src/pcm/pcm_alaw.c

   1 /*
   2  *  PCM - A-Law conversion
   3  *  Copyright (c) 2000 by Abramo Bagnara <abramo@alsa-project.org>
   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., 675 Mass Ave, Cambridge, MA 02139, USA.
  19  *
  20  */
  21
  22 #include <byteswap.h>
  23 #include "pcm_local.h"
  24 #include "pcm_plugin.h"
  25
  26 typedef void (*alaw_f)(const snd_pcm_channel_area_t *src_areas,
  27                         snd_pcm_uframes_t src_offset,
  28                         const snd_pcm_channel_area_t *dst_areas,
  29                         snd_pcm_uframes_t dst_offset,
  30                         unsigned int channels, snd_pcm_uframes_t frames, int getputidx);
  31
  32 typedef struct {
  33         /* This field need to be the first */
  34         snd_pcm_plugin_t plug;
  35         int getput_idx;
  36         alaw_f func;
  37         int sformat;
  38 } snd_pcm_alaw_t;
  39
  40 static inline int val_seg(int val)
  41 {
  42         int r = 1;
  43         val >>= 8;
  44         if (val & 0xf0) {
  45                 val >>= 4;
  46                 r += 4;
  47         }
  48         if (val & 0x0c) {
  49                 val >>= 2;
  50                 r += 2;
  51         }
  52         if (val & 0x02)
  53                 r += 1;
  54         return r;
  55 }
  56
  57 /*
  58  * s16_to_alaw() - Convert a 16-bit linear PCM value to 8-bit A-law
  59  *
  60  * s16_to_alaw() accepts an 16-bit integer and encodes it as A-law data.
  61  *
  62  *              Linear Input Code       Compressed Code
  63  *      ------------------------        ---------------
  64  *      0000000wxyza                    000wxyz
  65  *      0000001wxyza                    001wxyz
  66  *      000001wxyzab                    010wxyz
  67  *      00001wxyzabc                    011wxyz
  68  *      0001wxyzabcd                    100wxyz
  69  *      001wxyzabcde                    101wxyz
  70  *      01wxyzabcdef                    110wxyz
  71  *      1wxyzabcdefg                    111wxyz
  72  *
  73  * For further information see John C. Bellamy's Digital Telephony, 1982,
  74  * John Wiley & Sons, pps 98-111 and 472-476.
  75  */
  76
  77 static unsigned char s16_to_alaw(int pcm_val)
  78 {
  79         int             mask;
  80         int             seg;
  81         unsigned char   aval;
  82
  83         if (pcm_val >= 0) {
  84                 mask = 0xD5;
  85         } else {
  86                 mask = 0x55;
  87                 pcm_val = -pcm_val;
  88                 if (pcm_val > 0x7fff)
  89                         pcm_val = 0x7fff;
  90         }
  91
  92         if (pcm_val < 256)
  93                 aval = pcm_val >> 4;
  94         else {
  95                 /* Convert the scaled magnitude to segment number. */
  96                 seg = val_seg(pcm_val);
  97                 aval = (seg << 4) | ((pcm_val >> (seg + 3)) & 0x0f);
  98         }
  99         return aval ^ mask;
 100 }
 101
 102 /*
 103  * alaw_to_s16() - Convert an A-law value to 16-bit linear PCM
 104  *
 105  */
 106 static int alaw_to_s16(unsigned char a_val)
 107 {
 108         int             t;
 109         int             seg;
 110
 111         a_val ^= 0x55;
 112         t = a_val & 0x7f;
 113         if (t < 16)
 114                 t = (t << 4) + 8;
 115         else {
 116                 seg = (t >> 4) & 0x07;
 117                 t = ((t & 0x0f) << 4) + 0x108;
 118                 t <<= seg -1;
 119         }
 120         return ((a_val & 0x80) ? t : -t);
 121 }
 122
 123 static void alaw_decode(const snd_pcm_channel_area_t *src_areas,
 124                         snd_pcm_uframes_t src_offset,
