1/*
2 * Copyrightm (C) 2010 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#include "AudioCodec.h"
18
19namespace {
20
21const int8_t gExponents[128] = {
22    0, 1, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4,
23    5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,
24    6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
25    6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
26    7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
27    7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
28    7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
29    7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
30};
31
32//------------------------------------------------------------------------------
33
34class UlawCodec : public AudioCodec
35{
36public:
37    int set(int sampleRate, const char *fmtp) {
38        mSampleCount = sampleRate / 50;
39        return mSampleCount;
40    }
41    int encode(void *payload, int16_t *samples);
42    int decode(int16_t *samples, int count, void *payload, int length);
43private:
44    int mSampleCount;
45};
46
47int UlawCodec::encode(void *payload, int16_t *samples)
48{
49    int8_t *ulaws = (int8_t *)payload;
50    for (int i = 0; i < mSampleCount; ++i) {
51        int sample = samples[i];
52        int sign = (sample >> 8) & 0x80;
53        if (sample < 0) {
54            sample = -sample;
55        }
56        sample += 132;
57        if (sample > 32767) {
58            sample = 32767;
59        }
60        int exponent = gExponents[sample >> 8];
61        int mantissa = (sample >> (exponent + 3)) & 0x0F;
62        ulaws[i] = ~(sign | (exponent << 4) | mantissa);
63    }
64    return mSampleCount;
65}
66
67int UlawCodec::decode(int16_t *samples, int count, void *payload, int length)
68{
69    int8_t *ulaws = (int8_t *)payload;
70    if (length > count) {
71        length = count;
72    }
73    for (int i = 0; i < length; ++i) {
74        int ulaw = ~ulaws[i];
75        int exponent = (ulaw >> 4) & 0x07;
76        int mantissa = ulaw & 0x0F;
77        int sample = (((mantissa << 3) + 132) << exponent) - 132;
78        samples[i] = (ulaw < 0 ? -sample : sample);
79    }
80    return length;
81}
82
83//------------------------------------------------------------------------------
84
85class AlawCodec : public AudioCodec
86{
87public:
88    int set(int sampleRate, const char *fmtp) {
89        mSampleCount = sampleRate / 50;
90        return mSampleCount;
91    }
92    int encode(void *payload, int16_t *samples);
93    int decode(int16_t *samples, int count, void *payload, int length);
94private:
95    int mSampleCount;
96};
97
98int AlawCodec::encode(void *payload, int16_t *samples)
99{
100    int8_t *alaws = (int8_t *)payload;
101    for (int i = 0; i < mSampleCount; ++i) {
102        int sample = samples[i];
103        int sign = (sample >> 8) & 0x80;
104        if (sample < 0) {
105            sample = -sample;
106        }
107        if (sample > 32767) {
108            sample = 32767;
109        }
110        int exponent = gExponents[sample >> 8];
111        int mantissa = (sample >> (exponent == 0 ? 4 : exponent + 3)) & 0x0F;
112        alaws[i] = (sign | (exponent << 4) | mantissa) ^ 0xD5;
113    }
114    return mSampleCount;
115}
116
117int AlawCodec::decode(int16_t *samples, int count, void *payload, int length)
118{
119    int8_t *alaws = (int8_t *)payload;
120    if (length > count) {
121        length = count;
122    }
123    for (int i = 0; i < length; ++i) {
124        int alaw = alaws[i] ^ 0x55;
125        int exponent = (alaw >> 4) & 0x07;
126        int mantissa = alaw & 0x0F;
127        int sample = (exponent == 0 ? (mantissa << 4) + 8 :
128            ((mantissa << 3) + 132) << exponent);
129        samples[i] = (alaw < 0 ? sample : -sample);
130    }
131    return length;
132}
133
134} // namespace
135
136AudioCodec *newUlawCodec()
137{
138    return new UlawCodec;
139}
140
141AudioCodec *newAlawCodec()
142{
143    return new AlawCodec;
144}
145