ref: 40d6302b5f289ad8a617d12fa911197dddafc634
dir: /sys/src/cmd/audio/libFLAC/private/bitmath.h/
/* libFLAC - Free Lossless Audio Codec library * Copyright (C) 2001-2009 Josh Coalson * Copyright (C) 2011-2014 Xiph.Org Foundation * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * - Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * - Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * - Neither the name of the Xiph.org Foundation nor the names of its * contributors may be used to endorse or promote products derived from * this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #ifndef FLAC__PRIVATE__BITMATH_H #define FLAC__PRIVATE__BITMATH_H #include "FLAC/ordinals.h" #include "FLAC/assert.h" /* for CHAR_BIT */ #include <limits.h> #include "share/compat.h" #if defined(_MSC_VER) && (_MSC_VER >= 1400) #include <intrin.h> /* for _BitScanReverse* */ #endif /* Will never be emitted for MSVC, GCC, Intel compilers */ static inline unsigned int FLAC__clz_soft_uint32(unsigned int word) { static const unsigned char byte_to_unary_table[] = { 8, 7, 6, 6, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, }; return (word) > 0xffffff ? byte_to_unary_table[(word) >> 24] : (word) > 0xffff ? byte_to_unary_table[(word) >> 16] + 8 : (word) > 0xff ? byte_to_unary_table[(word) >> 8] + 16 : byte_to_unary_table[(word)] + 24; } static inline unsigned int FLAC__clz_uint32(FLAC__uint32 v) { /* Never used with input 0 */ FLAC__ASSERT(v > 0); #if defined(__INTEL_COMPILER) return _bit_scan_reverse(v) ^ 31U; #elif defined(__GNUC__) && (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)) /* This will translate either to (bsr ^ 31U), clz , ctlz, cntlz, lzcnt depending on * -march= setting or to a software routine in exotic machines. */ return __builtin_clz(v); #elif defined(_MSC_VER) && (_MSC_VER >= 1400) { unsigned long idx; _BitScanReverse(&idx, v); return idx ^ 31U; } #else return FLAC__clz_soft_uint32(v); #endif } /* This one works with input 0 */ static inline unsigned int FLAC__clz2_uint32(FLAC__uint32 v) { if (!v) return 32; return FLAC__clz_uint32(v); } /* An example of what FLAC__bitmath_ilog2() computes: * * ilog2( 0) = assertion failure * ilog2( 1) = 0 * ilog2( 2) = 1 * ilog2( 3) = 1 * ilog2( 4) = 2 * ilog2( 5) = 2 * ilog2( 6) = 2 * ilog2( 7) = 2 * ilog2( 8) = 3 * ilog2( 9) = 3 * ilog2(10) = 3 * ilog2(11) = 3 * ilog2(12) = 3 * ilog2(13) = 3 * ilog2(14) = 3 * ilog2(15) = 3 * ilog2(16) = 4 * ilog2(17) = 4 * ilog2(18) = 4 */ static inline unsigned FLAC__bitmath_ilog2(FLAC__uint32 v) { FLAC__ASSERT(v > 0); #if defined(__INTEL_COMPILER) return _bit_scan_reverse(v); #elif defined(_MSC_VER) && (_MSC_VER >= 1400) { unsigned long idx; _BitScanReverse(&idx, v); return idx; } #else return sizeof(FLAC__uint32) * CHAR_BIT - 1 - FLAC__clz_uint32(v); #endif } #ifdef FLAC__INTEGER_ONLY_LIBRARY /* Unused otherwise */ static inline unsigned FLAC__bitmath_ilog2_wide(FLAC__uint64 v) { FLAC__ASSERT(v > 0); #if defined(__GNUC__) && (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)) return sizeof(FLAC__uint64) * CHAR_BIT - 1 - __builtin_clzll(v); /* Sorry, only supported in x64/Itanium.. and both have fast FPU which makes integer-only encoder pointless */ #elif (defined(_MSC_VER) && (_MSC_VER >= 1400)) && (defined(_M_IA64) || defined(_M_X64)) { unsigned long idx; _BitScanReverse64(&idx, v); return idx; } #else /* Brain-damaged compilers will use the fastest possible way that is, de Bruijn sequences (http://supertech.csail.mit.edu/papers/debruijn.pdf) (C) Timothy B. Terriberry ([email protected]) 2001-2009 CC0 (Public domain). */ { static const unsigned char DEBRUIJN_IDX64[64]={ 0, 1, 2, 7, 3,13, 8,19, 4,25,14,28, 9,34,20,40, 5,17,26,38,15,46,29,48,10,31,35,54,21,50,41,57, 63, 6,12,18,24,27,33,39,16,37,45,47,30,53,49,56, 62,11,23,32,36,44,52,55,61,22,43,51,60,42,59,58 }; v|= v>>1; v|= v>>2; v|= v>>4; v|= v>>8; v|= v>>16; v|= v>>32; v= (v>>1)+1; return DEBRUIJN_IDX64[v*0x218A392CD3D5DBF>>58&0x3F]; } #endif } #endif unsigned FLAC__bitmath_silog2(int v); unsigned FLAC__bitmath_silog2_wide(FLAC__int64 v); #endif