| | 1 | /* |
| | 2 | * Copyright (c) 1993 Martin Birgmeier |
| | 3 | * All rights reserved. |
| | 4 | * |
| | 5 | * You may redistribute unmodified or modified versions of this source |
| | 6 | * code provided that the above copyright notice and this and the |
| | 7 | * following conditions are retained. |
| | 8 | * |
| | 9 | * This software is provided ``as is'', and comes with no warranties |
| | 10 | * of any kind. I shall in no event be liable for anything that happens |
| | 11 | * to anyone/anything when using this software. |
| | 12 | * |
| | 13 | * $FreeBSD: src/lib/libc/gen/rand48.h,v 1.2 2002/02/01 01:32:19 obrien Exp $ |
| | 14 | */ |
| | 15 | |
| | 16 | #ifndef _RAND48_H_ |
| | 17 | #define _RAND48_H_ |
| | 18 | |
| | 19 | #include <math.h> |
| | 20 | #include <stdlib.h> |
| | 21 | |
| | 22 | #define RAND48_SEED_0 (0x330e) |
| | 23 | #define RAND48_SEED_1 (0xabcd) |
| | 24 | #define RAND48_SEED_2 (0x1234) |
| | 25 | #define RAND48_MULT_0 (0xe66d) |
| | 26 | #define RAND48_MULT_1 (0xdeec) |
| | 27 | #define RAND48_MULT_2 (0x0005) |
| | 28 | #define RAND48_ADD (0x000b) |
| | 29 | |
| | 30 | typedef unsigned long long uint48; |
| | 31 | |
| | 32 | extern uint48 _rand48_seed; |
| | 33 | extern uint48 _rand48_mult; |
| | 34 | extern uint48 _rand48_add; |
| | 35 | |
| | 36 | #define TOUINT48(x,y,z) \ |
| | 37 | ((uint48)(x) + (((uint48)(y)) << 16) + (((uint48)(z)) << 32)) |
| | 38 | |
| | 39 | #define RAND48_SEED TOUINT48(RAND48_SEED_0, RAND48_SEED_1, RAND48_SEED_2) |
| | 40 | #define RAND48_MULT TOUINT48(RAND48_MULT_0, RAND48_MULT_1, RAND48_MULT_2) |
| | 41 | |
| | 42 | #define LOADRAND48(l,x) \ |
| | 43 | (l) = TOUINT48((x)[0], (x)[1], (x)[2]) |
| | 44 | |
| | 45 | #define STORERAND48(l,x) \ |
| | 46 | (x)[0] = (unsigned short)(l); \ |
| | 47 | (x)[1] = (unsigned short)((l) >> 16); \ |
| | 48 | (x)[2] = (unsigned short)((l) >> 32) |
| | 49 | |
| | 50 | #define _DORAND48(l) \ |
| | 51 | (l) = (l) * _rand48_mult + _rand48_add |
| | 52 | |
| | 53 | #define DORAND48(l,x) \ |
| | 54 | LOADRAND48(l, x); \ |
| | 55 | _DORAND48(l); \ |
| | 56 | STORERAND48(l, x) |
| | 57 | |
| | 58 | #include "fpmath.h" |
| | 59 | |
| | 60 | /* |
| | 61 | * Optimization for speed: avoid int-to-double conversion. Assume doubles |
| | 62 | * are IEEE-754 and insert the bits directly. To normalize, the (1 << 52) |
| | 63 | * is the hidden bit, which the first set bit is shifted to. |
| | 64 | */ |
| | 65 | #define ERAND48_BEGIN \ |
| | 66 | union { \ |
| | 67 | union IEEEd2bits ieee; \ |
| | 68 | unsigned long long l; \ |
| | 69 | } u; \ |
| | 70 | int s |
| | 71 | |
| | 72 | #define ERAND48_END(x) \ |
| | 73 | u.l = ((x) & 0xffffffffffffULL); \ |
| | 74 | if (u.l == 0) \ |
| | 75 | return 0.0; \ |
| | 76 | u.l <<= 5; \ |
| | 77 | for(s = 0; !(u.l & (1LL << 52)); s++, u.l <<= 1) {} \ |
| | 78 | u.ieee.bits.exp = 1022 - s; \ |
| | 79 | return u.ieee.d |
| | 80 | |
| | 81 | #endif /* _RAND48_H_ */ |
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