src/pcm/pcm_alaw.c

   1 /**
   2  * \file pcm/pcm_alaw.c
   3  * \ingroup PCM_Plugins
   4  * \brief PCM A-Law Conversion Plugin Interface
   5  * \author Abramo Bagnara <abramo@alsa-project.org>
   6  * \date 2000-2001
   7  */
   8 /*
   9  *  PCM - A-Law conversion
  10  *  Copyright (c) 2000 by Abramo Bagnara <abramo@alsa-project.org>
  11  *
  12  *
  13  *   This library is free software; you can redistribute it and/or modify
  14  *   it under the terms of the GNU Lesser General Public License as
  15  *   published by the Free Software Foundation; either version 2.1 of
  16  *   the License, or (at your option) any later version.
  17  *
  18  *   This program is distributed in the hope that it will be useful,
  19  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  20  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21  *   GNU Lesser General Public License for more details.
  22  *
  23  *   You should have received a copy of the GNU Lesser General Public
  24  *   License along with this library; if not, write to the Free Software
  25  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  26  *
  27  */
  28
  29 #include <byteswap.h>
  30 #include "pcm_local.h"
  31 #include "pcm_plugin.h"
  32
  33 #include "plugin_ops.h"
  34
  35 #ifndef PIC
  36 /* entry for static linking */
  37 const char *_snd_module_pcm_alaw = "";
  38 #endif
  39
  40 #ifndef DOC_HIDDEN
  41
  42 typedef void (*alaw_f)(const snd_pcm_channel_area_t *dst_areas,
  43                        snd_pcm_uframes_t dst_offset,
  44                        const snd_pcm_channel_area_t *src_areas,
  45                        snd_pcm_uframes_t src_offset,
  46                        unsigned int channels, snd_pcm_uframes_t frames,
  47                        unsigned int getputidx);
  48
  49 typedef struct {
  50         /* This field need to be the first */
  51         snd_pcm_plugin_t plug;
  52         unsigned int getput_idx;
  53         alaw_f func;
  54         snd_pcm_format_t sformat;
  55 } snd_pcm_alaw_t;
  56
  57 #endif
  58
  59 static inline int val_seg(int val)
  60 {
  61         int r = 1;
  62         val >>= 8;
  63         if (val & 0xf0) {
  64                 val >>= 4;
  65                 r += 4;
  66         }
  67         if (val & 0x0c) {
  68                 val >>= 2;
  69                 r += 2;
  70         }
  71         if (val & 0x02)
  72                 r += 1;
  73         return r;
  74 }
  75
  76 /*
  77  * s16_to_alaw() - Convert a 16-bit linear PCM value to 8-bit A-law
  78  *
  79  * s16_to_alaw() accepts an 16-bit integer and encodes it as A-law data.
  80  *
  81  *              Linear Input Code       Compressed Code
  82  *      ------------------------        ---------------
  83  *      0000000wxyza                    000wxyz
  84  *      0000001wxyza                    001wxyz
  85  *      000001wxyzab                    010wxyz
  86  *      00001wxyzabc                    011wxyz
  87  *      0001wxyzabcd                    100wxyz
  88  *      001wxyzabcde                    101wxyz
  89  *      01wxyzabcdef                    110wxyz
  90  *      1wxyzabcdefg                    111wxyz
  91  *
  92  * For further information see John C. Bellamy's Digital Telephony, 1982,
  93  * John Wiley & Sons, pps 98-111 and 472-476.
