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https://github.com/OpenTTD/OpenTTD.git
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154 lines
3.5 KiB
C++
154 lines
3.5 KiB
C++
/* $Id$ */
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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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Randomizer _random, _interactive_random;
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uint32 Randomizer::Next()
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{
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const uint32 s = this->state[0];
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const uint32 t = this->state[1];
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this->state[0] = s + ROR(t ^ 0x1234567F, 7) + 1;
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return this->state[1] = ROR(s, 3) - 1;
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}
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uint32 Randomizer::Next(uint16 max)
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{
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return GB(this->Next(), 0, 16) * max >> 16;
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}
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void Randomizer::SetSeed(uint32 seed)
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{
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this->state[0] = seed;
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this->state[1] = seed;
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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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_random.SetSeed(seed);
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_interactive_random.SetSeed(seed * 0x1234567);
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}
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#ifdef RANDOM_DEBUG
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#include "../network/network_data.h"
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#include "../variables.h" /* _frame_counter */
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#include "../player_func.h"
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uint32 DoRandom(int line, const char *file)
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{
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if (_networking && (DEREF_CLIENT(0)->status != STATUS_INACTIVE || !_network_server)) {
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printf("Random [%d/%d] %s:%d\n",_frame_counter, (byte)_current_player, file, line);
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}
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return _random.Next();
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}
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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 */
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