godot/thirdparty/thekla_atlas/nvmath/Random.cpp
Hein-Pieter van Braam bf05309af7 Import thekla_atlas
As requested by reduz, an import of thekla_atlas into thirdparty/
2017-12-08 15:47:15 +01:00

55 lines
1.3 KiB
C++

// This code is in the public domain -- castanyo@yahoo.es
#include <nvmath/Random.h>
#include <time.h>
using namespace nv;
// Statics
const uint16 Rand48::a0 = 0xE66D;
const uint16 Rand48::a1 = 0xDEEC;
const uint16 Rand48::a2 = 0x0005;
const uint16 Rand48::c0 = 0x000B;
/// Get a random seed based on the current time.
uint Rand::randomSeed()
{
return (uint)time(NULL);
}
void MTRand::initialize( uint32 seed )
{
// Initialize generator state with seed
// See Knuth TAOCP Vol 2, 3rd Ed, p.106 for multiplier.
// In previous versions, most significant bits (MSBs) of the seed affect
// only MSBs of the state array. Modified 9 Jan 2002 by Makoto Matsumoto.
uint32 *s = state;
uint32 *r = state;
int i = 1;
*s++ = seed & 0xffffffffUL;
for( ; i < N; ++i )
{
*s++ = ( 1812433253UL * ( *r ^ (*r >> 30) ) + i ) & 0xffffffffUL;
r++;
}
}
void MTRand::reload()
{
// Generate N new values in state
// Made clearer and faster by Matthew Bellew (matthew.bellew@home.com)
uint32 *p = state;
int i;
for( i = N - M; i--; ++p )
*p = twist( p[M], p[0], p[1] );
for( i = M; --i; ++p )
*p = twist( p[M-N], p[0], p[1] );
*p = twist( p[M-N], p[0], state[0] );
left = N, next = state;
}