diff --git a/backends/frotz/random.c b/backends/frotz/random.c new file mode 100644 index 0000000000000000000000000000000000000000..6ea14d89c999abd0648a8b043c5eb29a18c850fe --- /dev/null +++ b/backends/frotz/random.c @@ -0,0 +1,82 @@ +/* random.c - Z-machine random number generator + * Copyright (c) 1995-1997 Stefan Jokisch + * + * This file is part of Frotz. + * + * Frotz is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * Frotz is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA + */ + +#include "frotz.h" + +static long A = 1; + +static int interval = 0; +static int counter = 0; + +/* + * seed_random + * + * Set the seed value for the random number generator. + * + */ + +void seed_random (int value) +{ + + if (value == 0) { /* ask interface for seed value */ + A = os_random_seed (); + interval = 0; + } else if (value < 1000) { /* special seed value */ + counter = 0; + interval = value; + } else { /* standard seed value */ + A = value; + interval = 0; + } + +}/* seed_random */ + +/* + * z_random, store a random number or set the random number seed. + * + * zargs[0] = range (positive) or seed value (negative) + * + */ + +void z_random () +{ + + if ((short) zargs[0] <= 0) { /* set random seed */ + + seed_random (- (short) zargs[0]); + store (0); + + } else { /* generate random number */ + + zword result; + + if (interval != 0) { /* ...in special mode */ + result = counter++; + if (counter == interval) counter = 0; + } else { /* ...in standard mode */ + A = 0x015a4e35L * A + 1; + result = (A >> 16) & 0x7fff; + } + + store ((zword) (result % zargs[0] + 1)); + + } + +}/* z_random */