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)(snd_pcm_channel_area_t *src_areas,
  27                         size_t src_offset,
  28                         snd_pcm_channel_area_t *dst_areas,
  29                         size_t dst_offset,
  30                         size_t frames, size_t channels, 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(snd_pcm_channel_area_t *src_areas,
 124                         size_t src_offset,
 125                         snd_pcm_channel_area_t *dst_areas,
 126                         size_t dst_offset,
 127                         size_t frames, size_t channels, int putidx)
 128 {
 129 #define PUT16_LABELS
 130 #include "plugin_ops.h"
 131 #undef PUT16_LABELS
 132         void *put = put16_labels[putidx];
 133         size_t channel;
 134         for (channel = 0; channel < channels; ++channel) {
 135                 char *src;
 136                 char *dst;
 137                 int src_step, dst_step;
 138                 size_t frames1;
 139                 snd_pcm_channel_area_t *src_area = &src_areas[channel];
 140                 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(snd_pcm_channel_area_t *src_areas,
 169                          size_t src_offset,
 170                          snd_pcm_channel_area_t *dst_areas,
 171                          size_t dst_offset,
 172                          size_t frames, size_t channels, int getidx)
 173 {
 174 #define GET16_LABELS
 175 #include "plugin_ops.h"
 176 #undef GET16_LABELS
 177         void *get = get16_labels[getidx];
 178         size_t 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                 size_t frames1;
 185                 snd_pcm_channel_area_t *src_area = &src_areas[channel];
 186                 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_info(snd_pcm_t *pcm, snd_pcm_hw_info_t * info)
 215 {
 216         snd_pcm_alaw_t *alaw = pcm->private;
 217         unsigned int format_mask, access_mask;
 218         int err;
 219         info->access_mask &= (SND_PCM_ACCBIT_MMAP_INTERLEAVED |
 220                               SND_PCM_ACCBIT_RW_INTERLEAVED |
 221                               SND_PCM_ACCBIT_MMAP_NONINTERLEAVED |
 222                               SND_PCM_ACCBIT_RW_NONINTERLEAVED);
 223         access_mask = info->access_mask;
 224         if (access_mask == 0)
 225                 return -EINVAL;
 226         if (alaw->sformat == SND_PCM_FORMAT_MU_LAW)
 227                 info->format_mask &= SND_PCM_FMTBIT_LINEAR;
 228         else
 229                 info->format_mask &= SND_PCM_FMTBIT_MU_LAW;
 230         format_mask = info->format_mask;
 231         if (format_mask == 0)
 232                 return -EINVAL;
 233
 234         info->format_mask = 1U << alaw->sformat;
 235         info->access_mask = SND_PCM_ACCBIT_MMAP;
 236         err = snd_pcm_hw_info(alaw->plug.slave, info);
 237         if (info->format_mask)
 238                 info->format_mask = format_mask;
 239         if (info->access_mask) {
 240                 alaw->plug.saccess_mask = info->access_mask;
 241                 info->access_mask = access_mask;
 242         }
 243         if (err < 0)
 244                 return err;
 245         info->info &= ~(SND_PCM_INFO_MMAP | SND_PCM_INFO_MMAP_VALID);
 246         snd_pcm_hw_info_complete(info);
 247         return 0;
 248 }
 249
 250 static int snd_pcm_alaw_hw_params(snd_pcm_t *pcm, snd_pcm_hw_params_t * params)
 251 {
 252         snd_pcm_alaw_t *alaw = pcm->private;
 253         snd_pcm_t *slave = alaw->plug.slave;
 254         unsigned int format, access;
 255         int err;
 256         format = params->format;
 257         access = params->access;
 258         params->format = alaw->sformat;
 259         if (alaw->plug.saccess_mask & SND_PCM_ACCBIT_MMAP_INTERLEAVED)
 260                 params->access = SND_PCM_ACCESS_MMAP_INTERLEAVED;
 261         else if (alaw->plug.saccess_mask & SND_PCM_ACCBIT_MMAP_NONINTERLEAVED)
 262                 params->access = SND_PCM_ACCESS_MMAP_NONINTERLEAVED;
 263         else
 264                 assert(0);
 265         err = snd_pcm_hw_params(slave, params);
 266         params->format = format;
 267         params->access = access;
 268         if (err < 0)
 269                 return err;
 270         if (pcm->stream == SND_PCM_STREAM_PLAYBACK) {
 271                 if (alaw->sformat == SND_PCM_FORMAT_MU_LAW) {
