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 "rand48.h" 15 16 unsigned short _rand48_seed[3] = { 17 RAND48_SEED_0, 18 RAND48_SEED_1, 19 RAND48_SEED_2 20 }; 21 unsigned short _rand48_mult[3] = { 22 RAND48_MULT_0, 23 RAND48_MULT_1, 24 RAND48_MULT_2 25 }; 26 unsigned short _rand48_add = RAND48_ADD; 27 28 void _dorand48(unsigned short xseed[3])29_dorand48(unsigned short xseed[3]) 30 { 31 unsigned long accu; 32 unsigned short temp[2]; 33 34 accu = (unsigned long) _rand48_mult[0] * (unsigned long) xseed[0] + 35 (unsigned long) _rand48_add; 36 temp[0] = (unsigned short) accu; /* lower 16 bits */ 37 accu >>= sizeof(unsigned short) * 8; 38 accu += (unsigned long) _rand48_mult[0] * (unsigned long) xseed[1] + 39 (unsigned long) _rand48_mult[1] * (unsigned long) xseed[0]; 40 temp[1] = (unsigned short) accu; /* middle 16 bits */ 41 accu >>= sizeof(unsigned short) * 8; 42 accu += _rand48_mult[0] * xseed[2] + _rand48_mult[1] * xseed[1] + _rand48_mult[2] * xseed[0]; 43 xseed[0] = temp[0]; 44 xseed[1] = temp[1]; 45 xseed[2] = (unsigned short) accu; 46 } 47