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Linux/sound/core/oss/rate.c

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  1 /*
  2  *  Rate conversion Plug-In
  3  *  Copyright (c) 1999 by Jaroslav Kysela <perex@perex.cz>
  4  *
  5  *
  6  *   This library is free software; you can redistribute it and/or modify
  7  *   it under the terms of the GNU Library General Public License as
  8  *   published by the Free Software Foundation; either version 2 of
  9  *   the License, or (at your option) any later version.
 10  *
 11  *   This program is distributed in the hope that it will be useful,
 12  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 13  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 14  *   GNU Library General Public License for more details.
 15  *
 16  *   You should have received a copy of the GNU Library General Public
 17  *   License along with this library; if not, write to the Free Software
 18  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 19  *
 20  */
 21   
 22 #include <linux/time.h>
 23 #include <sound/core.h>
 24 #include <sound/pcm.h>
 25 #include "pcm_plugin.h"
 26 
 27 #define SHIFT   11
 28 #define BITS    (1<<SHIFT)
 29 #define R_MASK  (BITS-1)
 30 
 31 /*
 32  *  Basic rate conversion plugin
 33  */
 34 
 35 struct rate_channel {
 36         signed short last_S1;
 37         signed short last_S2;
 38 };
 39  
 40 typedef void (*rate_f)(struct snd_pcm_plugin *plugin,
 41                        const struct snd_pcm_plugin_channel *src_channels,
 42                        struct snd_pcm_plugin_channel *dst_channels,
 43                        int src_frames, int dst_frames);
 44 
 45 struct rate_priv {
 46         unsigned int pitch;
 47         unsigned int pos;
 48         rate_f func;
 49         snd_pcm_sframes_t old_src_frames, old_dst_frames;
 50         struct rate_channel channels[0];
 51 };
 52 
 53 static void rate_init(struct snd_pcm_plugin *plugin)
 54 {
 55         unsigned int channel;
 56         struct rate_priv *data = (struct rate_priv *)plugin->extra_data;
 57         data->pos = 0;
 58         for (channel = 0; channel < plugin->src_format.channels; channel++) {
 59                 data->channels[channel].last_S1 = 0;
 60                 data->channels[channel].last_S2 = 0;
 61         }
 62 }
 63 
 64 static void resample_expand(struct snd_pcm_plugin *plugin,
 65                             const struct snd_pcm_plugin_channel *src_channels,
 66                             struct snd_pcm_plugin_channel *dst_channels,
 67                             int src_frames, int dst_frames)
 68 {
 69         unsigned int pos = 0;
 70         signed int val;
 71         signed short S1, S2;
 72         signed short *src, *dst;
 73         unsigned int channel;
 74         int src_step, dst_step;
 75         int src_frames1, dst_frames1;
 76         struct rate_priv *data = (struct rate_priv *)plugin->extra_data;
 77         struct rate_channel *rchannels = data->channels;
 78         
 79         for (channel = 0; channel < plugin->src_format.channels; channel++) {
 80                 pos = data->pos;
 81                 S1 = rchannels->last_S1;
 82                 S2 = rchannels->last_S2;
 83                 if (!src_channels[channel].enabled) {
 84                         if (dst_channels[channel].wanted)
 85                                 snd_pcm_area_silence(&dst_channels[channel].area, 0, dst_frames, plugin->dst_format.format);
 86                         dst_channels[channel].enabled = 0;
 87                         continue;
 88                 }
 89                 dst_channels[channel].enabled = 1;
 90                 src = (signed short *)src_channels[channel].area.addr +
 91                         src_channels[channel].area.first / 8 / 2;
 92                 dst = (signed short *)dst_channels[channel].area.addr +
 93                         dst_channels[channel].area.first / 8 / 2;
 94                 src_step = src_channels[channel].area.step / 8 / 2;
 95                 dst_step = dst_channels[channel].area.step / 8 / 2;
 96                 src_frames1 = src_frames;
 97                 dst_frames1 = dst_frames;
 98                 while (dst_frames1-- > 0) {
 99                         if (pos & ~R_MASK) {
100                                 pos &= R_MASK;
101                                 S1 = S2;
102                                 if (src_frames1-- > 0) {
103                                         S2 = *src;
104                                         src += src_step;
105                                 }
106                         }
107                         val = S1 + ((S2 - S1) * (signed int)pos) / BITS;
108                         if (val < -32768)
109                                 val = -32768;
110                         else if (val > 32767)
111                                 val = 32767;
112                         *dst = val;
113                         dst += dst_step;
114                         pos += data->pitch;
115                 }
116                 rchannels->last_S1 = S1;
