diff options
Diffstat (limited to 'mersenne.c')
-rw-r--r-- | mersenne.c | 145 |
1 files changed, 73 insertions, 72 deletions
diff --git a/mersenne.c b/mersenne.c index 98170084f..a30bc0cf5 100644 --- a/mersenne.c +++ b/mersenne.c @@ -1,72 +1,73 @@ -#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
\ No newline at end of file +#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 */ + |