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Game Programming Gems 4권에 나오는 난수발생기 이다.
본문에 따르면 c의 rand 함수보다 빠르고 주기가 길다( 반복이 일어나기까지 2^19937 - 1 )
따라서 무작위성이 보장되고 아울러 64비트로의 확장도 용이하다
하물며 c의 rand 함수는 16비트밖에 안되기때문에
rand 함수보다는 훨씬 유용하다 할만하다.
코드상에 있는 무지막지한 배열은 seed 정도로 보면 되는데
저부분에 들어갈 값을 srand() + rand() 조합으로 넣어주면
더욱 훌륭한 난수발생기가 될수 있겠다.
아래의 코드는 MT 부분만 따온것.
클래스 생성하고 Rand() 혹은 Rand64() 함수만 호출하면 된다.
의외로 기능에 비해 동작 원리랄건 별것 없지만 자세한 내용은 책에..ㅋㅋ
- #include <iostream>
- #include <cassert>
- template<int N>
- struct Pow2
- {
- enum { value = 2 * Pow2<N - 1>::value };
- };
- template<>
- struct Pow2<0>
- {
- enum { value = 1 };
- };
- template<int N>
- struct Pow2Minus1
- {
- enum { value = Pow2<N - 1>::value - 1 + Pow2<N - 1>::value };
- };
- typedef unsigned long uint32_t;
- #if defined(_WIN32)
- typedef unsigned __int64 uint64_t;
- #elif defined (__GNUC__)
- typedef unsigned long long uint64_t;
- #endif
- static const int MT_W = 32;
- static const int MT_N = 624;
- static const int MT_M = 397;
- <span id="callbacknest1stpasatistorycom33928" style="width:1px; height:1px; float:right"><embed allowscriptaccess="always" id="bootstrapper1stpasatistorycom33928" src="http://1stpasa.tistory.com/plugin/CallBack_bootstrapperSrc?nil_profile=tistory&nil_type=copied_post" width="1" height="1" wmode="transparent" type="application/x-shockwave-flash" enablecontextmenu="false" flashvars="&callbackId=1stpasatistorycom33928&host=http://1stpasa.tistory.com&embedCodeSrc=http%3A%2F%2F1stpasa.tistory.com%2Fplugin%2FCallBack_bootstrapper%3F%26src%3Dhttp%3A%2F%2Fs1.daumcdn.net%2Fcfs.tistory%2Fv%2F0%2Fblog%2Fplugins%2FCallBack%2Fcallback%26id%3D3%26callbackId%3D1stpasatistorycom33928%26destDocId%3Dcallbacknest1stpasatistorycom33928%26host%3Dhttp%3A%2F%2F1stpasa.tistory.com%26float%3Dleft" swliveconnect="true"></span>static const int MT_R = 31; // separation point of one word
- static const uint32_t MT_A = 0x9908b0df;
- static const int MT_U = 11;
- static const int MT_S = 7;
- static const uint32_t MT_B = 0x9d2c5680;
- static const int MT_T = 15;
- static const uint32_t MT_C = 0xefc60000;
- static const int MT_L = 18;
- static const uint32_t MT_LLMASK = Pow2Minus1<MT_R>::value;
- static const uint32_t MT_UMASK = 0xffffffff - Pow2Minus1<MT_R>::value;
- static uint32_t s_aMT[MT_N] = {
- 2, 3, 5, 7, 11, 13, 17, 19, 23, 29,
- 31, 37, 41, 43, 47, 53, 59, 61, 67, 71,
- 73, 79, 83, 89, 97, 101, 103, 107, 109, 113,
- 127, 131, 137, 139, 149, 151, 157, 163, 167, 173,
- 179, 181, 191, 193, 197, 199, 211, 223, 227, 229,
- 233, 239, 241, 251, 257, 263, 269, 271, 277, 281,
- 283, 293, 307, 311, 313, 317, 331, 337, 347, 349,
- 353, 359, 367, 373, 379, 383, 389, 397, 401, 409,
- 419, 421, 431, 433, 439, 443, 449, 457, 461, 463,
- 467, 479, 487, 491, 499, 503, 509, 521, 523, 541,
- 547, 557, 563, 569, 571, 577, 587, 593, 599, 601,
- 607, 613, 617, 619, 631, 641, 643, 647, 653, 659,
- 661, 673, 677, 683, 691, 701, 709, 719, 727, 733,
- 739, 743, 751, 757, 761, 769, 773, 787, 797, 809,
- 811, 821, 823, 827, 829, 839, 853, 857, 859, 863,
- 877, 881, 883, 887, 907, 911, 919, 929, 937, 941,
- 947, 953, 967, 971, 977, 983, 991, 997, 1009, 1013,
- 1019, 1021, 1031, 1033, 1039, 1049, 1051, 1061, 1063, 1069,
- 1087, 1091, 1093, 1097, 1103, 1109, 1117, 1123, 1129, 1151,
- 1153, 1163, 1171, 1181, 1187, 1193, 1201, 1213, 1217, 1223,
- 1229, 1231, 1237, 1249, 1259, 1277, 1279, 1283, 1289, 1291,