  94  */
  95
  96 static unsigned char s16_to_alaw(int pcm_val)
  97 {
  98         int             mask;
  99         int             seg;
 100         unsigned char   aval;
 101
 102         if (pcm_val >= 0) {
 103                 mask = 0xD5;
 104         } else {
 105                 mask = 0x55;
 106                 pcm_val = -pcm_val;
 107                 if (pcm_val > 0x7fff)
 108                         pcm_val = 0x7fff;
 109         }
 110
 111         if (pcm_val < 256)
 112                 aval = pcm_val >> 4;
 113         else {
 114                 /* Convert the scaled magnitude to segment number. */
 115                 seg = val_seg(pcm_val);
 116                 aval = (seg << 4) | ((pcm_val >> (seg + 3)) & 0x0f);
 117         }
 118         return aval ^ mask;
 119 }
 120
 121 /*
 122  * alaw_to_s16() - Convert an A-law value to 16-bit linear PCM
 123  *
 124  */
 125 static int alaw_to_s16(unsigned char a_val)
 126 {
 127         int             t;
 128         int             seg;
 129
 130         a_val ^= 0x55;
 131         t = a_val & 0x7f;
 132         if (t < 16)
 133                 t = (t << 4) + 8;
 134         else {
 135                 seg = (t >> 4) & 0x07;
 136                 t = ((t & 0x0f) << 4) + 0x108;
 137                 t <<= seg -1;
 138         }
 139         return ((a_val & 0x80) ? t : -t);
 140 }
 141
 142 #ifndef DOC_HIDDEN
 143
 144 void snd_pcm_alaw_decode(const snd_pcm_channel_area_t *dst_areas,
 145                          snd_pcm_uframes_t dst_offset,
 146                          const snd_pcm_channel_area_t *src_areas,
 147                          snd_pcm_uframes_t src_offset,
 148                          unsigned int channels, snd_pcm_uframes_t frames,
 149                          unsigned int putidx)
 150 {
 151 #define PUT16_LABELS
 152 #include "plugin_ops.h"
 153 #undef PUT16_LABELS
 154         void *put = put16_labels[putidx];
 155         unsigned int channel;
 156         for (channel = 0; channel < channels; ++channel) {
 157                 const unsigned char *src;
 158                 char *dst;
 159                 int src_step, dst_step;
 160                 snd_pcm_uframes_t frames1;
 161                 const snd_pcm_channel_area_t *src_area = &src_areas[channel];
 162                 const snd_pcm_channel_area_t *dst_area = &dst_areas[channel];
 163                 src = snd_pcm_channel_area_addr(src_area, src_offset);
 164                 dst = snd_pcm_channel_area_addr(dst_area, dst_offset);
 165                 src_step = snd_pcm_channel_area_step(src_area);
 166                 dst_step = snd_pcm_channel_area_step(dst_area);
 167                 frames1 = frames;
 168                 while (frames1-- > 0) {
 169                         int16_t sample = alaw_to_s16(*src);
 170                         goto *put;
 171 #define PUT16_END after
 172 #include "plugin_ops.h"
 173 #undef PUT16_END
 174                 after:
 175                         src += src_step;
 176                         dst += dst_step;
 177                 }
 178         }
 179 }
 180
 181 void snd_pcm_alaw_encode(const snd_pcm_channel_area_t *dst_areas,
 182                          snd_pcm_uframes_t dst_offset,
 183                          const snd_pcm_channel_area_t *src_areas,
 184                          snd_pcm_uframes_t src_offset,
 185                          unsigned int channels, snd_pcm_uframes_t frames,
 186                          unsigned int getidx)
 187 {
 188 #define GET16_LABELS
 189 #include "plugin_ops.h"
 190 #undef GET16_LABELS
 191         void *get = get16_labels[getidx];
 192         unsigned int channel;
 193         int16_t sample = 0;
 194         for (channel = 0; channel < channels; ++channel) {
 195                 const char *src;
 196                 char *dst;
 197                 int src_step, dst_step;
 198                 snd_pcm_uframes_t frames1;
 199                 const snd_pcm_channel_area_t *src_area = &src_areas[channel];
 200                 const snd_pcm_channel_area_t *dst_area = &dst_areas[channel];
