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 *dst_areas,
  27                        snd_pcm_uframes_t dst_offset,
  28                        const snd_pcm_channel_area_t *src_areas,
  29                        snd_pcm_uframes_t src_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         snd_pcm_format_t 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 void snd_pcm_alaw_decode(const snd_pcm_channel_area_t *dst_areas,
 124                          snd_pcm_uframes_t dst_offset,
 125                          const snd_pcm_channel_area_t *src_areas,
 126                          snd_pcm_uframes_t src_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 void snd_pcm_alaw_encode(const snd_pcm_channel_area_t *dst_areas,
 169                          snd_pcm_uframes_t dst_offset,
 170                          const snd_pcm_channel_area_t *src_areas,
 171                          snd_pcm_uframes_t src_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_cprepare(snd_pcm_t *pcm, snd_pcm_hw_params_t *params)
 215 {
 216         snd_pcm_alaw_t *alaw = pcm->private;
 217         int err;
 218         snd_pcm_access_mask_t access_mask = { SND_PCM_ACCBIT_PLUGIN };
 219         err = _snd_pcm_hw_param_set_mask(params, SND_PCM_HW_PARAM_ACCESS,
 220                                          &access_mask);
 221         if (err < 0)
 222                 return err;
 223         if (alaw->sformat == SND_PCM_FORMAT_A_LAW) {
 224                 snd_pcm_format_mask_t format_mask = { SND_PCM_FMTBIT_LINEAR };
 225                 err = _snd_pcm_hw_param_set_mask(params, SND_PCM_HW_PARAM_FORMAT,
 226                                                  &format_mask);
 227         } else {
 228                 err = _snd_pcm_hw_params_set_format(params,
 229                                                    SND_PCM_FORMAT_A_LAW);
 230         }
 231         if (err < 0)
 232                 return err;
 233         err = _snd_pcm_hw_params_set_subformat(params, SND_PCM_SUBFORMAT_STD);
 234         if (err < 0)
 235                 return err;
 236         params->info &= ~(SND_PCM_INFO_MMAP | SND_PCM_INFO_MMAP_VALID);
 237         return 0;
 238 }
 239
 240 static int snd_pcm_alaw_hw_refine_sprepare(snd_pcm_t *pcm, snd_pcm_hw_params_t *sparams)
 241 {
 242         snd_pcm_alaw_t *alaw = pcm->private;
 243         snd_pcm_access_mask_t saccess_mask = { SND_PCM_ACCBIT_MMAP };
 244         _snd_pcm_hw_params_any(sparams);
 245         _snd_pcm_hw_param_set_mask(sparams, SND_PCM_HW_PARAM_ACCESS,
 246                                    &saccess_mask);
 247         _snd_pcm_hw_params_set_format(sparams, alaw->sformat);
 248         _snd_pcm_hw_params_set_subformat(sparams, SND_PCM_SUBFORMAT_STD);
 249         return 0;
 250 }
 251
 252 static int snd_pcm_alaw_hw_refine_schange(snd_pcm_t *pcm ATTRIBUTE_UNUSED, snd_pcm_hw_params_t *params,
 253                                             snd_pcm_hw_params_t *sparams)
 254 {
 255         int err;
 256         unsigned int links = (SND_PCM_HW_PARBIT_CHANNELS |
 257                               SND_PCM_HW_PARBIT_RATE |
 258                               SND_PCM_HW_PARBIT_PERIOD_SIZE |
 259                               SND_PCM_HW_PARBIT_BUFFER_SIZE |
 260                               SND_PCM_HW_PARBIT_PERIODS |
 261                               SND_PCM_HW_PARBIT_PERIOD_TIME |
 262                               SND_PCM_HW_PARBIT_BUFFER_TIME |
 263                               SND_PCM_HW_PARBIT_TICK_TIME);
 264         err = _snd_pcm_hw_params_refine(sparams, links, params);
 265         if (err < 0)
 266                 return err;
 267         return 0;
 268 }
 269
 270 static int snd_pcm_alaw_hw_refine_cchange(snd_pcm_t *pcm ATTRIBUTE_UNUSED, snd_pcm_hw_params_t *params,
 271                                             snd_pcm_hw_params_t *sparams)
 272 {
 273         int err;
 274         unsigned int links = (SND_PCM_HW_PARBIT_CHANNELS |
