/* Arithmetic.
- Copyright (C) 2001-2002 Free Software Foundation, Inc.
+ Copyright (C) 2001-2002, 2006, 2009-2010 Free Software Foundation, Inc.
Written by Bruno Haible <bruno@clisp.org>, 2001.
- This program is free software; you can redistribute it and/or modify
+ 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, or (at your option)
- any later version.
+ 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
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. */
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
+#include <config.h>
+
+/* This file can also be used to define gcd functions for other unsigned
+ types, such as 'unsigned long long' or 'uintmax_t'. */
+#ifndef WORD_T
/* Specification. */
-#include "gcd.h"
+# include "gcd.h"
+# define WORD_T unsigned long
+# define GCD gcd
+#endif
#include <stdlib.h>
/* Return the greatest common divisor of a > 0 and b > 0. */
-unsigned long
-gcd (a, b)
- unsigned long a;
- unsigned long b;
+WORD_T
+GCD (WORD_T a, WORD_T b)
{
/* Why no division, as in Euclid's algorithm? Because in Euclid's algorithm
the division result floor(a/b) or floor(b/a) is very often = 1 or = 2,
bit in a single instruction, and the algorithm uses fewer variables than
Euclid's algorithm. */
- unsigned long c = a | b;
+ WORD_T c = a | b;
c = c ^ (c - 1);
/* c = largest power of 2 that divides a and b. */
if (a & c)
{
if (b & c)
- goto odd_odd;
+ goto odd_odd;
else
- goto odd_even;
+ goto odd_even;
}
else
{
if (b & c)
- goto even_odd;
+ goto even_odd;
else
- abort ();
+ abort ();
}
for (;;)
{
odd_odd: /* a/c and b/c both odd */
if (a == b)
- break;
+ break;
if (a > b)
- {
- a = a - b;
- even_odd: /* a/c even, b/c odd */
- do
- a = a >> 1;
- while ((a & c) == 0);
- }
+ {
+ a = a - b;
+ even_odd: /* a/c even, b/c odd */
+ do
+ a = a >> 1;
+ while ((a & c) == 0);
+ }
else
- {
- b = b - a;
- odd_even: /* a/c odd, b/c even */
- do
- b = b >> 1;
- while ((b & c) == 0);
- }
+ {
+ b = b - a;
+ odd_even: /* a/c odd, b/c even */
+ do
+ b = b >> 1;
+ while ((b & c) == 0);
+ }
}
/* a = b */