 201                 src = snd_pcm_channel_area_addr(src_area, src_offset);
 202                 dst = snd_pcm_channel_area_addr(dst_area, dst_offset);
 203                 src_step = snd_pcm_channel_area_step(src_area);
 204                 dst_step = snd_pcm_channel_area_step(dst_area);
 205                 frames1 = frames;
 206                 while (frames1-- > 0) {
 207                         goto *get;
 208 #define GET16_END after
 209 #include "plugin_ops.h"
 210 #undef GET16_END
 211                 after:
 212                         *dst = s16_to_alaw(sample);
 213                         src += src_step;
 214                         dst += dst_step;
 215                 }
 216         }
 217 }
 218
 219 #endif /* DOC_HIDDEN */
 220
 221 static int snd_pcm_alaw_hw_refine_cprepare(snd_pcm_t *pcm, snd_pcm_hw_params_t *params)
 222 {
 223         snd_pcm_alaw_t *alaw = pcm->private_data;
 224         int err;
 225         snd_pcm_access_mask_t access_mask = { SND_PCM_ACCBIT_SHM };
 226         err = _snd_pcm_hw_param_set_mask(params, SND_PCM_HW_PARAM_ACCESS,
 227                                          &access_mask);
 228         if (err < 0)
 229                 return err;
 230         if (alaw->sformat == SND_PCM_FORMAT_A_LAW) {
 231                 snd_pcm_format_mask_t format_mask = { SND_PCM_FMTBIT_LINEAR };
 232                 err = _snd_pcm_hw_param_set_mask(params, SND_PCM_HW_PARAM_FORMAT,
 233                                                  &format_mask);
 234         } else {
 235                 err = _snd_pcm_hw_params_set_format(params,
 236                                                    SND_PCM_FORMAT_A_LAW);
 237         }
 238         if (err < 0)
 239                 return err;
 240         err = _snd_pcm_hw_params_set_subformat(params, SND_PCM_SUBFORMAT_STD);
 241         if (err < 0)
 242                 return err;
 243         params->info &= ~(SND_PCM_INFO_MMAP | SND_PCM_INFO_MMAP_VALID);
 244         return 0;
 245 }
 246
 247 static int snd_pcm_alaw_hw_refine_sprepare(snd_pcm_t *pcm, snd_pcm_hw_params_t *sparams)
 248 {
 249         snd_pcm_alaw_t *alaw = pcm->private_data;
 250         snd_pcm_access_mask_t saccess_mask = { SND_PCM_ACCBIT_MMAP };
 251         _snd_pcm_hw_params_any(sparams);
 252         _snd_pcm_hw_param_set_mask(sparams, SND_PCM_HW_PARAM_ACCESS,
 253                                    &saccess_mask);
 254         _snd_pcm_hw_params_set_format(sparams, alaw->sformat);
 255         _snd_pcm_hw_params_set_subformat(sparams, SND_PCM_SUBFORMAT_STD);
 256         return 0;
 257 }
 258
 259 static int snd_pcm_alaw_hw_refine_schange(snd_pcm_t *pcm ATTRIBUTE_UNUSED, snd_pcm_hw_params_t *params,
 260                                             snd_pcm_hw_params_t *sparams)
 261 {
 262         int err;
 263         unsigned int links = (SND_PCM_HW_PARBIT_CHANNELS |
 264                               SND_PCM_HW_PARBIT_RATE |
 265                               SND_PCM_HW_PARBIT_PERIOD_SIZE |
 266                               SND_PCM_HW_PARBIT_BUFFER_SIZE |
 267                               SND_PCM_HW_PARBIT_PERIODS |
 268                               SND_PCM_HW_PARBIT_PERIOD_TIME |
 269                               SND_PCM_HW_PARBIT_BUFFER_TIME |
 270                               SND_PCM_HW_PARBIT_TICK_TIME);
 271         err = _snd_pcm_hw_params_refine(sparams, links, params);
 272         if (err < 0)
 273                 return err;
 274         return 0;
 275 }
 276
 277 static int snd_pcm_alaw_hw_refine_cchange(snd_pcm_t *pcm ATTRIBUTE_UNUSED, snd_pcm_hw_params_t *params,
 278                                             snd_pcm_hw_params_t *sparams)
 279 {
 280         int err;
 281         unsigned int links = (SND_PCM_HW_PARBIT_CHANNELS |
 282                               SND_PCM_HW_PARBIT_RATE |
 283                               SND_PCM_HW_PARBIT_PERIOD_SIZE |
 284                               SND_PCM_HW_PARBIT_BUFFER_SIZE |
 285                               SND_PCM_HW_PARBIT_PERIODS |
