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67 lines
2.0 KiB
67 lines
2.0 KiB
/* |
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* copyright (c) 2016 Ganesh Ajjanagadde <gajjanag@gmail.com> |
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* |
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* This file is part of FFmpeg. |
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* |
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* FFmpeg is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU Lesser General Public |
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* License as published by the Free Software Foundation; either |
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* version 2.1 of the License, or (at your option) any later version. |
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* |
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* FFmpeg is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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* Lesser General Public License for more details. |
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* |
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* You should have received a copy of the GNU Lesser General Public |
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* License along with FFmpeg; if not, write to the Free Software |
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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*/ |
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/** |
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* @file |
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* internal math functions header |
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*/ |
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#ifndef AVUTIL_FFMATH_H |
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#define AVUTIL_FFMATH_H |
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#include "attributes.h" |
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#include "libm.h" |
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/** |
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* Compute 10^x for floating point values. Note: this function is by no means |
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* "correctly rounded", and is meant as a fast, reasonably accurate approximation. |
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* For instance, maximum relative error for the double precision variant is |
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* ~ 1e-13 for very small and very large values. |
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* This is ~2x faster than GNU libm's approach, which is still off by 2ulp on |
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* some inputs. |
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* @param x exponent |
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* @return 10^x |
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*/ |
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static av_always_inline double ff_exp10(double x) |
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{ |
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return exp2(M_LOG2_10 * x); |
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} |
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static av_always_inline float ff_exp10f(float x) |
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{ |
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return exp2f(M_LOG2_10 * x); |
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} |
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/** |
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* Compute x^y for floating point x, y. Note: this function is faster than the |
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* libm variant due to mainly 2 reasons: |
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* 1. It does not handle any edge cases. In particular, this is only guaranteed |
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* to work correctly for x > 0. |
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* 2. It is not as accurate as a standard nearly "correctly rounded" libm variant. |
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* @param x base |
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* @param y exponent |
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* @return x^y |
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*/ |
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static av_always_inline float ff_fast_powf(float x, float y) |
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{ |
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return expf(logf(x) * y); |
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} |
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#endif /* AVUTIL_FFMATH_H */
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