 125                         const snd_pcm_channel_area_t *dst_areas,
 126                         snd_pcm_uframes_t dst_offset,
 127                         unsigned int channels, snd_pcm_uframes_t frames, int putidx)
 128 {
 129 #define PUT16_LABELS
 130 #include "plugin_ops.h"
 131 #undef PUT16_LABELS
 132         void *put = put16_labels[putidx];
 133         unsigned int channel;
 134         for (channel = 0; channel < channels; ++channel) {
 135                 char *src;
 136                 char *dst;
 137                 int src_step, dst_step;
 138                 snd_pcm_uframes_t frames1;
 139                 const snd_pcm_channel_area_t *src_area = &src_areas[channel];
 140                 const snd_pcm_channel_area_t *dst_area = &dst_areas[channel];
 141 #if 0
 142                 if (!src_area->enabled) {
 143                         if (dst_area->wanted)
 144                                 snd_pcm_area_silence(&dst_areas[channel], dst_offset, frames, dst_sfmt);
 145                         dst_area->enabled = 0;
 146                         continue;
 147                 }
 148                 dst_area->enabled = 1;
 149 #endif
 150                 src = snd_pcm_channel_area_addr(src_area, src_offset);
 151                 dst = snd_pcm_channel_area_addr(dst_area, dst_offset);
 152                 src_step = snd_pcm_channel_area_step(src_area);
 153                 dst_step = snd_pcm_channel_area_step(dst_area);
 154                 frames1 = frames;
 155                 while (frames1-- > 0) {
 156                         int16_t sample = alaw_to_s16(*src);
 157                         goto *put;
 158 #define PUT16_END after
 159 #include "plugin_ops.h"
 160 #undef PUT16_END
 161                 after:
 162                         src += src_step;
 163                         dst += dst_step;
 164                 }
 165         }
 166 }
 167
 168 static void alaw_encode(const snd_pcm_channel_area_t *src_areas,
 169                          snd_pcm_uframes_t src_offset,
 170                          const snd_pcm_channel_area_t *dst_areas,
 171                          snd_pcm_uframes_t dst_offset,
 172                          unsigned int channels, snd_pcm_uframes_t frames, int getidx)
 173 {
 174 #define GET16_LABELS
 175 #include "plugin_ops.h"
 176 #undef GET16_LABELS
 177         void *get = get16_labels[getidx];
 178         unsigned int channel;
 179         int16_t sample = 0;
 180         for (channel = 0; channel < channels; ++channel) {
 181                 char *src;
 182                 char *dst;
 183                 int src_step, dst_step;
 184                 snd_pcm_uframes_t frames1;
 185                 const snd_pcm_channel_area_t *src_area = &src_areas[channel];
 186                 const snd_pcm_channel_area_t *dst_area = &dst_areas[channel];
 187 #if 0
 188                 if (!src_area->enabled) {
 189                         if (dst_area->wanted)
 190                                 snd_pcm_area_silence(&dst_area->area, 0, frames, dst_sfmt);
 191                         dst_area->enabled = 0;
 192                         continue;
 193                 }
 194                 dst_area->enabled = 1;
 195 #endif
 196                 src = snd_pcm_channel_area_addr(src_area, src_offset);
 197                 dst = snd_pcm_channel_area_addr(dst_area, dst_offset);
 198                 src_step = snd_pcm_channel_area_step(src_area);
 199                 dst_step = snd_pcm_channel_area_step(dst_area);
 200                 frames1 = frames;
 201                 while (frames1-- > 0) {
 202                         goto *get;
 203 #define GET16_END after
 204 #include "plugin_ops.h"
 205 #undef GET16_END
 206                 after:
 207                         *dst = s16_to_alaw(sample);
 208                         src += src_step;
 209                         dst += dst_step;
 210                 }
 211         }
 212 }
 213
 214 static int snd_pcm_alaw_hw_refine(snd_pcm_t *pcm, snd_pcm_hw_params_t *params)
 215 {
 216         snd_pcm_alaw_t *alaw = pcm->private;
 217         snd_pcm_t *slave = alaw->plug.slave;
 218         int err;
 219         unsigned int cmask, lcmask;
 220         snd_pcm_hw_params_t sparams;
 221         mask_t *access_mask = alloca(mask_sizeof());
 222         mask_t *saccess_mask = alloca(mask_sizeof());
 223         mask_load(access_mask, SND_PCM_ACCBIT_PLUGIN);
 224         mask_load(saccess_mask, SND_PCM_ACCBIT_MMAP);
 225         cmask = params->cmask;
 226         params->cmask = 0;
 227         err = _snd_pcm_hw_param_mask(params, SND_PCM_HW_PARAM_ACCESS,
 228                                       access_mask);
 229         if (err < 0)
 230                 return err;
 231         if (alaw->sformat == SND_PCM_FORMAT_A_LAW) {
 232                 mask_t *format_mask = alloca(mask_sizeof());
 233                 mask_load(format_mask, SND_PCM_FMTBIT_LINEAR);
 234                 err = _snd_pcm_hw_param_mask(params,
 235                                               SND_PCM_HW_PARAM_FORMAT,
 236                                               format_mask);
 237                 if (err < 0)
 238                         return err;
 239         } else {
 240                 err = _snd_pcm_hw_param_set(params,
 241                                              SND_PCM_HW_PARAM_FORMAT,
 242                                              SND_PCM_FORMAT_A_LAW, 0);
 243                 if (err < 0)
 244                         return err;
 245         }
 246         err = _snd_pcm_hw_param_set(params, SND_PCM_HW_PARAM_SUBFORMAT,
 247                                      SND_PCM_SUBFORMAT_STD, 0);
 248         if (err < 0)
 249                 return err;
 250         lcmask = params->cmask;
 251         params->cmask |= cmask;
 252
 253         _snd_pcm_hw_params_any(&sparams);
 254         _snd_pcm_hw_param_mask(&sparams, SND_PCM_HW_PARAM_ACCESS,
 255                                saccess_mask);
 256         _snd_pcm_hw_param_set(&sparams, SND_PCM_HW_PARAM_FORMAT,
 257                               alaw->sformat, 0);
 258         _snd_pcm_hw_param_set(&sparams, SND_PCM_HW_PARAM_SUBFORMAT,
 259                               SND_PCM_SUBFORMAT_STD, 0);
 260         err = snd_pcm_hw_refine2(params, &sparams,
 261                                  snd_pcm_generic_hw_link, slave,
 262                                  SND_PCM_HW_PARBIT_CHANNELS |
 263                                  SND_PCM_HW_PARBIT_RATE |
 264                                  SND_PCM_HW_PARBIT_PERIOD_SIZE |
 265                                  SND_PCM_HW_PARBIT_BUFFER_SIZE |
 266                                  SND_PCM_HW_PARBIT_PERIODS |
 267                                  SND_PCM_HW_PARBIT_PERIOD_TIME |
 268                                  SND_PCM_HW_PARBIT_BUFFER_TIME |
 269                                  SND_PCM_HW_PARBIT_TICK_TIME);
 270         params->cmask |= lcmask;
 271         if (err < 0)
 272                 return err;
 273         params->info &= ~(SND_PCM_INFO_MMAP | SND_PCM_INFO_MMAP_VALID);
 274         return 0;
 275 }
 276
 277 static int snd_pcm_alaw_hw_params(snd_pcm_t *pcm, snd_pcm_hw_params_t * params)
 278 {
 279         snd_pcm_alaw_t *alaw = pcm->private;
 280         snd_pcm_t *slave = alaw->plug.slave;
 281         int err;
 282         snd_pcm_hw_params_t sparams;
 283         unsigned int links;
 284         mask_t *saccess_mask = alloca(mask_sizeof());
