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pcm_lib.c

/*
 *  Digital Audio (PCM) abstract layer
 *  Copyright (c) by Jaroslav Kysela <perex@suse.cz>
 *                   Abramo Bagnara <abramo@alsa-project.org>
 *
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *
 */

#include <sound/driver.h>
#include <linux/slab.h>
#include <linux/time.h>
#include <sound/core.h>
#include <sound/control.h>
#include <sound/info.h>
#include <sound/pcm.h>
#include <sound/pcm_params.h>
#include <sound/timer.h>

/*
 * fill ring buffer with silence
 * runtime->silence_start: starting pointer to silence area
 * runtime->silence_filled: size filled with silence
 * runtime->silence_threshold: threshold from application
 * runtime->silence_size: maximal size from application
 *
 * when runtime->silence_size >= runtime->boundary - fill processed area with silence immediately
 */
void snd_pcm_playback_silence(struct snd_pcm_substream *substream, snd_pcm_uframes_t new_hw_ptr)
{
      struct snd_pcm_runtime *runtime = substream->runtime;
      snd_pcm_uframes_t frames, ofs, transfer;

      if (runtime->silence_size < runtime->boundary) {
            snd_pcm_sframes_t noise_dist, n;
            if (runtime->silence_start != runtime->control->appl_ptr) {
                  n = runtime->control->appl_ptr - runtime->silence_start;
                  if (n < 0)
                        n += runtime->boundary;
                  if ((snd_pcm_uframes_t)n < runtime->silence_filled)
                        runtime->silence_filled -= n;
                  else
                        runtime->silence_filled = 0;
                  runtime->silence_start = runtime->control->appl_ptr;
            }
            if (runtime->silence_filled >= runtime->buffer_size)
                  return;
            noise_dist = snd_pcm_playback_hw_avail(runtime) + runtime->silence_filled;
            if (noise_dist >= (snd_pcm_sframes_t) runtime->silence_threshold)
                  return;
            frames = runtime->silence_threshold - noise_dist;
            if (frames > runtime->silence_size)
                  frames = runtime->silence_size;
      } else {
            if (new_hw_ptr == ULONG_MAX) {      /* initialization */
                  snd_pcm_sframes_t avail = snd_pcm_playback_hw_avail(runtime);
                  runtime->silence_filled = avail > 0 ? avail : 0;
                  runtime->silence_start = (runtime->status->hw_ptr +
                                      runtime->silence_filled) %
                                     runtime->boundary;
            } else {
                  ofs = runtime->status->hw_ptr;
                  frames = new_hw_ptr - ofs;
                  if ((snd_pcm_sframes_t)frames < 0)
                        frames += runtime->boundary;
                  runtime->silence_filled -= frames;
                  if ((snd_pcm_sframes_t)runtime->silence_filled < 0) {
                        runtime->silence_filled = 0;
                        runtime->silence_start = (ofs + frames) - runtime->buffer_size;
                  } else {
                        runtime->silence_start = ofs - runtime->silence_filled;
                  }
                  if ((snd_pcm_sframes_t)runtime->silence_start < 0)
                        runtime->silence_start += runtime->boundary;
            }
            frames = runtime->buffer_size - runtime->silence_filled;
      }
      snd_assert(frames <= runtime->buffer_size, return);
      if (frames == 0)
            return;
      ofs = (runtime->silence_start + runtime->silence_filled) % runtime->buffer_size;
      while (frames > 0) {
            transfer = ofs + frames > runtime->buffer_size ? runtime->buffer_size - ofs : frames;
            if (runtime->access == SNDRV_PCM_ACCESS_RW_INTERLEAVED ||
                runtime->access == SNDRV_PCM_ACCESS_MMAP_INTERLEAVED) {
                  if (substream->ops->silence) {
                        int err;
                        err = substream->ops->silence(substream, -1, ofs, transfer);
                        snd_assert(err >= 0, );
                  } else {
                        char *hwbuf = runtime->dma_area + frames_to_bytes(runtime, ofs);
                        snd_pcm_format_set_silence(runtime->format, hwbuf, transfer * runtime->channels);
                  }
            } else {
                  unsigned int c;
                  unsigned int channels = runtime->channels;
                  if (substream->ops->silence) {
                        for (c = 0; c < channels; ++c) {
                              int err;
                              err = substream->ops->silence(substream, c, ofs, transfer);
                              snd_assert(err >= 0, );
                        }
                  } else {
                        size_t dma_csize = runtime->dma_bytes / channels;
                        for (c = 0; c < channels; ++c) {
                              char *hwbuf = runtime->dma_area + (c * dma_csize) + samples_to_bytes(runtime, ofs);
                              snd_pcm_format_set_silence(runtime->format, hwbuf, transfer);
                        }
                  }
            }
            runtime->silence_filled += transfer;
            frames -= transfer;
            ofs = 0;
      }
}

