14a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project/*---------------------------------------------------------------------------* 24a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project * filter.h * 34a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project * * 44a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project * Copyright 2007, 2008 Nuance Communciations, Inc. * 54a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project * * 64a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project * Licensed under the Apache License, Version 2.0 (the 'License'); * 74a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project * you may not use this file except in compliance with the License. * 84a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project * * 94a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project * You may obtain a copy of the License at * 104a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project * http://www.apache.org/licenses/LICENSE-2.0 * 114a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project * * 124a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project * Unless required by applicable law or agreed to in writing, software * 134a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project * distributed under the License is distributed on an 'AS IS' BASIS, * 144a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * 154a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project * See the License for the specific language governing permissions and * 164a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project * limitations under the License. * 174a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project * * 184a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project *---------------------------------------------------------------------------*/ 194a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project 204a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project#ifndef __FILTER_H__ 214a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project#define __FILTER_H__ 224a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project 234a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project// Define new data types 244a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project 254a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Projecttypedef short typeSample; // for input and output samples 264a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Projecttypedef short typeCoeff; // FIR filter coefficients 274a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Projecttypedef long typeAccum; // FIR filter accumulator 284a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project 294a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project#define FACTOR_UP 1 // upsampling factor 304a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project#define FACTOR_DOWN 4 // downsampling factor 314a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project 324a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project#define u16ScaleFilterCoeff_up1_down4 15 334a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project 344a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Projecttypedef struct fir_struct 354a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project{ 364a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project int state; // state of FIR delay line (index of next slot to fill) 374a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project typeSample *z; // pointer to delay line 384a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project 394a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project unsigned int factor_up; 404a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project unsigned int factor_down; 414a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project 424a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project unsigned int nTaps; // length of FIR filter 434a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project unsigned int scale; // fixed-point filter scale factor 444a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project const typeCoeff *h; // pointer to FIR filter coefficients 454a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project typeAccum round; // used for roundoff 464a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project} FIR_struct; 474a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project 484a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Projectextern const typeCoeff ps16FilterCoeff_up1_down4[]; 494a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project 504a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Projectextern unsigned int filter_length; 514a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project 524a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Projectextern void FIR_downsample(unsigned int nInput, typeSample *pInput, 534a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project typeSample *pOutput, FIR_struct *pFIR); 544a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project 554a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Projectextern FIR_struct* FIR_construct(unsigned int nTaps, const typeCoeff *pCoeffs, int scale, int factor_up, int factor_down); 564a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project 574a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Projectextern int FIR_deconstruct(FIR_struct *pFIR); 584a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project 594a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Projectextern void FIR_reset(FIR_struct *pFIR); 604a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project 614a68b3365c8c50aa93505e99ead2565ab73dcdb0The Android Open Source Project#endif 62