summaryrefslogtreecommitdiffstats
path: root/sound/core/oss/rate.c
blob: 66f1dbe492cfb5eed0a9a8f1e708bf3c2b2d1145 (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
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
/*
 *  Rate conversion Plug-In
 *  Copyright (c) 1999 by Jaroslav Kysela <perex@suse.cz>
 *
 *
 *   This library is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Library 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 Library General Public License for more details.
 *
 *   You should have received a copy of the GNU Library General Public
 *   License along with this library; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *
 */
  
#include <sound/driver.h>
#include <linux/time.h>
#include <sound/core.h>
#include <sound/pcm.h>
#include "pcm_plugin.h"

#define SHIFT	11
#define BITS	(1<<SHIFT)
#define R_MASK	(BITS-1)

/*
 *  Basic rate conversion plugin
 */

struct rate_channel {
	signed short last_S1;
	signed short last_S2;
};
 
typedef void (*rate_f)(struct snd_pcm_plugin *plugin,
		       const struct snd_pcm_plugin_channel *src_channels,
		       struct snd_pcm_plugin_channel *dst_channels,
		       int src_frames, int dst_frames);

struct rate_priv {
	unsigned int pitch;
	unsigned int pos;
	rate_f func;
	snd_pcm_sframes_t old_src_frames, old_dst_frames;
	struct rate_channel channels[0];
};

static void rate_init(struct snd_pcm_plugin *plugin)
{
	unsigned int channel;
	struct rate_priv *data = (struct rate_priv *)plugin->extra_data;
	data->pos = 0;
	for (channel = 0; channel < plugin->src_format.channels; channel++) {
		data->channels[channel].last_S1 = 0;
		data->channels[channel].last_S2 = 0;
	}
}

static void resample_expand(struct snd_pcm_plugin *plugin,
			    const struct snd_pcm_plugin_channel *src_channels,
			    struct snd_pcm_plugin_channel *dst_channels,
			    int src_frames, int dst_frames)
{
	unsigned int pos = 0;
	signed int val;
	signed short S1, S2;
	signed short *src, *dst;
	unsigned int channel;
	int src_step, dst_step;
	int src_frames1, dst_frames1;
	struct rate_priv *data = (struct rate_priv *)plugin->extra_data;
	struct rate_channel *rchannels = data->channels;
	
	for (channel = 0; channel < plugin->src_format.channels; channel++) {
		pos = data->pos;
		S1 = rchannels->last_S1;
		S2 = rchannels->last_S2;
		if (!src_channels[channel].enabled) {
			if (dst_channels[channel].wanted)
				snd_pcm_area_silence(&dst_channels[channel].area, 0, dst_frames, plugin->dst_format.format);
			dst_channels[channel].enabled = 0;
			continue;
		}
		dst_channels[channel].enabled = 1;
		src = (signed short *)src_channels[channel].area.addr +
			src_channels[channel].area.first / 8 / 2;
		dst = (signed short *)dst_channels[channel].area.addr +
			dst_channels[channel].area.first / 8 / 2;
		src_step = src_channels[channel].area.step / 8 / 2;
		dst_step = dst_channels[channel].area.step / 8 / 2;
		src_frames1 = src_frames;
		dst_frames1 = dst_frames;
		while (dst_frames1-- > 0) {
			if (pos & ~R_MASK) {
				pos &= R_MASK;
				S1 = S2;
				if (src_frames1-- > 0) {
					S2 = *src;
					src += src_step;
				}
			}
			val = S1 + ((S2 - S1) * (signed int)pos) / BITS;
			if (val < -32768)
				val = -32768;
			else if (val > 32767)
				val = 32767;
			*dst = val;
			dst += dst_step;
			pos += data->pitch;
		}
		rchannels->last_S1 = S1;
		rchannels->last_S2 = S2;
		rchannels++;
	}
	data->pos = pos;
}

