linux/sound/core/pcm_misc.c
<<
>>
Prefs
   1/*
   2 *  PCM Interface - misc routines
   3 *  Copyright (c) 1998 by Jaroslav Kysela <perex@perex.cz>
   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., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  19 *
  20 */
  21  
  22#include <linux/time.h>
  23#include <linux/export.h>
  24#include <sound/core.h>
  25#include <sound/pcm.h>
  26
  27#include "pcm_local.h"
  28
  29#define SND_PCM_FORMAT_UNKNOWN (-1)
  30
  31/* NOTE: "signed" prefix must be given below since the default char is
  32 *       unsigned on some architectures!
  33 */
  34struct pcm_format_data {
  35        unsigned char width;    /* bit width */
  36        unsigned char phys;     /* physical bit width */
  37        signed char le; /* 0 = big-endian, 1 = little-endian, -1 = others */
  38        signed char signd;      /* 0 = unsigned, 1 = signed, -1 = others */
  39        unsigned char silence[8];       /* silence data to fill */
  40};
  41
  42/* we do lots of calculations on snd_pcm_format_t; shut up sparse */
  43#define INT     __force int
  44
  45static bool valid_format(snd_pcm_format_t format)
  46{
  47        return (INT)format >= 0 && (INT)format <= (INT)SNDRV_PCM_FORMAT_LAST;
  48}
  49
  50static const struct pcm_format_data pcm_formats[(INT)SNDRV_PCM_FORMAT_LAST+1] = {
  51        [SNDRV_PCM_FORMAT_S8] = {
  52                .width = 8, .phys = 8, .le = -1, .signd = 1,
  53                .silence = {},
  54        },
  55        [SNDRV_PCM_FORMAT_U8] = {
  56                .width = 8, .phys = 8, .le = -1, .signd = 0,
  57                .silence = { 0x80 },
  58        },
  59        [SNDRV_PCM_FORMAT_S16_LE] = {
  60                .width = 16, .phys = 16, .le = 1, .signd = 1,
  61                .silence = {},
  62        },
  63        [SNDRV_PCM_FORMAT_S16_BE] = {
  64                .width = 16, .phys = 16, .le = 0, .signd = 1,
  65                .silence = {},
  66        },
  67        [SNDRV_PCM_FORMAT_U16_LE] = {
  68                .width = 16, .phys = 16, .le = 1, .signd = 0,
  69                .silence = { 0x00, 0x80 },
  70        },
  71        [SNDRV_PCM_FORMAT_U16_BE] = {
  72                .width = 16, .phys = 16, .le = 0, .signd = 0,
  73                .silence = { 0x80, 0x00 },
  74        },
  75        [SNDRV_PCM_FORMAT_S24_LE] = {
  76                .width = 24, .phys = 32, .le = 1, .signd = 1,
  77                .silence = {},
  78        },
  79        [SNDRV_PCM_FORMAT_S24_BE] = {
  80                .width = 24, .phys = 32, .le = 0, .signd = 1,
  81                .silence = {},
  82        },
  83        [SNDRV_PCM_FORMAT_U24_LE] = {
  84                .width = 24, .phys = 32, .le = 1, .signd = 0,
  85                .silence = { 0x00, 0x00, 0x80 },
  86        },
  87        [SNDRV_PCM_FORMAT_U24_BE] = {
  88                .width = 24, .phys = 32, .le = 0, .signd = 0,
  89                .silence = { 0x00, 0x80, 0x00, 0x00 },
  90        },
  91        [SNDRV_PCM_FORMAT_S32_LE] = {
  92                .width = 32, .phys = 32, .le = 1, .signd = 1,
  93                .silence = {},
  94        },
  95        [SNDRV_PCM_FORMAT_S32_BE] = {
  96                .width = 32, .phys = 32, .le = 0, .signd = 1,
  97                .silence = {},
  98        },
  99        [SNDRV_PCM_FORMAT_U32_LE] = {
 100                .width = 32, .phys = 32, .le = 1, .signd = 0,
 101                .silence = { 0x00, 0x00, 0x00, 0x80 },
 102        },
 103        [SNDRV_PCM_FORMAT_U32_BE] = {
 104                .width = 32, .phys = 32, .le = 0, .signd = 0,
