Import of Empire 4.2.12

src/lib/gen/chance.c

@@ -0,0 +1,87 @@
+/*
+ *  Empire - A multi-player, client/server Internet based war game.
+ *  Copyright (C) 1986-2000, Dave Pare, Jeff Bailey, Thomas Ruschak,
+ *                           Ken Stevens, Steve McClure
+ *
+ *  This program 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.
+ *
+ *  This program 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
+ *
+ *  ---
+ *
+ *  See the "LEGAL", "LICENSE", "CREDITS" and "README" files for all the
+ *  related information and legal notices. It is expected that any future
+ *  projects/authors will amend these files as needed.
+ *
+ *  ---
+ *
+ *  chance.c: return 1 if "roll" is under the chance.
+ * 
+ *  Known contributors to this file:
+ *     
+ */
+
+#include "gen.h"
+
+#ifdef hpux
+void
+srandom(unsigned int n)
+{
+	extern void srand48();
+
+	srand48(n);
+}
+
+long
+random(void)
+{
+	extern	long lrand48();
+
+	return (lrand48());	/* 5/28/91 by bailey@mcs.kent.edu */
+}
+#endif
+
+int
+chance(double d)
+{
+	double	roll;
+
+	roll = (random() & 0x7fff);
+
+	if (d >  roll/32768.0)
+		return 1;
+	return 0;
+}
+
+int
+roll(int n)
+{
+	return (random() % n) + 1;
+}
+
+/*
+ * round value to nearest int (on the average). E.g. rounds up
+ * with a chance proportional to the size of the fractional part.
+ */
+int
+roundavg(double val)
+{
+	int	flr;
+
+	flr = (int) val;
+	if (val < 0)
+		flr -= chance(flr - val);
+	else
+		flr += chance(val - flr);
+	return flr;
+}