projects / apple / libc.git / blame
| Commit | Line | Data |
|---|---|---|
| 224c7076 A |
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_ */ |