/*
* Empire - A multi-player, client/server Internet based war game.
* Copyright (C) 1986-2013, Dave Pare, Jeff Bailey, Thomas Ruschak,
* Ken Stevens, Steve McClure, Markus Armbruster
*
* Empire 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 3 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, see .
*
* ---
*
* See files README, COPYING and CREDITS in the root of the source
* tree for related information and legal notices. It is expected
* that future projects/authors will amend these files as needed.
*
* ---
*
* chance.c: Roll dice
*
* Known contributors to this file:
* Markus Armbruster, 2006-2012
*/
#include
#include
#include
#include "chance.h"
/*
* Return non-zero with probability D.
*/
int
chance(double d)
{
return d > (random() % 32768) / 32768.0;
}
/*
* Return non-zero with probability PCT%.
*/
int
pct_chance(int pct)
{
return roll(100) <= pct;
}
/*
* Return a random number in [0..N-1].
*/
int
roll0(int n)
{
return random() % n;
}
/*
* Return a random number in [1..N].
*/
int
roll(int n)
{
return 1 + random() % n;
}
/*
* Round VAL to nearest integer (on the average).
* VAL's fractional part is chance to round up.
*/
int
roundavg(double val)
{
double flr = floor(val);
return (int)(flr + chance(val - flr));
}
/*
* Seed the pseudo-random number generator with SEED.
* The sequence of pseudo-random numbers is repeatable by seeding it
* with the same value.
*/
void
seed_prng(unsigned seed)
{
srandom(seed);
}