projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| 78ed81a3 | 1 | // This may look like C code, but it is really -*- C++ -*- |
| 2 | /* | |
| 3 | Copyright (C) 1989 Free Software Foundation | |
| 4 | ||
| 5 | This file is part of the GNU C++ Library. This library is free | |
| 6 | software; you can redistribute it and/or modify it under the terms of | |
| 7 | the GNU Library General Public License as published by the Free | |
| 8 | Software Foundation; either version 2 of the License, or (at your | |
| 9 | option) any later version. This library is distributed in the hope | |
| 10 | that it will be useful, but WITHOUT ANY WARRANTY; without even the | |
| 11 | implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR | |
| 12 | PURPOSE. See the GNU Library General Public License for more details. | |
| 13 | You should have received a copy of the GNU Library General Public | |
| 14 | License along with this library; if not, write to the Free Software | |
| 15 | Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. | |
| 16 | */ | |
| 15637ed4 RG |
17 | #ifdef __GNUG__ |
| 18 | #pragma implementation | |
| 19 | #endif | |
| 78ed81a3 | 20 | #include <MLCG.h> |
| 15637ed4 RG |
21 | // |
| 22 | // SEED_TABLE_SIZE must be a power of 2 | |
| 23 | // | |
| 24 | ||
| 25 | ||
| 26 | #define SEED_TABLE_SIZE 32 | |
| 27 | ||
| 28 | static long seedTable[SEED_TABLE_SIZE] = { | |
| 29 | 0xbdcc47e5, 0x54aea45d, 0xec0df859, 0xda84637b, | |
| 30 | 0xc8c6cb4f, 0x35574b01, 0x28260b7d, 0x0d07fdbf, | |
| 31 | 0x9faaeeb0, 0x613dd169, 0x5ce2d818, 0x85b9e706, | |
| 32 | 0xab2469db, 0xda02b0dc, 0x45c60d6e, 0xffe49d10, | |
| 33 | 0x7224fea3, 0xf9684fc9, 0xfc7ee074, 0x326ce92a, | |
| 34 | 0x366d13b5, 0x17aaa731, 0xeb83a675, 0x7781cb32, | |
| 35 | 0x4ec7c92d, 0x7f187521, 0x2cf346b4, 0xad13310f, | |
| 36 | 0xb89cff2b, 0x12164de1, 0xa865168d, 0x32b56cdf | |
| 37 | }; | |
| 38 | ||
| 39 | MLCG::MLCG(long seed1, long seed2) | |
| 40 | { | |
| 41 | initialSeedOne = seed1; | |
| 42 | initialSeedTwo = seed2; | |
| 43 | reset(); | |
| 44 | } | |
| 45 | ||
| 46 | void | |
| 47 | MLCG::reset() | |
| 48 | { | |
| 49 | long seed1 = initialSeedOne; | |
| 50 | long seed2 = initialSeedTwo; | |
| 51 | ||
| 52 | // | |
| 53 | // Most people pick stupid seed numbers that do not have enough | |
| 54 | // bits. In this case, if they pick a small seed number, we | |
| 55 | // map that to a specific seed. | |
| 56 | // | |
| 57 | if (seed1 < 0) { | |
| 58 | seed1 = (seed1 + 2147483561); | |
| 59 | seed1 = (seed1 < 0) ? -seed1 : seed1; | |
| 60 | } | |
| 61 | ||
| 62 | if (seed2 < 0) { | |
| 63 | seed2 = (seed2 + 2147483561); | |
| 64 | seed2 = (seed2 < 0) ? -seed2 : seed2; | |
| 65 | } | |
| 66 | ||
| 67 | if (seed1 > -1 && seed1 < SEED_TABLE_SIZE) { | |
| 68 | seedOne = seedTable[seed1]; | |
| 69 | } else { | |
| 70 | seedOne = seed1 ^ seedTable[seed1 & (SEED_TABLE_SIZE-1)]; | |
| 71 | } | |
| 72 | ||
| 73 | if (seed2 > -1 && seed2 < SEED_TABLE_SIZE) { | |
| 74 | seedTwo = seedTable[seed2]; | |
| 75 | } else { | |
| 76 | seedTwo = seed2 ^ seedTable[ seed2 & (SEED_TABLE_SIZE-1) ]; | |
| 77 | } | |
| 78 | seedOne = (seedOne % 2147483561) + 1; | |
| 79 | seedTwo = (seedTwo % 2147483397) + 1; | |
| 80 | } | |
| 81 | ||
| 82 | unsigned long MLCG::asLong() | |
| 83 | { | |
| 84 | long k = seedOne % 53668; | |
| 85 | ||
| 86 | seedOne = 40014 * (seedOne-k * 53668) - k * 12211; | |
| 87 | if (seedOne < 0) { | |
| 88 | seedOne += 2147483563; | |
| 89 | } | |
| 90 | ||
| 91 | k = seedTwo % 52774; | |
| 92 | seedTwo = 40692 * (seedTwo - k * 52774) - k * 3791; | |
| 93 | if (seedTwo < 0) { | |
| 94 | seedTwo += 2147483399; | |
| 95 | } | |
| 96 | ||
| 97 | long z = seedOne - seedTwo; | |
| 98 | if (z < 1) { | |
| 99 | z += 2147483562; | |
| 100 | } | |
| 101 | return( (unsigned long) z); | |
| 102 | } | |
| 103 |