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