 286                               SND_PCM_HW_PARBIT_PERIOD_TIME |
 287                               SND_PCM_HW_PARBIT_BUFFER_TIME |
 288                               SND_PCM_HW_PARBIT_TICK_TIME);
 289         err = _snd_pcm_hw_params_refine(params, links, sparams);
 290         if (err < 0)
 291                 return err;
 292         return 0;
 293 }
 294
 295 static int snd_pcm_alaw_hw_refine(snd_pcm_t *pcm, snd_pcm_hw_params_t *params)
 296 {
 297         return snd_pcm_hw_refine_slave(pcm, params,
 298                                        snd_pcm_alaw_hw_refine_cprepare,
 299                                        snd_pcm_alaw_hw_refine_cchange,
 300                                        snd_pcm_alaw_hw_refine_sprepare,
 301                                        snd_pcm_alaw_hw_refine_schange,
 302                                        snd_pcm_generic_hw_refine);
 303 }
 304
 305 static int snd_pcm_alaw_hw_params(snd_pcm_t *pcm, snd_pcm_hw_params_t * params)
 306 {
 307         snd_pcm_alaw_t *alaw = pcm->private_data;
 308         snd_pcm_format_t format;
 309         int err = snd_pcm_hw_params_slave(pcm, params,
 310                                           snd_pcm_alaw_hw_refine_cchange,
 311                                           snd_pcm_alaw_hw_refine_sprepare,
 312                                           snd_pcm_alaw_hw_refine_schange,
 313                                           snd_pcm_generic_hw_params);
 314         if (err < 0)
 315                 return err;
 316
 317         err = INTERNAL(snd_pcm_hw_params_get_format)(params, &format);
 318         if (err < 0)
 319                 return err;
 320
 321         if (pcm->stream == SND_PCM_STREAM_PLAYBACK) {
 322                 if (alaw->sformat == SND_PCM_FORMAT_A_LAW) {
 323                         alaw->getput_idx = snd_pcm_linear_get_index(format, SND_PCM_FORMAT_S16);
 324                         alaw->func = snd_pcm_alaw_encode;
 325                 } else {
 326                         alaw->getput_idx = snd_pcm_linear_put_index(SND_PCM_FORMAT_S16, alaw->sformat);
 327                         alaw->func = snd_pcm_alaw_decode;
 328                 }
 329         } else {
 330                 if (alaw->sformat == SND_PCM_FORMAT_A_LAW) {
 331                         alaw->getput_idx = snd_pcm_linear_put_index(SND_PCM_FORMAT_S16, format);
 332                         alaw->func = snd_pcm_alaw_decode;
 333                 } else {
 334                         alaw->getput_idx = snd_pcm_linear_get_index(alaw->sformat, SND_PCM_FORMAT_S16);
 335                         alaw->func = snd_pcm_alaw_encode;
 336                 }
 337         }
 338         return 0;
 339 }
 340
 341 static snd_pcm_uframes_t
 342 snd_pcm_alaw_write_areas(snd_pcm_t *pcm,
 343                          const snd_pcm_channel_area_t *areas,
 344                          snd_pcm_uframes_t offset,
 345                          snd_pcm_uframes_t size,
 346                          const snd_pcm_channel_area_t *slave_areas,
 347                          snd_pcm_uframes_t slave_offset,
 348                          snd_pcm_uframes_t *slave_sizep)
 349 {
 350         snd_pcm_alaw_t *alaw = pcm->private_data;
 351         if (size > *slave_sizep)
 352                 size = *slave_sizep;
 353         alaw->func(slave_areas, slave_offset,
 354                    areas, offset,
 355                    pcm->channels, size,
 356                    alaw->getput_idx);
 357         *slave_sizep = size;
 358         return size;
 359 }
 360
 361 static snd_pcm_uframes_t
 362 snd_pcm_alaw_read_areas(snd_pcm_t *pcm,
 363                         const snd_pcm_channel_area_t *areas,
 364                         snd_pcm_uframes_t offset,
 365                         snd_pcm_uframes_t size,
 366                         const snd_pcm_channel_area_t *slave_areas,
 367                         snd_pcm_uframes_t slave_offset,
 368                         snd_pcm_uframes_t *slave_sizep)
 369 {
