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