1 /* $NetBSD: _rand48.c,v 1.6 1999/09/20 04:39:35 lukem Exp $ */ 2 3 /* 4 * Copyright (c) 1993 Martin Birgmeier 5 * All rights reserved. 6 * 7 * You may redistribute unmodified or modified versions of this source 8 * code provided that the above copyright notice and this and the 9 * following conditions are retained. 10 * 11 * This software is provided ``as is'', and comes with no warranties 12 * of any kind. I shall in no event be liable for anything that happens 13 * to anyone/anything when using this software. 14 */ 15 16 #include <assert.h> 17 18 #include "rand48.h" 19 20 unsigned short __rand48_seed[3] = { 21 RAND48_SEED_0, 22 RAND48_SEED_1, 23 RAND48_SEED_2 24 }; 25 unsigned short __rand48_mult[3] = { 26 RAND48_MULT_0, 27 RAND48_MULT_1, 28 RAND48_MULT_2 29 }; 30 unsigned short __rand48_add = RAND48_ADD; 31 32 void 33 __dorand48(unsigned short xseed[3]) 34 { 35 unsigned long accu; 36 unsigned short temp[2]; 37 38 _DIAGASSERT(xseed != NULL); 39 40 accu = (unsigned long) __rand48_mult[0] * (unsigned long) xseed[0] + 41 (unsigned long) __rand48_add; 42 temp[0] = (unsigned short) accu; /* lower 16 bits */ 43 accu >>= sizeof(unsigned short) * 8; 44 accu += (unsigned long) __rand48_mult[0] * (unsigned long) xseed[1] + 45 (unsigned long) __rand48_mult[1] * (unsigned long) xseed[0]; 46 temp[1] = (unsigned short) accu; /* middle 16 bits */ 47 accu >>= sizeof(unsigned short) * 8; 48 accu += __rand48_mult[0] * xseed[2] + __rand48_mult[1] * xseed[1] + __rand48_mult[2] * xseed[0]; 49 xseed[0] = temp[0]; 50 xseed[1] = temp[1]; 51 xseed[2] = (unsigned short) accu; 52 } 53