 370         snd_pcm_alaw_t *alaw = pcm->private_data;
 371         if (size > *slave_sizep)
 372                 size = *slave_sizep;
 373         alaw->func(areas, offset,
 374                    slave_areas, slave_offset,
 375                    pcm->channels, size,
 376                    alaw->getput_idx);
 377         *slave_sizep = size;
 378         return size;
 379 }
 380
 381 static void snd_pcm_alaw_dump(snd_pcm_t *pcm, snd_output_t *out)
 382 {
 383         snd_pcm_alaw_t *alaw = pcm->private_data;
 384         snd_output_printf(out, "A-Law conversion PCM (%s)\n",
 385                 snd_pcm_format_name(alaw->sformat));
 386         if (pcm->setup) {
 387                 snd_output_printf(out, "Its setup is:\n");
 388                 snd_pcm_dump_setup(pcm, out);
 389         }
 390         snd_output_printf(out, "Slave: ");
 391         snd_pcm_dump(alaw->plug.gen.slave, out);
 392 }
 393
 394 static const snd_pcm_ops_t snd_pcm_alaw_ops = {
 395         .close = snd_pcm_generic_close,
 396         .info = snd_pcm_generic_info,
 397         .hw_refine = snd_pcm_alaw_hw_refine,
 398         .hw_params = snd_pcm_alaw_hw_params,
 399         .hw_free = snd_pcm_generic_hw_free,
 400         .sw_params = snd_pcm_generic_sw_params,
 401         .channel_info = snd_pcm_generic_channel_info,
 402         .dump = snd_pcm_alaw_dump,
 403         .nonblock = snd_pcm_generic_nonblock,
 404         .async = snd_pcm_generic_async,
 405         .mmap = snd_pcm_generic_mmap,
 406         .munmap = snd_pcm_generic_munmap,
 407 };
 408
 409 /**
 410  * \brief Creates a new A-Law conversion PCM
 411  * \param pcmp Returns created PCM handle
 412  * \param name Name of PCM
 413  * \param sformat Slave (destination) format
 414  * \param slave Slave PCM handle
 415  * \param close_slave When set, the slave PCM handle is closed with copy PCM
 416  * \retval zero on success otherwise a negative error code
 417  * \warning Using of this function might be dangerous in the sense
 418  *          of compatibility reasons. The prototype might be freely
 419  *          changed in future.
 420  */
 421 int snd_pcm_alaw_open(snd_pcm_t **pcmp, const char *name, snd_pcm_format_t sformat, snd_pcm_t *slave, int close_slave)
 422 {
 423         snd_pcm_t *pcm;
 424         snd_pcm_alaw_t *alaw;
 425         int err;
 426         assert(pcmp && slave);
 427         if (snd_pcm_format_linear(sformat) != 1 &&
 428             sformat != SND_PCM_FORMAT_A_LAW)
 429                 return -EINVAL;
 430         alaw = calloc(1, sizeof(snd_pcm_alaw_t));
 431         if (!alaw) {
 432                 return -ENOMEM;
 433         }
 434         snd_pcm_plugin_init(&alaw->plug);
 435         alaw->sformat = sformat;
 436         alaw->plug.read = snd_pcm_alaw_read_areas;
 437         alaw->plug.write = snd_pcm_alaw_write_areas;
 438         alaw->plug.undo_read = snd_pcm_plugin_undo_read_generic;
 439         alaw->plug.undo_write = snd_pcm_plugin_undo_write_generic;
 440         alaw->plug.gen.slave = slave;
 441         alaw->plug.gen.close_slave = close_slave;
 442
 443         err = snd_pcm_new(&pcm, SND_PCM_TYPE_ALAW, name, slave->stream, slave->mode);
 444         if (err < 0) {
 445                 free(alaw);
 446                 return err;
 447         }
 448         pcm->ops = &snd_pcm_alaw_ops;
 449         pcm->fast_ops = &snd_pcm_plugin_fast_ops;
 450         pcm->private_data = alaw;
 451         pcm->poll_fd = slave->poll_fd;
 452         pcm->poll_events = slave->poll_events;
 453         pcm->monotonic = slave->monotonic;
 454         snd_pcm_set_hw_ptr(pcm, &alaw->plug.hw_ptr, -1, 0);
 455         snd_pcm_set_appl_ptr(pcm, &alaw->plug.appl_ptr, -1, 0);
 456         *pcmp = pcm;
 457
 458         return 0;
 459 }
 460
 461 /*! \page pcm_plugins
 462
 463 \section pcm_plugins_alaw Plugin: A-Law
 464
 465 This plugin converts A-Law samples to linear or linear to A-Law samples
 466 from master A-Law conversion PCM to given slave PCM. The channel count,
 467 format and rate must match for both of them.