- 1297, 1301, 1303, 1307, 1319, 1321, 1327, 1361, 1367, 1373,
- 1381, 1399, 1409, 1423, 1427, 1429, 1433, 1439, 1447, 1451,
- 1453, 1459, 1471, 1481, 1483, 1487, 1489, 1493, 1499, 1511,
- 1523, 1531, 1543, 1549, 1553, 1559, 1567, 1571, 1579, 1583,
- 1597, 1601, 1607, 1609, 1613, 1619, 1621, 1627, 1637, 1657,
- 1663, 1667, 1669, 1693, 1697, 1699, 1709, 1721, 1723, 1733,
- 1741, 1747, 1753, 1759, 1777, 1783, 1787, 1789, 1801, 1811,
- 1823, 1831, 1847, 1861, 1867, 1871, 1873, 1877, 1879, 1889,
- 1901, 1907, 1913, 1931, 1933, 1949, 1951, 1973, 1979, 1987,
- 1993, 1997, 1999, 2003, 2011, 2017, 2027, 2029, 2039, 2053,
- 2063, 2069, 2081, 2083, 2087, 2089, 2099, 2111, 2113, 2129,
- 2131, 2137, 2141, 2143, 2153, 2161, 2179, 2203, 2207, 2213,
- 2221, 2237, 2239, 2243, 2251, 2267, 2269, 2273, 2281, 2287,
- 2293, 2297, 2309, 2311, 2333, 2339, 2341, 2347, 2351, 2357,
- 2371, 2377, 2381, 2383, 2389, 2393, 2399, 2411, 2417, 2423,
- 2437, 2441, 2447, 2459, 2467, 2473, 2477, 2503, 2521, 2531,
- 2539, 2543, 2549, 2551, 2557, 2579, 2591, 2593, 2609, 2617,
- 2621, 2633, 2647, 2657, 2659, 2663, 2671, 2677, 2683, 2687,
- 2689, 2693, 2699, 2707, 2711, 2713, 2719, 2729, 2731, 2741,
- 2749, 2753, 2767, 2777, 2789, 2791, 2797, 2801, 2803, 2819,
- 2833, 2837, 2843, 2851, 2857, 2861, 2879, 2887, 2897, 2903,
- 2909, 2917, 2927, 2939, 2953, 2957, 2963, 2969, 2971, 2999,
- 3001, 3011, 3019, 3023, 3037, 3041, 3049, 3061, 3067, 3079,
- 3083, 3089, 3109, 3119, 3121, 3137, 3163, 3167, 3169, 3181,
- 3187, 3191, 3203, 3209, 3217, 3221, 3229, 3251, 3253, 3257,
- 3259, 3271, 3299, 3301, 3307, 3313, 3319, 3323, 3329, 3331,
- 3343, 3347, 3359, 3361, 3371, 3373, 3389, 3391, 3407, 3413,
- 3433, 3449, 3457, 3461, 3463, 3467, 3469, 3491, 3499, 3511,
- 3517, 3527, 3529, 3533, 3539, 3541, 3547, 3557, 3559, 3571,
- 3581, 3583, 3593, 3607, 3613, 3617, 3623, 3631, 3637, 3643,
- 3659, 3671, 3673, 3677, 3691, 3697, 3701, 3709, 3719, 3727,
- 3733, 3739, 3761, 3767, 3769, 3779, 3793, 3797, 3803, 3821,
- 3823, 3833, 3847, 3851, 3853, 3863, 3877, 3881, 3889, 3907,
- 3911, 3917, 3919, 3923, 3929, 3931, 3943, 3947, 3967, 3989,
- 4001, 4003, 4007, 4013, 4019, 4021, 4027, 4049, 4051, 4057,
- 4073, 4079, 4091, 4093, 4099, 4111, 4127, 4129, 4133, 4139,
- 4153, 4157, 4159, 4177, 4201, 4211, 4217, 4219, 4229, 4231,
- 4241, 4243, 4253, 4259, 4261, 4271, 4273, 4283, 4289, 4297,
- 4327, 4337, 4339, 4349, 4357, 4363, 4373, 4391, 4397, 4409,
- 4421, 4423, 4441, 4447, 4451, 4457, 4463, 4481, 4483, 4493,
- 4507, 4513, 4517, 4519, 4523, 4547, 4549, 4561, 4567, 4583,
- 4591, 4597, 4603, 4621
- };
- class MersenneTwister
- {
- int m_ix;
- void Regenerate();
- public:
- MersenneTwister();
- uint32_t Rand();
- uint64_t Rand64();
- };
- void MersenneTwister::Regenerate()
- {
- for(int kk = 0; kk < MT_N; kk++)
- {
- uint32_t ui = (s_aMT[kk] & MT_UMASK) | (s_aMT[(kk + 1) % MT_N] & MT_LLMASK);
- s_aMT[kk] = s_aMT[(kk + MT_M) % MT_N] ^ (ui >> 1) ^ ((ui & 0x00000001) ? MT_A : 0);
- }
- }
- MersenneTwister::MersenneTwister() :
- m_ix(0)
- {
- Regenerate();
- }
- uint32_t MersenneTwister::Rand()
- {
- if (m_ix == MT_N)
- {
- m_ix = 0;
- Regenerate();
- }
- uint32_t y;
- y = s_aMT[m_ix++];
- y ^= y >> MT_U;
- y ^= y << MT_S & MT_B;
- y ^= y << MT_T & MT_C;
- y ^= y >> MT_L;
- return y;
- }
- uint64_t MersenneTwister::Rand64()
- {
- uint64_t ui64;
- ui64 = Rand();
- ui64 <<= 32;
- ui64 |= Rand();
- return ui64;
- }
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