static void xrun(struct snd_pcm_substream *substream)
{
      snd_pcm_stop(substream, SNDRV_PCM_STATE_XRUN);
#ifdef CONFIG_SND_PCM_XRUN_DEBUG
      if (substream->pstr->xrun_debug) {
            snd_printd(KERN_DEBUG "XRUN: pcmC%dD%d%c\n",
                     substream->pcm->card->number,
                     substream->pcm->device,
                     substream->stream ? 'c' : 'p');
            if (substream->pstr->xrun_debug > 1)
                  dump_stack();
      }
#endif
}

static inline snd_pcm_uframes_t snd_pcm_update_hw_ptr_pos(struct snd_pcm_substream *substream,
                                            struct snd_pcm_runtime *runtime)
{
      snd_pcm_uframes_t pos;

      pos = substream->ops->pointer(substream);
      if (pos == SNDRV_PCM_POS_XRUN)
            return pos; /* XRUN */
      if (runtime->tstamp_mode & SNDRV_PCM_TSTAMP_MMAP)
            getnstimeofday((struct timespec *)&runtime->status->tstamp);
#ifdef CONFIG_SND_DEBUG
      if (pos >= runtime->buffer_size) {
            snd_printk(KERN_ERR  "BUG: stream = %i, pos = 0x%lx, buffer size = 0x%lx, period size = 0x%lx\n", substream->stream, pos, runtime->buffer_size, runtime->period_size);
      }
#endif
      pos -= pos % runtime->min_align;
      return pos;
}

static inline int snd_pcm_update_hw_ptr_post(struct snd_pcm_substream *substream,
                                   struct snd_pcm_runtime *runtime)
{
      snd_pcm_uframes_t avail;

      if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
            avail = snd_pcm_playback_avail(runtime);
      else
            avail = snd_pcm_capture_avail(runtime);
      if (avail > runtime->avail_max)
            runtime->avail_max = avail;
      if (avail >= runtime->stop_threshold) {
            if (substream->runtime->status->state == SNDRV_PCM_STATE_DRAINING)
                  snd_pcm_drain_done(substream);
            else
                  xrun(substream);
            return -EPIPE;
      }
      if (avail >= runtime->control->avail_min)
            wake_up(&runtime->sleep);
      return 0;
}

static inline int snd_pcm_update_hw_ptr_interrupt(struct snd_pcm_substream *substream)
{
      struct snd_pcm_runtime *runtime = substream->runtime;
      snd_pcm_uframes_t pos;
      snd_pcm_uframes_t new_hw_ptr, hw_ptr_interrupt;
      snd_pcm_sframes_t delta;

      pos = snd_pcm_update_hw_ptr_pos(substream, runtime);
      if (pos == SNDRV_PCM_POS_XRUN) {
            xrun(substream);
            return -EPIPE;
      }
      if (runtime->period_size == runtime->buffer_size)
            goto __next_buf;
      new_hw_ptr = runtime->hw_ptr_base + pos;
      hw_ptr_interrupt = runtime->hw_ptr_interrupt + runtime->period_size;

