ref: 3a77c01f43821dcc4f7cae54aff89bb20f2d95a5
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 (tterribe@xiph.org) 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