 272                         alaw->getput_idx = get_index(format, SND_PCM_FORMAT_S16);
 273                         alaw->func = alaw_encode;
 274                 } else {
 275                         alaw->getput_idx = put_index(SND_PCM_FORMAT_S16, alaw->sformat);
 276                         alaw->func = alaw_decode;
 277                 }
 278         } else {
 279                 if (alaw->sformat == SND_PCM_FORMAT_MU_LAW) {
 280                         alaw->getput_idx = put_index(SND_PCM_FORMAT_S16, format);
 281                         alaw->func = alaw_decode;
 282                 } else {
 283                         alaw->getput_idx = get_index(alaw->sformat, SND_PCM_FORMAT_S16);
 284                         alaw->func = alaw_encode;
 285                 }
 286         }
 287         return 0;
 288 }
 289
 290 static ssize_t snd_pcm_alaw_write_areas(snd_pcm_t *pcm,
 291                                         snd_pcm_channel_area_t *areas,
 292                                         size_t offset,
 293                                         size_t size,
 294                                         size_t *slave_sizep)
 295 {
 296         snd_pcm_alaw_t *alaw = pcm->private;
 297         snd_pcm_t *slave = alaw->plug.slave;
 298         size_t xfer = 0;
 299         ssize_t err = 0;
 300         if (slave_sizep && *slave_sizep < size)
 301                 size = *slave_sizep;
 302         assert(size > 0);
 303         while (xfer < size) {
 304                 size_t frames = snd_pcm_mmap_playback_xfer(slave, size - xfer);
 305                 alaw->func(areas, offset,
 306                             snd_pcm_mmap_areas(slave), snd_pcm_mmap_offset(slave),
 307                             frames, pcm->channels,
 308                             alaw->getput_idx);
 309                 err = snd_pcm_mmap_forward(slave, frames);
 310                 if (err < 0)
 311                         break;
 312                 assert((size_t)err == frames);
 313                 offset += err;
 314                 xfer += err;
 315                 snd_pcm_mmap_hw_forward(pcm, err);
 316         }
 317         if (xfer > 0) {
 318                 if (slave_sizep)
 319                         *slave_sizep = xfer;
 320                 return xfer;
 321         }
 322         return err;
 323 }
 324
 325 static ssize_t snd_pcm_alaw_read_areas(snd_pcm_t *pcm,
 326                                        snd_pcm_channel_area_t *areas,
 327                                        size_t offset,
 328                                        size_t size,
 329                                        size_t *slave_sizep)
 330 {
 331         snd_pcm_alaw_t *alaw = pcm->private;
 332         snd_pcm_t *slave = alaw->plug.slave;
 333         size_t xfer = 0;
 334         ssize_t err = 0;
 335         if (slave_sizep && *slave_sizep < size)
 336                 size = *slave_sizep;
 337         assert(size > 0);
 338         while (xfer < size) {
 339                 size_t frames = snd_pcm_mmap_capture_xfer(slave, size - xfer);
 340                 alaw->func(snd_pcm_mmap_areas(slave), snd_pcm_mmap_offset(slave),
 341                            areas, offset,
 342                            frames, pcm->channels,
 343                            alaw->getput_idx);
 344                 err = snd_pcm_mmap_forward(slave, frames);
 345                 if (err < 0)
 346                         break;
 347                 assert((size_t)err == frames);
 348                 offset += err;
 349                 xfer += err;
 350                 snd_pcm_mmap_hw_forward(pcm, err);
 351         }
 352         if (xfer > 0) {
 353                 if (slave_sizep)
 354                         *slave_sizep = xfer;
 355                 return xfer;
 356         }
 357         return err;
 358 }
 359
 360 static void snd_pcm_alaw_dump(snd_pcm_t *pcm, FILE *fp)
 361 {
 362         snd_pcm_alaw_t *alaw = pcm->private;
 363         fprintf(fp, "A-Law conversion PCM (%s)\n",
 364                 snd_pcm_format_name(alaw->sformat));
 365         if (pcm->setup) {
 366                 fprintf(fp, "Its setup is:\n");
 367                 snd_pcm_dump_setup(pcm, fp);
 368         }
 369         fprintf(fp, "Slave: ");
 370         snd_pcm_dump(alaw->plug.slave, fp);
 371 }
 372
 373 snd_pcm_ops_t snd_pcm_alaw_ops = {
