| The Android Open Source Project | 1dc9e47 | 2009-03-03 19:28:35 -0800 | [diff] [blame^] | 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 | |
| 14 | #include <sys/cdefs.h> |
| 15 | #include "rand48.h" |
| 16 | |
| 17 | unsigned short _rand48_seed[3] = { |
| 18 | RAND48_SEED_0, |
| 19 | RAND48_SEED_1, |
| 20 | RAND48_SEED_2 |
| 21 | }; |
| 22 | unsigned short _rand48_mult[3] = { |
| 23 | RAND48_MULT_0, |
| 24 | RAND48_MULT_1, |
| 25 | RAND48_MULT_2 |
| 26 | }; |
| 27 | unsigned short _rand48_add = RAND48_ADD; |
| 28 | |
| 29 | void |
| 30 | _dorand48(unsigned short xseed[3]) |
| 31 | { |
| 32 | unsigned long accu; |
| 33 | unsigned short temp[2]; |
| 34 | |
| 35 | accu = (unsigned long) _rand48_mult[0] * (unsigned long) xseed[0] + |
| 36 | (unsigned long) _rand48_add; |
| 37 | temp[0] = (unsigned short) accu; /* lower 16 bits */ |
| 38 | accu >>= sizeof(unsigned short) * 8; |
| 39 | accu += (unsigned long) _rand48_mult[0] * (unsigned long) xseed[1] + |
| 40 | (unsigned long) _rand48_mult[1] * (unsigned long) xseed[0]; |
| 41 | temp[1] = (unsigned short) accu; /* middle 16 bits */ |
| 42 | accu >>= sizeof(unsigned short) * 8; |
| 43 | accu += _rand48_mult[0] * xseed[2] + _rand48_mult[1] * xseed[1] + _rand48_mult[2] * xseed[0]; |
| 44 | xseed[0] = temp[0]; |
| 45 | xseed[1] = temp[1]; |
| 46 | xseed[2] = (unsigned short) accu; |
| 47 | } |