA_X[i] = s;
}
for (i=0; i<19; i++) MOA_Random_32();
}

void MOA_Fill_Random_Region (void *reg, int size)
{
uint32_t *r32;
uint8_t *r8;
int i;

r32 = (uint32_t *) reg;
r8 = (uint8_t *) reg;
for (i = 0; i < size/4; i++) r32[i] = MOA_Random_32();
for (i *= 4; i < size; i++) r8[i] = MOA_Random_W(8, 1);
}

``````