ce188d4d |
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 | */ |
63 | unsigned 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 | } |