sound/core/oss/rate.c

   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 <sound/driver.h>
  23 #include <linux/time.h>
  24 #include <sound/core.h>
  25 #include <sound/pcm.h>
  26 #include "pcm_plugin.h"
  27
  28 #define SHIFT   11
  29 #define BITS    (1<<SHIFT)
  30 #define R_MASK  (BITS-1)
  31
  32 /*
  33  *  Basic rate conversion plugin
  34  */
  35
  36 struct rate_channel {
  37         signed short last_S1;
  38         signed short last_S2;
  39 };
  40
  41 typedef void (*rate_f)(struct snd_pcm_plugin *plugin,
  42                        const struct snd_pcm_plugin_channel *src_channels,
  43                        struct snd_pcm_plugin_channel *dst_channels,
  44                        int src_frames, int dst_frames);
  45
  46 struct rate_priv {
  47         unsigned int pitch;
  48         unsigned int pos;
  49         rate_f func;
  50         snd_pcm_sframes_t old_src_frames, old_dst_frames;
  51         struct rate_channel channels[0];
  52 };
  53
  54 static void rate_init(struct snd_pcm_plugin *plugin)
  55 {
  56         unsigned int channel;
  57         struct rate_priv *data = (struct rate_priv *)plugin->extra_data;
  58         data->pos = 0;
  59         for (channel = 0; channel < plugin->src_format.channels; channel++) {
  60                 data->channels[channel].last_S1 = 0;
  61                 data->channels[channel].last_S2 = 0;
  62         }
  63 }
  64
  65 static void resample_expand(struct snd_pcm_plugin *plugin,
  66                             const struct snd_pcm_plugin_channel *src_channels,
  67                             struct snd_pcm_plugin_channel *dst_channels,
  68                             int src_frames, int dst_frames)
  69 {
  70         unsigned int pos = 0;
  71         signed int val;
  72         signed short S1, S2;
  73         signed short *src, *dst;
  74         unsigned int channel;
  75         int src_step, dst_step;
  76         int src_frames1, dst_frames1;
  77         struct rate_priv *data = (struct rate_priv *)plugin->extra_data;
  78         struct rate_channel *rchannels = data->channels;
  79
  80         for (channel = 0; channel < plugin->src_format.channels; channel++) {
  81                 pos = data->pos;
  82                 S1 = rchannels->last_S1;
  83                 S2 = rchannels->last_S2;
  84                 if (!src_channels[channel].enabled) {
  85                         if (dst_channels[channel].wanted)
  86                                 snd_pcm_area_silence(&dst_channels[channel].area, 0, dst_frames, plugin->dst_format.format);
  87                         dst_channels[channel].enabled = 0;
  88                         continue;
  89                 }
  90                 dst_channels[channel].enabled = 1;
  91                 src = (signed short *)src_channels[channel].area.addr +
  92                         src_channels[channel].area.first / 8 / 2;
  93                 dst = (signed short *)dst_channels[channel].area.addr +
  94                         dst_channels[channel].area.first / 8 / 2;
  95                 src_step = src_channels[channel].area.step / 8 / 2;
  96                 dst_step = dst_channels[channel].area.step / 8 / 2;
  97                 src_frames1 = src_frames;
  98                 dst_frames1 = dst_frames;
  99                 while (dst_frames1-- > 0) {
 100                         if (pos & ~R_MASK) {
 101                                 pos &= R_MASK;
 102                                 S1 = S2;
 103                                 if (src_frames1-- > 0) {
 104                                         S2 = *src;
 105                                         src += src_step;
 106                                 }
 107                         }
 108                         val = S1 + ((S2 - S1) * (signed int)pos) / BITS;
 109                         if (val < -32768)
 110                                 val = -32768;
 111                         else if (val > 32767)
 112                                 val = 32767;
 113                         *dst = val;
 114                         dst += dst_step;
 115                         pos += data->pitch;
 116                 }
 117                 rchannels->last_S1 = S1;
 118                 rchannels->last_S2 = S2;
 119                 rchannels++;
 120         }
 121         data->pos = pos;
