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