 275                               SND_PCM_HW_PARBIT_RATE |
 276                               SND_PCM_HW_PARBIT_PERIOD_SIZE |
 277                               SND_PCM_HW_PARBIT_BUFFER_SIZE |
 278                               SND_PCM_HW_PARBIT_PERIODS |
 279                               SND_PCM_HW_PARBIT_PERIOD_TIME |
 280                               SND_PCM_HW_PARBIT_BUFFER_TIME |
 281                               SND_PCM_HW_PARBIT_TICK_TIME);
 282         err = _snd_pcm_hw_params_refine(params, links, sparams);
 283         if (err < 0)
 284                 return err;
 285         return 0;
 286 }
 287
 288 static int snd_pcm_alaw_hw_refine(snd_pcm_t *pcm, snd_pcm_hw_params_t *params)
 289 {
 290         return snd_pcm_hw_refine_slave(pcm, params,
 291                                        snd_pcm_alaw_hw_refine_cprepare,
 292                                        snd_pcm_alaw_hw_refine_cchange,
 293                                        snd_pcm_alaw_hw_refine_sprepare,
 294                                        snd_pcm_alaw_hw_refine_schange,
 295                                        snd_pcm_plugin_hw_refine_slave);
 296 }
 297
 298 static int snd_pcm_alaw_hw_params(snd_pcm_t *pcm, snd_pcm_hw_params_t * params)
 299 {
 300         snd_pcm_alaw_t *alaw = pcm->private;
 301         int err = snd_pcm_hw_params_slave(pcm, params,
 302                                           snd_pcm_alaw_hw_refine_cchange,
 303                                           snd_pcm_alaw_hw_refine_sprepare,
 304                                           snd_pcm_alaw_hw_refine_schange,
 305                                           snd_pcm_plugin_hw_params_slave);
 306         if (err < 0)
 307                 return err;
 308
 309         if (pcm->stream == SND_PCM_STREAM_PLAYBACK) {
 310                 if (alaw->sformat == SND_PCM_FORMAT_A_LAW) {
 311                         alaw->getput_idx = snd_pcm_linear_get_index(snd_pcm_hw_params_get_format(params), SND_PCM_FORMAT_S16);
 312                         alaw->func = snd_pcm_alaw_encode;
 313                 } else {
 314                         alaw->getput_idx = snd_pcm_linear_put_index(SND_PCM_FORMAT_S16, alaw->sformat);
 315                         alaw->func = snd_pcm_alaw_decode;
 316                 }
 317         } else {
 318                 if (alaw->sformat == SND_PCM_FORMAT_A_LAW) {
 319                         alaw->getput_idx = snd_pcm_linear_put_index(SND_PCM_FORMAT_S16, snd_pcm_hw_params_get_format(params));
 320                         alaw->func = snd_pcm_alaw_decode;
 321                 } else {
 322                         alaw->getput_idx = snd_pcm_linear_get_index(alaw->sformat, SND_PCM_FORMAT_S16);
 323                         alaw->func = snd_pcm_alaw_encode;
 324                 }
 325         }
 326         return 0;
 327 }
 328
 329 static snd_pcm_sframes_t snd_pcm_alaw_write_areas(snd_pcm_t *pcm,
 330                                         const snd_pcm_channel_area_t *areas,
 331                                         snd_pcm_uframes_t offset,
 332                                         snd_pcm_uframes_t size,
 333                                         snd_pcm_uframes_t *slave_sizep)
 334 {
 335         snd_pcm_alaw_t *alaw = pcm->private;
 336         snd_pcm_t *slave = alaw->plug.slave;
 337         snd_pcm_uframes_t xfer = 0;
 338         snd_pcm_sframes_t err = 0;
 339         if (slave_sizep && *slave_sizep < size)
 340                 size = *slave_sizep;
 341         assert(size > 0);
 342         while (xfer < size) {
 343                 snd_pcm_uframes_t frames = snd_pcm_mmap_playback_xfer(slave, size - xfer);
 344                 alaw->func(snd_pcm_mmap_areas(slave), snd_pcm_mmap_offset(slave),
 345                            areas, offset,
 346                            pcm->channels, frames,
 347                            alaw->getput_idx);
