1 files changed, 67 insertions, 0 deletions
diff --git a/media/ffvpx/libavutil/ffmath.h b/media/ffvpx/libavutil/ffmath.h
new file mode 100644
index 0000000000..aad1347f26
--- /dev/null
+++ b/media/ffvpx/libavutil/ffmath.h
@@ -0,0 +1,67 @@
+/*
+ * copyright (c) 2016 Ganesh Ajjanagadde <gajjanag@gmail.com>
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * internal math functions header
+ */
+
+#ifndef AVUTIL_FFMATH_H
+#define AVUTIL_FFMATH_H
+
+#include "attributes.h"
+#include "libm.h"
+
+/**
+ * Compute 10^x for floating point values. Note: this function is by no means
+ * "correctly rounded", and is meant as a fast, reasonably accurate approximation.
+ * For instance, maximum relative error for the double precision variant is
+ * ~ 1e-13 for very small and very large values.
+ * This is ~2x faster than GNU libm's approach, which is still off by 2ulp on
+ * some inputs.
+ * @param x exponent
+ * @return 10^x
+ */
+static av_always_inline double ff_exp10(double x)
+{
+    return exp2(M_LOG2_10 * x);
+}
+
+static av_always_inline float ff_exp10f(float x)
+{
+    return exp2f(M_LOG2_10 * x);
+}
+
+/**
+ * Compute x^y for floating point x, y. Note: this function is faster than the
+ * libm variant due to mainly 2 reasons:
+ * 1. It does not handle any edge cases. In particular, this is only guaranteed
+ * to work correctly for x > 0.
+ * 2. It is not as accurate as a standard nearly "correctly rounded" libm variant.
+ * @param x base
+ * @param y exponent
+ * @return x^y
+ */
+static av_always_inline float ff_fast_powf(float x, float y)
+{
+    return expf(logf(x) * y);
+}
+
+#endif /* AVUTIL_FFMATH_H */