cos / mirrors / cros / chromiumos / third_party / webrtc-apm / refs/heads/stabilize-13020.87.B / . / common_audio / signal_processing / sqrt_of_one_minus_x_squared.c

/* | |

* Copyright (c) 2011 The WebRTC project authors. All Rights Reserved. | |

* | |

* Use of this source code is governed by a BSD-style license | |

* that can be found in the LICENSE file in the root of the source | |

* tree. An additional intellectual property rights grant can be found | |

* in the file PATENTS. All contributing project authors may | |

* be found in the AUTHORS file in the root of the source tree. | |

*/ | |

/* | |

* This file contains the function WebRtcSpl_SqrtOfOneMinusXSquared(). | |

* The description header can be found in signal_processing_library.h | |

* | |

*/ | |

#include "common_audio/signal_processing/include/signal_processing_library.h" | |

void WebRtcSpl_SqrtOfOneMinusXSquared(int16_t *xQ15, size_t vector_length, | |

int16_t *yQ15) | |

{ | |

int32_t sq; | |

size_t m; | |

int16_t tmp; | |

for (m = 0; m < vector_length; m++) | |

{ | |

tmp = xQ15[m]; | |

sq = tmp * tmp; // x^2 in Q30 | |

sq = 1073741823 - sq; // 1-x^2, where 1 ~= 0.99999999906 is 1073741823 in Q30 | |

sq = WebRtcSpl_Sqrt(sq); // sqrt(1-x^2) in Q15 | |

yQ15[m] = (int16_t)sq; | |

} | |

} |