 468
 469 \code
 470 pcm.name {
 471         type alaw               # A-Law conversion PCM
 472         slave STR               # Slave name
 473         # or
 474         slave {                 # Slave definition
 475                 pcm STR         # Slave PCM name
 476                 # or
 477                 pcm { }         # Slave PCM definition
 478                 format STR      # Slave format
 479         }
 480 }
 481 \endcode
 482
 483 \subsection pcm_plugins_alaw_funcref Function reference
 484
 485 <UL>
 486   <LI>snd_pcm_alaw_open()
 487   <LI>_snd_pcm_alaw_open()
 488 </UL>
 489
 490 */
 491
 492 /**
 493  * \brief Creates a new A-Law conversion PCM
 494  * \param pcmp Returns created PCM handle
 495  * \param name Name of PCM
 496  * \param root Root configuration node
 497  * \param conf Configuration node with copy PCM description
 498  * \param stream Stream type
 499  * \param mode Stream mode
 500  * \retval zero on success otherwise a negative error code
 501  * \warning Using of this function might be dangerous in the sense
 502  *          of compatibility reasons. The prototype might be freely
 503  *          changed in future.
 504  */
 505 int _snd_pcm_alaw_open(snd_pcm_t **pcmp, const char *name,
 506                        snd_config_t *root, snd_config_t *conf,
 507                        snd_pcm_stream_t stream, int mode)
 508 {
 509         snd_config_iterator_t i, next;
 510         int err;
 511         snd_pcm_t *spcm;
 512         snd_config_t *slave = NULL, *sconf;
 513         snd_pcm_format_t sformat;
 514         snd_config_for_each(i, next, conf) {
 515                 snd_config_t *n = snd_config_iterator_entry(i);
 516                 const char *id;
 517                 if (snd_config_get_id(n, &id) < 0)
 518                         continue;
 519                 if (snd_pcm_conf_generic_id(id))
 520                         continue;
 521                 if (strcmp(id, "slave") == 0) {
 522                         slave = n;
 523                         continue;
 524                 }
 525                 SNDERR("Unknown field %s", id);
 526                 return -EINVAL;
 527         }
 528         if (!slave) {
 529                 SNDERR("slave is not defined");
 530                 return -EINVAL;
 531         }
 532         err = snd_pcm_slave_conf(root, slave, &sconf, 1,
 533                                  SND_PCM_HW_PARAM_FORMAT, SCONF_MANDATORY, &sformat);
 534         if (err < 0)
 535                 return err;
 536         if (snd_pcm_format_linear(sformat) != 1 &&
 537             sformat != SND_PCM_FORMAT_A_LAW) {
 538                 snd_config_delete(sconf);
 539                 SNDERR("invalid slave format");
 540                 return -EINVAL;
 541         }
 542         err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode, conf);
 543         snd_config_delete(sconf);
 544         if (err < 0)
 545                 return err;
 546         err = snd_pcm_alaw_open(pcmp, name, sformat, spcm, 1);
 547         if (err < 0)
 548                 snd_pcm_close(spcm);
 549         return err;
 550 }
 551 #ifndef DOC_HIDDEN
 552 SND_DLSYM_BUILD_VERSION(_snd_pcm_alaw_open, SND_PCM_DLSYM_VERSION);
 553 #endif