117                 rchannels->last_S2 = S2;
118                 rchannels++;
119         }
120         data->pos = pos;
121 }
122 
123 static void resample_shrink(struct snd_pcm_plugin *plugin,
124                             const struct snd_pcm_plugin_channel *src_channels,
125                             struct snd_pcm_plugin_channel *dst_channels,
126                             int src_frames, int dst_frames)
127 {
128         unsigned int pos = 0;
129         signed int val;
130         signed short S1, S2;
131         signed short *src, *dst;
132         unsigned int channel;
133         int src_step, dst_step;
134         int src_frames1, dst_frames1;
135         struct rate_priv *data = (struct rate_priv *)plugin->extra_data;
136         struct rate_channel *rchannels = data->channels;
137 
138         for (channel = 0; channel < plugin->src_format.channels; ++channel) {
139                 pos = data->pos;
140                 S1 = rchannels->last_S1;
141                 S2 = rchannels->last_S2;
142                 if (!src_channels[channel].enabled) {
143                         if (dst_channels[channel].wanted)
144                                 snd_pcm_area_silence(&dst_channels[channel].area, 0, dst_frames, plugin->dst_format.format);
145                         dst_channels[channel].enabled = 0;
146                         continue;
147                 }
148                 dst_channels[channel].enabled = 1;
149                 src = (signed short *)src_channels[channel].area.addr +
150                         src_channels[channel].area.first / 8 / 2;
151                 dst = (signed short *)dst_channels[channel].area.addr +
152                         dst_channels[channel].area.first / 8 / 2;
153                 src_step = src_channels[channel].area.step / 8 / 2;
154                 dst_step = dst_channels[channel].area.step / 8 / 2;
155                 src_frames1 = src_frames;
156                 dst_frames1 = dst_frames;
157                 while (dst_frames1 > 0) {
158                         S1 = S2;
159                         if (src_frames1-- > 0) {
160                                 S2 = *src;
161                                 src += src_step;
162                         }
163                         if (pos & ~R_MASK) {
164                                 pos &= R_MASK;
165                                 val = S1 + ((S2 - S1) * (signed int)pos) / BITS;
166                                 if (val < -32768)
167                                         val = -32768;
168                                 else if (val > 32767)
169                                         val = 32767;
170                                 *dst = val;
171                                 dst += dst_step;
172                                 dst_frames1--;
173                         }
174                         pos += data->pitch;
175                 }
176                 rchannels->last_S1 = S1;
177                 rchannels->last_S2 = S2;
178                 rchannels++;
179         }
180         data->pos = pos;
181 }
182 
183 static snd_pcm_sframes_t rate_src_frames(struct snd_pcm_plugin *plugin, snd_pcm_uframes_t frames)
184 {
185         struct rate_priv *data;
186         snd_pcm_sframes_t res;
187 
188         if (snd_BUG_ON(!plugin))
189                 return -ENXIO;
190         if (frames == 0)
191                 return 0;
192         data = (struct rate_priv *)plugin->extra_data;
193         if (plugin->src_format.rate < plugin->dst_format.rate) {
194                 res = (((frames * data->pitch) + (BITS/2)) >> SHIFT);
195         } else {
196                 res = (((frames << SHIFT) + (data->pitch / 2)) / data->pitch);          
197         }
198         if (data->old_src_frames > 0) {
199                 snd_pcm_sframes_t frames1 = frames, res1 = data->old_dst_frames;
200                 while (data->old_src_frames < frames1) {
201                         frames1 >>= 1;
202                         res1 <<= 1;
203                 }
204                 while (data->old_src_frames > frames1) {
205                         frames1 <<= 1;
206                         res1 >>= 1;
207                 }
208                 if (data->old_src_frames == frames1)
209                         return res1;
210         }
211         data->old_src_frames = frames;
212         data->old_dst_frames = res;
213         return res;
214 }
215 
216 static snd_pcm_sframes_t rate_dst_frames(struct snd_pcm_plugin *plugin, snd_pcm_uframes_t frames)
217 {
218         struct rate_priv *data;
219         snd_pcm_sframes_t res;
220 
221         if (snd_BUG_ON(!plugin))
222                 return -ENXIO;
223         if (frames == 0)
224                 return 0;
225         data = (struct rate_priv *)plugin->extra_data;
226         if (plugin->src_format.rate < plugin->dst_format.rate) {
227                 res = (((frames << SHIFT) + (data->pitch / 2)) / data->pitch);
228         } else {
229                 res = (((frames * data->pitch) + (BITS/2)) >> SHIFT);
230         }
