1/** 2 * \file pcm/pcm_mulaw.c 3 * \ingroup PCM_Plugins 4 * \brief PCM Mu-Law Conversion Plugin Interface 5 * \author Abramo Bagnara <abramo@alsa-project.org> 6 * \date 2000-2001 7 */ 8/* 9 * PCM - Mu-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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 26 * 27 */ 28 29#include "pcm_local.h" 30#include "pcm_plugin.h" 31#include "plugin_ops.h" 32#include "bswap.h" 33 34#ifndef PIC 35/* entry for static linking */ 36const char *_snd_module_pcm_mulaw = ""; 37#endif 38 39#ifndef DOC_HIDDEN 40 41typedef void (*mulaw_f)(const snd_pcm_channel_area_t *src_areas, 42 snd_pcm_uframes_t src_offset, 43 const snd_pcm_channel_area_t *dst_areas, 44 snd_pcm_uframes_t dst_offset, 45 unsigned int channels, snd_pcm_uframes_t frames, 46 unsigned int getputidx); 47 48typedef struct { 49 /* This field need to be the first */ 50 snd_pcm_plugin_t plug; 51 unsigned int getput_idx; 52 mulaw_f func; 53 snd_pcm_format_t sformat; 54} snd_pcm_mulaw_t; 55 56#endif 57 58static inline int val_seg(int val) 59{ 60 int r = 0; 61 val >>= 7; 62 if (val & 0xf0) { 63 val >>= 4; 64 r += 4; 65 } 66 if (val & 0x0c) { 67 val >>= 2; 68 r += 2; 69 } 70 if (val & 0x02) 71 r += 1; 72 return r; 73} 74 75/* 76 * s16_to_ulaw() - Convert a linear PCM value to u-law 77 * 78 * In order to simplify the encoding process, the original linear magnitude 79 * is biased by adding 33 which shifts the encoding range from (0 - 8158) to 80 * (33 - 8191). The result can be seen in the following encoding table: 81 * 82 * Biased Linear Input Code Compressed Code 83 * ------------------------ --------------- 84 * 00000001wxyza 000wxyz 85 * 0000001wxyzab 001wxyz 86 * 000001wxyzabc 010wxyz 87 * 00001wxyzabcd 011wxyz 88 * 0001wxyzabcde 100wxyz 89 * 001wxyzabcdef 101wxyz 90 * 01wxyzabcdefg 110wxyz 91 * 1wxyzabcdefgh 111wxyz 92 * 93 * Each biased linear code has a leading 1 which identifies the segment 94 * number. The value of the segment number is equal to 7 minus the number 95 * of leading 0's. The quantization interval is directly available as the 96 * four bits wxyz. * The trailing bits (a - h) are ignored. 97 * 98 * Ordinarily the complement of the resulting code word is used for 99 * transmission, and so the code word is complemented before it is returned. 100 * 101 * For further information see John C. Bellamy's Digital Telephony, 1982, 102 * John Wiley & Sons, pps 98-111 and 472-476. 