| 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@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 |