1 /* libFLAC - Free Lossless Audio Codec library
2 * Copyright (C) 2001-2009 Josh Coalson
3 * Copyright (C) 2011-2016 Xiph.Org Foundation
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * - Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 *
12 * - Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * - Neither the name of the Xiph.org Foundation nor the names of its
17 * contributors may be used to endorse or promote products derived from
18 * this software without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
23 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR
24 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
25 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
26 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
27 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
28 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
29 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
30 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 */
32
33 #ifdef HAVE_CONFIG_H
34 # include <config.h>
35 #endif
36
37 #include "private/bitmath.h"
38
39 /* An example of what FLAC__bitmath_silog2() computes:
40 *
41 * silog2(-10) = 5
42 * silog2(- 9) = 5
43 * silog2(- 8) = 4
44 * silog2(- 7) = 4
45 * silog2(- 6) = 4
46 * silog2(- 5) = 4
47 * silog2(- 4) = 3
48 * silog2(- 3) = 3
49 * silog2(- 2) = 2
50 * silog2(- 1) = 2
51 * silog2( 0) = 0
52 * silog2( 1) = 2
53 * silog2( 2) = 3
54 * silog2( 3) = 3
55 * silog2( 4) = 4
56 * silog2( 5) = 4
57 * silog2( 6) = 4
58 * silog2( 7) = 4
59 * silog2( 8) = 5
60 * silog2( 9) = 5
61 * silog2( 10) = 5
62 */
FLAC__bitmath_silog2(FLAC__int64 v)63 uint32_t FLAC__bitmath_silog2(FLAC__int64 v)
64 {
65 if(v == 0)
66 return 0;
67
68 if(v == -1)
69 return 2;
70
71 v = (v < 0) ? (-(v+1)) : v;
72 return FLAC__bitmath_ilog2_wide(v)+2;
73 }
74