231         if (data->old_dst_frames > 0) {
232                 snd_pcm_sframes_t frames1 = frames, res1 = data->old_src_frames;
233                 while (data->old_dst_frames < frames1) {
234                         frames1 >>= 1;
235                         res1 <<= 1;
236                 }
237                 while (data->old_dst_frames > frames1) {
238                         frames1 <<= 1;
239                         res1 >>= 1;
240                 }
241                 if (data->old_dst_frames == frames1)
242                         return res1;
243         }
244         data->old_dst_frames = frames;
245         data->old_src_frames = res;
246         return res;
247 }
248 
249 static snd_pcm_sframes_t rate_transfer(struct snd_pcm_plugin *plugin,
250                              const struct snd_pcm_plugin_channel *src_channels,
251                              struct snd_pcm_plugin_channel *dst_channels,
252                              snd_pcm_uframes_t frames)
253 {
254         snd_pcm_uframes_t dst_frames;
255         struct rate_priv *data;
256 
257         if (snd_BUG_ON(!plugin || !src_channels || !dst_channels))
258                 return -ENXIO;
259         if (frames == 0)
260                 return 0;
261 #ifdef CONFIG_SND_DEBUG
262         {
263                 unsigned int channel;
264                 for (channel = 0; channel < plugin->src_format.channels; channel++) {
265                         if (snd_BUG_ON(src_channels[channel].area.first % 8 ||
266                                        src_channels[channel].area.step % 8))
267                                 return -ENXIO;
268                         if (snd_BUG_ON(dst_channels[channel].area.first % 8 ||
269                                        dst_channels[channel].area.step % 8))
270                                 return -ENXIO;
271                 }
272         }
273 #endif
274 
275         dst_frames = rate_dst_frames(plugin, frames);
276         if (dst_frames > dst_channels[0].frames)
277                 dst_frames = dst_channels[0].frames;
278         data = (struct rate_priv *)plugin->extra_data;
279         data->func(plugin, src_channels, dst_channels, frames, dst_frames);
280         return dst_frames;
281 }
282 
283 static int rate_action(struct snd_pcm_plugin *plugin,
284                        enum snd_pcm_plugin_action action,
285                        unsigned long udata)
286 {
287         if (snd_BUG_ON(!plugin))
288                 return -ENXIO;
289         switch (action) {
290         case INIT:
291         case PREPARE:
292                 rate_init(plugin);
293                 break;
294         default:
295                 break;
296         }
297         return 0;       /* silenty ignore other actions */
298 }
299 
300 int snd_pcm_plugin_build_rate(struct snd_pcm_substream *plug,
301                               struct snd_pcm_plugin_format *src_format,
302                               struct snd_pcm_plugin_format *dst_format,
303                               struct snd_pcm_plugin **r_plugin)
304 {
305         int err;
306         struct rate_priv *data;
307         struct snd_pcm_plugin *plugin;
308 
309         if (snd_BUG_ON(!r_plugin))
310                 return -ENXIO;
311         *r_plugin = NULL;
312 
313         if (snd_BUG_ON(src_format->channels != dst_format->channels))
314                 return -ENXIO;
315         if (snd_BUG_ON(src_format->channels <= 0))
316                 return -ENXIO;
317         if (snd_BUG_ON(src_format->format != SNDRV_PCM_FORMAT_S16))
318                 return -ENXIO;
319         if (snd_BUG_ON(dst_format->format != SNDRV_PCM_FORMAT_S16))
320                 return -ENXIO;
321         if (snd_BUG_ON(src_format->rate == dst_format->rate))
322                 return -ENXIO;
323 
324         err = snd_pcm_plugin_build(plug, "rate conversion",
325                                    src_format, dst_format,
326                                    sizeof(struct rate_priv) +
327                                    src_format->channels * sizeof(struct rate_channel),
328                                    &plugin);
329         if (err < 0)
330                 return err;
331         data = (struct rate_priv *)plugin->extra_data;
332         if (src_format->rate < dst_format->rate) {
333                 data->pitch = ((src_format->rate << SHIFT) + (dst_format->rate >> 1)) / dst_format->rate;
334                 data->func = resample_expand;
335         } else {
336                 data->pitch = ((dst_format->rate << SHIFT) + (src_format->rate >> 1)) / src_format->rate;
337                 data->func = resample_shrink;
338         }
339         data->pos = 0;
340         rate_init(plugin);
341         data->old_src_frames = data->old_dst_frames = 0;
342         plugin->transfer = rate_transfer;
343         plugin->src_frames = rate_src_frames;
344         plugin->dst_frames = rate_dst_frames;
345         plugin->action = rate_action;
346         *r_plugin = plugin;
347         return 0;
348 }
349 

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