mirror of
https://github.com/portapack-mayhem/mayhem-firmware.git
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87 lines
2.3 KiB
C++
87 lines
2.3 KiB
C++
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/*
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* Copyright (C) 2023 Bernd Herzog
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*
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* This file is part of PortaPack.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; see the file COPYING. If not, write to
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* the Free Software Foundation, Inc., 51 Franklin Street,
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* Boston, MA 02110-1301, USA.
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*/
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#include "random.hpp"
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static unsigned long state[N]; /* the array for the state vector */
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static int rnd_left = 1;
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static int rnd_init = 0;
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static unsigned long *rnd_next;
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/* initializes state[N] with a seed */
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void init_genrand(unsigned long s)
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{
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int j;
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state[0] = s & 0xffffffffUL;
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for (j = 1; j < N; j++)
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{
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state[j] = (1812433253UL * (state[j - 1] ^ (state[j - 1] >> 30)) + j);
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/* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */
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/* In the previous versions, MSBs of the seed affect */
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/* only MSBs of the array state[]. */
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/* 2002/01/09 modified by Makoto Matsumoto */
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state[j] &= 0xffffffffUL; /* for >32 bit machines */
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}
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rnd_left = 1;
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rnd_init = 1;
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}
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static void next_state(void)
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{
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unsigned long *p = state;
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int j;
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/* if init_genrand() has not been called, */
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/* a default initial seed is used */
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if (rnd_init == 0)
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init_genrand(5489UL);
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rnd_left = N;
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rnd_next = state;
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for (j = N - M + 1; --j; p++)
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*p = p[M] ^ TWIST(p[0], p[1]);
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for (j = M; --j; p++)
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*p = p[M - N] ^ TWIST(p[0], p[1]);
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*p = p[M - N] ^ TWIST(p[0], state[0]);
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}
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long genrand_int31(void)
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{
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unsigned long y;
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if (--rnd_left == 0)
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next_state();
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y = *rnd_next++;
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/* Tempering */
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y ^= (y >> 11);
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y ^= (y << 7) & 0x9d2c5680UL;
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y ^= (y << 15) & 0xefc60000UL;
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y ^= (y >> 18);
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return (long)(y >> 1);
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}
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