e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync/* Copyright (c) 2001, Stanford University
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync * All rights reserved
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync *
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync * See the file LICENSE.txt for information on redistributing this software.
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync */
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync#include "cr_rand.h"
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync#ifdef WINDOWS
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync#define WIN32_LEAN_AND_MEAN
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync#include <windows.h>
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync#else
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync#include <sys/time.h>
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync#endif
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync/* Period parameters */
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync#define N 624
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync#define M 397
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync#define MATRIX_A 0x9908b0df /* constant vector a */
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync#define UPPER_MASK 0x80000000 /* most significant w-r bits */
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync#define LOWER_MASK 0x7fffffff /* least significant r bits */
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync/* Tempering parameters */
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync#define TEMPERING_MASK_B 0x9d2c5680
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync#define TEMPERING_MASK_C 0xefc60000
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync#define TEMPERING_SHIFT_U(y) (y >> 11)
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync#define TEMPERING_SHIFT_S(y) (y << 7)
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync#define TEMPERING_SHIFT_T(y) (y << 15)
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync#define TEMPERING_SHIFT_L(y) (y >> 18)
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsyncstatic unsigned long mt[N]; /* the array for the state vector */
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsyncstatic int mti=N+1; /* mti==N+1 means mt[N] is not initialized */
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsyncvoid crRandSeed(unsigned long seed)
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync{
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync /* setting initial seeds to mt[N] using the generator Line 25 of Table 1
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync in [KNUTH 1981, The Art of Computer Programming Vol. 2 (2nd Ed.),
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync pp102
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync */
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync if (seed == 0)
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync seed = 4357; /* pick default seed if seed=0 (Guy Zadickario) */
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync mt[0]= seed & 0xffffffff;
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync for (mti=1; mti<N; mti++)
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync mt[mti] = (69069 * mt[mti-1]) & 0xffffffff;
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync}
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync/*
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync * Seed the generator based on time of day or a system counter.
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync */
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsyncvoid crRandAutoSeed(void)
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync{
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync#if defined(WINDOWS)
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync LARGE_INTEGER counter;
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync QueryPerformanceCounter( &counter );
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync crRandSeed((unsigned long) counter.QuadPart);
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync#else
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync struct timeval timeofday;
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync gettimeofday( &timeofday, 0 );
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync crRandSeed((unsigned long) timeofday.tv_usec);
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync#endif
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync}
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsyncstatic double genrand( void )
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync{
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync unsigned long y;
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync static unsigned long mag01[2]={0x0, MATRIX_A};
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync /* mag01[x] = x * MATRIX_A for x=0,1 */
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync if (mti >= N) { /* generate N words at one time */
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync int kk;
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync if (mti == N+1) /* if sgenrand() has not been called, */
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync crRandSeed(4357); /* a default initial seed is used */
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync for (kk=0;kk<N-M;kk++) {
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync mt[kk] = mt[kk+M] ^ (y >> 1) ^ mag01[y & 0x1];
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync }
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync for (;kk<N-1;kk++) {
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync y = (mt[kk]&UPPER_MASK)|(mt[kk+1]&LOWER_MASK);
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync mt[kk] = mt[kk+(M-N)] ^ (y >> 1) ^ mag01[y & 0x1];
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync }
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync y = (mt[N-1]&UPPER_MASK)|(mt[0]&LOWER_MASK);
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync mt[N-1] = mt[M-1] ^ (y >> 1) ^ mag01[y & 0x1];
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync mti = 0;
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync }
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync y = mt[mti++];
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync y ^= TEMPERING_SHIFT_U(y);
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync y ^= TEMPERING_SHIFT_S(y) & TEMPERING_MASK_B;
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync y ^= TEMPERING_SHIFT_T(y) & TEMPERING_MASK_C;
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync y ^= TEMPERING_SHIFT_L(y);
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync return ( (double)y / (unsigned long)0xffffffff ); /* reals */
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync /* return y; */ /* for integer generation */
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync}
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsyncfloat crRandFloat(float min, float max)
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync{
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync double t = genrand();
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync return (float) (t*min + (1-t)*max);
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync}
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync/* return a random integer in [min, max] (inclusive). */
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsyncint crRandInt(int min, int max)
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync{
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync double t = genrand();
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync return min + (int) (t * (max - min + 1));
e0e0c19eefceaf5d4ec40f9466b58a771f50e799vboxsync}