1/*
2 * Copyright (C) 2007 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef ANDROID_AUDIO_RESAMPLER_CUBIC_H
18#define ANDROID_AUDIO_RESAMPLER_CUBIC_H
19
20#include <stdint.h>
21#include <sys/types.h>
22#include <cutils/log.h>
23
24#include "AudioResampler.h"
25
26namespace android {
27// ----------------------------------------------------------------------------
28
29class AudioResamplerCubic : public AudioResampler {
30public:
31    AudioResamplerCubic(int inChannelCount, int32_t sampleRate) :
32        AudioResampler(inChannelCount, sampleRate, MED_QUALITY) {
33    }
34    virtual void resample(int32_t* out, size_t outFrameCount,
35            AudioBufferProvider* provider);
36private:
37    // number of bits used in interpolation multiply - 14 bits avoids overflow
38    static const int kNumInterpBits = 14;
39
40    // bits to shift the phase fraction down to avoid overflow
41    static const int kPreInterpShift = kNumPhaseBits - kNumInterpBits;
42    typedef struct {
43        int32_t a, b, c, y0, y1, y2, y3;
44    } state;
45    void init();
46    void resampleMono16(int32_t* out, size_t outFrameCount,
47            AudioBufferProvider* provider);
48    void resampleStereo16(int32_t* out, size_t outFrameCount,
49            AudioBufferProvider* provider);
50    static inline int32_t interp(state* p, int32_t x) {
51        return (((((p->a * x >> 14) + p->b) * x >> 14) + p->c) * x >> 14) + p->y1;
52    }
53    static inline void advance(state* p, int16_t in) {
54        p->y0 = p->y1;
55        p->y1 = p->y2;
56        p->y2 = p->y3;
57        p->y3 = in;
58        p->a = (3 * (p->y1 - p->y2) - p->y0 + p->y3) >> 1;
59        p->b = (p->y2 << 1) + p->y0 - (((5 * p->y1 + p->y3)) >> 1);
60        p->c = (p->y2 - p->y0) >> 1;
61    }
62    state left, right;
63};
64
65// ----------------------------------------------------------------------------
66}; // namespace android
67
68#endif /*ANDROID_AUDIO_RESAMPLER_CUBIC_H*/
69