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