 105                .silence = { 0x80, 0x00, 0x00, 0x00 },
 106        },
 107        [SNDRV_PCM_FORMAT_FLOAT_LE] = {
 108                .width = 32, .phys = 32, .le = 1, .signd = -1,
 109                .silence = {},
 110        },
 111        [SNDRV_PCM_FORMAT_FLOAT_BE] = {
 112                .width = 32, .phys = 32, .le = 0, .signd = -1,
 113                .silence = {},
 114        },
 115        [SNDRV_PCM_FORMAT_FLOAT64_LE] = {
 116                .width = 64, .phys = 64, .le = 1, .signd = -1,
 117                .silence = {},
 118        },
 119        [SNDRV_PCM_FORMAT_FLOAT64_BE] = {
 120                .width = 64, .phys = 64, .le = 0, .signd = -1,
 121                .silence = {},
 122        },
 123        [SNDRV_PCM_FORMAT_IEC958_SUBFRAME_LE] = {
 124                .width = 32, .phys = 32, .le = 1, .signd = -1,
 125                .silence = {},
 126        },
 127        [SNDRV_PCM_FORMAT_IEC958_SUBFRAME_BE] = {
 128                .width = 32, .phys = 32, .le = 0, .signd = -1,
 129                .silence = {},
 130        },
 131        [SNDRV_PCM_FORMAT_MU_LAW] = {
 132                .width = 8, .phys = 8, .le = -1, .signd = -1,
 133                .silence = { 0x7f },
 134        },
 135        [SNDRV_PCM_FORMAT_A_LAW] = {
 136                .width = 8, .phys = 8, .le = -1, .signd = -1,
 137                .silence = { 0x55 },
 138        },
 139        [SNDRV_PCM_FORMAT_IMA_ADPCM] = {
 140                .width = 4, .phys = 4, .le = -1, .signd = -1,
 141                .silence = {},
 142        },
 143        [SNDRV_PCM_FORMAT_G723_24] = {
 144                .width = 3, .phys = 3, .le = -1, .signd = -1,
 145                .silence = {},
 146        },
 147        [SNDRV_PCM_FORMAT_G723_40] = {
 148                .width = 5, .phys = 5, .le = -1, .signd = -1,
 149                .silence = {},
 150        },
 151        [SNDRV_PCM_FORMAT_DSD_U8] = {
 152                .width = 8, .phys = 8, .le = 1, .signd = 0,
 153                .silence = { 0x69 },
 154        },
 155        [SNDRV_PCM_FORMAT_DSD_U16_LE] = {
 156                .width = 16, .phys = 16, .le = 1, .signd = 0,
 157                .silence = { 0x69, 0x69 },
 158        },
 159        [SNDRV_PCM_FORMAT_DSD_U32_LE] = {
 160                .width = 32, .phys = 32, .le = 1, .signd = 0,
 161                .silence = { 0x69, 0x69, 0x69, 0x69 },
 162        },
 163        [SNDRV_PCM_FORMAT_DSD_U16_BE] = {
 164                .width = 16, .phys = 16, .le = 0, .signd = 0,
 165                .silence = { 0x69, 0x69 },
 166        },
 167        [SNDRV_PCM_FORMAT_DSD_U32_BE] = {
 168                .width = 32, .phys = 32, .le = 0, .signd = 0,
 169                .silence = { 0x69, 0x69, 0x69, 0x69 },
 170        },
 171        /* FIXME: the following two formats are not defined properly yet */
 172        [SNDRV_PCM_FORMAT_MPEG] = {
 173                .le = -1, .signd = -1,
 174        },
 175        [SNDRV_PCM_FORMAT_GSM] = {
 176                .le = -1, .signd = -1,
 177        },
 178        [SNDRV_PCM_FORMAT_S20_LE] = {
 179                .width = 20, .phys = 32, .le = 1, .signd = 1,
 180                .silence = {},
 181        },
 182        [SNDRV_PCM_FORMAT_S20_BE] = {
 183                .width = 20, .phys = 32, .le = 0, .signd = 1,
 184                .silence = {},
 185        },
 186        [SNDRV_PCM_FORMAT_U20_LE] = {
 187                .width = 20, .phys = 32, .le = 1, .signd = 0,
 188                .silence = { 0x00, 0x00, 0x08, 0x00 },
 189        },