 348                 err = snd_pcm_mmap_forward(slave, frames);
 349                 if (err < 0)
 350                         break;
 351                 assert((snd_pcm_uframes_t)err == frames);
 352                 offset += err;
 353                 xfer += err;
 354                 snd_pcm_mmap_hw_forward(pcm, err);
 355         }
 356         if (xfer > 0) {
 357                 if (slave_sizep)
 358                         *slave_sizep = xfer;
 359                 return xfer;
 360         }
 361         return err;
 362 }
 363
 364 static snd_pcm_sframes_t snd_pcm_alaw_read_areas(snd_pcm_t *pcm,
 365                                        const snd_pcm_channel_area_t *areas,
 366                                        snd_pcm_uframes_t offset,
 367                                        snd_pcm_uframes_t size,
 368                                        snd_pcm_uframes_t *slave_sizep)
 369 {
 370         snd_pcm_alaw_t *alaw = pcm->private;
 371         snd_pcm_t *slave = alaw->plug.slave;
 372         snd_pcm_uframes_t xfer = 0;
 373         snd_pcm_sframes_t err = 0;
 374         if (slave_sizep && *slave_sizep < size)
 375                 size = *slave_sizep;
 376         assert(size > 0);
 377         while (xfer < size) {
 378                 snd_pcm_uframes_t frames = snd_pcm_mmap_capture_xfer(slave, size - xfer);
 379                 alaw->func(areas, offset,
 380                            snd_pcm_mmap_areas(slave), snd_pcm_mmap_offset(slave),
 381                            pcm->channels, frames,
 382                            alaw->getput_idx);
 383                 err = snd_pcm_mmap_forward(slave, frames);
 384                 if (err < 0)
 385                         break;
 386                 assert((snd_pcm_uframes_t)err == frames);
 387                 offset += err;
 388                 xfer += err;
 389                 snd_pcm_mmap_hw_forward(pcm, err);
 390         }
 391         if (xfer > 0) {
 392                 if (slave_sizep)
 393                         *slave_sizep = xfer;
 394                 return xfer;
 395         }
 396         return err;
 397 }
 398
 399 static void snd_pcm_alaw_dump(snd_pcm_t *pcm, snd_output_t *out)
 400 {
 401         snd_pcm_alaw_t *alaw = pcm->private;
 402         snd_output_printf(out, "A-Law conversion PCM (%s)\n",
 403                 snd_pcm_format_name(alaw->sformat));
 404         if (pcm->setup) {
 405                 snd_output_printf(out, "Its setup is:\n");
 406                 snd_pcm_dump_setup(pcm, out);
 407         }
 408         snd_output_printf(out, "Slave: ");
 409         snd_pcm_dump(alaw->plug.slave, out);
 410 }
 411
 412 snd_pcm_ops_t snd_pcm_alaw_ops = {
 413         close: snd_pcm_plugin_close,
 414         info: snd_pcm_plugin_info,
 415         hw_refine: snd_pcm_alaw_hw_refine,
 416         hw_params: snd_pcm_alaw_hw_params,
 417         hw_free: snd_pcm_plugin_hw_free,
 418         sw_params: snd_pcm_plugin_sw_params,
 419         channel_info: snd_pcm_plugin_channel_info,
 420         dump: snd_pcm_alaw_dump,
 421         nonblock: snd_pcm_plugin_nonblock,
 422         async: snd_pcm_plugin_async,
 423         mmap: snd_pcm_plugin_mmap,
 424         munmap: snd_pcm_plugin_munmap,
 425 };
 426
 427 int snd_pcm_alaw_open(snd_pcm_t **pcmp, char *name, snd_pcm_format_t sformat, snd_pcm_t *slave, int close_slave)
 428 {
 429         snd_pcm_t *pcm;
 430         snd_pcm_alaw_t *alaw;
 431         assert(pcmp && slave);
 432         if (snd_pcm_format_linear(sformat) != 1 &&
 433             sformat != SND_PCM_FORMAT_A_LAW)
 434                 return -EINVAL;
 435         alaw = calloc(1, sizeof(snd_pcm_alaw_t));
 436         if (!alaw) {
 437                 return -ENOMEM;
 438         }
 439         alaw->sformat = sformat;
 440         alaw->plug.read = snd_pcm_alaw_read_areas;
 441         alaw->plug.write = snd_pcm_alaw_write_areas;
