LCOV - code coverage report
Current view: top level - src/libavutil - ffmath.h (source / functions) Hit Total Coverage
Test: coverage.info Lines: 4 4 100.0 %
Date: 2017-01-21 09:32:20 Functions: 2 2 100.0 %

          Line data    Source code
       1             : /*
       2             :  * copyright (c) 2016 Ganesh Ajjanagadde <gajjanag@gmail.com>
       3             :  *
       4             :  * This file is part of FFmpeg.
       5             :  *
       6             :  * FFmpeg is free software; you can redistribute it and/or
       7             :  * modify it under the terms of the GNU Lesser General Public
       8             :  * License as published by the Free Software Foundation; either
       9             :  * version 2.1 of the License, or (at your option) any later version.
      10             :  *
      11             :  * FFmpeg is distributed in the hope that it will be useful,
      12             :  * but WITHOUT ANY WARRANTY; without even the implied warranty of
      13             :  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      14             :  * Lesser General Public License for more details.
      15             :  *
      16             :  * You should have received a copy of the GNU Lesser General Public
      17             :  * License along with FFmpeg; if not, write to the Free Software
      18             :  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
      19             :  */
      20             : 
      21             : /**
      22             :  * @file
      23             :  * internal math functions header
      24             :  */
      25             : 
      26             : #ifndef AVUTIL_FFMATH_H
      27             : #define AVUTIL_FFMATH_H
      28             : 
      29             : #include "attributes.h"
      30             : #include "libm.h"
      31             : 
      32             : /**
      33             :  * Compute 10^x for floating point values. Note: this function is by no means
      34             :  * "correctly rounded", and is meant as a fast, reasonably accurate approximation.
      35             :  * For instance, maximum relative error for the double precision variant is
      36             :  * ~ 1e-13 for very small and very large values.
      37             :  * This is ~2x faster than GNU libm's approach, which is still off by 2ulp on
      38             :  * some inputs.
      39             :  * @param x exponent
      40             :  * @return 10^x
      41             :  */
      42      266390 : static av_always_inline double ff_exp10(double x)
      43             : {
      44      266390 :     return exp2(M_LOG2_10 * x);
      45             : }
      46             : 
      47             : static av_always_inline float ff_exp10f(float x)
      48             : {
      49             :     return exp2f(M_LOG2_10 * x);
      50             : }
      51             : 
      52             : /**
      53             :  * Compute x^y for floating point x, y. Note: this function is faster than the
      54             :  * libm variant due to mainly 2 reasons:
      55             :  * 1. It does not handle any edge cases. In particular, this is only guaranteed
      56             :  * to work correctly for x > 0.
      57             :  * 2. It is not as accurate as a standard nearly "correctly rounded" libm variant.
      58             :  * @param x base
      59             :  * @param y exponent
      60             :  * @return x^y
      61             :  */
      62     9356218 : static av_always_inline float ff_fast_powf(float x, float y)
      63             : {
      64     9356218 :     return expf(logf(x) * y);
      65             : }
      66             : 
      67             : #endif /* AVUTIL_FFMATH_H */

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