 190        [SNDRV_PCM_FORMAT_U20_BE] = {
 191                .width = 20, .phys = 32, .le = 0, .signd = 0,
 192                .silence = { 0x00, 0x08, 0x00, 0x00 },
 193        },
 194        /* FIXME: the following format is not defined properly yet */
 195        [SNDRV_PCM_FORMAT_SPECIAL] = {
 196                .le = -1, .signd = -1,
 197        },
 198        [SNDRV_PCM_FORMAT_S24_3LE] = {
 199                .width = 24, .phys = 24, .le = 1, .signd = 1,
 200                .silence = {},
 201        },
 202        [SNDRV_PCM_FORMAT_S24_3BE] = {
 203                .width = 24, .phys = 24, .le = 0, .signd = 1,
 204                .silence = {},
 205        },
 206        [SNDRV_PCM_FORMAT_U24_3LE] = {
 207                .width = 24, .phys = 24, .le = 1, .signd = 0,
 208                .silence = { 0x00, 0x00, 0x80 },
 209        },
 210        [SNDRV_PCM_FORMAT_U24_3BE] = {
 211                .width = 24, .phys = 24, .le = 0, .signd = 0,
 212                .silence = { 0x80, 0x00, 0x00 },
 213        },
 214        [SNDRV_PCM_FORMAT_S20_3LE] = {
 215                .width = 20, .phys = 24, .le = 1, .signd = 1,
 216                .silence = {},
 217        },
 218        [SNDRV_PCM_FORMAT_S20_3BE] = {
 219                .width = 20, .phys = 24, .le = 0, .signd = 1,
 220                .silence = {},
 221        },
 222        [SNDRV_PCM_FORMAT_U20_3LE] = {
 223                .width = 20, .phys = 24, .le = 1, .signd = 0,
 224                .silence = { 0x00, 0x00, 0x08 },
 225        },
 226        [SNDRV_PCM_FORMAT_U20_3BE] = {
 227                .width = 20, .phys = 24, .le = 0, .signd = 0,
 228                .silence = { 0x08, 0x00, 0x00 },
 229        },
 230        [SNDRV_PCM_FORMAT_S18_3LE] = {
 231                .width = 18, .phys = 24, .le = 1, .signd = 1,
 232                .silence = {},
 233        },
 234        [SNDRV_PCM_FORMAT_S18_3BE] = {
 235                .width = 18, .phys = 24, .le = 0, .signd = 1,
 236                .silence = {},
 237        },
 238        [SNDRV_PCM_FORMAT_U18_3LE] = {
 239                .width = 18, .phys = 24, .le = 1, .signd = 0,
 240                .silence = { 0x00, 0x00, 0x02 },
 241        },
 242        [SNDRV_PCM_FORMAT_U18_3BE] = {
 243                .width = 18, .phys = 24, .le = 0, .signd = 0,
 244                .silence = { 0x02, 0x00, 0x00 },
 245        },
 246        [SNDRV_PCM_FORMAT_G723_24_1B] = {
 247                .width = 3, .phys = 8, .le = -1, .signd = -1,
 248                .silence = {},
 249        },
 250        [SNDRV_PCM_FORMAT_G723_40_1B] = {
 251                .width = 5, .phys = 8, .le = -1, .signd = -1,
 252                .silence = {},
 253        },
 254};
 255
 256
 257/**
 258 * snd_pcm_format_signed - Check the PCM format is signed linear
 259 * @format: the format to check
 260 *
 261 * Return: 1 if the given PCM format is signed linear, 0 if unsigned
 262 * linear, and a negative error code for non-linear formats.
 263 */
 264int snd_pcm_format_signed(snd_pcm_format_t format)
 265{
 266        int val;
 267        if (!valid_format(format))
 268                return -EINVAL;
 269        if ((val = pcm_formats[(INT)format].signd) < 0)
 270                return -EINVAL;
 271        return val;
 272}
 273EXPORT_SYMBOL(snd_pcm_format_signed);
 274
 275/**
 276 * snd_pcm_format_unsigned - Check the PCM format is unsigned linear
 277 * @format: the format to check
 278 *
 279 * Return: 1 if the given PCM format is unsigned linear, 0 if signed
 280 * linear, and a negative error code for non-linear formats.
