1 /*
2 * libmad - MPEG audio decoder library
3 * Copyright (C) 2000-2004 Underbit Technologies, Inc.
4 *
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 2 of the License, or
8 * (at your option) any later version.
9 *
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.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 *
19 * $Id: fixed.c,v 1.13 2004/01/23 09:41:32 rob Exp $
20 */
21
22 # ifdef HAVE_CONFIG_H
23 # include "config.h"
24 # endif
25
26 # include "global.h"
27
28 # include "fixed.h"
29
30 /*
31 * NAME: fixed->abs()
32 * DESCRIPTION: return absolute value of a fixed-point number
33 */
mad_f_abs(mad_fixed_t x)34 mad_fixed_t mad_f_abs(mad_fixed_t x)
35 {
36 return x < 0 ? -x : x;
37 }
38
39 /*
40 * NAME: fixed->div()
41 * DESCRIPTION: perform division using fixed-point math
42 */
mad_f_div(mad_fixed_t x,mad_fixed_t y)43 mad_fixed_t mad_f_div(mad_fixed_t x, mad_fixed_t y)
44 {
45 mad_fixed_t q, r;
46 unsigned int bits;
47
48 q = mad_f_abs(x / y);
49
50 if (x < 0) {
51 x = -x;
52 y = -y;
53 }
54
55 r = x % y;
56
57 if (y < 0) {
58 x = -x;
59 y = -y;
60 }
61
62 if (q > mad_f_intpart(MAD_F_MAX) &&
63 !(q == -mad_f_intpart(MAD_F_MIN) && r == 0 && (x < 0) != (y < 0)))
64 return 0;
65
66 for (bits = MAD_F_FRACBITS; bits && r; --bits) {
67 q <<= 1, r <<= 1;
68 if (r >= y)
69 r -= y, ++q;
70 }
71
72 /* round */
73 if (2 * r >= y)
74 ++q;
75
76 /* fix sign */
77 if ((x < 0) != (y < 0))
78 q = -q;
79
80 return q << bits;
81 }
82