projects / unix-history / blame
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1 | /* |
| 2 | * Copyright (c) 1988 The Regents of the University of California. | |
| 3 | * All rights reserved. | |
| 4 | * | |
| 5 | * This code is derived from software contributed to Berkeley by | |
| 6 | * Timothy C. Stoehr. | |
| 7 | * | |
| 8 | * Redistribution and use in source and binary forms are permitted | |
| 9 | * provided that the above copyright notice and this paragraph are | |
| 10 | * duplicated in all such forms and that any documentation, | |
| 11 | * advertising materials, and other materials related to such | |
| 12 | * distribution and use acknowledge that the software was developed | |
| 13 | * by the University of California, Berkeley. The name of the | |
| 14 | * University may not be used to endorse or promote products derived | |
| 15 | * from this software without specific prior written permission. | |
| 16 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR | |
| 17 | * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED | |
| 18 | * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. | |
| 19 | */ | |
| 20 | ||
| b3afadef | 21 | #ifndef lint |
| fc3e88fd | 22 | static char sccsid[] = "@(#)random.c 5.2 (Berkeley) %G%"; |
| b3afadef KB |
23 | #endif /* not lint */ |
| 24 | ||
| fc3e88fd KB |
25 | /* |
| 26 | * random.c | |
| 27 | * | |
| 28 | * This source herein may be modified and/or distributed by anybody who | |
| 29 | * so desires, with the following restrictions: | |
| 30 | * 1.) No portion of this notice shall be removed. | |
| 31 | * 2.) Credit shall not be taken for the creation of this source. | |
| 32 | * 3.) This code is not to be traded, sold, or used for personal | |
| 33 | * gain or profit. | |
| 34 | * | |
| 35 | */ | |
| 36 | ||
| b3afadef KB |
37 | static long rntb[32] = { |
| 38 | 3, 0x9a319039, 0x32d9c024, 0x9b663182, 0x5da1f342, | |
| 39 | 0xde3b81e0, 0xdf0a6fb5, 0xf103bc02, 0x48f340fb, 0x7449e56b, | |
| 40 | 0xbeb1dbb0, 0xab5c5918, 0x946554fd, 0x8c2e680f, 0xeb3d799f, | |
| 41 | 0xb11ee0b7, 0x2d436b86, 0xda672e2a, 0x1588ca88, 0xe369735d, | |
| 42 | 0x904f35f7, 0xd7158fd6, 0x6fa6f051, 0x616e6b96, 0xac94efdc, | |
| 43 | 0x36413f93, 0xc622c298, 0xf5a42ab8, 0x8a88d77b, 0xf5ad9d0e, | |
| 44 | 0x8999220b, 0x27fb47b9 | |
| 45 | }; | |
| 46 | ||
| 47 | static long *fptr = &rntb[4]; | |
| 48 | static long *rptr = &rntb[1]; | |
| 49 | static long *state = &rntb[1]; | |
| 50 | static int rand_type = 3; | |
| 51 | static int rand_deg = 31; | |
| 52 | static int rand_sep = 3; | |
| 53 | static long *end_ptr = &rntb[32]; | |
| 54 | ||
| 55 | srrandom(x) | |
| 56 | int x; | |
| 57 | { | |
| 58 | register int i; | |
| 59 | long rrandom(); | |
| 60 | ||
| 61 | state[0] = (long) x; | |
| 62 | if (rand_type != 0) { | |
| 63 | for (i = 1; i < rand_deg; i++) { | |
| 64 | state[i] = 1103515245 * state[i - 1] + 12345; | |
| 65 | } | |
| 66 | fptr = &state[rand_sep]; | |
| 67 | rptr = &state[0]; | |
| 68 | for (i = 0; i < 10 * rand_deg; i++) { | |
| 69 | (void) rrandom(); | |
| 70 | } | |
| 71 | } | |
| 72 | } | |
| 73 | ||
| 74 | long | |
| 75 | rrandom() | |
| 76 | { | |
| 77 | long i; | |
| 78 | ||
| 79 | if (rand_type == 0) { | |
| 80 | i = state[0] = (state[0]*1103515245 + 12345) & 0x7fffffff; | |
| 81 | } else { | |
| 82 | *fptr += *rptr; | |
| 83 | i = (*fptr >> 1) & 0x7fffffff; | |
| 84 | if (++fptr >= end_ptr) { | |
| 85 | fptr = state; | |
| 86 | ++rptr; | |
| 87 | } else { | |
| 88 | if (++rptr >= end_ptr) { | |
| 89 | rptr = state; | |
| 90 | } | |
| 91 | } | |
| 92 | } | |
| 93 | return(i); | |
| 94 | } | |
| 95 | ||
| 96 | get_rand(x, y) | |
| 97 | register int x, y; | |
| 98 | { | |
| 99 | register int r, t; | |
| 100 | long lr; | |
| 101 | ||
| 102 | if (x > y) { | |
| 103 | t = y; | |
| 104 | y = x; | |
| 105 | x = t; | |
| 106 | } | |
| 107 | lr = rrandom(); | |
| 108 | lr &= (long) 0x00003fff; | |
| 109 | r = (int) lr; | |
| 110 | r = (r % ((y - x) + 1)) + x; | |
| 111 | return(r); | |
| 112 | } | |
| 113 | ||
| 114 | rand_percent(percentage) | |
| 115 | register int percentage; | |
| 116 | { | |
| 117 | return(get_rand(1, 100) <= percentage); | |
| 118 | } | |
| 119 | ||
| 120 | coin_toss() | |
| 121 | { | |
| 122 | ||
| 123 | return(((rrandom() & 01) ? 1 : 0)); | |
| 124 | } |