103 */ 104 105static unsigned char s16_to_ulaw(int pcm_val) /* 2's complement (16-bit range) */ 106{ 107 int mask; 108 int seg; 109 unsigned char uval; 110 111 if (pcm_val < 0) { 112 pcm_val = 0x84 - pcm_val; 113 mask = 0x7f; 114 } else { 115 pcm_val += 0x84; 116 mask = 0xff; 117 } 118 if (pcm_val > 0x7fff) 119 pcm_val = 0x7fff; 120 121 /* Convert the scaled magnitude to segment number. */ 122 seg = val_seg(pcm_val); 123 124 /* 125 * Combine the sign, segment, quantization bits; 126 * and complement the code word. 127 */ 128 uval = (seg << 4) | ((pcm_val >> (seg + 3)) & 0x0f); 129 return uval ^ mask; 130} 131 132/* 133 * ulaw_to_s16() - Convert a u-law value to 16-bit linear PCM 134 * 135 * First, a biased linear code is derived from the code word. An unbiased 136 * output can then be obtained by subtracting 33 from the biased code. 137 * 138 * Note that this function expects to be passed the complement of the 139 * original code word. This is in keeping with ISDN conventions. 140 */ 141static int ulaw_to_s16(unsigned char u_val) 142{ 143 int t; 144 145 /* Complement to obtain normal u-law value. */ 146 u_val = ~u_val; 147 148 /* 149 * Extract and bias the quantization bits. Then 150 * shift up by the segment number and subtract out the bias. 151 */ 152 t = ((u_val & 0x0f) << 3) + 0x84; 153 t <<= (u_val & 0x70) >> 4; 154 155 return ((u_val & 0x80) ? (0x84 - t) : (t - 0x84)); 156} 157 158#ifndef DOC_HIDDEN 159 160void snd_pcm_mulaw_decode(const snd_pcm_channel_area_t *dst_areas, 161 snd_pcm_uframes_t dst_offset, 162 const snd_pcm_channel_area_t *src_areas, 163 snd_pcm_uframes_t src_offset, 164 unsigned int channels, snd_pcm_uframes_t frames, 165 unsigned int putidx) 166{ 167#define PUT16_LABELS 168#include "plugin_ops.h" 169#undef PUT16_LABELS 170 void *put = put16_labels[putidx]; 171 unsigned int channel; 172 for (channel = 0; channel < channels; ++channel) { 173 const unsigned char *src; 174 char *dst; 175 int src_step, dst_step; 176 snd_pcm_uframes_t frames1; 177 const snd_pcm_channel_area_t *src_area = &src_areas[channel]; 178 const snd_pcm_channel_area_t *dst_area = &dst_areas[channel]; 179 src = snd_pcm_channel_area_addr(src_area, src_offset); 180 dst = snd_pcm_channel_area_addr(dst_area, dst_offset); 181 src_step = snd_pcm_channel_area_step(src_area); 182 dst_step = snd_pcm_channel_area_step(dst_area); 183 frames1 = frames; 184 while (frames1-- > 0) { 185 int16_t sample = ulaw_to_s16(*src); 186 goto *put; 187#define PUT16_END after 188#include "plugin_ops.h" 189#undef PUT16_END 190 after: 191 src += src_step; 192 dst += dst_step; 193 } 194 } 195} 196 197void snd_pcm_mulaw_encode(const snd_pcm_channel_area_t *dst_areas, 198 snd_pcm_uframes_t dst_offset, 199 const snd_pcm_channel_area_t *src_areas, 200 snd_pcm_uframes_t src_offset, 201 unsigned int channels, snd_pcm_uframes_t frames, 202 unsigned int getidx) 203{ 204#define GET16_LABELS 205#include "plugin_ops.h" 206#undef GET16_LABELS 207 void *get = get16_labels[getidx]; 208 unsigned int channel; 209 int16_t sample = 0; 210 for (channel = 0; channel < channels; ++channel) { 211 const char *src; 212 char *dst; 213 int src_step, dst_step; 214 snd_pcm_uframes_t frames1; 215 const snd_pcm_channel_area_t *src_area = &src_areas[channel]; 216 const snd_pcm_channel_area_t *dst_area = &dst_areas[channel]; 217 src = snd_pcm_channel_area_addr(src_area, src_offset); 218 dst = snd_pcm_channel_area_addr(dst_area, dst_offset); 219 src_step = snd_pcm_channel_area_step(src_area); 220 dst_step = snd_pcm_channel_area_step(dst_area); 221 frames1 = frames; 222 while (frames1-- > 0) { 223 goto *get; 224#define GET16_END after 225#include "plugin_ops.h" 226#undef GET16_END 227 after: 228 *dst = s16_to_ulaw(sample); 229 src += src_step; 230 dst += dst_step; 231 } 232 } 233} 234 235#endif /* DOC_HIDDEN */ 236 237static int snd_pcm_mulaw_hw_refine_cprepare(snd_pcm_t *pcm, snd_pcm_hw_params_t *params) 238{ 239 snd_pcm_mulaw_t *mulaw = pcm->private_data; 240 int err; 241 snd_pcm_access_mask_t access_mask = { SND_PCM_ACCBIT_SHM }; 242 err = _snd_pcm_hw_param_set_mask(params, SND_PCM_HW_PARAM_ACCESS, 243 &access_mask); 244 if (err < 0) 245 return err; 246 if (mulaw->sformat == SND_PCM_FORMAT_MU_LAW) { 247 snd_pcm_format_mask_t format_mask= { SND_PCM_FMTBIT_LINEAR }; 248 err = _snd_pcm_hw_param_set_mask(params, SND_PCM_HW_PARAM_FORMAT, 249 &format_mask); 250 } else { 251 err = _snd_pcm_hw_params_set_format(params, 252 SND_PCM_FORMAT_MU_LAW); 253 } 254 err = _snd_pcm_hw_params_set_subformat(params, SND_PCM_SUBFORMAT_STD); 255 if (err < 0) 256 return err; 257 params->info &= ~(SND_PCM_INFO_MMAP | SND_PCM_INFO_MMAP_VALID); 258 return 0; 259} 260 261static int snd_pcm_mulaw_hw_refine_sprepare(snd_pcm_t *pcm, snd_pcm_hw_params_t *sparams) 262{ 263 snd_pcm_mulaw_t *mulaw = pcm->private_data; 264 snd_pcm_access_mask_t saccess_mask = { SND_PCM_ACCBIT_MMAP }; 265 _snd_pcm_hw_params_any(sparams); 266 _snd_pcm_hw_param_set_mask(sparams, SND_PCM_HW_PARAM_ACCESS, 267 &saccess_mask); 268 _snd_pcm_hw_params_set_format(sparams, mulaw->sformat); 269 _snd_pcm_hw_params_set_subformat(sparams, SND_PCM_SUBFORMAT_STD); 270 return 0; 271} 272 273static int snd_pcm_mulaw_hw_refine_schange(snd_pcm_t *pcm ATTRIBUTE_UNUSED, snd_pcm_hw_params_t *params, 274 snd_pcm_hw_params_t *sparams) 275{ 276 int err; 277 unsigned int links = (SND_PCM_HW_PARBIT_CHANNELS | 278 SND_PCM_HW_PARBIT_RATE | 279 SND_PCM_HW_PARBIT_PERIOD_SIZE | 280 SND_PCM_HW_PARBIT_BUFFER_SIZE | 281 SND_PCM_HW_PARBIT_PERIODS | 282 SND_PCM_HW_PARBIT_PERIOD_TIME | 283 SND_PCM_HW_PARBIT_BUFFER_TIME | 284 SND_PCM_HW_PARBIT_TICK_TIME); 285 err = _snd_pcm_hw_params_refine(sparams, links, params); 286 if (err < 0) 287 return err; 288 return 0; 289} 290 291static int snd_pcm_mulaw_hw_refine_cchange(snd_pcm_t *pcm ATTRIBUTE_UNUSED, snd_pcm_hw_params_t *params, 292 snd_pcm_hw_params_t *sparams) 293{ 294 int err; 295 unsigned int links = (SND_PCM_HW_PARBIT_CHANNELS | 296 SND_PCM_HW_PARBIT_RATE | 297 SND_PCM_HW_PARBIT_PERIOD_SIZE | 298 SND_PCM_HW_PARBIT_BUFFER_SIZE | 