/* $Id$ */ #include "stdafx.h" #include "openttd.h" #ifdef MERSENNE_TWISTER // Source code for Mersenne Twister. // A Random number generator with much higher quality random numbers. #define N (624) // length of _mt_state vector #define M (397) // a period parameter #define K (0x9908B0DFU) // a magic constant #define hiBit(u) ((u) & 0x80000000U) // mask all but highest bit of u #define loBit(u) ((u) & 0x00000001U) // mask all but lowest bit of u #define loBits(u) ((u) & 0x7FFFFFFFU) // mask the highest bit of u #define mixBits(u, v) (hiBit(u)|loBits(v)) // move hi bit of u to hi bit of v static uint32 _mt_state[N+1]; // _mt_state vector + 1 extra to not violate ANSI C static uint32 *_mt_next; // _mt_next random value is computed from here static int _mt_left = -1; // can *_mt_next++ this many times before reloading void SeedMT(uint32 seed) { register uint32 x = (seed | 1U) & 0xFFFFFFFFU, *s = _mt_state; register int j; for(_mt_left=0, *s++=x, j=N; --j; *s++ = (x*=69069U) & 0xFFFFFFFFU); } static uint32 ReloadMT(void) { register uint32 *p0=_mt_state, *p2=_mt_state+2, *pM=_mt_state+M, s0, s1; register int j; if(_mt_left < -1) SeedMT(4357U); _mt_left=N-1, _mt_next=_mt_state+1; for(s0=_mt_state[0], s1=_mt_state[1], j=N-M+1; --j; s0=s1, s1=*p2++) *p0++ = *pM++ ^ (mixBits(s0, s1) >> 1) ^ (loBit(s1) ? K : 0U); for(pM=_mt_state, j=M; --j; s0=s1, s1=*p2++) *p0++ = *pM++ ^ (mixBits(s0, s1) >> 1) ^ (loBit(s1) ? K : 0U); s1=_mt_state[0], *p0 = *pM ^ (mixBits(s0, s1) >> 1) ^ (loBit(s1) ? K : 0U); s1 ^= (s1 >> 11); s1 ^= (s1 << 7) & 0x9D2C5680U; s1 ^= (s1 << 15) & 0xEFC60000U; return(s1 ^ (s1 >> 18)); } uint32 RandomMT(void) { uint32 y; if(--_mt_left < 0) return ReloadMT(); y = *_mt_next++; y ^= (y >> 11); y ^= (y << 7) & 0x9D2C5680U; y ^= (y << 15) & 0xEFC60000U; return y ^ (y >> 18); } #else void SeedMT(uint32 seed) {} #endif /* MERSENNE_TWISTER */