gem5/src/base/random_mt.cc

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/*
* A C-program for MT19937, with initialization improved 2002/1/26.
* Coded by Takuji Nishimura and Makoto Matsumoto.
*
* Before using, initialize the state by using init_genrand(seed)
* or init_by_array(init_key, key_length).
*
* Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura,
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided
* with the distribution.
*
* 3. The names of its contributors may not be used to endorse or
* promote products derived from this software without specific
* prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*
*
* Any feedback is very welcome.
* http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html
* email: m-mat @ math.sci.hiroshima-u.ac.jp (remove space)
*/
#include "base/random.hh"
/* initializes mt[N] with a seed */
void
Random::init(uint32_t s)
{
mti = N + 1;
mt[0] = s & (uint32_t)0xffffffff;
for (mti = 1; mti < N; mti++) {
mt[mti] = 1812433253UL * (mt[mti-1] ^ (mt[mti-1] >> 30)) + mti;
/* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */
/* In the previous versions, MSBs of the seed affect */
/* only MSBs of the array mt[]. */
/* 2002/01/09 modified by Makoto Matsumoto */
mt[mti] &= (uint32_t)0xffffffff;
/* for >32 bit machines */
}
}
/* initialize by an array with array-length */
/* init_key is the array for initializing keys */
/* key_length is its length */
/* slight change for C++, 2004/2/26 */
void
Random::init(uint32_t init_key[], int key_length)
{
int i = 1;
int j = 0;
int k = (N > key_length) ? N : key_length;
init(19650218);
for (; k; k--) {
mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * (uint32_t)1664525))
+ init_key[j] + j; /* non linear */
mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
i++;
j++;
if (i >= N) {
mt[0] = mt[N - 1];
i = 1;
}
if (j >= key_length)
j = 0;
}
for (k = N - 1; k; k--) {
/* non linear */
mt[i] = (mt[i] ^ ((mt[i - 1] ^ (mt[i - 1] >> 30)) * 1566083941UL)) - i;
/* for WORDSIZE > 32 machines */
mt[i] &= (uint32_t)0xffffffff;
i++;
if (i >= N) {
mt[0] = mt[N - 1];
i = 1;
}
}
/* MSB is 1; assuring non-zero initial array */
mt[0] = (uint32_t)0x80000000;
}
/* generates a random number on [0,0xffffffff]-interval */
uint32_t
Random::genrand()
{
uint32_t y;
static uint32_t mag01[2] = { 0, MATRIX_A};
if (mti >= N) { /* generate N words at one time */
int kk;
for (kk = 0; kk < N - M; kk++) {
y = (mt[kk] & UPPER_MASK) | (mt[kk+1] & LOWER_MASK);
mt[kk] = mt[kk + M] ^ (y >> 1) ^ mag01[y & 0x1UL];
}
for (; kk < N - 1; kk++) {
y = (mt[kk] & UPPER_MASK) | (mt[kk+1] & LOWER_MASK);
mt[kk] = mt[kk + (M - N)] ^ (y >> 1) ^ mag01[y & 0x1UL];
}
y = (mt[N - 1] & UPPER_MASK) | (mt[0] & LOWER_MASK);
mt[N - 1] = mt[M - 1] ^ (y >> 1) ^ mag01[y & 0x1UL];
mti = 0;
}
y = mt[mti++];
/* Tempering */
y ^= (y >> 11);
y ^= (y << 7) & (uint32_t)0x9d2c5680;
y ^= (y << 15) & (uint32_t)0xefc60000;
y ^= (y >> 18);
return y;
}