 281 */
 282int snd_pcm_format_unsigned(snd_pcm_format_t format)
 283{
 284        int val;
 285
 286        val = snd_pcm_format_signed(format);
 287        if (val < 0)
 288                return val;
 289        return !val;
 290}
 291EXPORT_SYMBOL(snd_pcm_format_unsigned);
 292
 293/**
 294 * snd_pcm_format_linear - Check the PCM format is linear
 295 * @format: the format to check
 296 *
 297 * Return: 1 if the given PCM format is linear, 0 if not.
 298 */
 299int snd_pcm_format_linear(snd_pcm_format_t format)
 300{
 301        return snd_pcm_format_signed(format) >= 0;
 302}
 303EXPORT_SYMBOL(snd_pcm_format_linear);
 304
 305/**
 306 * snd_pcm_format_little_endian - Check the PCM format is little-endian
 307 * @format: the format to check
 308 *
 309 * Return: 1 if the given PCM format is little-endian, 0 if
 310 * big-endian, or a negative error code if endian not specified.
 311 */
 312int snd_pcm_format_little_endian(snd_pcm_format_t format)
 313{
 314        int val;
 315        if (!valid_format(format))
 316                return -EINVAL;
 317        if ((val = pcm_formats[(INT)format].le) < 0)
 318                return -EINVAL;
 319        return val;
 320}
 321EXPORT_SYMBOL(snd_pcm_format_little_endian);
 322
 323/**
 324 * snd_pcm_format_big_endian - Check the PCM format is big-endian
 325 * @format: the format to check
 326 *
 327 * Return: 1 if the given PCM format is big-endian, 0 if
 328 * little-endian, or a negative error code if endian not specified.
 329 */
 330int snd_pcm_format_big_endian(snd_pcm_format_t format)
 331{
 332        int val;
 333
 334        val = snd_pcm_format_little_endian(format);
 335        if (val < 0)
 336                return val;
 337        return !val;
 338}
 339EXPORT_SYMBOL(snd_pcm_format_big_endian);
 340
 341/**
 342 * snd_pcm_format_width - return the bit-width of the format
 343 * @format: the format to check
 344 *
 345 * Return: The bit-width of the format, or a negative error code
 346 * if unknown format.
 347 */
 348int snd_pcm_format_width(snd_pcm_format_t format)
 349{
 350        int val;
 351        if (!valid_format(format))
 352                return -EINVAL;
 353        if ((val = pcm_formats[(INT)format].width) == 0)
 354                return -EINVAL;
 355        return val;
 356}
 357EXPORT_SYMBOL(snd_pcm_format_width);
 358
 359/**
 360 * snd_pcm_format_physical_width - return the physical bit-width of the format
 361 * @format: the format to check
 362 *
 363 * Return: The physical bit-width of the format, or a negative error code
 364 * if unknown format.
 365 */
 366int snd_pcm_format_physical_width(snd_pcm_format_t format)
 367{
 368        int val;
 369        if (!valid_format(format))
 370                return -EINVAL;
 371        if ((val = pcm_formats[(INT)format].phys) == 0)
 372                return -EINVAL;
 373        return val;
 374}
 375EXPORT_SYMBOL(snd_pcm_format_physical_width);
 376
 377/**
 378 * snd_pcm_format_size - return the byte size of samples on the given format
 379 * @format: the format to check
 380 * @samples: sampling rate
 381 *
 382 * Return: The byte size of the given samples for the format, or a
 383 * negative error code if unknown format.
 384 */
 385ssize_t snd_pcm_format_size(snd_pcm_format_t format, size_t samples)
 386{
 387        int phys_width = snd_pcm_format_physical_width(format);
 388        if (phys_width < 0)
 389                return -EINVAL;
 390        return samples * phys_width / 8;
 391}
 392EXPORT_SYMBOL(snd_pcm_format_size);
 393
 394/**
 395 * snd_pcm_format_silence_64 - return the silent data in 8 bytes array
 396 * @format: the format to check
 397 *
 398 * Return: The format pattern to fill or %NULL if error.
