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