 285         mask_load(saccess_mask, SND_PCM_ACCBIT_MMAP);
 286
 287         _snd_pcm_hw_params_any(&sparams);
 288         _snd_pcm_hw_param_mask(&sparams, SND_PCM_HW_PARAM_ACCESS,
 289                                saccess_mask);
 290         _snd_pcm_hw_param_set(&sparams, SND_PCM_HW_PARAM_FORMAT,
 291                               alaw->sformat, 0);
 292         _snd_pcm_hw_param_set(&sparams, SND_PCM_HW_PARAM_SUBFORMAT,
 293                               SND_PCM_SUBFORMAT_STD, 0);
 294         links = SND_PCM_HW_PARBIT_CHANNELS |
 295                 SND_PCM_HW_PARBIT_RATE |
 296                 SND_PCM_HW_PARBIT_PERIOD_SIZE |
 297                 SND_PCM_HW_PARBIT_BUFFER_SIZE |
 298                 SND_PCM_HW_PARBIT_PERIODS |
 299                 SND_PCM_HW_PARBIT_PERIOD_TIME |
 300                 SND_PCM_HW_PARBIT_BUFFER_TIME |
 301                 SND_PCM_HW_PARBIT_TICK_TIME;
 302         err = snd_pcm_hw_params_refine(&sparams, links, params);
 303         assert(err >= 0);
 304         err = snd_pcm_hw_params(slave, &sparams);
 305         params->cmask = 0;
 306         sparams.cmask = ~0U;
 307         snd_pcm_hw_params_refine(params, links, &sparams);
 308         if (err < 0)
 309                 return err;
 310         params->info &= ~(SND_PCM_INFO_MMAP | SND_PCM_INFO_MMAP_VALID);
 311         if (pcm->stream == SND_PCM_STREAM_PLAYBACK) {
 312                 if (alaw->sformat == SND_PCM_FORMAT_A_LAW) {
 313                         alaw->getput_idx = get_index(snd_pcm_hw_param_value(params, SND_PCM_HW_PARAM_FORMAT, 0), SND_PCM_FORMAT_S16);
 314                         alaw->func = alaw_encode;
 315                 } else {
 316                         alaw->getput_idx = put_index(SND_PCM_FORMAT_S16, alaw->sformat);
 317                         alaw->func = alaw_decode;
 318                 }
 319         } else {
 320                 if (alaw->sformat == SND_PCM_FORMAT_A_LAW) {
 321                         alaw->getput_idx = put_index(SND_PCM_FORMAT_S16, snd_pcm_hw_param_value(params, SND_PCM_HW_PARAM_FORMAT, 0));
 322                         alaw->func = alaw_decode;
 323                 } else {
 324                         alaw->getput_idx = get_index(alaw->sformat, SND_PCM_FORMAT_S16);
 325                         alaw->func = alaw_encode;
 326                 }
 327         }
 328         return 0;
 329 }
 330
 331 static snd_pcm_sframes_t snd_pcm_alaw_write_areas(snd_pcm_t *pcm,
 332                                         const snd_pcm_channel_area_t *areas,
 333                                         snd_pcm_uframes_t offset,
 334                                         snd_pcm_uframes_t size,
 335                                         snd_pcm_uframes_t *slave_sizep)
 336 {
 337         snd_pcm_alaw_t *alaw = pcm->private;
 338         snd_pcm_t *slave = alaw->plug.slave;
 339         snd_pcm_uframes_t xfer = 0;
 340         snd_pcm_sframes_t err = 0;
 341         if (slave_sizep && *slave_sizep < size)
 342                 size = *slave_sizep;
 343         assert(size > 0);
 344         while (xfer < size) {
 345                 snd_pcm_uframes_t frames = snd_pcm_mmap_playback_xfer(slave, size - xfer);
 346                 alaw->func(areas, offset,
 347                             snd_pcm_mmap_areas(slave), snd_pcm_mmap_offset(slave),
 348                             pcm->channels, frames,
 349                             alaw->getput_idx);
 350                 err = snd_pcm_mmap_forward(slave, frames);
 351                 if (err < 0)
 352                         break;
 353                 assert((snd_pcm_uframes_t)err == frames);
 354                 offset += err;
 355                 xfer += err;