 399 */
 400const unsigned char *snd_pcm_format_silence_64(snd_pcm_format_t format)
 401{
 402        if (!valid_format(format))
 403                return NULL;
 404        if (! pcm_formats[(INT)format].phys)
 405                return NULL;
 406        return pcm_formats[(INT)format].silence;
 407}
 408EXPORT_SYMBOL(snd_pcm_format_silence_64);
 409
 410/**
 411 * snd_pcm_format_set_silence - set the silence data on the buffer
 412 * @format: the PCM format
 413 * @data: the buffer pointer
 414 * @samples: the number of samples to set silence
 415 *
 416 * Sets the silence data on the buffer for the given samples.
 417 *
 418 * Return: Zero if successful, or a negative error code on failure.
 419 */
 420int snd_pcm_format_set_silence(snd_pcm_format_t format, void *data, unsigned int samples)
 421{
 422        int width;
 423        unsigned char *dst;
 424        const unsigned char *pat;
 425
 426        if (!valid_format(format))
 427                return -EINVAL;
 428        if (samples == 0)
 429                return 0;
 430        width = pcm_formats[(INT)format].phys; /* physical width */
 431        pat = pcm_formats[(INT)format].silence;
 432        if (! width)
 433                return -EINVAL;
 434        /* signed or 1 byte data */
 435        if (pcm_formats[(INT)format].signd == 1 || width <= 8) {
 436                unsigned int bytes = samples * width / 8;
 437                memset(data, *pat, bytes);
 438                return 0;
 439        }
 440        /* non-zero samples, fill using a loop */
 441        width /= 8;
 442        dst = data;
 443#if 0
 444        while (samples--) {
 445                memcpy(dst, pat, width);
 446                dst += width;
 447        }
 448#else
 449        /* a bit optimization for constant width */
 450        switch (width) {
 451        case 2:
 452                while (samples--) {
 453                        memcpy(dst, pat, 2);
 454                        dst += 2;
 455                }
 456                break;
 457        case 3:
 458                while (samples--) {
 459                        memcpy(dst, pat, 3);
 460                        dst += 3;
 461                }
 462                break;
 463        case 4:
 464                while (samples--) {
 465                        memcpy(dst, pat, 4);
 466                        dst += 4;
 467                }
 468                break;
 469        case 8:
 470                while (samples--) {
 471                        memcpy(dst, pat, 8);
 472                        dst += 8;
 473                }
 474                break;
 475        }
 476#endif
 477        return 0;
 478}
 479EXPORT_SYMBOL(snd_pcm_format_set_silence);
 480
 481/**
 482 * snd_pcm_hw_limit_rates - determine rate_min/rate_max fields
 483 * @hw: the pcm hw instance
 484 *
 485 * Determines the rate_min and rate_max fields from the rates bits of
 486 * the given hw.
 487 *
 488 * Return: Zero if successful.
 489 */
 490int snd_pcm_hw_limit_rates(struct snd_pcm_hardware *hw)
 491{
 492        int i;
 493        for (i = 0; i < (int)snd_pcm_known_rates.count; i++) {
 494                if (hw->rates & (1 << i)) {
 495                        hw->rate_min = snd_pcm_known_rates.list[i];
 496                        break;
 497                }
 498        }
 499        for (i = (int)snd_pcm_known_rates.count - 1; i >= 0; i--) {
 500                if (hw->rates & (1 << i)) {
 501                        hw->rate_max = snd_pcm_known_rates.list[i];
 502                        break;
 503                }
 504        }
 505        return 0;
 506}
 507EXPORT_SYMBOL(snd_pcm_hw_limit_rates);
 508
 509/**
 510 * snd_pcm_rate_to_rate_bit - converts sample rate to SNDRV_PCM_RATE_xxx bit
 511 * @rate: the sample rate to convert
 512 *
 513 * Return: The SNDRV_PCM_RATE_xxx flag that corresponds to the given rate, or
 514 * SNDRV_PCM_RATE_KNOT for an unknown rate.