299 SND_PCM_HW_PARBIT_PERIODS | 300 SND_PCM_HW_PARBIT_PERIOD_TIME | 301 SND_PCM_HW_PARBIT_BUFFER_TIME | 302 SND_PCM_HW_PARBIT_TICK_TIME); 303 err = _snd_pcm_hw_params_refine(params, links, sparams); 304 if (err < 0) 305 return err; 306 return 0; 307} 308 309static int snd_pcm_mulaw_hw_refine(snd_pcm_t *pcm, snd_pcm_hw_params_t *params) 310{ 311 return snd_pcm_hw_refine_slave(pcm, params, 312 snd_pcm_mulaw_hw_refine_cprepare, 313 snd_pcm_mulaw_hw_refine_cchange, 314 snd_pcm_mulaw_hw_refine_sprepare, 315 snd_pcm_mulaw_hw_refine_schange, 316 snd_pcm_generic_hw_refine); 317} 318 319static int snd_pcm_mulaw_hw_params(snd_pcm_t *pcm, snd_pcm_hw_params_t * params) 320{ 321 snd_pcm_mulaw_t *mulaw = pcm->private_data; 322 snd_pcm_format_t format; 323 int err = snd_pcm_hw_params_slave(pcm, params, 324 snd_pcm_mulaw_hw_refine_cchange, 325 snd_pcm_mulaw_hw_refine_sprepare, 326 snd_pcm_mulaw_hw_refine_schange, 327 snd_pcm_generic_hw_params); 328 if (err < 0) 329 return err; 330 331 err = INTERNAL(snd_pcm_hw_params_get_format)(params, &format); 332 if (err < 0) 333 return err; 334 335 if (pcm->stream == SND_PCM_STREAM_PLAYBACK) { 336 if (mulaw->sformat == SND_PCM_FORMAT_MU_LAW) { 337 mulaw->getput_idx = snd_pcm_linear_get_index(format, SND_PCM_FORMAT_S16); 338 mulaw->func = snd_pcm_mulaw_encode; 339 } else { 340 mulaw->getput_idx = snd_pcm_linear_put_index(SND_PCM_FORMAT_S16, mulaw->sformat); 341 mulaw->func = snd_pcm_mulaw_decode; 342 } 343 } else { 344 if (mulaw->sformat == SND_PCM_FORMAT_MU_LAW) { 345 mulaw->getput_idx = snd_pcm_linear_put_index(SND_PCM_FORMAT_S16, format); 346 mulaw->func = snd_pcm_mulaw_decode; 347 } else { 348 mulaw->getput_idx = snd_pcm_linear_get_index(mulaw->sformat, SND_PCM_FORMAT_S16); 349 mulaw->func = snd_pcm_mulaw_encode; 350 } 351 } 352 return 0; 353} 354 355static snd_pcm_uframes_t 356snd_pcm_mulaw_write_areas(snd_pcm_t *pcm, 357 const snd_pcm_channel_area_t *areas, 358 snd_pcm_uframes_t offset, 359 snd_pcm_uframes_t size, 360 const snd_pcm_channel_area_t *slave_areas, 361 snd_pcm_uframes_t slave_offset, 362 snd_pcm_uframes_t *slave_sizep) 363{ 364 snd_pcm_mulaw_t *mulaw = pcm->private_data; 365 if (size > *slave_sizep) 366 size = *slave_sizep; 367 mulaw->func(slave_areas, slave_offset, 368 areas, offset, 369 pcm->channels, size, 370 mulaw->getput_idx); 371 *slave_sizep = size; 372 return size; 373} 374 375static snd_pcm_uframes_t 376snd_pcm_mulaw_read_areas(snd_pcm_t *pcm, 377 const snd_pcm_channel_area_t *areas, 378 snd_pcm_uframes_t offset, 379 snd_pcm_uframes_t size, 380 const snd_pcm_channel_area_t *slave_areas, 381 snd_pcm_uframes_t slave_offset, 382 snd_pcm_uframes_t *slave_sizep) 383{ 384 snd_pcm_mulaw_t *mulaw = pcm->private_data; 385 if (size > *slave_sizep) 386 size = *slave_sizep; 387 mulaw->func(areas, offset, 388 slave_areas, slave_offset, 