media/base/vector_math.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef MEDIA_BASE_VECTOR_MATH_H_
   6 #define MEDIA_BASE_VECTOR_MATH_H_
   7
   8 #include <utility>
   9
  10 #include "media/base/media_export.h"
  11
  12 namespace media {
  13 namespace vector_math {
  14
  15 // Required alignment for inputs and outputs to all vector math functions
  16 enum { kRequiredAlignment = 16 };
  17
  18 // Selects runtime specific optimizations such as SSE.  Must be called prior to
  19 // calling FMAC() or FMUL().  Called during media library initialization; most
  20 // users should never have to call this.
  21 MEDIA_EXPORT void Initialize();
  22
  23 // Multiply each element of |src| (up to |len|) by |scale| and add to |dest|.
  24 // |src| and |dest| must be aligned by kRequiredAlignment.
  25 MEDIA_EXPORT void FMAC(const float src[], float scale, int len, float dest[]);
  26
  27 // Multiply each element of |src| by |scale| and store in |dest|.  |src| and
  28 // |dest| must be aligned by kRequiredAlignment.
  29 MEDIA_EXPORT void FMUL(const float src[], float scale, int len, float dest[]);
  30
  31 // Computes the exponentially-weighted moving average power of a signal by
  32 // iterating the recurrence:
  33 //
  34 //   y[-1] = initial_value
  35 //   y[n] = smoothing_factor * src[n]^2 + (1-smoothing_factor) * y[n-1]
  36 //
  37 // Returns the final average power and the maximum squared element value.
  38 MEDIA_EXPORT std::pair<float, float> EWMAAndMaxPower(
  39     float initial_value, const float src[], int len, float smoothing_factor);
  40
  41 }  // namespace vector_math
  42 }  // namespace media
  43
  44 #endif  // MEDIA_BASE_VECTOR_MATH_H_