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/* $Id$ */

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/** @file random_func.cpp */

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#include "../stdafx.h"

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#include "random_func.hpp"

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#include "bitmath_func.hpp"

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{

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}

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{

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}

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#ifdef MERSENNE_TWISTER

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// Source code for Mersenne Twister.

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// A Random number generator with much higher quality random numbers.

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#define N              (624)                 // length of _mt_state vector

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#define M              (397)                 // a period parameter

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#define K              (0x9908B0DFU)         // a magic constant

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#define hiBit(u)       ((u) & 0x80000000U)   // mask all but highest   bit of u

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#define loBit(u)       ((u) & 0x00000001U)   // mask all but lowest    bit of u

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#define loBits(u)      ((u) & 0x7FFFFFFFU)   // mask     the highest   bit of u

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#define mixBits(u, v)  (hiBit(u)|loBits(v))  // move hi bit of u to hi bit of v

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static uint32 _mt_state[N+1];     // _mt_state vector + 1 extra to not violate ANSI C

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static uint32 *_mt_next;          // _mt_next random value is computed from here

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static int    _mt_left = -1;      // can *_mt_next++ this many times before reloading

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void SetRandomSeed(register uint32 seed)

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{

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	register uint32 *s = _mt_state;

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	_mt_left = 0;

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	seed |= 1U;

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	seed &= 0xFFFFFFFFU;

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	*s = seed;

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	for (register uint i = N; i != 0; i--) {

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		seed *= 69069U;

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		*s++;

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		*s = seed & 0xFFFFFFFFU;

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	}

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}

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static uint32 ReloadRandom()

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{

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	if (_mt_left < -1) SetRandomSeed(4357U);

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	_mt_left = N - 1;

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	_mt_next = _mt_state + 1;

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	register uint32 *p0 = _mt_state;

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	register uint32 *p2 = _mt_state + 2;

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	register uint32 *pM = _mt_state + M;

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	register uint32 s0 = _mt_state[0];

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	register uint32 s1 = _mt_state[1];

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	register uint i = 0;

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	for (i = (N - M + 1); i != 0; i--) {

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		s0 = s1;

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		s1 = *p2;

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		*p0 = *pM ^ (mixBits(s0, s1) >> 1) ^ (loBit(s1) ? K : 0U);

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		*p0++;

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		*p2++;

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		*pM++;

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	}

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	pM = _mt_state;

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	for (i = M; i != 0; i--) {

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		s0 = s1;

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		s1 = *p2;

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		*p0 = *pM ^ (mixBits(s0, s1) >> 1) ^ (loBit(s1) ? K : 0U);

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		*p0++;

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		*p2++;

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		*pM++;

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	}

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	s1 = _mt_state[0];

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	*p0 = *pM ^ (mixBits(s0, s1) >> 1) ^ (loBit(s1) ? K : 0U);

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	s1 ^= (s1 >> 11);

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	s1 ^= (s1 <<  7) & 0x9D2C5680U;

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	s1 ^= (s1 << 15) & 0xEFC60000U;

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	s1 ^= (s1 >> 18);

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	return s1;

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}

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uint32 Random()

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{

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	_mt_left--;

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	if (_mt_left < 0) return ReloadRandom();

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	uint32 y = *_mt_next;

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	*_mt_next++;

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	y ^= (y >> 11);

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	y ^= (y <<  7) & 0x9D2C5680U;

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	y ^= (y << 15) & 0xEFC60000U;

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	y ^= (y >> 18);

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	return y;

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}

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#else /* MERSENNE_TWISTER */

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void SetRandomSeed(uint32 seed)

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{

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}

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#ifdef RANDOM_DEBUG

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#include "../network/network_data.h"

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uint32 DoRandom(int line, const char *file)

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{

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		printf("Random [%d/%d] %s:%d\n",_frame_counter, (byte)_current_player, file, line);

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#endif /* RANDOM_DEBUG */

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#endif /* MERSENNE_TWISTER */

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#if defined(RANDOM_DEBUG) && !defined(MERSENNE_TWISTER)

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uint DoRandomRange(uint max, int line, const char *file)

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{

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	return GB(DoRandom(line, file), 0, 16) * max >> 16;

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}

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#endif /* RANDOM_DEBUG & !MERSENNE_TWISTER */