/*--------------------------------------------------------------------------- * Gamedriver: Random Generator 'Mersenne Twister' * * A C-program for MT19937, with initialization improved 2002/2/10. * Coded by Takuji Nishimura and Makoto Matsumoto. * This is a faster version by taking Shawn Cokus's optimization, * Matthe Bellew's simplification, Isaku Wada's real version. * * 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.keio.ac.jp/matumoto/emt.html * email: matumoto@math.keio.ac.jp *--------------------------------------------------------------------------- */ #include "driver.h" #include "random.h" /* Period parameters */ #define N 624 #define M 397 #define MATRIX_A 0x9908b0dfUL /* constant vector a */ #define UMASK 0x80000000UL /* most significant w-r bits */ #define LMASK 0x7fffffffUL /* least significant r bits */ #define MIXBITS(u,v) ( ((u) & UMASK) | ((v) & LMASK) ) #define TWIST(u,v) ((MIXBITS(u,v) >> 1) ^ ((v)&1UL ? MATRIX_A : 0UL)) static unsigned long state[N]; /* the array for the state vector */ static int left = 1; static int initf = 0; static unsigned long *next; /* initializes state[N] with a seed */ void init_genrand(unsigned long s) { int j; state[0]= s & 0xffffffffUL; for (j=1; j> 30)) + j); /* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */ /* In the previous versions, MSBs of the seed affect */ /* only MSBs of the array state[]. */ /* 2002/01/09 modified by Makoto Matsumoto */ state[j] &= 0xffffffffUL; /* for >32 bit machines */ } left = 1; initf = 1; } /* 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 init_by_array(unsigned long init_key[], int key_length) { int i, j, k; init_genrand(19650218UL); i=1; j=0; k = (N>key_length ? N : key_length); for (; k; k--) { state[i] = (state[i] ^ ((state[i-1] ^ (state[i-1] >> 30)) * 1664525UL)) + init_key[j] + j; /* non linear */ state[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */ i++; j++; if (i>=N) { state[0] = state[N-1]; i=1; } if (j>=key_length) j=0; } for (k=N-1; k; k--) { state[i] = (state[i] ^ ((state[i-1] ^ (state[i-1] >> 30)) * 1566083941UL)) - i; /* non linear */ state[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */ i++; if (i>=N) { state[0] = state[N-1]; i=1; } } state[0] = 0x80000000UL; /* MSB is 1; assuring non-zero initial array */ left = 1; initf = 1; } static void next_state(void) { unsigned long *p=state; int j; /* if init_genrand() has not been called, */ /* a default initial seed is used */ if (initf==0) init_genrand(5489UL); left = N; next = state; for (j=N-M+1; --j; p++) *p = p[M] ^ TWIST(p[0], p[1]); for (j=M; --j; p++) *p = p[M-N] ^ TWIST(p[0], p[1]); *p = p[M-N] ^ TWIST(p[0], state[0]); } /* generates a random number on [0,0xffffffff]-interval */ unsigned long genrand_int32(void) { unsigned long y; if (--left == 0) next_state(); y = *next++; /* Tempering */ y ^= (y >> 11); y ^= (y << 7) & 0x9d2c5680UL; y ^= (y << 15) & 0xefc60000UL; y ^= (y >> 18); return y; } #if 0 /** LDMud doesn't use the following functions - yet. **/ /* generates a random number on [0,0x7fffffff]-interval */ long genrand_int31(void) { unsigned long y; if (--left == 0) next_state(); y = *next++; /* Tempering */ y ^= (y >> 11); y ^= (y << 7) & 0x9d2c5680UL; y ^= (y << 15) & 0xefc60000UL; y ^= (y >> 18); return (long)(y>>1); } /* generates a random number on [0,1]-real-interval */ double genrand_real1(void) { unsigned long y; if (--left == 0) next_state(); y = *next++; /* Tempering */ y ^= (y >> 11); y ^= (y << 7) & 0x9d2c5680UL; y ^= (y << 15) & 0xefc60000UL; y ^= (y >> 18); return (double)y * (1.0/4294967295.0); /* divided by 2^32-1 */ } /* generates a random number on [0,1)-real-interval */ double genrand_real2(void) { unsigned long y; if (--left == 0) next_state(); y = *next++; /* Tempering */ y ^= (y >> 11); y ^= (y << 7) & 0x9d2c5680UL; y ^= (y << 15) & 0xefc60000UL; y ^= (y >> 18); return (double)y * (1.0/4294967296.0); /* divided by 2^32 */ } /* generates a random number on (0,1)-real-interval */ double genrand_real3(void) { unsigned long y; if (--left == 0) next_state(); y = *next++; /* Tempering */ y ^= (y >> 11); y ^= (y << 7) & 0x9d2c5680UL; y ^= (y << 15) & 0xefc60000UL; y ^= (y >> 18); return ((double)y + 0.5) * (1.0/4294967296.0); /* divided by 2^32 */ } /* generates a random number on [0,1) with 53-bit resolution*/ double genrand_res53(void) { unsigned long a=genrand_int32()>>5, b=genrand_int32()>>6; return(a*67108864.0+b)*(1.0/9007199254740992.0); } /* These real versions are due to Isaku Wada, 2002/01/09 added */ #endif /*+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/ /* Driver interface functions */ /*-------------------------------------------------------------------------*/ void seed_random (uint32 seed) /* Initialize the generator */ { unsigned long init[4]; init[0] = seed & 0xFFF; init[1] = (seed >>= 8) & 0xFFF; init[2] = (seed >>= 8) & 0xFFF; init[3] = (seed >>= 8) & 0xFFF; init_by_array(init, 4); } /* seed_random() */ /*-------------------------------------------------------------------------*/ uint32 random_number (uint32 n) /* Return a random number in the range 0..n-1. * * The MT FAQ suggests: * If the application is not sensitive to the rounding off error, then please * multiply N to [0,1)-real uniform random numbers and take the integer part * (this is sufficient for most applications). * */ { return genrand_int32() * (1.0/4294967296.0) * n; /* * Since most compilers compute the constant when it is compiled, so this * code runs with the same speed with the standard C codes, and portability * and readability are better. */ } /* random_number() */ /***************************************************************************/