static void resample_shrink(struct snd_pcm_plugin *plugin,
			    const struct snd_pcm_plugin_channel *src_channels,
			    struct snd_pcm_plugin_channel *dst_channels,
			    int src_frames, int dst_frames)
{
	unsigned int pos = 0;
	signed int val;
	signed short S1, S2;
	signed short *src, *dst;
	unsigned int channel;
	int src_step, dst_step;
	int src_frames1, dst_frames1;
	struct rate_priv *data = (struct rate_priv *)plugin->extra_data;
	struct rate_channel *rchannels = data->channels;

	for (channel = 0; channel < plugin->src_format.channels; ++channel) {
		pos = data->pos;
		S1 = rchannels->last_S1;
		S2 = rchannels->last_S2;
		if (!src_channels[channel].enabled) {
			if (dst_channels[channel].wanted)
				snd_pcm_area_silence(&dst_channels[channel].area, 0, dst_frames, plugin->dst_format.format);
			dst_channels[channel].enabled = 0;
			continue;
		}
		dst_channels[channel].enabled = 1;
		src = (signed short *)src_channels[channel].area.addr +
			src_channels[channel].area.first / 8 / 2;
		dst = (signed short *)dst_channels[channel].area.addr +
			dst_channels[channel].area.first / 8 / 2;
		src_step = src_channels[channel].area.step / 8 / 2;
		dst_step = dst_channels[channel].area.step / 8 / 2;
		src_frames1 = src_frames;
		dst_frames1 = dst_frames;
		while (dst_frames1 > 0) {
			S1 = S2;
			if (src_frames1-- > 0) {
				S1 = *src;
				src += src_step;
			}
			if (pos & ~R_MASK) {
				pos &= R_MASK;
				val = S1 + ((S2 - S1) * (signed int)pos) / BITS;
				if (val < -32768)
					val = -32768;
				else if (val > 32767)
					val = 32767;
				*dst = val;
				dst += dst_step;
				dst_frames1--;
			}
			pos += data->pitch;
		}
		rchannels->last_S1 = S1;
		rchannels->last_S2 = S2;
		rchannels++;
	}
	data->pos = pos;
}

static snd_pcm_sframes_t rate_src_frames(struct snd_pcm_plugin *plugin, snd_pcm_uframes_t frames)
{
	struct rate_priv *data;
	snd_pcm_sframes_t res;

	snd_assert(plugin != NULL, return -ENXIO);
	if (frames == 0)
		return 0;
	data = (struct rate_priv *)plugin->extra_data;
	if (plugin->src_format.rate < plugin->dst_format.rate) {
		res = (((frames * data->pitch) + (BITS/2)) >> SHIFT);
	} else {
		res = (((frames << SHIFT) + (data->pitch / 2)) / data->pitch);		
	}
	if (data->old_src_frames > 0) {
		snd_pcm_sframes_t frames1 = frames, res1 = data->old_dst_frames;
		while (data->old_src_frames < frames1) {
			frames1 >>= 1;
			res1 <<= 1;
		}
		while (data->old_src_frames > frames1) {
			frames1 <<= 1;
			res1 >>= 1;
		}
		if (data->old_src_frames == frames1)
			return res1;
	}
	data->old_src_frames = frames;
	data->old_dst_frames = res;
	return res;
}

static snd_pcm_sframes_t rate_dst_frames(struct snd_pcm_plugin *plugin, snd_pcm_uframes_t frames)
{
	struct rate_priv *data;
	snd_pcm_sframes_t res;

	snd_assert(plugin != NULL, return -ENXIO);
	if (frames == 0)
		return 0;
	data = (struct rate_priv *)plugin->extra_data;
	if (plugin->src_format.rate < plugin->dst_format.rate) {
		res = (((frames << SHIFT) + (data->pitch / 2)) / data->pitch);
	} else {
		res = (((frames * data->pitch) + (BITS/2)) >> SHIFT);
	}
	if (data->old_dst_frames > 0) {
		snd_pcm_sframes_t frames1 = frames, res1 = data->old_src_frames;
		while (data->old_dst_frames < frames1) {
			frames1 >>= 1;
			res1 <<= 1;
		}
		while (data->old_dst_frames > frames1) {
			frames1 <<= 1;
			res1 >>= 1;
		}
		if (data->old_dst_frames == frames1)
			return res1;
	}
	data->old_dst_frames = frames;
	data->old_src_frames = res;
	return res;
}

