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Location: cpp/openttd-patchpack/source/mersenne.c - annotation
r3080:b7535a3e8c6b
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(svn r3669) Really wipe all data when making a void tile
Thanks to Belugas, egladil and Rubidium for their inspiration and hard work, which all this stuff is based on
Thanks to Belugas, egladil and Rubidium for their inspiration and hard work, which all this stuff is based on
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#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 */
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