 122 }
 123
 124 static void resample_shrink(struct snd_pcm_plugin *plugin,
 125                             const struct snd_pcm_plugin_channel *src_channels,
 126                             struct snd_pcm_plugin_channel *dst_channels,
 127                             int src_frames, int dst_frames)
 128 {
 129         unsigned int pos = 0;
 130         signed int val;
 131         signed short S1, S2;
 132         signed short *src, *dst;
 133         unsigned int channel;
 134         int src_step, dst_step;
 135         int src_frames1, dst_frames1;
 136         struct rate_priv *data = (struct rate_priv *)plugin->extra_data;
 137         struct rate_channel *rchannels = data->channels;
 138
 139         for (channel = 0; channel < plugin->src_format.channels; ++channel) {
 140                 pos = data->pos;
 141                 S1 = rchannels->last_S1;
 142                 S2 = rchannels->last_S2;
 143                 if (!src_channels[channel].enabled) {
 144                         if (dst_channels[channel].wanted)
 145                                 snd_pcm_area_silence(&dst_channels[channel].area, 0, dst_frames, plugin->dst_format.format);
 146                         dst_channels[channel].enabled = 0;
 147                         continue;
 148                 }
 149                 dst_channels[channel].enabled = 1;
 150                 src = (signed short *)src_channels[channel].area.addr +
 151                         src_channels[channel].area.first / 8 / 2;
 152                 dst = (signed short *)dst_channels[channel].area.addr +
 153                         dst_channels[channel].area.first / 8 / 2;
 154                 src_step = src_channels[channel].area.step / 8 / 2;
 155                 dst_step = dst_channels[channel].area.step / 8 / 2;
 156                 src_frames1 = src_frames;
 157                 dst_frames1 = dst_frames;
 158                 while (dst_frames1 > 0) {
 159                         S1 = S2;
 160                         if (src_frames1-- > 0) {
 161                                 S1 = *src;
 162                                 src += src_step;
 163                         }
 164                         if (pos & ~R_MASK) {
 165                                 pos &= R_MASK;
 166                                 val = S1 + ((S2 - S1) * (signed int)pos) / BITS;
 167                                 if (val < -32768)
 168                                         val = -32768;
 169                                 else if (val > 32767)
 170                                         val = 32767;
 171                                 *dst = val;
 172                                 dst += dst_step;
 173                                 dst_frames1--;
 174                         }
 175                         pos += data->pitch;
 176                 }
 177                 rchannels->last_S1 = S1;
 178                 rchannels->last_S2 = S2;
 179                 rchannels++;
 180         }
 181         data->pos = pos;
 182 }
 183
 184 static snd_pcm_sframes_t rate_src_frames(struct snd_pcm_plugin *plugin, snd_pcm_uframes_t frames)
 185 {
 186         struct rate_priv *data;
 187         snd_pcm_sframes_t res;
 188
 189         snd_assert(plugin != NULL, 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         snd_assert(plugin != NULL, return -ENXIO);
 222         if (frames == 0)
 223                 return 0;
 224         data = (struct rate_priv *)plugin->extra_data;
 225         if (plugin->src_format.rate < plugin->dst_format.rate) {
 226                 res = (((frames << SHIFT) + (data->pitch / 2)) / data->pitch);
 227         } else {
 228                 res = (((frames * data->pitch) + (BITS/2)) >> SHIFT);
 229         }
 230         if (data->old_dst_frames > 0) {
 231                 snd_pcm_sframes_t frames1 = frames, res1 = data->old_src_frames;
 232                 while (data->old_dst_frames < frames1) {
 233                         frames1 >>= 1;
 234                         res1 <<= 1;
 235                 }
 236                 while (data->old_dst_frames > frames1) {
 237                         frames1 <<= 1;
 238                         res1 >>= 1;
 239                 }
 240                 if (data->old_dst_frames == frames1)
 241                         return res1;
 242         }
 243         data->old_dst_frames = frames;