static snd_pcm_sframes_t rate_transfer(struct snd_pcm_plugin *plugin,
			     const struct snd_pcm_plugin_channel *src_channels,
			     struct snd_pcm_plugin_channel *dst_channels,
			     snd_pcm_uframes_t frames)
{
	snd_pcm_uframes_t dst_frames;
	struct rate_priv *data;

	snd_assert(plugin != NULL && src_channels != NULL && dst_channels != NULL, return -ENXIO);
	if (frames == 0)
		return 0;
#ifdef CONFIG_SND_DEBUG
	{
		unsigned int channel;
		for (channel = 0; channel < plugin->src_format.channels; channel++) {
			snd_assert(src_channels[channel].area.first % 8 == 0 &&
				   src_channels[channel].area.step % 8 == 0,
				   return -ENXIO);
			snd_assert(dst_channels[channel].area.first % 8 == 0 &&
				   dst_channels[channel].area.step % 8 == 0,
				   return -ENXIO);
		}
	}
#endif

	dst_frames = rate_dst_frames(plugin, frames);
	if (dst_frames > dst_channels[0].frames)
		dst_frames = dst_channels[0].frames;
	data = (struct rate_priv *)plugin->extra_data;
	data->func(plugin, src_channels, dst_channels, frames, dst_frames);
	return dst_frames;
}

static int rate_action(struct snd_pcm_plugin *plugin,
		       enum snd_pcm_plugin_action action,
		       unsigned long udata)
{
	snd_assert(plugin != NULL, return -ENXIO);
	switch (action) {
	case INIT:
	case PREPARE:
		rate_init(plugin);
		break;
	default:
		break;
	}
	return 0;	/* silenty ignore other actions */
}

int snd_pcm_plugin_build_rate(struct snd_pcm_substream *plug,
			      struct snd_pcm_plugin_format *src_format,
			      struct snd_pcm_plugin_format *dst_format,
			      struct snd_pcm_plugin **r_plugin)
{
	int err;
	struct rate_priv *data;
	struct snd_pcm_plugin *plugin;

	snd_assert(r_plugin != NULL, return -ENXIO);
	*r_plugin = NULL;

	snd_assert(src_format->channels == dst_format->channels, return -ENXIO);
	snd_assert(src_format->channels > 0, return -ENXIO);
	snd_assert(src_format->format == SNDRV_PCM_FORMAT_S16, return -ENXIO);
	snd_assert(dst_format->format == SNDRV_PCM_FORMAT_S16, return -ENXIO);
	snd_assert(src_format->rate != dst_format->rate, return -ENXIO);

	err = snd_pcm_plugin_build(plug, "rate conversion",
				   src_format, dst_format,
				   sizeof(struct rate_priv) +
				   src_format->channels * sizeof(struct rate_channel),
				   &plugin);
	if (err < 0)
		return err;
	data = (struct rate_priv *)plugin->extra_data;
	if (src_format->rate < dst_format->rate) {
		data->pitch = ((src_format->rate << SHIFT) + (dst_format->rate >> 1)) / dst_format->rate;
		data->func = resample_expand;
	} else {
		data->pitch = ((dst_format->rate << SHIFT) + (src_format->rate >> 1)) / src_format->rate;
		data->func = resample_shrink;
	}
	data->pos = 0;
	rate_init(plugin);
	data->old_src_frames = data->old_dst_frames = 0;
	plugin->transfer = rate_transfer;
	plugin->src_frames = rate_src_frames;
	plugin->dst_frames = rate_dst_frames;
	plugin->action = rate_action;
	*r_plugin = plugin;
	return 0;
}