389 pcm->channels, size, 390 mulaw->getput_idx); 391 *slave_sizep = size; 392 return size; 393} 394 395static void snd_pcm_mulaw_dump(snd_pcm_t *pcm, snd_output_t *out) 396{ 397 snd_pcm_mulaw_t *mulaw = pcm->private_data; 398 snd_output_printf(out, "Mu-Law conversion PCM (%s)\n", 399 snd_pcm_format_name(mulaw->sformat)); 400 if (pcm->setup) { 401 snd_output_printf(out, "Its setup is:\n"); 402 snd_pcm_dump_setup(pcm, out); 403 } 404 snd_output_printf(out, "Slave: "); 405 snd_pcm_dump(mulaw->plug.gen.slave, out); 406} 407 408static const snd_pcm_ops_t snd_pcm_mulaw_ops = { 409 .close = snd_pcm_generic_close, 410 .info = snd_pcm_generic_info, 411 .hw_refine = snd_pcm_mulaw_hw_refine, 412 .hw_params = snd_pcm_mulaw_hw_params, 413 .hw_free = snd_pcm_generic_hw_free, 414 .sw_params = snd_pcm_generic_sw_params, 415 .channel_info = snd_pcm_generic_channel_info, 416 .dump = snd_pcm_mulaw_dump, 417 .nonblock = snd_pcm_generic_nonblock, 418 .async = snd_pcm_generic_async, 419 .mmap = snd_pcm_generic_mmap, 420 .munmap = snd_pcm_generic_munmap, 421 .get_chmap = snd_pcm_generic_get_chmap, 422 .set_chmap = snd_pcm_generic_set_chmap, 423}; 424 425/** 426 * \brief Creates a new Mu-Law conversion PCM 427 * \param pcmp Returns created PCM handle 428 * \param name Name of PCM 429 * \param sformat Slave (destination) format 430 * \param slave Slave PCM handle 431 * \param close_slave When set, the slave PCM handle is closed with copy PCM 432 * \retval zero on success otherwise a negative error code 433 * \warning Using of this function might be dangerous in the sense 434 * of compatibility reasons. The prototype might be freely 435 * changed in future. 436 */ 437int snd_pcm_mulaw_open(snd_pcm_t **pcmp, const char *name, snd_pcm_format_t sformat, snd_pcm_t *slave, int close_slave) 438{ 439 snd_pcm_t *pcm; 440 snd_pcm_mulaw_t *mulaw; 441 int err; 442 assert(pcmp && slave); 443 if (snd_pcm_format_linear(sformat) != 1 && 444 sformat != SND_PCM_FORMAT_MU_LAW) 445 return -EINVAL; 446 mulaw = calloc(1, sizeof(snd_pcm_mulaw_t)); 447 if (!mulaw) { 448 return -ENOMEM; 449 } 450 snd_pcm_plugin_init(&mulaw->plug); 451 mulaw->sformat = sformat; 452 mulaw->plug.read = snd_pcm_mulaw_read_areas; 453 mulaw->plug.write = snd_pcm_mulaw_write_areas; 454 mulaw->plug.undo_read = snd_pcm_plugin_undo_read_generic; 455 mulaw->plug.undo_write = snd_pcm_plugin_undo_write_generic; 456 mulaw->plug.gen.slave = slave; 457 mulaw->plug.gen.close_slave = close_slave; 458 459 err = snd_pcm_new(&pcm, SND_PCM_TYPE_MULAW, name, slave->stream, slave->mode); 460 if (err < 0) { 461 free(mulaw); 462 return err; 463 } 464 pcm->ops = &snd_pcm_mulaw_ops; 465 pcm->fast_ops = &snd_pcm_plugin_fast_ops; 466 pcm->private_data = mulaw; 467 pcm->poll_fd = slave->poll_fd; 468 pcm->poll_events = slave->poll_events; 469 pcm->tstamp_type = slave->tstamp_type; 470 snd_pcm_set_hw_ptr(pcm, &mulaw->plug.hw_ptr, -1, 0); 471 snd_pcm_set_appl_ptr(pcm, &mulaw->plug.appl_ptr, -1, 0); 472 *pcmp = pcm; 473 474 return 0; 475} 476 477/*! \page pcm_plugins 478 479\section pcm_plugins_mulaw Plugin: Mu-Law 480 481This plugin converts Mu-Law samples to linear or linear to Mu-Law samples 482from master Mu-Law conversion PCM to given slave PCM. The channel count, 483format and rate must match for both of them. 484 485\code 486pcm.name { 487 type mulaw # Mu-Law conversion PCM 488 slave STR # Slave name 489 # or 490 slave { # Slave definition 491 pcm STR # Slave PCM name 492 # or 493 pcm { } # Slave PCM definition 494 format STR # Slave format 495 } 496} 497\endcode 498 499\subsection pcm_plugins_mulaw_funcref Function reference 500 501<UL> 502 <LI>snd_pcm_mulaw_open() 503 <LI>_snd_pcm_mulaw_open() 504</UL> 505 506*/ 507 508/** 509 * \brief Creates a new Mu-Law conversion PCM 510 * \param pcmp Returns created PCM handle 511 * \param name Name of PCM 512 * \param root Root configuration node 513 * \param conf Configuration node with copy PCM description 514 * \param stream Stream type 515 * \param mode Stream mode 516 * \retval zero on success otherwise a negative error code 517 * \warning Using of this function might be dangerous in the sense 518 * of compatibility reasons. The prototype might be freely 519 * changed in future. 520 */ 521int _snd_pcm_mulaw_open(snd_pcm_t **pcmp, const char *name, 522 snd_config_t *root, snd_config_t *conf, 523 snd_pcm_stream_t stream, int mode) 524{ 525 snd_config_iterator_t i, next; 526 int err; 527 snd_pcm_t *spcm; 528 snd_config_t *slave = NULL, *sconf; 529 snd_pcm_format_t sformat; 530 snd_config_for_each(i, next, conf) { 531 snd_config_t *n = snd_config_iterator_entry(i); 532 const char *id; 533 if (snd_config_get_id(n, &id) < 0) 534 continue; 535 if (snd_pcm_conf_generic_id(id)) 536 continue; 537 if (strcmp(id, "slave") == 0) { 538 slave = n; 539 continue; 540 } 541 SNDERR("Unknown field %s", id); 542 return -EINVAL; 543 } 544 if (!slave) { 545 SNDERR("slave is not defined"); 546 return -EINVAL; 547 } 548 err = snd_pcm_slave_conf(root, slave, &sconf, 1, 549 SND_PCM_HW_PARAM_FORMAT, SCONF_MANDATORY, &sformat); 550 if (err < 0) 551 return err; 552 if (snd_pcm_format_linear(sformat) != 1 && 553 sformat != SND_PCM_FORMAT_MU_LAW) { 554 snd_config_delete(sconf); 555 SNDERR("invalid slave format"); 556 return -EINVAL; 557 } 558 err = snd_pcm_open_slave(&spcm, root, sconf, stream, mode, conf); 559 snd_config_delete(sconf); 560 if (err < 0) 561 return err; 562 err = snd_pcm_mulaw_open(pcmp, name, sformat, spcm, 1); 563 if (err < 0) 564 snd_pcm_close(spcm); 565 return err; 566} 567#ifndef DOC_HIDDEN 568SND_DLSYM_BUILD_VERSION(_snd_pcm_mulaw_open, SND_PCM_DLSYM_VERSION); 569#endif 570