projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| b3afadef KB |
1 | #ifndef lint |
| 2 | static char sccsid[] = "@(#)random.c 5.1 (Berkeley) %G%"; | |
| 3 | #endif /* not lint */ | |
| 4 | ||
| 5 | static long rntb[32] = { | |
| 6 | 3, 0x9a319039, 0x32d9c024, 0x9b663182, 0x5da1f342, | |
| 7 | 0xde3b81e0, 0xdf0a6fb5, 0xf103bc02, 0x48f340fb, 0x7449e56b, | |
| 8 | 0xbeb1dbb0, 0xab5c5918, 0x946554fd, 0x8c2e680f, 0xeb3d799f, | |
| 9 | 0xb11ee0b7, 0x2d436b86, 0xda672e2a, 0x1588ca88, 0xe369735d, | |
| 10 | 0x904f35f7, 0xd7158fd6, 0x6fa6f051, 0x616e6b96, 0xac94efdc, | |
| 11 | 0x36413f93, 0xc622c298, 0xf5a42ab8, 0x8a88d77b, 0xf5ad9d0e, | |
| 12 | 0x8999220b, 0x27fb47b9 | |
| 13 | }; | |
| 14 | ||
| 15 | static long *fptr = &rntb[4]; | |
| 16 | static long *rptr = &rntb[1]; | |
| 17 | static long *state = &rntb[1]; | |
| 18 | static int rand_type = 3; | |
| 19 | static int rand_deg = 31; | |
| 20 | static int rand_sep = 3; | |
| 21 | static long *end_ptr = &rntb[32]; | |
| 22 | ||
| 23 | srrandom(x) | |
| 24 | int x; | |
| 25 | { | |
| 26 | register int i; | |
| 27 | long rrandom(); | |
| 28 | ||
| 29 | state[0] = (long) x; | |
| 30 | if (rand_type != 0) { | |
| 31 | for (i = 1; i < rand_deg; i++) { | |
| 32 | state[i] = 1103515245 * state[i - 1] + 12345; | |
| 33 | } | |
| 34 | fptr = &state[rand_sep]; | |
| 35 | rptr = &state[0]; | |
| 36 | for (i = 0; i < 10 * rand_deg; i++) { | |
| 37 | (void) rrandom(); | |
| 38 | } | |
| 39 | } | |
| 40 | } | |
| 41 | ||
| 42 | long | |
| 43 | rrandom() | |
| 44 | { | |
| 45 | long i; | |
| 46 | ||
| 47 | if (rand_type == 0) { | |
| 48 | i = state[0] = (state[0]*1103515245 + 12345) & 0x7fffffff; | |
| 49 | } else { | |
| 50 | *fptr += *rptr; | |
| 51 | i = (*fptr >> 1) & 0x7fffffff; | |
| 52 | if (++fptr >= end_ptr) { | |
| 53 | fptr = state; | |
| 54 | ++rptr; | |
| 55 | } else { | |
| 56 | if (++rptr >= end_ptr) { | |
| 57 | rptr = state; | |
| 58 | } | |
| 59 | } | |
| 60 | } | |
| 61 | return(i); | |
| 62 | } | |
| 63 | ||
| 64 | get_rand(x, y) | |
| 65 | register int x, y; | |
| 66 | { | |
| 67 | register int r, t; | |
| 68 | long lr; | |
| 69 | ||
| 70 | if (x > y) { | |
| 71 | t = y; | |
| 72 | y = x; | |
| 73 | x = t; | |
| 74 | } | |
| 75 | lr = rrandom(); | |
| 76 | lr &= (long) 0x00003fff; | |
| 77 | r = (int) lr; | |
| 78 | r = (r % ((y - x) + 1)) + x; | |
| 79 | return(r); | |
| 80 | } | |
| 81 | ||
| 82 | rand_percent(percentage) | |
| 83 | register int percentage; | |
| 84 | { | |
| 85 | return(get_rand(1, 100) <= percentage); | |
| 86 | } | |
| 87 | ||
| 88 | coin_toss() | |
| 89 | { | |
| 90 | ||
| 91 | return(((rrandom() & 01) ? 1 : 0)); | |
| 92 | } |