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 # include "global.h"
23 # include "fixed.h"
24
25 /*
26 * NAME: fixed->abs()
27 * DESCRIPTION: return absolute value of a fixed-point number
28 */
mad_f_abs(mad_fixed_t x)29 mad_fixed_t mad_f_abs(mad_fixed_t x)
30 {
31 return x < 0 ? -x : x;
32 }
33
34 /*
35 * NAME: fixed->div()
36 * DESCRIPTION: perform division using fixed-point math
37 */
mad_f_div(mad_fixed_t x,mad_fixed_t y)38 mad_fixed_t mad_f_div(mad_fixed_t x, mad_fixed_t y)
39 {
40 mad_fixed_t q, r;
41 unsigned int bits;
42
43 q = mad_f_abs(x / y);
44
45 if (x < 0) {
46 x = -x;
47 y = -y;
48 }
49
50 r = x % y;
51
52 if (y < 0) {
53 x = -x;
54 y = -y;
55 }
56
57 if (q > mad_f_intpart(MAD_F_MAX) &&
58 !(q == -mad_f_intpart(MAD_F_MIN) && r == 0 && (x < 0) != (y < 0)))
59 return 0;
60
61 for (bits = MAD_F_FRACBITS; bits && r; --bits) {
62 q <<= 1, r <<= 1;
63 if (r >= y)
64 r -= y, ++q;
65 }
66
67 /* round */
68 if (2 * r >= y)
69 ++q;
70
71 /* fix sign */
72 if ((x < 0) != (y < 0))
73 q = -q;
74
75 return q << bits;
76 }
77