 356                 snd_pcm_mmap_hw_forward(pcm, err);
 357         }
 358         if (xfer > 0) {
 359                 if (slave_sizep)
 360                         *slave_sizep = xfer;
 361                 return xfer;
 362         }
 363         return err;
 364 }
 365
 366 static snd_pcm_sframes_t snd_pcm_alaw_read_areas(snd_pcm_t *pcm,
 367                                        const snd_pcm_channel_area_t *areas,
 368                                        snd_pcm_uframes_t offset,
 369                                        snd_pcm_uframes_t size,
 370                                        snd_pcm_uframes_t *slave_sizep)
 371 {
 372         snd_pcm_alaw_t *alaw = pcm->private;
 373         snd_pcm_t *slave = alaw->plug.slave;
 374         snd_pcm_uframes_t xfer = 0;
 375         snd_pcm_sframes_t err = 0;
 376         if (slave_sizep && *slave_sizep < size)
 377                 size = *slave_sizep;
 378         assert(size > 0);
 379         while (xfer < size) {
 380                 snd_pcm_uframes_t frames = snd_pcm_mmap_capture_xfer(slave, size - xfer);
 381                 alaw->func(snd_pcm_mmap_areas(slave), snd_pcm_mmap_offset(slave),
 382                            areas, offset,
 383                            pcm->channels, frames,
 384                            alaw->getput_idx);
 385                 err = snd_pcm_mmap_forward(slave, frames);
 386                 if (err < 0)
 387                         break;
 388                 assert((snd_pcm_uframes_t)err == frames);
 389                 offset += err;
 390                 xfer += err;
 391                 snd_pcm_mmap_hw_forward(pcm, err);
 392         }
 393         if (xfer > 0) {
 394                 if (slave_sizep)
 395                         *slave_sizep = xfer;
 396                 return xfer;
 397         }
 398         return err;
 399 }
 400
 401 static void snd_pcm_alaw_dump(snd_pcm_t *pcm, snd_output_t *out)
 402 {
 403         snd_pcm_alaw_t *alaw = pcm->private;
 404         snd_output_printf(out, "A-Law conversion PCM (%s)\n",
 405                 snd_pcm_format_name(alaw->sformat));
 406         if (pcm->setup) {
 407                 snd_output_printf(out, "Its setup is:\n");
 408                 snd_pcm_dump_setup(pcm, out);
 409         }
 410         snd_output_printf(out, "Slave: ");
 411         snd_pcm_dump(alaw->plug.slave, out);
 412 }
 413
 414 snd_pcm_ops_t snd_pcm_alaw_ops = {
 415         close: snd_pcm_plugin_close,
 416         card: snd_pcm_plugin_card,
 417         info: snd_pcm_plugin_info,
 418         hw_refine: snd_pcm_alaw_hw_refine,
 419         hw_params: snd_pcm_alaw_hw_params,
 420         sw_params: snd_pcm_plugin_sw_params,
 421         channel_info: snd_pcm_plugin_channel_info,
 422         dump: snd_pcm_alaw_dump,
 423         nonblock: snd_pcm_plugin_nonblock,
 424         async: snd_pcm_plugin_async,
 425         mmap: snd_pcm_plugin_mmap,
 426         munmap: snd_pcm_plugin_munmap,
 427 };
 428
 429 int snd_pcm_alaw_open(snd_pcm_t **pcmp, char *name, int sformat, snd_pcm_t *slave, int close_slave)
 430 {
 431         snd_pcm_t *pcm;
 432         snd_pcm_alaw_t *alaw;
 433         assert(pcmp && slave);
 434         if (snd_pcm_format_linear(sformat) != 1 &&
 435             sformat != SND_PCM_FORMAT_A_LAW)
 436                 return -EINVAL;
 437         alaw = calloc(1, sizeof(snd_pcm_alaw_t));
 438         if (!alaw) {
 439                 return -ENOMEM;
 440         }
 441         alaw->sformat = sformat;
 442         alaw->plug.read = snd_pcm_alaw_read_areas;
 443         alaw->plug.write = snd_pcm_alaw_write_areas;
 444         alaw->plug.slave = slave;
 445         alaw->plug.close_slave = close_slave;
