diff options
Diffstat (limited to 'media/libeffects/loudness/common/core/math.h')
-rw-r--r-- | media/libeffects/loudness/common/core/math.h | 89 |
1 files changed, 89 insertions, 0 deletions
diff --git a/media/libeffects/loudness/common/core/math.h b/media/libeffects/loudness/common/core/math.h new file mode 100644 index 0000000..3f302cc --- /dev/null +++ b/media/libeffects/loudness/common/core/math.h @@ -0,0 +1,89 @@ +/* + * Copyright (C) 2013 The Android Open Source Project + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +#ifndef LE_FX_ENGINE_COMMON_CORE_MATH_H_ +#define LE_FX_ENGINE_COMMON_CORE_MATH_H_ + +#include <math.h> +#include <algorithm> +using ::std::min; +using ::std::max; +using ::std::fill; +using ::std::fill_n;using ::std::lower_bound; +#include <cmath> +#include <math.h> +//using ::std::fpclassify; + +#include "common/core/os.h" +#include "common/core/types.h" + +namespace le_fx { +namespace math { + +// A fast approximation to log2(.) +inline float fast_log2(float val) { + int* const exp_ptr = reinterpret_cast <int *> (&val); + int x = *exp_ptr; + const int log_2 = ((x >> 23) & 255) - 128; + x &= ~(255 << 23); + x += 127 << 23; + *exp_ptr = x; + val = ((-1.0f / 3) * val + 2) * val - 2.0f / 3; + return static_cast<float>(val + log_2); +} + +// A fast approximation to log(.) +inline float fast_log(float val) { + return fast_log2(val) * + 0.693147180559945286226763982995180413126945495605468750f; +} + +// An approximation of the exp(.) function using a 5-th order Taylor expansion. +// It's pretty accurate between +-0.1 and accurate to 10e-3 between +-1 +template <typename T> +inline T ExpApproximationViaTaylorExpansionOrder5(T x) { + const T x2 = x * x; + const T x3 = x2 * x; + const T x4 = x2 * x2; + const T x5 = x3 * x2; + return 1.0f + x + 0.5f * x2 + + 0.16666666666666665741480812812369549646973609924316406250f * x3 + + 0.0416666666666666643537020320309238741174340248107910156250f * x4 + + 0.008333333333333333217685101601546193705871701240539550781250f * x5; +} + +} // namespace math +} // namespace le_fx + +// Math functions missing in Android NDK: +#if defined(LE_FX_OS_ANDROID) + +namespace std { + +// +// Round to the nearest integer: We need this implementation +// since std::round is missing on android. +// +template <typename T> +inline T round(const T &x) { + return static_cast<T>(std::floor(static_cast<double>(x) + 0.5)); +} + +} // namespace std + +#endif // LE_FX_OS_ANDROID + +#endif // LE_FX_ENGINE_COMMON_CORE_MATH_H_ |