aboutsummaryrefslogtreecommitdiff
path: root/engines/tinsel/adpcm.cpp
blob: 9de3dff341c278b361ba7c140f72dec8d5144ee9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 */

#include "common/stream.h"
#include "common/util.h"

#include "tinsel/adpcm.h"

namespace Tinsel {

static const double TinselFilterTable[4][2] = {
	{0, 0 },
	{0.9375, 0},
	{1.796875, -0.8125},
	{1.53125, -0.859375}
};

void Tinsel_ADPCMStream::readBufferTinselHeader() {
	uint8 start = _stream->readByte();
	uint8 filterVal = (start & 0xC0) >> 6;

	if ((start & 0x20) != 0) {
		//Lower 6 bit are negative

		// Negate
		start = ~(start | 0xC0) + 1;

		_status.predictor = (unsigned long long int)1 << start;
	} else {
		// Lower 6 bit are positive

		// Truncate
		start &= 0x1F;

		_status.predictor = ((double) 1.0) / ((unsigned long long int)1 << start);
	}

	_status.K0 = TinselFilterTable[filterVal][0];
	_status.K1 = TinselFilterTable[filterVal][1];
}

int16 Tinsel_ADPCMStream::decodeTinsel(int16 code, double eVal) {
	double sample;

	sample = (double)code;
	sample *= eVal * _status.predictor;
	sample += (_status.d0 * _status.K0) + (_status.d1 * _status.K1);

	_status.d1 = _status.d0;
	_status.d0 = sample;

	return (int16) CLIP<double>(sample, -32768.0, 32767.0);
}

int Tinsel4_ADPCMStream::readBuffer(int16 *buffer, const int numSamples) {
	int samples;
	uint16 data;
	const double eVal = 1.142822265;

	samples = 0;

	assert(numSamples % 2 == 0);

	while (samples < numSamples && !_stream->eos() && _stream->pos() < _endpos) {
		if (_blockPos[0] == _blockAlign) {
			readBufferTinselHeader();
			_blockPos[0] = 0;
		}

		for (; samples < numSamples && _blockPos[0] < _blockAlign && !_stream->eos() && _stream->pos() < _endpos; samples += 2, _blockPos[0]++) {
			// Read 1 byte = 8 bits = two 4 bit blocks
			data = _stream->readByte();
			buffer[samples] = decodeTinsel((data << 8) & 0xF000, eVal);
			buffer[samples+1] = decodeTinsel((data << 12) & 0xF000, eVal);
		}
	}

	return samples;
}

int Tinsel6_ADPCMStream::readBuffer(int16 *buffer, const int numSamples) {
	int samples;
	const double eVal = 1.032226562;

	samples = 0;

	while (samples < numSamples && !_stream->eos() && _stream->pos() < _endpos) {
		if (_blockPos[0] == _blockAlign) {
			readBufferTinselHeader();
			_blockPos[0] = 0;
			_chunkPos = 0;
		}

		for (; samples < numSamples && _blockPos[0] < _blockAlign && !_stream->eos() && _stream->pos() < _endpos; samples++, _chunkPos = (_chunkPos + 1) % 4) {

			switch (_chunkPos) {
			case 0:
				_chunkData = _stream->readByte();
				buffer[samples] = decodeTinsel((_chunkData << 8) & 0xFC00, eVal);
				break;
			case 1:
				_chunkData = (_chunkData << 8) | (_stream->readByte());
				buffer[samples] = decodeTinsel((_chunkData << 6) & 0xFC00, eVal);
				_blockPos[0]++;
				break;
			case 2:
				_chunkData = (_chunkData << 8) | (_stream->readByte());
				buffer[samples] = decodeTinsel((_chunkData << 4) & 0xFC00, eVal);
				_blockPos[0]++;
				break;
			case 3:
				_chunkData = (_chunkData << 8);
				buffer[samples] = decodeTinsel((_chunkData << 2) & 0xFC00, eVal);
				_blockPos[0]++;
				break;
			}

		}

	}

	return samples;
}

int Tinsel8_ADPCMStream::readBuffer(int16 *buffer, const int numSamples) {
	int samples;
	byte data;
	const double eVal = 1.007843258;

	samples = 0;

	while (samples < numSamples && !_stream->eos() && _stream->pos() < _endpos) {
		if (_blockPos[0] == _blockAlign) {
			readBufferTinselHeader();
			_blockPos[0] = 0;
		}

		for (; samples < numSamples && _blockPos[0] < _blockAlign && !_stream->eos() && _stream->pos() < _endpos; samples++, _blockPos[0]++) {
			// Read 1 byte = 8 bits = one 8 bit block
			data = _stream->readByte();
			buffer[samples] = decodeTinsel(data << 8, eVal);
		}
	}

	return samples;
}


} // End of namespace Tinsel