      delta = hw_ptr_interrupt - new_hw_ptr;
      if (delta > 0) {
            if ((snd_pcm_uframes_t)delta < runtime->buffer_size / 2) {
#ifdef CONFIG_SND_PCM_XRUN_DEBUG
                  if (runtime->periods > 1 && substream->pstr->xrun_debug) {
                        snd_printd(KERN_ERR "Unexpected hw_pointer value [1] (stream = %i, delta: -%ld, max jitter = %ld): wrong interrupt acknowledge?\n", substream->stream, (long) delta, runtime->buffer_size / 2);
                        if (substream->pstr->xrun_debug > 1)
                              dump_stack();
                  }
#endif
                  return 0;
            }
            __next_buf:
            runtime->hw_ptr_base += runtime->buffer_size;
            if (runtime->hw_ptr_base == runtime->boundary)
                  runtime->hw_ptr_base = 0;
            new_hw_ptr = runtime->hw_ptr_base + pos;
      }

      if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&
          runtime->silence_size > 0)
            snd_pcm_playback_silence(substream, new_hw_ptr);

      runtime->status->hw_ptr = new_hw_ptr;
      runtime->hw_ptr_interrupt = new_hw_ptr - new_hw_ptr % runtime->period_size;

      return snd_pcm_update_hw_ptr_post(substream, runtime);
}

/* CAUTION: call it with irq disabled */
int snd_pcm_update_hw_ptr(struct snd_pcm_substream *substream)
{
      struct snd_pcm_runtime *runtime = substream->runtime;
      snd_pcm_uframes_t pos;
      snd_pcm_uframes_t old_hw_ptr, new_hw_ptr;
      snd_pcm_sframes_t delta;

      old_hw_ptr = runtime->status->hw_ptr;
      pos = snd_pcm_update_hw_ptr_pos(substream, runtime);
      if (pos == SNDRV_PCM_POS_XRUN) {
            xrun(substream);
            return -EPIPE;
      }
      new_hw_ptr = runtime->hw_ptr_base + pos;

      delta = old_hw_ptr - new_hw_ptr;
      if (delta > 0) {
            if ((snd_pcm_uframes_t)delta < runtime->buffer_size / 2) {
#ifdef CONFIG_SND_PCM_XRUN_DEBUG
                  if (runtime->periods > 2 && substream->pstr->xrun_debug) {
                        snd_printd(KERN_ERR "Unexpected hw_pointer value [2] (stream = %i, delta: -%ld, max jitter = %ld): wrong interrupt acknowledge?\n", substream->stream, (long) delta, runtime->buffer_size / 2);
                        if (substream->pstr->xrun_debug > 1)
                              dump_stack();
                  }
#endif
                  return 0;
            }
            runtime->hw_ptr_base += runtime->buffer_size;
            if (runtime->hw_ptr_base == runtime->boundary)
                  runtime->hw_ptr_base = 0;
            new_hw_ptr = runtime->hw_ptr_base + pos;
      }
      if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&
          runtime->silence_size > 0)
            snd_pcm_playback_silence(substream, new_hw_ptr);

      runtime->status->hw_ptr = new_hw_ptr;

      return snd_pcm_update_hw_ptr_post(substream, runtime);
}

/**
 * snd_pcm_set_ops - set the PCM operators
 * @pcm: the pcm instance
 * @direction: stream direction, SNDRV_PCM_STREAM_XXX
 * @ops: the operator table
 *
 * Sets the given PCM operators to the pcm instance.
 */
void snd_pcm_set_ops(struct snd_pcm *pcm, int direction, struct snd_pcm_ops *ops)
{
      struct snd_pcm_str *stream = &pcm->streams[direction];
      struct snd_pcm_substream *substream;
      
      for (substream = stream->substream; substream != NULL; substream = substream->next)
            substream->ops = ops;
}

EXPORT_SYMBOL(snd_pcm_set_ops);

