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 #ifndef FLAC__PRIVATE__BITMATH_H 34 #define FLAC__PRIVATE__BITMATH_H 35 36 #include "FLAC/ordinals.h" 37 #include "FLAC/assert.h" 38 39 #include "share/compat.h" 40 41 #if defined(_MSC_VER) 42 #include <intrin.h> /* for _BitScanReverse* */ 43 #endif 44 45 /* Will never be emitted for MSVC, GCC, Intel compilers */ 46 static inline unsigned int FLAC__clz_soft_uint32(FLAC__uint32 word) 47 { 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, 65 }; 66 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; 71 } 72 73 static inline unsigned int FLAC__clz_uint32(FLAC__uint32 v) 74 { 75 /* Never used with input 0 */ 76 FLAC__ASSERT(v > 0); 77 #if defined(__INTEL_COMPILER) 78 return _bit_scan_reverse(v) ^ 31U; 79 #elif defined(__GNUC__) && (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)) 80 /* This will translate either to (bsr ^ 31U), clz , ctlz, cntlz, lzcnt depending on 81 * -march= setting or to a software routine in exotic machines. */ 82 return __builtin_clz(v); 83 #elif defined(_MSC_VER) 84 { 85 unsigned long idx; 86 _BitScanReverse(&idx, v); 87 return idx ^ 31U; 88 } 89 #else 90 return FLAC__clz_soft_uint32(v); 91 #endif 92 } 93 94 /* Used when 64-bit bsr/clz is unavailable; can use 32-bit bsr/clz when possible */ 95 static inline unsigned int FLAC__clz_soft_uint64(FLAC__uint64 word) 96 { 97 return (FLAC__uint32)(word>>32) ? FLAC__clz_uint32((FLAC__uint32)(word>>32)) : 98 FLAC__clz_uint32((FLAC__uint32)word) + 32; 99 } 100 101 static inline unsigned int FLAC__clz_uint64(FLAC__uint64 v) 102 { 103 /* Never used with input 0 */ 104 FLAC__ASSERT(v > 0); 105 #if defined(__GNUC__) && (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)) 106 return __builtin_clzll(v); 107 #elif (defined(__INTEL_COMPILER) || defined(_MSC_VER)) && (defined(_M_IA64) || defined(_M_X64)) 108 { 109 unsigned long idx; 110 _BitScanReverse64(&idx, v); 111 return idx ^ 63U; 112 } 113 #else 114 return FLAC__clz_soft_uint64(v); 115 #endif 116 } 117 118 /* These two functions work with input 0 */ 119 static inline unsigned int FLAC__clz2_uint32(FLAC__uint32 v) 120 { 121 if (!v) 122 return 32; 123 return FLAC__clz_uint32(v); 124 } 125 126 static inline unsigned int FLAC__clz2_uint64(FLAC__uint64 v) 127 { 128 if (!v) 129 return 64; 130 return FLAC__clz_uint64(v); 131 } 132 133 /* An example of what FLAC__bitmath_ilog2() computes: 134 * 135 * ilog2( 0) = assertion failure 136 * ilog2( 1) = 0 137 * ilog2( 2) = 1 138 * ilog2( 3) = 1 139 * ilog2( 4) = 2 140 * ilog2( 5) = 2 141 * ilog2( 6) = 2 142 * ilog2( 7) = 2 143 * ilog2( 8) = 3 144 * ilog2( 9) = 3 145 * ilog2(10) = 3 146 * ilog2(11) = 3 147 * ilog2(12) = 3 148 * ilog2(13) = 3 149 * ilog2(14) = 3 150 * ilog2(15) = 3 151 * ilog2(16) = 4 152 * ilog2(17) = 4 153 * ilog2(18) = 4 154 */ 155 156 static inline unsigned FLAC__bitmath_ilog2(FLAC__uint32 v) 157 { 158 FLAC__ASSERT(v > 0); 159 #if defined(__INTEL_COMPILER) 160 return _bit_scan_reverse(v); 161 #elif defined(_MSC_VER) 162 { 163 unsigned long idx; 164 _BitScanReverse(&idx, v); 165 return idx; 166 } 167 #else 168 return FLAC__clz_uint32(v) ^ 31U; 169 #endif 170 } 171 172 static inline unsigned FLAC__bitmath_ilog2_wide(FLAC__uint64 v) 173 { 174 FLAC__ASSERT(v > 0); 175 #if defined(__GNUC__) && (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)) 176 return __builtin_clzll(v) ^ 63U; 177 /* Sorry, only supported in x64/Itanium.. and both have fast FPU which makes integer-only encoder pointless */ 178 #elif (defined(__INTEL_COMPILER) || defined(_MSC_VER)) && (defined(_M_IA64) || defined(_M_X64)) 179 { 180 unsigned long idx; 181 _BitScanReverse64(&idx, v); 182 return idx; 183 } 184 #else 185 /* Brain-damaged compilers will use the fastest possible way that is, 186 de Bruijn sequences (http://supertech.csail.mit.edu/papers/debruijn.pdf) 187 (C) Timothy B. Terriberry (tterribe (at) xiph.org) 2001-2009 CC0 (Public domain). 188 */ 189 { 190 static const unsigned char DEBRUIJN_IDX64[64]={ 191 0, 1, 2, 7, 3,13, 8,19, 4,25,14,28, 9,34,20,40, 192 5,17,26,38,15,46,29,48,10,31,35,54,21,50,41,57, 193 63, 6,12,18,24,27,33,39,16,37,45,47,30,53,49,56, 194 62,11,23,32,36,44,52,55,61,22,43,51,60,42,59,58 195 }; 196 v|= v>>1; 197 v|= v>>2; 198 v|= v>>4; 199 v|= v>>8; 200 v|= v>>16; 201 v|= v>>32; 202 v= (v>>1)+1; 203 return DEBRUIJN_IDX64[v*FLAC__U64L(0x218A392CD3D5DBF)>>58&0x3F]; 204 } 205 #endif 206 } 207 208 unsigned FLAC__bitmath_silog2(FLAC__int64 v); 209 210 #endif 211