 442         alaw->plug.slave = slave;
 443         alaw->plug.close_slave = close_slave;
 444
 445         pcm = calloc(1, sizeof(snd_pcm_t));
 446         if (!pcm) {
 447                 free(alaw);
 448                 return -ENOMEM;
 449         }
 450         if (name)
 451                 pcm->name = strdup(name);
 452         pcm->type = SND_PCM_TYPE_ALAW;
 453         pcm->stream = slave->stream;
 454         pcm->mode = slave->mode;
 455         pcm->ops = &snd_pcm_alaw_ops;
 456         pcm->op_arg = pcm;
 457         pcm->fast_ops = &snd_pcm_plugin_fast_ops;
 458         pcm->fast_op_arg = pcm;
 459         pcm->private = alaw;
 460         pcm->poll_fd = slave->poll_fd;
 461         pcm->hw_ptr = &alaw->plug.hw_ptr;
 462         pcm->appl_ptr = &alaw->plug.appl_ptr;
 463         *pcmp = pcm;
 464
 465         return 0;
 466 }
 467
 468 int _snd_pcm_alaw_open(snd_pcm_t **pcmp, char *name,
 469                          snd_config_t *conf,
 470                          snd_pcm_stream_t stream, int mode)
 471 {
 472         snd_config_iterator_t i;
 473         const char *sname = NULL;
 474         int err;
 475         snd_pcm_t *spcm;
 476         snd_pcm_format_t sformat = SND_PCM_FORMAT_UNKNOWN;
 477         snd_config_foreach(i, conf) {
 478                 snd_config_t *n = snd_config_iterator_entry(i);
 479                 const char *id = snd_config_get_id(n);
 480                 if (strcmp(id, "comment") == 0)
 481                         continue;
 482                 if (strcmp(id, "type") == 0)
 483                         continue;
 484                 if (strcmp(id, "stream") == 0)
 485                         continue;
 486                 if (strcmp(id, "sname") == 0) {
 487                         err = snd_config_get_string(n, &sname);
 488                         if (err < 0) {
 489                                 ERR("Invalid type for %s", id);
 490                                 return -EINVAL;
 491                         }
 492                         continue;
 493                 }
 494                 if (strcmp(id, "sformat") == 0) {
 495                         const char *f;
 496                         err = snd_config_get_string(n, &f);
 497                         if (err < 0) {
 498                                 ERR("Invalid type for %s", id);
 499                                 return -EINVAL;
 500                         }
 501                         sformat = snd_pcm_format_value(f);
 502                         if (sformat == SND_PCM_FORMAT_UNKNOWN) {
 503                                 ERR("Unknown sformat");
 504                                 return -EINVAL;
 505                         }
 506                         if (snd_pcm_format_linear(sformat) != 1 &&
 507                             sformat != SND_PCM_FORMAT_A_LAW) {
 508                                 ERR("Invalid sformat");
 509                                 return -EINVAL;
 510                         }
 511                         continue;
 512                 }
 513                 ERR("Unknown field %s", id);
 514                 return -EINVAL;
 515         }
 516         if (!sname) {
 517                 ERR("sname is not defined");
 518                 return -EINVAL;
 519         }
 520         if (sformat == SND_PCM_FORMAT_UNKNOWN) {
 521                 ERR("sformat is not defined");
 522                 return -EINVAL;
 523         }
 524         /* This is needed cause snd_config_update may destroy config */
 525         sname = strdup(sname);
 526         if (!sname)
 527                 return  -ENOMEM;
 528         err = snd_pcm_open(&spcm, sname, stream, mode);
 529         free((void *) sname);
 530         if (err < 0)
 531                 return err;
 532         err = snd_pcm_alaw_open(pcmp, name, sformat, spcm, 1);
 533         if (err < 0)
 534                 snd_pcm_close(spcm);
 535         return err;
 536 }
 537
 538