/**
 * snd_pcm_sync - set the PCM sync id
 * @substream: the pcm substream
 *
 * Sets the PCM sync identifier for the card.
 */
void snd_pcm_set_sync(struct snd_pcm_substream *substream)
{
      struct snd_pcm_runtime *runtime = substream->runtime;
      
      runtime->sync.id32[0] = substream->pcm->card->number;
      runtime->sync.id32[1] = -1;
      runtime->sync.id32[2] = -1;
      runtime->sync.id32[3] = -1;
}

EXPORT_SYMBOL(snd_pcm_set_sync);

/*
 *  Standard ioctl routine
 */

static inline unsigned int div32(unsigned int a, unsigned int b, 
                         unsigned int *r)
{
      if (b == 0) {
            *r = 0;
            return UINT_MAX;
      }
      *r = a % b;
      return a / b;
}

static inline unsigned int div_down(unsigned int a, unsigned int b)
{
      if (b == 0)
            return UINT_MAX;
      return a / b;
}

static inline unsigned int div_up(unsigned int a, unsigned int b)
{
      unsigned int r;
      unsigned int q;
      if (b == 0)
            return UINT_MAX;
      q = div32(a, b, &r);
      if (r)
            ++q;
      return q;
}

static inline unsigned int mul(unsigned int a, unsigned int b)
{
      if (a == 0)
            return 0;
      if (div_down(UINT_MAX, a) < b)
            return UINT_MAX;
      return a * b;
}

static inline unsigned int muldiv32(unsigned int a, unsigned int b,
                            unsigned int c, unsigned int *r)
{
      u_int64_t n = (u_int64_t) a * b;
      if (c == 0) {
            snd_assert(n > 0, );
            *r = 0;
            return UINT_MAX;
      }
      div64_32(&n, c, r);
      if (n >= UINT_MAX) {
            *r = 0;
            return UINT_MAX;
      }
      return n;
}

/**
 * snd_interval_refine - refine the interval value of configurator
 * @i: the interval value to refine
 * @v: the interval value to refer to
 *
 * Refines the interval value with the reference value.
 * The interval is changed to the range satisfying both intervals.
 * The interval status (min, max, integer, etc.) are evaluated.
 *
 * Returns non-zero if the value is changed, zero if not changed.
 */
int snd_interval_refine(struct snd_interval *i, const struct snd_interval *v)
{
      int changed = 0;
      snd_assert(!snd_interval_empty(i), return -EINVAL);
      if (i->min < v->min) {
            i->min = v->min;
            i->openmin = v->openmin;
            changed = 1;
      } else if (i->min == v->min && !i->openmin && v->openmin) {
            i->openmin = 1;
            changed = 1;
      }
      if (i->max > v->max) {
            i->max = v->max;
            i->openmax = v->openmax;
            changed = 1;
      } else if (i->max == v->max && !i->openmax && v->openmax) {
            i->openmax = 1;
            changed = 1;
      }
      if (!i->integer && v->integer) {
            i->integer = 1;
            changed = 1;
      }
      if (i->integer) {
            if (i->openmin) {
                  i->min++;
                  i->openmin = 0;
            }
            if (i->openmax) {
                  i->max--;
                  i->openmax = 0;
            }
      } else if (!i->openmin && !i->openmax && i->min == i->max)
            i->integer = 1;
      if (snd_interval_checkempty(i)) {
            snd_interval_none(i);
            return -EINVAL;
      }
      return changed;
}

EXPORT_SYMBOL(snd_interval_refine);

static int snd_interval_refine_first(struct snd_interval *i)
{
      snd_assert(!snd_interval_empty(i), return -EINVAL);
      if (snd_interval_single(i))
            return 0;
      i->max = i->min;
      i->openmax = i->openmin;
      if (i->openmax)
            i->max++;
      return 1;
}

static int snd_interval_refine_last(struct snd_interval *i)
{
      snd_assert(!snd_interval_empty(i), return -EINVAL);
      if (snd_interval_single(i))
            return 0;
      i->min = i->max;
      i->openmin = i->openmax;
      if (i->openmin)
            i->min--;
      return 1;
}

void snd_interval_mul(const struct snd_interval *a, const struct snd_interval *b, struct snd_interval *c)
{
      if (a->empty || b->empty) {
            snd_interval_none(c);
            return;
      }
      c->empty = 0;
      c->min = mul(a->min, b->min);
      c->openmin = (a->openmin || b->openmin);
      c->max = mul(a->max,  b->max);
      c->openmax = (a->openmax || b->openmax);
      c->integer = (a->integer && b->integer);
}

