1 /* libFLAC - Free Lossless Audio Codec library
2 * Copyright (C) 2001,2002,2003,2004,2005,2006,2007,2008,2009 Josh Coalson
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
8 * - Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
11 * - Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
15 * - Neither the name of the Xiph.org Foundation nor the names of its
16 * contributors may be used to endorse or promote products derived from
17 * this software without specific prior written permission.
19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
21 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
22 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR
23 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
24 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
25 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
26 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
27 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
28 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
29 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 #ifndef FLAC__PRIVATE__BITMATH_H
33 #define FLAC__PRIVATE__BITMATH_H
35 #include "FLAC/ordinals.h"
39 #include "share/compat.h"
41 #if defined(_MSC_VER) && (_MSC_VER >= 1400)
42 #include <intrin.h> /* for _BitScanReverse* */
45 /* Will never be emitted for MSVC, GCC, Intel compilers */
46 static inline unsigned int FLAC__clz_soft_uint32(unsigned int word)
48 static const unsigned char byte_to_unary_table[] = {
49 8, 7, 6, 6, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4,
50 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
51 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
52 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
53 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
54 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
55 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
56 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
57 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
58 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
59 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
60 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
61 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
62 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
63 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
64 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
67 return (word) > 0xffffff ? byte_to_unary_table[(word) >> 24] :
68 (word) > 0xffff ? byte_to_unary_table[(word) >> 16] + 8 :
69 (word) > 0xff ? byte_to_unary_table[(word) >> 8] + 16 :
70 byte_to_unary_table[(word)] + 24;
73 static inline unsigned int FLAC__clz_uint32(FLAC__uint32 v)
75 /* Never used with input 0 */
76 #if defined(__INTEL_COMPILER)
77 return _bit_scan_reverse(n) ^ 31U;
78 #elif defined(__GNUC__) && (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4))
79 /* This will translate either to (bsr ^ 31U), clz , ctlz, cntlz, lzcnt depending on
80 * -march= setting or to a software rutine in exotic machines. */
81 return __builtin_clz(v);
82 #elif defined(_MSC_VER) && (_MSC_VER >= 1400)
84 _BitScanReverse(&idx, v);
87 return FLAC__clz_soft_uint32(v);
91 /* This one works with input 0 */
92 static inline unsigned int FLAC__clz2_uint32(FLAC__uint32 v)
96 return FLAC__clz_uint32(v);
99 /* An example of what FLAC__bitmath_ilog2() computes:
101 * ilog2( 0) = undefined
122 static inline unsigned FLAC__bitmath_ilog2(FLAC__uint32 v)
124 return sizeof(FLAC__uint32) * CHAR_BIT - 1 - FLAC__clz_uint32(v);
128 #ifdef FLAC__INTEGER_ONLY_LIBRARY /*Unused otherwise */
130 static inline unsigned FLAC__bitmath_ilog2_wide(FLAC__uint64 v)
134 #if && defined(__GNUC__) && (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4))
135 return sizeof(FLAC__uint64) * CHAR_BIT - 1 - __builtin_clzll(v);
136 /* Sorry, only supported in win64/Itanium.. */
137 #elif (defined(_MSC_VER) && (_MSC_VER >= 1400)) && (defined(_M_IA64) || defined(_WIN64))
139 _BitScanReverse64(&idx, v);
142 /* Brain-damaged compilers will use the fastest possible way that is,
143 de Bruijn sequences (http://supertech.csail.mit.edu/papers/debruijn.pdf)
144 (C) Timothy B. Terriberry (tterribe@xiph.org) 2001-2009 LGPL (v2 or later).
146 static const unsigned char DEBRUIJN_IDX64[64]={
147 0, 1, 2, 7, 3,13, 8,19, 4,25,14,28, 9,34,20,40,
148 5,17,26,38,15,46,29,48,10,31,35,54,21,50,41,57,
149 63, 6,12,18,24,27,33,39,16,37,45,47,30,53,49,56,
150 62,11,23,32,36,44,52,55,61,22,43,51,60,42,59,58
161 ret+=DEBRUIJN_IDX64[v*0x218A392CD3D5DBF>>58&0x3F];
167 unsigned FLAC__bitmath_silog2(int v);
168 unsigned FLAC__bitmath_silog2_wide(FLAC__int64 v);