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 */ 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 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 */ 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 */ 126 127 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 */ 145 146 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 (at) 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
