1*600f14f4SXin Li /* libFLAC - Free Lossless Audio Codec library
2*600f14f4SXin Li * Copyright (C) 2001-2009 Josh Coalson
3*600f14f4SXin Li * Copyright (C) 2011-2023 Xiph.Org Foundation
4*600f14f4SXin Li *
5*600f14f4SXin Li * Redistribution and use in source and binary forms, with or without
6*600f14f4SXin Li * modification, are permitted provided that the following conditions
7*600f14f4SXin Li * are met:
8*600f14f4SXin Li *
9*600f14f4SXin Li * - Redistributions of source code must retain the above copyright
10*600f14f4SXin Li * notice, this list of conditions and the following disclaimer.
11*600f14f4SXin Li *
12*600f14f4SXin Li * - Redistributions in binary form must reproduce the above copyright
13*600f14f4SXin Li * notice, this list of conditions and the following disclaimer in the
14*600f14f4SXin Li * documentation and/or other materials provided with the distribution.
15*600f14f4SXin Li *
16*600f14f4SXin Li * - Neither the name of the Xiph.org Foundation nor the names of its
17*600f14f4SXin Li * contributors may be used to endorse or promote products derived from
18*600f14f4SXin Li * this software without specific prior written permission.
19*600f14f4SXin Li *
20*600f14f4SXin Li * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
21*600f14f4SXin Li * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22*600f14f4SXin Li * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
23*600f14f4SXin Li * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR
24*600f14f4SXin Li * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
25*600f14f4SXin Li * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
26*600f14f4SXin Li * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
27*600f14f4SXin Li * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
28*600f14f4SXin Li * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
29*600f14f4SXin Li * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
30*600f14f4SXin Li * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31*600f14f4SXin Li */
32*600f14f4SXin Li
33*600f14f4SXin Li #ifdef HAVE_CONFIG_H
34*600f14f4SXin Li # include <config.h>
35*600f14f4SXin Li #endif
36*600f14f4SXin Li
37*600f14f4SXin Li #include "private/bitmath.h"
38*600f14f4SXin Li
39*600f14f4SXin Li /* An example of what FLAC__bitmath_silog2() computes:
40*600f14f4SXin Li *
41*600f14f4SXin Li * silog2(-10) = 5
42*600f14f4SXin Li * silog2(- 9) = 5
43*600f14f4SXin Li * silog2(- 8) = 4
44*600f14f4SXin Li * silog2(- 7) = 4
45*600f14f4SXin Li * silog2(- 6) = 4
46*600f14f4SXin Li * silog2(- 5) = 4
47*600f14f4SXin Li * silog2(- 4) = 3
48*600f14f4SXin Li * silog2(- 3) = 3
49*600f14f4SXin Li * silog2(- 2) = 2
50*600f14f4SXin Li * silog2(- 1) = 2
51*600f14f4SXin Li * silog2( 0) = 0
52*600f14f4SXin Li * silog2( 1) = 2
53*600f14f4SXin Li * silog2( 2) = 3
54*600f14f4SXin Li * silog2( 3) = 3
55*600f14f4SXin Li * silog2( 4) = 4
56*600f14f4SXin Li * silog2( 5) = 4
57*600f14f4SXin Li * silog2( 6) = 4
58*600f14f4SXin Li * silog2( 7) = 4
59*600f14f4SXin Li * silog2( 8) = 5
60*600f14f4SXin Li * silog2( 9) = 5
61*600f14f4SXin Li * silog2( 10) = 5
62*600f14f4SXin Li */
FLAC__bitmath_silog2(FLAC__int64 v)63*600f14f4SXin Li uint32_t FLAC__bitmath_silog2(FLAC__int64 v)
64*600f14f4SXin Li {
65*600f14f4SXin Li if(v == 0)
66*600f14f4SXin Li return 0;
67*600f14f4SXin Li
68*600f14f4SXin Li if(v == -1)
69*600f14f4SXin Li return 2;
70*600f14f4SXin Li
71*600f14f4SXin Li v = (v < 0) ? (-(v+1)) : v;
72*600f14f4SXin Li return FLAC__bitmath_ilog2_wide(v)+2;
73*600f14f4SXin Li }
74