/**
 * snd_interval_div - refine the interval value with division
 * @a: dividend
 * @b: divisor
 * @c: quotient
 *
 * c = a / b
 *
 * Returns non-zero if the value is changed, zero if not changed.
 */
void snd_interval_div(const struct snd_interval *a, const struct snd_interval *b, struct snd_interval *c)
{
      unsigned int r;
      if (a->empty || b->empty) {
            snd_interval_none(c);
            return;
      }
      c->empty = 0;
      c->min = div32(a->min, b->max, &r);
      c->openmin = (r || a->openmin || b->openmax);
      if (b->min > 0) {
            c->max = div32(a->max, b->min, &r);
            if (r) {
                  c->max++;
                  c->openmax = 1;
            } else
                  c->openmax = (a->openmax || b->openmin);
      } else {
            c->max = UINT_MAX;
            c->openmax = 0;
      }
      c->integer = 0;
}

/**
 * snd_interval_muldivk - refine the interval value
 * @a: dividend 1
 * @b: dividend 2
 * @k: divisor (as integer)
 * @c: result
  *
 * c = a * b / k
 *
 * Returns non-zero if the value is changed, zero if not changed.
 */
void snd_interval_muldivk(const struct snd_interval *a, const struct snd_interval *b,
                  unsigned int k, struct snd_interval *c)
{
      unsigned int r;
      if (a->empty || b->empty) {
            snd_interval_none(c);
            return;
      }
      c->empty = 0;
      c->min = muldiv32(a->min, b->min, k, &r);
      c->openmin = (r || a->openmin || b->openmin);
      c->max = muldiv32(a->max, b->max, k, &r);
      if (r) {
            c->max++;
            c->openmax = 1;
      } else
            c->openmax = (a->openmax || b->openmax);
      c->integer = 0;
}

/**
 * snd_interval_mulkdiv - refine the interval value
 * @a: dividend 1
 * @k: dividend 2 (as integer)
 * @b: divisor
 * @c: result
 *
 * c = a * k / b
 *
 * Returns non-zero if the value is changed, zero if not changed.
 */
void snd_interval_mulkdiv(const struct snd_interval *a, unsigned int k,
                  const struct snd_interval *b, struct snd_interval *c)
{
      unsigned int r;
      if (a->empty || b->empty) {
            snd_interval_none(c);
            return;
      }
      c->empty = 0;
      c->min = muldiv32(a->min, k, b->max, &r);
      c->openmin = (r || a->openmin || b->openmax);
      if (b->min > 0) {
            c->max = muldiv32(a->max, k, b->min, &r);
            if (r) {
                  c->max++;
                  c->openmax = 1;
            } else
                  c->openmax = (a->openmax || b->openmin);
      } else {
            c->max = UINT_MAX;
            c->openmax = 0;
      }
      c->integer = 0;
}

/* ---- */


/**
 * snd_interval_ratnum - refine the interval value
 * @i: interval to refine
 * @rats_count: number of ratnum_t 
 * @rats: ratnum_t array
 * @nump: pointer to store the resultant numerator
 * @denp: pointer to store the resultant denominator
 *
 * Returns non-zero if the value is changed, zero if not changed.
 */
int snd_interval_ratnum(struct snd_interval *i,
                  unsigned int rats_count, struct snd_ratnum *rats,
                  unsigned int *nump, unsigned int *denp)
{
      unsigned int best_num, best_diff, best_den;
      unsigned int k;
      struct snd_interval t;
      int err;

