1 /* buffer-lcm.c - compute a good buffer size for dealing with two files
3 Copyright (C) 2002-2013 Free Software Foundation, Inc.
5 This program is free software: you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation, either version 3 of the License, or
8 (at your option) any later version.
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <http://www.gnu.org/licenses/>. */
18 /* Written by Paul Eggert. */
21 #include "buffer-lcm.h"
23 /* Return a buffer size suitable for doing I/O with files whose block
24 sizes are A and B. However, never return a value greater than
28 buffer_lcm (size_t a, size_t b, size_t lcm_max)
32 /* Use reasonable values if buffer sizes are zero. */
34 size = b ? b : 8 * 1024;
39 /* Return lcm (A, B) if it is in range; otherwise, fall back
42 size_t lcm, m, n, q, r;
45 for (m = a, n = b; (r = m % n) != 0; m = n, n = r)
48 /* LCM = lcm (A, B), if in range. */
51 if (lcm <= lcm_max && lcm / b == q)
58 return size <= lcm_max ? size : lcm_max;