rtoss - Blame information for rev 26

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14 roytam 1 /*
2  * libmad - MPEG audio decoder library
26 roytam 3  * Copyright (C) 2000-2004 Underbit Technologies, Inc.
14 roytam 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  *
26 roytam 19  * $Id: fixed.c,v 1.13 2004/01/23 09:41:32 rob Exp $
14 roytam 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  */
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  */
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 }