      best_num = best_den = best_diff = 0;
      for (k = 0; k < rats_count; ++k) {
            unsigned int num = rats[k].num;
            unsigned int den;
            unsigned int q = i->min;
            int diff;
            if (q == 0)
                  q = 1;
            den = div_down(num, q);
            if (den < rats[k].den_min)
                  continue;
            if (den > rats[k].den_max)
                  den = rats[k].den_max;
            else {
                  unsigned int r;
                  r = (den - rats[k].den_min) % rats[k].den_step;
                  if (r != 0)
                        den -= r;
            }
            diff = num - q * den;
            if (best_num == 0 ||
                diff * best_den < best_diff * den) {
                  best_diff = diff;
                  best_den = den;
                  best_num = num;
            }
      }
      if (best_den == 0) {
            i->empty = 1;
            return -EINVAL;
      }
      t.min = div_down(best_num, best_den);
      t.openmin = !!(best_num % best_den);
      
      best_num = best_den = best_diff = 0;
      for (k = 0; k < rats_count; ++k) {
            unsigned int num = rats[k].num;
            unsigned int den;
            unsigned int q = i->max;
            int diff;
            if (q == 0) {
                  i->empty = 1;
                  return -EINVAL;
            }
            den = div_up(num, q);
            if (den > rats[k].den_max)
                  continue;
            if (den < rats[k].den_min)
                  den = rats[k].den_min;
            else {
                  unsigned int r;
                  r = (den - rats[k].den_min) % rats[k].den_step;
                  if (r != 0)
                        den += rats[k].den_step - r;
            }
            diff = q * den - num;
            if (best_num == 0 ||
                diff * best_den < best_diff * den) {
                  best_diff = diff;
                  best_den = den;
                  best_num = num;
            }
      }
      if (best_den == 0) {
            i->empty = 1;
            return -EINVAL;
      }
      t.max = div_up(best_num, best_den);
      t.openmax = !!(best_num % best_den);
      t.integer = 0;
      err = snd_interval_refine(i, &t);
      if (err < 0)
            return err;

      if (snd_interval_single(i)) {
            if (nump)
                  *nump = best_num;
            if (denp)
                  *denp = best_den;
      }
      return err;
}

EXPORT_SYMBOL(snd_interval_ratnum);

/**
 * snd_interval_ratden - refine the interval value
 * @i: interval to refine
 * @rats_count: number of struct ratden
 * @rats: struct ratden array
 * @nump: pointer to store the resultant numerator
 * @denp: pointer to store the resultant denominator
 *
 * Returns non-zero if the value is changed, zero if not changed.
 */
static int snd_interval_ratden(struct snd_interval *i,
                         unsigned int rats_count, struct snd_ratden *rats,
                         unsigned int *nump, unsigned int *denp)
{
      unsigned int best_num, best_diff, best_den;
      unsigned int k;
      struct snd_interval t;
      int err;

      best_num = best_den = best_diff = 0;
      for (k = 0; k < rats_count; ++k) {
            unsigned int num;
            unsigned int den = rats[k].den;
            unsigned int q = i->min;
            int diff;
            num = mul(q, den);
            if (num > rats[k].num_max)
                  continue;
            if (num < rats[k].num_min)
                  num = rats[k].num_max;
            else {
                  unsigned int r;
                  r = (num - rats[k].num_min) % rats[k].num_step;
                  if (r != 0)
                        num += rats[k].num_step - r;
            }
            diff = num - q * den;
            if (best_num == 0 ||
                diff * best_den < best_diff * den) {
                  best_diff = diff;
                  best_den = den;
                  best_num = num;
            }
      }
      if (best_den == 0) {
            i->empty = 1;
            return -EINVAL;
      }
      t.min = div_down(best_num, best_den);
      t.openmin = !!(best_num % best_den);
      
