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Annotation of 43BSDReno/games/rogue/random.c, revision 1.1.1.1

1.1       root        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: (1) source distributions retain this entire copyright
                     10:  * notice and comment, and (2) distributions including binaries display
                     11:  * the following acknowledgement:  ``This product includes software
                     12:  * developed by the University of California, Berkeley and its contributors''
                     13:  * in the documentation or other materials provided with the distribution
                     14:  * and in all advertising materials mentioning features or use of this
                     15:  * software. Neither the name of the University nor the names of its
                     16:  * contributors may be used to endorse or promote products derived
                     17:  * from this software without specific prior written permission.
                     18:  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
                     19:  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
                     20:  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
                     21:  */
                     22: 
                     23: #ifndef lint
                     24: static char sccsid[] = "@(#)random.c   5.3 (Berkeley) 6/1/90";
                     25: #endif /* not lint */
                     26: 
                     27: /*
                     28:  * random.c
                     29:  *
                     30:  * This source herein may be modified and/or distributed by anybody who
                     31:  * so desires, with the following restrictions:
                     32:  *    1.)  No portion of this notice shall be removed.
                     33:  *    2.)  Credit shall not be taken for the creation of this source.
                     34:  *    3.)  This code is not to be traded, sold, or used for personal
                     35:  *         gain or profit.
                     36:  *
                     37:  */
                     38: 
                     39: static long rntb[32] = {
                     40:                 3, 0x9a319039, 0x32d9c024, 0x9b663182, 0x5da1f342, 
                     41:        0xde3b81e0, 0xdf0a6fb5, 0xf103bc02, 0x48f340fb, 0x7449e56b,
                     42:        0xbeb1dbb0, 0xab5c5918, 0x946554fd, 0x8c2e680f, 0xeb3d799f,
                     43:        0xb11ee0b7, 0x2d436b86, 0xda672e2a, 0x1588ca88, 0xe369735d,
                     44:        0x904f35f7, 0xd7158fd6, 0x6fa6f051, 0x616e6b96, 0xac94efdc, 
                     45:        0x36413f93, 0xc622c298, 0xf5a42ab8, 0x8a88d77b, 0xf5ad9d0e,
                     46:        0x8999220b, 0x27fb47b9
                     47: };
                     48: 
                     49: static long *fptr = &rntb[4];
                     50: static long *rptr = &rntb[1];
                     51: static long *state = &rntb[1];
                     52: static int rand_type = 3;
                     53: static int rand_deg = 31;
                     54: static int rand_sep = 3;
                     55: static long *end_ptr = &rntb[32];
                     56: 
                     57: srrandom(x)
                     58: int x;
                     59: {
                     60:        register int i;
                     61:        long rrandom();
                     62: 
                     63:        state[0] = (long) x;
                     64:        if (rand_type != 0) {
                     65:                for (i = 1; i < rand_deg; i++) {
                     66:                        state[i] = 1103515245 * state[i - 1] + 12345;
                     67:                }
                     68:                fptr = &state[rand_sep];
                     69:                rptr = &state[0];
                     70:                for (i = 0; i < 10 * rand_deg; i++) {
                     71:                        (void) rrandom();
                     72:                }
                     73:        }
                     74: }
                     75: 
                     76: long
                     77: rrandom()
                     78: {
                     79:        long i;
                     80:        
                     81:        if (rand_type == 0) {
                     82:                i = state[0] = (state[0]*1103515245 + 12345) & 0x7fffffff;
                     83:        } else {
                     84:                *fptr += *rptr;
                     85:                i = (*fptr >> 1) & 0x7fffffff;
                     86:                if (++fptr >= end_ptr) {
                     87:                        fptr = state;
                     88:                        ++rptr;
                     89:                } else {
                     90:                        if (++rptr >= end_ptr) {
                     91:                                rptr = state;
                     92:                        }
                     93:                }
                     94:        }
                     95:        return(i);
                     96: }
                     97: 
                     98: get_rand(x, y)
                     99: register int x, y;
                    100: {
                    101:        register int r, t;
                    102:        long lr;
                    103: 
                    104:        if (x > y) {
                    105:                t = y;
                    106:                y = x;
                    107:                x = t;
                    108:        }
                    109:        lr = rrandom();
                    110:        lr &= (long) 0x00003fff;
                    111:        r = (int) lr;
                    112:        r = (r % ((y - x) + 1)) + x;
                    113:        return(r);
                    114: }
                    115: 
                    116: rand_percent(percentage)
                    117: register int percentage;
                    118: {
                    119:        return(get_rand(1, 100) <= percentage);
                    120: }
                    121: 
                    122: coin_toss()
                    123: {
                    124: 
                    125:        return(((rrandom() & 01) ? 1 : 0));
                    126: }

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