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Diffstat (limited to 'source/gameengine/GameLogic/SCA_RandomNumberGenerator.cpp')
| -rw-r--r-- | source/gameengine/GameLogic/SCA_RandomNumberGenerator.cpp | 125 |
1 files changed, 125 insertions, 0 deletions
diff --git a/source/gameengine/GameLogic/SCA_RandomNumberGenerator.cpp b/source/gameengine/GameLogic/SCA_RandomNumberGenerator.cpp new file mode 100644 index 00000000000..7faa76fd01d --- /dev/null +++ b/source/gameengine/GameLogic/SCA_RandomNumberGenerator.cpp @@ -0,0 +1,125 @@ +/** + * Generate random numbers that can be used by other components. We + * convert to different types/distributions elsewhere. This just + * delivers a clean, random bitvector. + * + * $Id$ + */ + +/* A C-program for MT19937: Real number version */ +/* genrand() generates one pseudorandom real number (double) */ +/* which is uniformly distributed on [0,1]-interval, for each */ +/* call. sgenrand(seed) set initial values to the working area */ +/* of 624 words. Before genrand(), sgenrand(seed) must be */ +/* called once. (seed is any 32-bit integer except for 0). */ +/* Integer generator is obtained by modifying two lines. */ +/* Coded by Takuji Nishimura, considering the suggestions by */ +/* Topher Cooper and Marc Rieffel in July-Aug. 1997. */ + +/* This library is free software; you can redistribute it and/or */ +/* modify it under the terms of the GNU Library General Public */ +/* License as published by the Free Software Foundation; either */ +/* version 2 of the License, or (at your option) any later */ +/* version. */ +/* This library is distributed in the hope that it will be useful, */ +/* but WITHOUT ANY WARRANTY; without even the implied warranty of */ +/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. */ +/* See the GNU Library General Public License for more details. */ +/* You should have received a copy of the GNU Library General */ +/* Public License along with this library; if not, write to the */ +/* Free Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA */ +/* 02111-1307 USA */ + +/* Copyright (C) 1997 Makoto Matsumoto and Takuji Nishimura. */ +/* When you use this, send an email to: matumoto@math.keio.ac.jp */ +/* with an appropriate reference to your work. */ + +#include <limits.h> +#include "SCA_RandomNumberGenerator.h" + +/* Period parameters */ +#define N 624 +#define M 397 +#define MATRIX_A 0x9908b0df /* constant vector a */ +#define UPPER_MASK 0x80000000 /* most significant w-r bits */ +#define LOWER_MASK 0x7fffffff /* least significant r bits */ + +/* Tempering parameters */ +#define TEMPERING_MASK_B 0x9d2c5680 +#define TEMPERING_MASK_C 0xefc60000 +#define TEMPERING_SHIFT_U(y) (y >> 11) +#define TEMPERING_SHIFT_S(y) (y << 7) +#define TEMPERING_SHIFT_T(y) (y << 15) +#define TEMPERING_SHIFT_L(y) (y >> 18) + +SCA_RandomNumberGenerator::SCA_RandomNumberGenerator(long seed) { + int mti = N + 1; + m_seed = seed; + SetStartVector(); +} + +SCA_RandomNumberGenerator::~SCA_RandomNumberGenerator() { + /* intentionally empty */ +} + +void SCA_RandomNumberGenerator::SetStartVector(void) { + /* setting initial seeds to mt[N] using */ + /* the generator Line 25 of Table 1 in */ + /* [KNUTH 1981, The Art of Computer Programming */ + /* Vol. 2 (2nd Ed.), pp102] */ + mt[0] = m_seed & 0xffffffff; + for (mti = 1; mti < N; mti++) + mt[mti] = (69069 * mt[mti-1]) & 0xffffffff; +} + +long SCA_RandomNumberGenerator::GetSeed() { return m_seed; } +void SCA_RandomNumberGenerator::SetSeed(long newseed) +{ + m_seed = newseed; + SetStartVector(); +} + +/** + * This is the important part: copied verbatim :) + */ +unsigned long SCA_RandomNumberGenerator::Draw() { + static unsigned long mag01[2] = { 0x0, MATRIX_A }; + /* mag01[x] = x * MATRIX_A for x=0,1 */ + + unsigned long y; + + if (mti >= N) { /* generate N words at one time */ + int kk; + + /* I set this in the constructor, so it is always satisfied ! */ +// if (mti == N+1) /* if sgenrand() has not been called, */ +// GEN_srand(4357); /* a default initial seed is used */ + + 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 & 0x1]; + } + 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 & 0x1]; + } + y = (mt[N-1] & UPPER_MASK) | (mt[0] & LOWER_MASK); + mt[N-1] = mt[M-1] ^ (y >> 1) ^ mag01[y & 0x1]; + + mti = 0; + } + + y = mt[mti++]; + y ^= TEMPERING_SHIFT_U(y); + y ^= TEMPERING_SHIFT_S(y) & TEMPERING_MASK_B; + y ^= TEMPERING_SHIFT_T(y) & TEMPERING_MASK_C; + y ^= TEMPERING_SHIFT_L(y); + + return y; +} + +float SCA_RandomNumberGenerator::DrawFloat() { + return ( (float) Draw()/ (unsigned long) 0xffffffff ); +} + +/* eof */ |