93 lines
3.2 KiB
C
93 lines
3.2 KiB
C
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/*
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**
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** Copyright 2009, The Android Open Source Project
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**
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** Licensed under the Apache License, Version 2.0 (the "License");
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** you may not use this file except in compliance with the License.
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** You may obtain a copy of the License at
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**
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** http://www.apache.org/licenses/LICENSE-2.0
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**
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** Unless required by applicable law or agreed to in writing, software
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** distributed under the License is distributed on an "AS IS" BASIS,
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** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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** See the License for the specific language governing permissions and
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** limitations under the License.
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*/
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#ifndef ANDROID_AUDIO_COMMON_H
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#define ANDROID_AUDIO_COMMON_H
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#include <stdint.h>
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#include <stddef.h>
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namespace android {
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// Audio coefficient type.
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typedef int32_t audio_coef_t;
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// Audio sample type.
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typedef int32_t audio_sample_t;
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// Accumulator type for coef x sample.
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typedef int64_t audio_coef_sample_acc_t;
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// Number of fraction bits for audio coefficient.
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static const int AUDIO_COEF_PRECISION = 24;
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// Audio coefficient with the value of 1.0
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static const audio_coef_t AUDIO_COEF_ONE = 1 << AUDIO_COEF_PRECISION;
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// Audio coefficient with the value of 0.5
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static const audio_coef_t AUDIO_COEF_HALF = 1 << (AUDIO_COEF_PRECISION - 1);
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// Number of fraction bits for audio sample.
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static const int AUDIO_SAMPLE_PRECISION = 24;
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// Audio sample with the value of 1.0
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static const audio_sample_t AUDIO_SAMPLE_ONE = 1 << AUDIO_SAMPLE_PRECISION;
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// TODO: These are just temporary naive implementations of the necessary
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// arithmetic operations needed for the filter. They should be moved to a more
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// generic location and implemented more efficiently.
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// Multiply a sample by a coefficient to return an accumulator.
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inline audio_coef_sample_acc_t mul_coef_sample(audio_coef_t x, audio_sample_t y) {
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return ((audio_coef_sample_acc_t) (x)) * y;
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}
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// Multiply and accumulate sample by a coefficient to return an accumulator.
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inline audio_coef_sample_acc_t mac_coef_sample(audio_coef_t x, audio_sample_t y, audio_coef_sample_acc_t acc) {
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return acc + ((audio_coef_sample_acc_t) (x)) * y;
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}
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// Convert a sample-coefficient accumulator to a sample.
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inline audio_sample_t coef_sample_acc_to_sample(audio_coef_sample_acc_t acc) {
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if (acc < 0) {
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acc += AUDIO_COEF_ONE - 1;
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}
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return (audio_sample_t) (acc >> AUDIO_COEF_PRECISION);
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}
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// Convert a S15 sample to audio_sample_t
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inline audio_sample_t s15_to_audio_sample_t(int16_t s15) {
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return audio_sample_t(s15) << 9;
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}
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// Convert a audio_sample_t sample to S15 (no clipping)
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inline int16_t audio_sample_t_to_s15(audio_sample_t sample) {
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return int16_t((sample + (1 << 8)) >> 9);
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}
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// Convert a audio_sample_t sample to S15 (with clipping)
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inline int16_t audio_sample_t_to_s15_clip(audio_sample_t sample) {
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// TODO: optimize for targets supporting this as an atomic operation.
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if (__builtin_expect(sample >= (0x7FFF << 9), 0)) {
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return 0x7FFF;
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} else if (__builtin_expect(sample <= -(0x8000 << 9), 0)) {
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return 0x8000;
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} else {
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return audio_sample_t_to_s15(sample);
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}
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}
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////////////////////////////////////////////////////////////////////////////////
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}
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#endif // ANDROID_AUDIO_COMMON_H
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