      best_num = best_den = best_diff = 0;
      for (k = 0; k < rats_count; ++k) {
            unsigned int num;
            unsigned int den = rats[k].den;
            unsigned int q = i->max;
            int diff;
            num = mul(q, den);
            if (num < rats[k].num_min)
                  continue;
            if (num > rats[k].num_max)
                  num = rats[k].num_max;
            else {
                  unsigned int r;
                  r = (num - rats[k].num_min) % rats[k].num_step;
                  if (r != 0)
                        num -= r;
            }
            diff = q * den - num;
            if (best_num == 0 ||
                diff * best_den < best_diff * den) {
                  best_diff = diff;
                  best_den = den;
                  best_num = num;
            }
      }
      if (best_den == 0) {
            i->empty = 1;
            return -EINVAL;
      }
      t.max = div_up(best_num, best_den);
      t.openmax = !!(best_num % best_den);
      t.integer = 0;
      err = snd_interval_refine(i, &t);
      if (err < 0)
            return err;

      if (snd_interval_single(i)) {
            if (nump)
                  *nump = best_num;
            if (denp)
                  *denp = best_den;
      }
      return err;
}

/**
 * snd_interval_list - refine the interval value from the list
 * @i: the interval value to refine
 * @count: the number of elements in the list
 * @list: the value list
 * @mask: the bit-mask to evaluate
 *
 * Refines the interval value from the list.
 * When mask is non-zero, only the elements corresponding to bit 1 are
 * evaluated.
 *
 * Returns non-zero if the value is changed, zero if not changed.
 */
int snd_interval_list(struct snd_interval *i, unsigned int count, unsigned int *list, unsigned int mask)
{
        unsigned int k;
      int changed = 0;
        for (k = 0; k < count; k++) {
            if (mask && !(mask & (1 << k)))
                  continue;
                if (i->min == list[k] && !i->openmin)
                        goto _l1;
                if (i->min < list[k]) {
                        i->min = list[k];
                  i->openmin = 0;
                  changed = 1;
                        goto _l1;
                }
        }
        i->empty = 1;
        return -EINVAL;
 _l1:
        for (k = count; k-- > 0;) {
            if (mask && !(mask & (1 << k)))
                  continue;
                if (i->max == list[k] && !i->openmax)
                        goto _l2;
                if (i->max > list[k]) {
                        i->max = list[k];
                  i->openmax = 0;
                  changed = 1;
                        goto _l2;
                }
        }
        i->empty = 1;
        return -EINVAL;
 _l2:
      if (snd_interval_checkempty(i)) {
            i->empty = 1;
            return -EINVAL;
      }
        return changed;
}

EXPORT_SYMBOL(snd_interval_list);

static int snd_interval_step(struct snd_interval *i, unsigned int min, unsigned int step)
{
      unsigned int n;
      int changed = 0;
      n = (i->min - min) % step;
      if (n != 0 || i->openmin) {
            i->min += step - n;
            changed = 1;
      }
      n = (i->max - min) % step;
      if (n != 0 || i->openmax) {
            i->max -= n;
            changed = 1;
      }
      if (snd_interval_checkempty(i)) {
            i->empty = 1;
            return -EINVAL;
      }
      return changed;
}

/* Info constraints helpers */

/**
 * snd_pcm_hw_rule_add - add the hw-constraint rule
 * @runtime: the pcm runtime instance
 * @cond: condition bits
 * @var: the variable to evaluate
 * @func: the evaluation function
 * @private: the private data pointer passed to function
 * @dep: the dependent variables
 *
 * Returns zero if successful, or a negative error code on failure.
 */
int snd_pcm_hw_rule_add(struct snd_pcm_runtime *runtime, unsigned int cond,
                  int var,
                  snd_pcm_hw_rule_func_t func, void *private,
                  int dep, ...)
{
      struct snd_pcm_hw_constraints *constrs = &runtime->hw_constraints;
      struct snd_pcm_hw_rule *c;
      unsigned int k;
      va_list args;
      va_start(args, dep);
      if (constrs->rules_num >= constrs->rules_all) {
            struct snd_pcm_hw_rule *new;
            unsigned int new_rules = constrs->rules_all + 16;
            new = kcalloc(new_rules, sizeof(*c), GFP_KERNEL);
            if (!new)
                  return -ENOMEM;
            if (constrs->rules) {
                  memcpy(new, constrs->rules,
                         constrs->rules_num * sizeof(*c));
                  kfree(constrs->rules);
            }
            constrs->rules = new;
            constrs->rules_all = new_rules;
      }
      c = &constrs->rules[constrs->rules_num];
      c->cond = cond;
      c->func = func;
      c->var = var;
      c->private = private;
      k = 0;
      while (1) {
            snd_assert(k < ARRAY_SIZE(c->deps), return -EINVAL);
            c->deps[k++] = dep;
            if (dep < 0)
                  break;
            dep = va_arg(args, int);
      }
      constrs->rules_num++;
      va_end(args);
      return 0;
}                           

