random_func.cpp

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00001 /* $Id: random_func.cpp 12050 2008-02-03 16:21:19Z rubidium $ */
00002 
00005 #include "../stdafx.h"
00006 #include "random_func.hpp"
00007 #include "bitmath_func.hpp"
00008 
00009 Randomizer _random, _interactive_random;
00010 
00011 uint32 Randomizer::Next()
00012 {
00013   const uint32 s = this->state[0];
00014   const uint32 t = this->state[1];
00015 
00016   this->state[0] = s + ROR(t ^ 0x1234567F, 7) + 1;
00017   return this->state[1] = ROR(s, 3) - 1;
00018 }
00019 
00020 uint32 Randomizer::Next(uint16 max)
00021 {
00022   return GB(this->Next(), 0, 16) * max >> 16;
00023 }
00024 
00025 void Randomizer::SetSeed(uint32 seed)
00026 {
00027   this->state[0] = seed;
00028   this->state[1] = seed;
00029 }
00030 
00031 #ifdef MERSENNE_TWISTER
00032 // Source code for Mersenne Twister.
00033 // A Random number generator with much higher quality random numbers.
00034 
00035 #define N              (624)                 // length of _mt_state vector
00036 #define M              (397)                 // a period parameter
00037 #define K              (0x9908B0DFU)         // a magic constant
00038 #define hiBit(u)       ((u) & 0x80000000U)   // mask all but highest   bit of u
00039 #define loBit(u)       ((u) & 0x00000001U)   // mask all but lowest    bit of u
00040 #define loBits(u)      ((u) & 0x7FFFFFFFU)   // mask     the highest   bit of u
00041 #define mixBits(u, v)  (hiBit(u)|loBits(v))  // move hi bit of u to hi bit of v
00042 
00043 static uint32 _mt_state[N+1];     // _mt_state vector + 1 extra to not violate ANSI C
00044 static uint32 *_mt_next;          // _mt_next random value is computed from here
00045 static int    _mt_left = -1;      // can *_mt_next++ this many times before reloading
00046 
00047 void SetRandomSeed(register uint32 seed)
00048 {
00049   register uint32 *s = _mt_state;
00050   _mt_left = 0;
00051 
00052   seed |= 1U;
00053   seed &= 0xFFFFFFFFU;
00054 
00055   *s = seed;
00056 
00057   for (register uint i = N; i != 0; i--) {
00058     seed *= 69069U;
00059     *s++;
00060     *s = seed & 0xFFFFFFFFU;
00061   }
00062 }
00063 
00064 static uint32 ReloadRandom()
00065 {
00066   if (_mt_left < -1) SetRandomSeed(4357U);
00067 
00068   _mt_left = N - 1;
00069   _mt_next = _mt_state + 1;
00070 
00071   register uint32 *p0 = _mt_state;
00072   register uint32 *p2 = _mt_state + 2;
00073   register uint32 *pM = _mt_state + M;
00074 
00075   register uint32 s0 = _mt_state[0];
00076   register uint32 s1 = _mt_state[1];
00077 
00078   register uint i = 0;
00079 
00080   for (i = (N - M + 1); i != 0; i--) {
00081     s0 = s1;
00082     s1 = *p2;
00083     *p0 = *pM ^ (mixBits(s0, s1) >> 1) ^ (loBit(s1) ? K : 0U);
00084     *p0++;
00085     *p2++;
00086     *pM++;
00087   }
00088 
00089   pM = _mt_state;
00090 
00091   for (i = M; i != 0; i--) {
00092     s0 = s1;
00093     s1 = *p2;
00094     *p0 = *pM ^ (mixBits(s0, s1) >> 1) ^ (loBit(s1) ? K : 0U);
00095     *p0++;
00096     *p2++;
00097     *pM++;
00098   }
00099 
00100   s1 = _mt_state[0];
00101   *p0 = *pM ^ (mixBits(s0, s1) >> 1) ^ (loBit(s1) ? K : 0U);
00102 
00103   s1 ^= (s1 >> 11);
00104   s1 ^= (s1 <<  7) & 0x9D2C5680U;
00105   s1 ^= (s1 << 15) & 0xEFC60000U;
00106   s1 ^= (s1 >> 18);
00107   return s1;
00108 }
00109 
00110 uint32 Random()
00111 {
00112   _mt_left--;
00113   if (_mt_left < 0) return ReloadRandom();
00114 
00115   uint32 y = *_mt_next;
00116   *_mt_next++;
00117 
00118   y ^= (y >> 11);
00119   y ^= (y <<  7) & 0x9D2C5680U;
00120   y ^= (y << 15) & 0xEFC60000U;
00121   y ^= (y >> 18);
00122   return y;
00123 }
00124 
00125 #else /* MERSENNE_TWISTER */
00126 void SetRandomSeed(uint32 seed)
00127 {
00128   _random.SetSeed(seed);
00129   _interactive_random.SetSeed(seed * 0x1234567);
00130 }
00131 
00132 #ifdef RANDOM_DEBUG
00133 #include "../network/network_data.h"
00134 #include "../variables.h" /* _frame_counter */
00135 #include "../player_func.h"
00136 
00137 uint32 DoRandom(int line, const char *file)
00138 {
00139   if (_networking && (DEREF_CLIENT(0)->status != STATUS_INACTIVE || !_network_server)) {
00140     printf("Random [%d/%d] %s:%d\n",_frame_counter, (byte)_current_player, file, line);
00141   }
00142 
00143   return _random.Next();
00144 }
00145 #endif /* RANDOM_DEBUG */
00146 #endif /* MERSENNE_TWISTER */
00147 
00148 #if defined(RANDOM_DEBUG) && !defined(MERSENNE_TWISTER)
00149 uint DoRandomRange(uint max, int line, const char *file)
00150 {
00151   return GB(DoRandom(line, file), 0, 16) * max >> 16;
00152 }
00153 #endif /* RANDOM_DEBUG & !MERSENNE_TWISTER */

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