 446
 447         pcm = calloc(1, sizeof(snd_pcm_t));
 448         if (!pcm) {
 449                 free(alaw);
 450                 return -ENOMEM;
 451         }
 452         if (name)
 453                 pcm->name = strdup(name);
 454         pcm->type = SND_PCM_TYPE_ALAW;
 455         pcm->stream = slave->stream;
 456         pcm->mode = slave->mode;
 457         pcm->ops = &snd_pcm_alaw_ops;
 458         pcm->op_arg = pcm;
 459         pcm->fast_ops = &snd_pcm_plugin_fast_ops;
 460         pcm->fast_op_arg = pcm;
 461         pcm->private = alaw;
 462         pcm->poll_fd = slave->poll_fd;
 463         pcm->hw_ptr = &alaw->plug.hw_ptr;
 464         pcm->appl_ptr = &alaw->plug.appl_ptr;
 465         *pcmp = pcm;
 466
 467         return 0;
 468 }
 469
 470 int _snd_pcm_alaw_open(snd_pcm_t **pcmp, char *name,
 471                          snd_config_t *conf,
 472                          int stream, int mode)
 473 {
 474         snd_config_iterator_t i;
 475         char *sname = NULL;
 476         int err;
 477         snd_pcm_t *spcm;
 478         int sformat = -1;
 479         snd_config_foreach(i, conf) {
 480                 snd_config_t *n = snd_config_entry(i);
 481                 if (strcmp(n->id, "comment") == 0)
 482                         continue;
 483                 if (strcmp(n->id, "type") == 0)
 484                         continue;
 485                 if (strcmp(n->id, "stream") == 0)
 486                         continue;
 487                 if (strcmp(n->id, "sname") == 0) {
 488                         err = snd_config_string_get(n, &sname);
 489                         if (err < 0) {
 490                                 ERR("Invalid type for %s", n->id);
 491                                 return -EINVAL;
 492                         }
 493                         continue;
 494                 }
 495                 if (strcmp(n->id, "sformat") == 0) {
 496                         char *f;
 497                         err = snd_config_string_get(n, &f);
 498                         if (err < 0) {
 499                                 ERR("Invalid type for %s", n->id);
 500                                 return -EINVAL;
 501                         }
 502                         sformat = snd_pcm_format_value(f);
 503                         if (sformat < 0) {
 504                                 ERR("Unknown sformat");
 505                                 return -EINVAL;
 506                         }
 507                         if (snd_pcm_format_linear(sformat) != 1 &&
 508                             sformat != SND_PCM_FORMAT_A_LAW) {
 509                                 ERR("Invalid sformat");
 510                                 return -EINVAL;
 511                         }
 512                         continue;
 513                 }
 514                 ERR("Unknown field %s", n->id);
 515                 return -EINVAL;
 516         }
 517         if (!sname) {
 518                 ERR("sname is not defined");
 519                 return -EINVAL;
 520         }
 521         if (sformat < 0) {
 522                 ERR("sformat is not defined");
 523                 return -EINVAL;
 524         }
 525         /* This is needed cause snd_config_update may destroy config */
 526         sname = strdup(sname);
 527         if (!sname)
 528                 return  -ENOMEM;
 529         err = snd_pcm_open(&spcm, sname, stream, mode);
 530         free(sname);
 531         if (err < 0)
 532                 return err;
 533         err = snd_pcm_alaw_open(pcmp, name, sformat, spcm, 1);
 534         if (err < 0)
 535                 snd_pcm_close(spcm);
 536         return err;
 537 }
 538
 539