diff options
Diffstat (limited to 'libFLAC/include/private/bitmath.h')
| -rw-r--r-- | libFLAC/include/private/bitmath.h | 150 |
1 files changed, 147 insertions, 3 deletions
diff --git a/libFLAC/include/private/bitmath.h b/libFLAC/include/private/bitmath.h index 87fa0fa..22d894f 100644 --- a/libFLAC/include/private/bitmath.h +++ b/libFLAC/include/private/bitmath.h @@ -1,5 +1,6 @@ /* libFLAC - Free Lossless Audio Codec library - * Copyright (C) 2001,2002,2003,2004,2005,2006,2007 Josh Coalson + * 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 @@ -33,9 +34,152 @@ #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_ilog2(FLAC__uint32 v); -unsigned FLAC__bitmath_ilog2_wide(FLAC__uint64 v); unsigned FLAC__bitmath_silog2(int v); unsigned FLAC__bitmath_silog2_wide(FLAC__int64 v); |