random.S revision 1.3.14.1
1 1.3.14.1 yamt /* $NetBSD: random.S,v 1.3.14.1 2014/05/22 11:41:04 yamt Exp $ */ 2 1.1 mycroft 3 1.1 mycroft /* 4 1.1 mycroft * Copyright (c) 1990,1993 The Regents of the University of California. 5 1.1 mycroft * All rights reserved. 6 1.1 mycroft * 7 1.1 mycroft * Redistribution and use in source and binary forms, with or without 8 1.1 mycroft * modification, are permitted provided that: (1) source code distributions 9 1.1 mycroft * retain the above copyright notice and this paragraph in its entirety, (2) 10 1.1 mycroft * distributions including binary code include the above copyright notice and 11 1.1 mycroft * this paragraph in its entirety in the documentation or other materials 12 1.1 mycroft * provided with the distribution, and (3) all advertising materials mentioning 13 1.1 mycroft * features or use of this software display the following acknowledgement: 14 1.1 mycroft * ``This product includes software developed by the University of California, 15 1.1 mycroft * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of 16 1.1 mycroft * the University nor the names of its contributors may be used to endorse 17 1.1 mycroft * or promote products derived from this software without specific prior 18 1.1 mycroft * written permission. 19 1.1 mycroft * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED 20 1.1 mycroft * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF 21 1.1 mycroft * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. 22 1.1 mycroft * 23 1.1 mycroft * Here is a very good random number generator. This implementation is 24 1.1 mycroft * based on ``Two Fast Implementations of the "Minimal Standard" Random 25 1.1 mycroft * Number Generator'', David G. Carta, Communications of the ACM, Jan 1990, 26 1.1 mycroft * Vol 33 No 1. Do NOT modify this code unless you have a very thorough 27 1.1 mycroft * understanding of the algorithm. It's trickier than you think. If 28 1.1 mycroft * you do change it, make sure that its 10,000'th invocation returns 29 1.1 mycroft * 1043618065. 30 1.1 mycroft * 31 1.1 mycroft * Here is easier-to-decipher pseudocode: 32 1.1 mycroft * 33 1.1 mycroft * p = (16807*seed)<30:0> # e.g., the low 31 bits of the product 34 1.1 mycroft * q = (16807*seed)<62:31> # e.g., the high 31 bits starting at bit 32 35 1.1 mycroft * if (p + q < 2^31) 36 1.1 mycroft * seed = p + q 37 1.1 mycroft * else 38 1.1 mycroft * seed = ((p + q) & (2^31 - 1)) + 1 39 1.1 mycroft * return (seed); 40 1.1 mycroft * 41 1.1 mycroft * The result is in (0,2^31), e.g., it's always positive. 42 1.1 mycroft */ 43 1.1 mycroft #include <machine/asm.h> 44 1.1 mycroft 45 1.1 mycroft .data 46 1.3.14.1 yamt .align 4 47 1.1 mycroft randseed: 48 1.1 mycroft .long 1 49 1.3 pooka 50 1.1 mycroft .text 51 1.1 mycroft ENTRY(random) 52 1.1 mycroft sethi %hi(16807), %o1 53 1.1 mycroft wr %o1, %lo(16807), %y 54 1.3.14.1 yamt #ifdef __PIC__ 55 1.3 pooka PIC_PROLOGUE(%o5, %o2) 56 1.3 pooka set randseed, %g1 57 1.3 pooka ld [%o5 + %g1], %g1 58 1.3 pooka ld [%g1], %o0 59 1.2 pooka #else 60 1.2 pooka sethi %hi(randseed), %g1 61 1.2 pooka ld [%g1 + %lo(randseed)], %o0 62 1.2 pooka #endif 63 1.2 pooka andcc %g0, 0, %o2 64 1.1 mycroft mulscc %o2, %o0, %o2 65 1.1 mycroft mulscc %o2, %o0, %o2 66 1.1 mycroft mulscc %o2, %o0, %o2 67 1.1 mycroft mulscc %o2, %o0, %o2 68 1.1 mycroft mulscc %o2, %o0, %o2 69 1.1 mycroft mulscc %o2, %o0, %o2 70 1.1 mycroft mulscc %o2, %o0, %o2 71 1.1 mycroft mulscc %o2, %o0, %o2 72 1.1 mycroft mulscc %o2, %o0, %o2 73 1.1 mycroft mulscc %o2, %o0, %o2 74 1.1 mycroft mulscc %o2, %o0, %o2 75 1.1 mycroft mulscc %o2, %o0, %o2 76 1.1 mycroft mulscc %o2, %o0, %o2 77 1.1 mycroft mulscc %o2, %o0, %o2 78 1.1 mycroft mulscc %o2, %o0, %o2 79 1.1 mycroft mulscc %o2, %g0, %o2 80 1.1 mycroft rd %y, %o3 81 1.1 mycroft srl %o2, 16, %o1 82 1.1 mycroft set 0xffff, %o4 83 1.1 mycroft and %o4, %o2, %o0 84 1.1 mycroft sll %o0, 15, %o0 85 1.1 mycroft srl %o3, 17, %o3 86 1.1 mycroft or %o3, %o0, %o0 87 1.1 mycroft addcc %o0, %o1, %o0 88 1.1 mycroft bneg 1f 89 1.2 pooka sethi %hi(0x7fffffff), %o1 90 1.1 mycroft retl 91 1.3.14.1 yamt #ifdef __PIC__ 92 1.3 pooka st %o0, [%g1] 93 1.2 pooka #else 94 1.2 pooka st %o0, [%g1 + %lo(randseed)] 95 1.2 pooka #endif 96 1.1 mycroft 1: 97 1.1 mycroft or %o1, %lo(0x7fffffff), %o1 98 1.1 mycroft add %o0, 1, %o0 99 1.1 mycroft and %o1, %o0, %o0 100 1.1 mycroft retl 101 1.3.14.1 yamt #ifdef __PIC__ 102 1.3 pooka st %o0, [%g1] 103 1.2 pooka #else 104 1.2 pooka st %o0, [%g1 + %lo(randseed)] 105 1.2 pooka #endif 106
Indexes created Tue Sep 23 14:10:03 GMT 2025