 244         data->old_src_frames = res;
 245         return res;
 246 }
 247
 248 static snd_pcm_sframes_t rate_transfer(struct snd_pcm_plugin *plugin,
 249                              const struct snd_pcm_plugin_channel *src_channels,
 250                              struct snd_pcm_plugin_channel *dst_channels,
 251                              snd_pcm_uframes_t frames)
 252 {
 253         snd_pcm_uframes_t dst_frames;
 254         struct rate_priv *data;
 255
 256         snd_assert(plugin != NULL && src_channels != NULL && dst_channels != NULL, return -ENXIO);
 257         if (frames == 0)
 258                 return 0;
 259 #ifdef CONFIG_SND_DEBUG
 260         {
 261                 unsigned int channel;
 262                 for (channel = 0; channel < plugin->src_format.channels; channel++) {
 263                         snd_assert(src_channels[channel].area.first % 8 == 0 &&
 264                                    src_channels[channel].area.step % 8 == 0,
 265                                    return -ENXIO);
 266                         snd_assert(dst_channels[channel].area.first % 8 == 0 &&
 267                                    dst_channels[channel].area.step % 8 == 0,
 268                                    return -ENXIO);
 269                 }
 270         }
 271 #endif
 272
 273         dst_frames = rate_dst_frames(plugin, frames);
 274         if (dst_frames > dst_channels[0].frames)
 275                 dst_frames = dst_channels[0].frames;
 276         data = (struct rate_priv *)plugin->extra_data;
 277         data->func(plugin, src_channels, dst_channels, frames, dst_frames);
 278         return dst_frames;
 279 }
 280
 281 static int rate_action(struct snd_pcm_plugin *plugin,
 282                        enum snd_pcm_plugin_action action,
 283                        unsigned long udata)
 284 {
 285         snd_assert(plugin != NULL, return -ENXIO);
 286         switch (action) {
 287         case INIT:
 288         case PREPARE:
 289                 rate_init(plugin);
 290                 break;
 291         default:
 292                 break;
 293         }
 294         return 0;       /* silenty ignore other actions */
 295 }
 296
 297 int snd_pcm_plugin_build_rate(struct snd_pcm_substream *plug,
 298                               struct snd_pcm_plugin_format *src_format,
 299                               struct snd_pcm_plugin_format *dst_format,
 300                               struct snd_pcm_plugin **r_plugin)
 301 {
 302         int err;
 303         struct rate_priv *data;
 304         struct snd_pcm_plugin *plugin;
 305
 306         snd_assert(r_plugin != NULL, return -ENXIO);
 307         *r_plugin = NULL;
 308
 309         snd_assert(src_format->channels == dst_format->channels, return -ENXIO);
 310         snd_assert(src_format->channels > 0, return -ENXIO);
 311         snd_assert(src_format->format == SNDRV_PCM_FORMAT_S16, return -ENXIO);
 312         snd_assert(dst_format->format == SNDRV_PCM_FORMAT_S16, return -ENXIO);
 313         snd_assert(src_format->rate != dst_format->rate, return -ENXIO);
 314
 315         err = snd_pcm_plugin_build(plug, "rate conversion",
 316                                    src_format, dst_format,
 317                                    sizeof(struct rate_priv) +
 318                                    src_format->channels * sizeof(struct rate_channel),
 319                                    &plugin);
 320         if (err < 0)
 321                 return err;
 322         data = (struct rate_priv *)plugin->extra_data;
 323         if (src_format->rate < dst_format->rate) {
 324                 data->pitch = ((src_format->rate << SHIFT) + (dst_format->rate >> 1)) / dst_format->rate;
 325                 data->func = resample_expand;
 326         } else {
 327                 data->pitch = ((dst_format->rate << SHIFT) + (src_format->rate >> 1)) / src_format->rate;
 328                 data->func = resample_shrink;
 329         }
 330         data->pos = 0;
 331         rate_init(plugin);
 332         data->old_src_frames = data->old_dst_frames = 0;
 333         plugin->transfer = rate_transfer;
 334         plugin->src_frames = rate_src_frames;
 335         plugin->dst_frames = rate_dst_frames;
 336         plugin->action = rate_action;
 337         *r_plugin = plugin;
 338         return 0;
 339 }