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Diffstat (limited to 'media/libtheora/lib/ocintrin.h')
| -rw-r--r-- | media/libtheora/lib/ocintrin.h | 128 |
1 files changed, 128 insertions, 0 deletions
diff --git a/media/libtheora/lib/ocintrin.h b/media/libtheora/lib/ocintrin.h new file mode 100644 index 000000000..d49ebb215 --- /dev/null +++ b/media/libtheora/lib/ocintrin.h @@ -0,0 +1,128 @@ +/******************************************************************** + * * + * THIS FILE IS PART OF THE OggTheora SOFTWARE CODEC SOURCE CODE. * + * USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS * + * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE * + * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING. * + * * + * THE Theora SOURCE CODE IS COPYRIGHT (C) 2002-2009 * + * by the Xiph.Org Foundation and contributors http://www.xiph.org/ * + * * + ******************************************************************** + + function: + last mod: $Id: ocintrin.h 16503 2009-08-22 18:14:02Z giles $ + + ********************************************************************/ + +/*Some common macros for potential platform-specific optimization.*/ +#include <math.h> +#if !defined(_ocintrin_H) +# define _ocintrin_H (1) + +/*Some specific platforms may have optimized intrinsic or inline assembly + versions of these functions which can substantially improve performance. + We define macros for them to allow easy incorporation of these non-ANSI + features.*/ + +/*Note that we do not provide a macro for abs(), because it is provided as a + library function, which we assume is translated into an intrinsic to avoid + the function call overhead and then implemented in the smartest way for the + target platform. + With modern gcc (4.x), this is true: it uses cmov instructions if the + architecture supports it and branchless bit-twiddling if it does not (the + speed difference between the two approaches is not measurable). + Interestingly, the bit-twiddling method was patented in 2000 (US 6,073,150) + by Sun Microsystems, despite prior art dating back to at least 1996: + http://web.archive.org/web/19961201174141/www.x86.org/ftp/articles/pentopt/PENTOPT.TXT + On gcc 3.x, however, our assumption is not true, as abs() is translated to a + conditional jump, which is horrible on deeply piplined architectures (e.g., + all consumer architectures for the past decade or more). + Also be warned that -C*abs(x) where C is a constant is mis-optimized as + abs(C*x) on every gcc release before 4.2.3. + See bug http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34130 */ + +/*Modern gcc (4.x) can compile the naive versions of min and max with cmov if + given an appropriate architecture, but the branchless bit-twiddling versions + are just as fast, and do not require any special target architecture. + Earlier gcc versions (3.x) compiled both code to the same assembly + instructions, because of the way they represented ((_b)>(_a)) internally.*/ +#define OC_MAXI(_a,_b) ((_a)-((_a)-(_b)&-((_b)>(_a)))) +#define OC_MINI(_a,_b) ((_a)+((_b)-(_a)&-((_b)<(_a)))) +/*Clamps an integer into the given range. + If _a>_c, then the lower bound _a is respected over the upper bound _c (this + behavior is required to meet our documented API behavior). + _a: The lower bound. + _b: The value to clamp. + _c: The upper boud.*/ +#define OC_CLAMPI(_a,_b,_c) (OC_MAXI(_a,OC_MINI(_b,_c))) +#define OC_CLAMP255(_x) ((unsigned char)((((_x)<0)-1)&((_x)|-((_x)>255)))) +/*This has a chance of compiling branchless, and is just as fast as the + bit-twiddling method, which is slightly less portable, since it relies on a + sign-extended rightshift, which is not guaranteed by ANSI (but present on + every relevant platform).*/ +#define OC_SIGNI(_a) (((_a)>0)-((_a)<0)) +/*Slightly more portable than relying on a sign-extended right-shift (which is + not guaranteed by ANSI), and just as fast, since gcc (3.x and 4.x both) + compile it into the right-shift anyway.*/ +#define OC_SIGNMASK(_a) (-((_a)<0)) +/*Divides an integer by a power of two, truncating towards 0. + _dividend: The integer to divide. + _shift: The non-negative power of two to divide by. + _rmask: (1<<_shift)-1*/ +#define OC_DIV_POW2(_dividend,_shift,_rmask)\ + ((_dividend)+(OC_SIGNMASK(_dividend)&(_rmask))>>(_shift)) +/*Divides _x by 65536, truncating towards 0.*/ +#define OC_DIV2_16(_x) OC_DIV_POW2(_x,16,0xFFFF) +/*Divides _x by 2, truncating towards 0.*/ +#define OC_DIV2(_x) OC_DIV_POW2(_x,1,0x1) +/*Divides _x by 8, truncating towards 0.*/ +#define OC_DIV8(_x) OC_DIV_POW2(_x,3,0x7) +/*Divides _x by 16, truncating towards 0.*/ +#define OC_DIV16(_x) OC_DIV_POW2(_x,4,0xF) +/*Right shifts _dividend by _shift, adding _rval, and subtracting one for + negative dividends first. + When _rval is (1<<_shift-1), this is equivalent to division with rounding + ties away from zero.*/ +#define OC_DIV_ROUND_POW2(_dividend,_shift,_rval)\ + ((_dividend)+OC_SIGNMASK(_dividend)+(_rval)>>(_shift)) +/*Divides a _x by 2, rounding towards even numbers.*/ +#define OC_DIV2_RE(_x) ((_x)+((_x)>>1&1)>>1) +/*Divides a _x by (1<<(_shift)), rounding towards even numbers.*/ +#define OC_DIV_POW2_RE(_x,_shift) \ + ((_x)+((_x)>>(_shift)&1)+((1<<(_shift))-1>>1)>>(_shift)) +/*Swaps two integers _a and _b if _a>_b.*/ +#define OC_SORT2I(_a,_b) \ + do{ \ + int t__; \ + t__=((_a)^(_b))&-((_b)<(_a)); \ + (_a)^=t__; \ + (_b)^=t__; \ + } \ + while(0) + +/*Accesses one of four (signed) bytes given an index. + This can be used to avoid small lookup tables.*/ +#define OC_BYTE_TABLE32(_a,_b,_c,_d,_i) \ + ((signed char) \ + (((_a)&0xFF|((_b)&0xFF)<<8|((_c)&0xFF)<<16|((_d)&0xFF)<<24)>>(_i)*8)) +/*Accesses one of eight (unsigned) nibbles given an index. + This can be used to avoid small lookup tables.*/ +#define OC_UNIBBLE_TABLE32(_a,_b,_c,_d,_e,_f,_g,_h,_i) \ + ((((_a)&0xF|((_b)&0xF)<<4|((_c)&0xF)<<8|((_d)&0xF)<<12| \ + ((_e)&0xF)<<16|((_f)&0xF)<<20|((_g)&0xF)<<24|((_h)&0xF)<<28)>>(_i)*4)&0xF) + + + +/*All of these macros should expect floats as arguments.*/ +#define OC_MAXF(_a,_b) ((_a)<(_b)?(_b):(_a)) +#define OC_MINF(_a,_b) ((_a)>(_b)?(_b):(_a)) +#define OC_CLAMPF(_a,_b,_c) (OC_MINF(_a,OC_MAXF(_b,_c))) +#define OC_FABSF(_f) ((float)fabs(_f)) +#define OC_SQRTF(_f) ((float)sqrt(_f)) +#define OC_POWF(_b,_e) ((float)pow(_b,_e)) +#define OC_LOGF(_f) ((float)log(_f)) +#define OC_IFLOORF(_f) ((int)floor(_f)) +#define OC_ICEILF(_f) ((int)ceil(_f)) + +#endif |