gronod/OpenTTD
1
0
Fork 0
mirror of https://github.com/OpenTTD/OpenTTD.git synced 2025-02-07 06:46:43 +00:00
Code Issues Packages Projects Releases Wiki Activity

(svn r12516) -Revert r2583: Removed mersenne PRNG cause it is not used and won't be used in the future

Browse Source
This commit is contained in:
skidd13 2008-03-31 16:07:50 +00:00
parent 4cc6140619
commit 9d914a803c
2 changed files with 1 additions and 103 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

100
src/core/random_func.cpp
View File

@ -28,101 +28,6 @@ void Randomizer::SetSeed(uint32 seed)
this->state[1] = seed;
}
#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 SetRandomSeed(register uint32 seed)
{
register uint32 *s = _mt_state;
_mt_left = 0;
seed |= 1U;
seed &= 0xFFFFFFFFU;
*s = seed;
for (register uint i = N; i != 0; i--) {
seed *= 69069U;
*s++;
*s = seed & 0xFFFFFFFFU;
}
}
static uint32 ReloadRandom()
{
if (_mt_left < -1) SetRandomSeed(4357U);
_mt_left = N - 1;
_mt_next = _mt_state + 1;
register uint32 *p0 = _mt_state;
register uint32 *p2 = _mt_state + 2;
register uint32 *pM = _mt_state + M;
register uint32 s0 = _mt_state[0];
register uint32 s1 = _mt_state[1];
register uint i = 0;
for (i = (N - M + 1); i != 0; i--) {
s0 = s1;
s1 = *p2;
*p0 = *pM ^ (mixBits(s0, s1) >> 1) ^ (loBit(s1) ? K : 0U);
*p0++;
*p2++;
*pM++;
}
pM = _mt_state;
for (i = M; i != 0; i--) {
s0 = s1;
s1 = *p2;
*p0 = *pM ^ (mixBits(s0, s1) >> 1) ^ (loBit(s1) ? K : 0U);
*p0++;
*p2++;
*pM++;
}
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;
s1 ^= (s1 >> 18);
return s1;
}
uint32 Random()
{
_mt_left--;
if (_mt_left < 0) return ReloadRandom();
uint32 y = *_mt_next;
*_mt_next++;
y ^= (y >> 11);
y ^= (y << 7) & 0x9D2C5680U;
y ^= (y << 15) & 0xEFC60000U;
y ^= (y >> 18);
return y;
}
#else /* MERSENNE_TWISTER */
void SetRandomSeed(uint32 seed)
{
_random.SetSeed(seed);
@ -142,12 +47,9 @@ uint32 DoRandom(int line, const char *file)
return _random.Next();
}
#endif /* RANDOM_DEBUG */
#endif /* MERSENNE_TWISTER */
#if defined(RANDOM_DEBUG) && !defined(MERSENNE_TWISTER)
uint DoRandomRange(uint max, int line, const char *file)
{
return GB(DoRandom(line, file), 0, 16) * max >> 16;
}
#endif /* RANDOM_DEBUG & !MERSENNE_TWISTER */
#endif /* RANDOM_DEBUG */

4
src/core/random_func.hpp
View File

@ -23,10 +23,6 @@
//#define RANDOM_DEBUG
// Enable this to produce higher quality random numbers.
// Doesn't work with network yet.
// #define MERSENNE_TWISTER
/**
* Structure to encapsulate the pseudo random number generators.
*/