1 /* libFLAC - Free Lossless Audio Codec library
2 * Copyright (C) 2001-2009 Josh Coalson
3 * Copyright (C) 2011-2014 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 #ifndef FLAC__PRIVATE__BITMATH_H
34 #define FLAC__PRIVATE__BITMATH_H
35
36 #include "FLAC/ordinals.h"
37 #include "FLAC/assert.h"
38
39 /* for CHAR_BIT */
40 #include <limits.h>
41 #include "share/compat.h"
42
43 #if defined(_MSC_VER) && (_MSC_VER >= 1400)
44 #include <intrin.h> /* for _BitScanReverse* */
45 #endif
46
47 /* Will never be emitted for MSVC, GCC, Intel compilers */
FLAC__clz_soft_uint32(unsigned int word)48 static inline unsigned int FLAC__clz_soft_uint32(unsigned int word)
49 {
50 static const unsigned char byte_to_unary_table[] = {
51 8, 7, 6, 6, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4,
52 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
53 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
54 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
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 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
58 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
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,
65 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
66 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
67 };
68
69 return (word) > 0xffffff ? byte_to_unary_table[(word) >> 24] :
70 (word) > 0xffff ? byte_to_unary_table[(word) >> 16] + 8 :
71 (word) > 0xff ? byte_to_unary_table[(word) >> 8] + 16 :
72 byte_to_unary_table[(word)] + 24;
73 }
74
FLAC__clz_uint32(FLAC__uint32 v)75 static inline unsigned int FLAC__clz_uint32(FLAC__uint32 v)
76 {
77 /* Never used with input 0 */
78 FLAC__ASSERT(v > 0);
79 #if defined(__INTEL_COMPILER)
80 return _bit_scan_reverse(v) ^ 31U;
81 #elif defined(__GNUC__) && (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4))
82 /* This will translate either to (bsr ^ 31U), clz , ctlz, cntlz, lzcnt depending on
83 * -march= setting or to a software routine in exotic machines. */
84 return __builtin_clz(v);
85 #elif defined(_MSC_VER) && (_MSC_VER >= 1400)
86 {
87 unsigned long idx;
88 _BitScanReverse(&idx, v);
89 return idx ^ 31U;
90 }
91 #else
92 return FLAC__clz_soft_uint32(v);
93 #endif
94 }
95
96 /* This one works with input 0 */
FLAC__clz2_uint32(FLAC__uint32 v)97 static inline unsigned int FLAC__clz2_uint32(FLAC__uint32 v)
98 {
99 if (!v)
100 return 32;
101 return FLAC__clz_uint32(v);
102 }
103
104 /* An example of what FLAC__bitmath_ilog2() computes:
105 *
106 * ilog2( 0) = assertion failure
107 * ilog2( 1) = 0
108 * ilog2( 2) = 1
109 * ilog2( 3) = 1
110 * ilog2( 4) = 2
111 * ilog2( 5) = 2
112 * ilog2( 6) = 2
113 * ilog2( 7) = 2
114 * ilog2( 8) = 3
115 * ilog2( 9) = 3
116 * ilog2(10) = 3
117 * ilog2(11) = 3
118 * ilog2(12) = 3
119 * ilog2(13) = 3
120 * ilog2(14) = 3
121 * ilog2(15) = 3
122 * ilog2(16) = 4
123 * ilog2(17) = 4
124 * ilog2(18) = 4
125 */
126
FLAC__bitmath_ilog2(FLAC__uint32 v)127 static inline unsigned FLAC__bitmath_ilog2(FLAC__uint32 v)
128 {
129 FLAC__ASSERT(v > 0);
130 #if defined(__INTEL_COMPILER)
131 return _bit_scan_reverse(v);
132 #elif defined(_MSC_VER) && (_MSC_VER >= 1400)
133 {
134 unsigned long idx;
135 _BitScanReverse(&idx, v);
136 return idx;
137 }
138 #else
139 return sizeof(FLAC__uint32) * CHAR_BIT - 1 - FLAC__clz_uint32(v);
140 #endif
141 }
142
143
144 #ifdef FLAC__INTEGER_ONLY_LIBRARY /* Unused otherwise */
145
FLAC__bitmath_ilog2_wide(FLAC__uint64 v)146 static inline unsigned FLAC__bitmath_ilog2_wide(FLAC__uint64 v)
147 {
148 FLAC__ASSERT(v > 0);
149 #if defined(__GNUC__) && (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4))
150 return sizeof(FLAC__uint64) * CHAR_BIT - 1 - __builtin_clzll(v);
151 /* Sorry, only supported in x64/Itanium.. and both have fast FPU which makes integer-only encoder pointless */
152 #elif (defined(_MSC_VER) && (_MSC_VER >= 1400)) && (defined(_M_IA64) || defined(_M_X64))
153 {
154 unsigned long idx;
155 _BitScanReverse64(&idx, v);
156 return idx;
157 }
158 #else
159 /* Brain-damaged compilers will use the fastest possible way that is,
160 de Bruijn sequences (http://supertech.csail.mit.edu/papers/debruijn.pdf)
161 (C) Timothy B. Terriberry (tterribe@xiph.org) 2001-2009 CC0 (Public domain).
162 */
163 {
164 static const unsigned char DEBRUIJN_IDX64[64]={
165 0, 1, 2, 7, 3,13, 8,19, 4,25,14,28, 9,34,20,40,
166 5,17,26,38,15,46,29,48,10,31,35,54,21,50,41,57,
167 63, 6,12,18,24,27,33,39,16,37,45,47,30,53,49,56,
168 62,11,23,32,36,44,52,55,61,22,43,51,60,42,59,58
169 };
170 v|= v>>1;
171 v|= v>>2;
172 v|= v>>4;
173 v|= v>>8;
174 v|= v>>16;
175 v|= v>>32;
176 v= (v>>1)+1;
177 return DEBRUIJN_IDX64[v*0x218A392CD3D5DBF>>58&0x3F];
178 }
179 #endif
180 }
181 #endif
182
183 unsigned FLAC__bitmath_silog2(int v);
184 unsigned FLAC__bitmath_silog2_wide(FLAC__int64 v);
185
186 #endif
187