src/core/random_func.cpp
branchNewGRF_ports
changeset 6871 5a9dc001e1ad
child 6872 1c4a4a609f85
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/core/random_func.cpp	Mon Dec 03 23:39:38 2007 +0000
@@ -0,0 +1,155 @@
+/* $Id$ */
+
+/** @file random_func.cpp */
+
+#include "../stdafx.h"
+#include "../macros.h"
+#include "../variables.h"
+#include "random_func.hpp"
+
+uint32 InteractiveRandom()
+{
+	const uint32 s = _random_seeds[1][0];
+	const uint32 t = _random_seeds[1][1];
+
+	_random_seeds[1][0] = s + ROR(t ^ 0x1234567F, 7) + 1;
+	return _random_seeds[1][1] = ROR(s, 3) - 1;
+}
+
+uint InteractiveRandomRange(uint max)
+{
+	return GB(InteractiveRandom(), 0, 16) * max >> 16;
+}
+
+#ifdef MERSENNE_TWISTER
+// Source code for Mersenne Twister.
+// A Random number generator with much higher quality random numbers.
+
+#define N              (624)                 // length of _mt_state vector
+#define M              (397)                 // a period parameter
+#define K              (0x9908B0DFU)         // a magic constant
+#define hiBit(u)       ((u) & 0x80000000U)   // mask all but highest   bit of u
+#define loBit(u)       ((u) & 0x00000001U)   // mask all but lowest    bit of u
+#define loBits(u)      ((u) & 0x7FFFFFFFU)   // mask     the highest   bit of u
+#define mixBits(u, v)  (hiBit(u)|loBits(v))  // move hi bit of u to hi bit of v
+
+static uint32 _mt_state[N+1];     // _mt_state vector + 1 extra to not violate ANSI C
+static uint32 *_mt_next;          // _mt_next random value is computed from here
+static int    _mt_left = -1;      // can *_mt_next++ this many times before reloading
+
+void SetRandomSeed(register uint32 seed)
+{
+	register uint32 *s = _mt_state;
+	_mt_left = 0;
+
+	seed |= 1U;
+	seed &= 0xFFFFFFFFU;
+
+	*s = seed;
+
+	for (register uint i = N; i != 0; i--) {
+		seed *= 69069U;
+		*s++;
+		*s = seed & 0xFFFFFFFFU;
+	}
+}
+
+static uint32 ReloadRandom()
+{
+	if (_mt_left < -1) SetRandomSeed(4357U);
+
+	_mt_left = N - 1;
+	_mt_next = _mt_state + 1;
+
+	register uint32 *p0 = _mt_state;
+	register uint32 *p2 = _mt_state + 2;
+	register uint32 *pM = _mt_state + M;
+
+	register uint32 s0 = _mt_state[0];
+	register uint32 s1 = _mt_state[1];
+
+	register uint i = 0;
+
+	for (i = (N - M + 1); i != 0; i--) {
+		s0 = s1;
+		s1 = *p2;
+		*p0 = *pM ^ (mixBits(s0, s1) >> 1) ^ (loBit(s1) ? K : 0U);
+		*p0++;
+		*p2++;
+		*pM++;
+	}
+
+	pM = _mt_state;
+
+	for (i = M; i != 0; i--) {
+		s0 = s1;
+		s1 = *p2;
+		*p0 = *pM ^ (mixBits(s0, s1) >> 1) ^ (loBit(s1) ? K : 0U);
+		*p0++;
+		*p2++;
+		*pM++;
+	}
+
+	s1 = _mt_state[0];
+	*p0 = *pM ^ (mixBits(s0, s1) >> 1) ^ (loBit(s1) ? K : 0U);
+
+	s1 ^= (s1 >> 11);
+	s1 ^= (s1 <<  7) & 0x9D2C5680U;
+	s1 ^= (s1 << 15) & 0xEFC60000U;
+	s1 ^= (s1 >> 18);
+	return s1;
+}
+
+uint32 Random()
+{
+	_mt_left--;
+	if (_mt_left < 0) return ReloadRandom();
+
+	uint32 y = *_mt_next;
+	*_mt_next++;
+
+	y ^= (y >> 11);
+	y ^= (y <<  7) & 0x9D2C5680U;
+	y ^= (y << 15) & 0xEFC60000U;
+	y ^= (y >> 18);
+	return y;
+}
+
+#else /* MERSENNE_TWISTER */
+void SetRandomSeed(uint32 seed)
+{
+	_random_seeds[0][0] = seed;
+	_random_seeds[0][1] = seed;
+	_random_seeds[1][0] = seed * 0x1234567;
+	_random_seeds[1][1] = _random_seeds[1][0];
+}
+
+#ifdef RANDOM_DEBUG
+#include "network/network_data.h"
+uint32 DoRandom(int line, const char *file)
+{
+	if (_networking && (DEREF_CLIENT(0)->status != STATUS_INACTIVE || !_network_server))
+		printf("Random [%d/%d] %s:%d\n",_frame_counter, (byte)_current_player, file, line);
+#else /* RANDOM_DEBUG */
+uint32 Random()
+{
+#endif /* RANDOM_DEBUG */
+	const uint32 s = _random_seeds[0][0];
+	const uint32 t = _random_seeds[0][1];
+
+	_random_seeds[0][0] = s + ROR(t ^ 0x1234567F, 7) + 1;
+	return _random_seeds[0][1] = ROR(s, 3) - 1;
+}
+#endif /* MERSENNE_TWISTER */
+
+#if defined(RANDOM_DEBUG) && !defined(MERSENNE_TWISTER)
+uint DoRandomRange(uint max, int line, const char *file)
+{
+	return GB(DoRandom(line, file), 0, 16) * max >> 16;
+}
+#else /* RANDOM_DEBUG & !MERSENNE_TWISTER */
+uint RandomRange(uint max)
+{
+	return GB(Random(), 0, 16) * max >> 16;
+}
+#endif /* RANDOM_DEBUG & !MERSENNE_TWISTER */