 515 */
 516unsigned int snd_pcm_rate_to_rate_bit(unsigned int rate)
 517{
 518        unsigned int i;
 519
 520        for (i = 0; i < snd_pcm_known_rates.count; i++)
 521                if (snd_pcm_known_rates.list[i] == rate)
 522                        return 1u << i;
 523        return SNDRV_PCM_RATE_KNOT;
 524}
 525EXPORT_SYMBOL(snd_pcm_rate_to_rate_bit);
 526
 527/**
 528 * snd_pcm_rate_bit_to_rate - converts SNDRV_PCM_RATE_xxx bit to sample rate
 529 * @rate_bit: the rate bit to convert
 530 *
 531 * Return: The sample rate that corresponds to the given SNDRV_PCM_RATE_xxx flag
 532 * or 0 for an unknown rate bit.
 533 */
 534unsigned int snd_pcm_rate_bit_to_rate(unsigned int rate_bit)
 535{
 536        unsigned int i;
 537
 538        for (i = 0; i < snd_pcm_known_rates.count; i++)
 539                if ((1u << i) == rate_bit)
 540                        return snd_pcm_known_rates.list[i];
 541        return 0;
 542}
 543EXPORT_SYMBOL(snd_pcm_rate_bit_to_rate);
 544
 545static unsigned int snd_pcm_rate_mask_sanitize(unsigned int rates)
 546{
 547        if (rates & SNDRV_PCM_RATE_CONTINUOUS)
 548                return SNDRV_PCM_RATE_CONTINUOUS;
 549        else if (rates & SNDRV_PCM_RATE_KNOT)
 550                return SNDRV_PCM_RATE_KNOT;
 551        return rates;
 552}
 553
 554/**
 555 * snd_pcm_rate_mask_intersect - computes the intersection between two rate masks
 556 * @rates_a: The first rate mask
 557 * @rates_b: The second rate mask
 558 *
 559 * This function computes the rates that are supported by both rate masks passed
 560 * to the function. It will take care of the special handling of
 561 * SNDRV_PCM_RATE_CONTINUOUS and SNDRV_PCM_RATE_KNOT.
 562 *
 563 * Return: A rate mask containing the rates that are supported by both rates_a
 564 * and rates_b.
 565 */
 566unsigned int snd_pcm_rate_mask_intersect(unsigned int rates_a,
 567        unsigned int rates_b)
 568{
 569        rates_a = snd_pcm_rate_mask_sanitize(rates_a);
 570        rates_b = snd_pcm_rate_mask_sanitize(rates_b);
 571
 572        if (rates_a & SNDRV_PCM_RATE_CONTINUOUS)
 573                return rates_b;
 574        else if (rates_b & SNDRV_PCM_RATE_CONTINUOUS)
 575                return rates_a;
 576        else if (rates_a & SNDRV_PCM_RATE_KNOT)
 577                return rates_b;
 578        else if (rates_b & SNDRV_PCM_RATE_KNOT)
 579                return rates_a;
 580        return rates_a & rates_b;
 581}
 582EXPORT_SYMBOL_GPL(snd_pcm_rate_mask_intersect);
 583
 584/**
 585 * snd_pcm_rate_range_to_bits - converts rate range to SNDRV_PCM_RATE_xxx bit
 586 * @rate_min: the minimum sample rate
 587 * @rate_max: the maximum sample rate
 588 *
 589 * This function has an implicit assumption: the rates in the given range have
 590 * only the pre-defined rates like 44100 or 16000.
 591 *
 592 * Return: The SNDRV_PCM_RATE_xxx flag that corresponds to the given rate range,
 593 * or SNDRV_PCM_RATE_KNOT for an unknown range.
 594 */
 595unsigned int snd_pcm_rate_range_to_bits(unsigned int rate_min,
 596        unsigned int rate_max)
 597{
 598        unsigned int rates = 0;
 599        int i;
 600
 601        for (i = 0; i < snd_pcm_known_rates.count; i++) {
 602                if (snd_pcm_known_rates.list[i] >= rate_min
 603                        && snd_pcm_known_rates.list[i] <= rate_max)
 604                        rates |= 1 << i;
 605        }
 606
 607        if (!rates)
 608                rates = SNDRV_PCM_RATE_KNOT;
 609
 610        return rates;
 611}
 612EXPORT_SYMBOL_GPL(snd_pcm_rate_range_to_bits);
 613