 374         close: snd_pcm_plugin_close,
 375         info: snd_pcm_plugin_info,
 376         hw_info: snd_pcm_alaw_hw_info,
 377         hw_params: snd_pcm_alaw_hw_params,
 378         sw_params: snd_pcm_plugin_sw_params,
 379         dig_info: snd_pcm_plugin_dig_info,
 380         dig_params: snd_pcm_plugin_dig_params,
 381         channel_info: snd_pcm_plugin_channel_info,
 382         dump: snd_pcm_alaw_dump,
 383         nonblock: snd_pcm_plugin_nonblock,
 384         async: snd_pcm_plugin_async,
 385         mmap: snd_pcm_plugin_mmap,
 386         munmap: snd_pcm_plugin_munmap,
 387 };
 388
 389 int snd_pcm_alaw_open(snd_pcm_t **pcmp, char *name, int sformat, snd_pcm_t *slave, int close_slave)
 390 {
 391         snd_pcm_t *pcm;
 392         snd_pcm_alaw_t *alaw;
 393         assert(pcmp && slave);
 394         if (snd_pcm_format_linear(sformat) != 1 &&
 395             sformat != SND_PCM_FORMAT_A_LAW)
 396                 return -EINVAL;
 397         alaw = calloc(1, sizeof(snd_pcm_alaw_t));
 398         if (!alaw) {
 399                 return -ENOMEM;
 400         }
 401         alaw->sformat = sformat;
 402         alaw->plug.read = snd_pcm_alaw_read_areas;
 403         alaw->plug.write = snd_pcm_alaw_write_areas;
 404         alaw->plug.slave = slave;
 405         alaw->plug.close_slave = close_slave;
 406
 407         pcm = calloc(1, sizeof(snd_pcm_t));
 408         if (!pcm) {
 409                 free(alaw);
 410                 return -ENOMEM;
 411         }
 412         if (name)
 413                 pcm->name = strdup(name);
 414         pcm->type = SND_PCM_TYPE_ALAW;
 415         pcm->stream = slave->stream;
 416         pcm->mode = slave->mode;
 417         pcm->ops = &snd_pcm_alaw_ops;
 418         pcm->op_arg = pcm;
 419         pcm->fast_ops = &snd_pcm_plugin_fast_ops;
 420         pcm->fast_op_arg = pcm;
 421         pcm->private = alaw;
 422         pcm->poll_fd = slave->poll_fd;
 423         pcm->hw_ptr = &alaw->plug.hw_ptr;
 424         pcm->appl_ptr = &alaw->plug.appl_ptr;
 425         *pcmp = pcm;
 426
 427         return 0;
 428 }
 429
 430 int _snd_pcm_alaw_open(snd_pcm_t **pcmp, char *name,
 431                          snd_config_t *conf,
 432                          int stream, int mode)
 433 {
 434         snd_config_iterator_t i;
 435         char *sname = NULL;
 436         int err;
 437         snd_pcm_t *spcm;
 438         int sformat = -1;
 439         snd_config_foreach(i, conf) {
 440                 snd_config_t *n = snd_config_entry(i);
 441                 if (strcmp(n->id, "comment") == 0)
 442                         continue;
 443                 if (strcmp(n->id, "type") == 0)
 444                         continue;
 445                 if (strcmp(n->id, "stream") == 0)
 446                         continue;
 447                 if (strcmp(n->id, "sname") == 0) {
 448                         err = snd_config_string_get(n, &sname);
 449                         if (err < 0)
 450                                 return -EINVAL;
 451                         continue;
 452                 }
 453                 if (strcmp(n->id, "sformat") == 0) {
 454                         char *f;
 455                         err = snd_config_string_get(n, &f);
 456                         if (err < 0)
 457                                 return -EINVAL;
 458                         sformat = snd_pcm_format_value(f);
 459                         if (sformat < 0)
 460                                 return -EINVAL;
 461                         if (snd_pcm_format_linear(sformat) != 1 &&
 462                             sformat != SND_PCM_FORMAT_A_LAW)
 463                                 return -EINVAL;
 464                         continue;
 465                 }
 466                 return -EINVAL;
 467         }
 468         if (!sname || !sformat)
 469                 return -EINVAL;
 470         /* This is needed cause snd_config_update may destroy config */
 471         sname = strdup(sname);
 472         if (!sname)
 473                 return  -ENOMEM;
 474         err = snd_pcm_open(&spcm, sname, stream, mode);
 475         free(sname);
 476         if (err < 0)
 477                 return err;
 478         err = snd_pcm_alaw_open(pcmp, name, sformat, spcm, 1);
 479         if (err < 0)
 480                 snd_pcm_close(spcm);
 481         return err;
 482 }
 483
 484