EXPORT_SYMBOL(snd_pcm_hw_rule_add);

/**
 * snd_pcm_hw_constraint_mask
 * @runtime: PCM runtime instance
 * @var: hw_params variable to apply the mask
 * @mask: the bitmap mask
 *
 * Apply the constraint of the given bitmap mask to a mask parameter.
 */
int snd_pcm_hw_constraint_mask(struct snd_pcm_runtime *runtime, snd_pcm_hw_param_t var,
                         u_int32_t mask)
{
      struct snd_pcm_hw_constraints *constrs = &runtime->hw_constraints;
      struct snd_mask *maskp = constrs_mask(constrs, var);
      *maskp->bits &= mask;
      memset(maskp->bits + 1, 0, (SNDRV_MASK_MAX-32) / 8); /* clear rest */
      if (*maskp->bits == 0)
            return -EINVAL;
      return 0;
}

/**
 * snd_pcm_hw_constraint_mask64
 * @runtime: PCM runtime instance
 * @var: hw_params variable to apply the mask
 * @mask: the 64bit bitmap mask
 *
 * Apply the constraint of the given bitmap mask to a mask parameter.
 */
int snd_pcm_hw_constraint_mask64(struct snd_pcm_runtime *runtime, snd_pcm_hw_param_t var,
                         u_int64_t mask)
{
      struct snd_pcm_hw_constraints *constrs = &runtime->hw_constraints;
      struct snd_mask *maskp = constrs_mask(constrs, var);
      maskp->bits[0] &= (u_int32_t)mask;
      maskp->bits[1] &= (u_int32_t)(mask >> 32);
      memset(maskp->bits + 2, 0, (SNDRV_MASK_MAX-64) / 8); /* clear rest */
      if (! maskp->bits[0] && ! maskp->bits[1])
            return -EINVAL;
      return 0;
}

/**
 * snd_pcm_hw_constraint_integer
 * @runtime: PCM runtime instance
 * @var: hw_params variable to apply the integer constraint
 *
 * Apply the constraint of integer to an interval parameter.
 */
int snd_pcm_hw_constraint_integer(struct snd_pcm_runtime *runtime, snd_pcm_hw_param_t var)
{
      struct snd_pcm_hw_constraints *constrs = &runtime->hw_constraints;
      return snd_interval_setinteger(constrs_interval(constrs, var));
}

EXPORT_SYMBOL(snd_pcm_hw_constraint_integer);

/**
 * snd_pcm_hw_constraint_minmax
 * @runtime: PCM runtime instance
 * @var: hw_params variable to apply the range
 * @min: the minimal value
 * @max: the maximal value
 * 
 * Apply the min/max range constraint to an interval parameter.
 */
int snd_pcm_hw_constraint_minmax(struct snd_pcm_runtime *runtime, snd_pcm_hw_param_t var,
                         unsigned int min, unsigned int max)
{
      struct snd_pcm_hw_constraints *constrs = &runtime->hw_constraints;
      struct snd_interval t;
      t.min = min;
      t.max = max;
      t.openmin = t.openmax = 0;
      t.integer = 0;
      return snd_interval_refine(constrs_interval(constrs, var), &t);
}

EXPORT_SYMBOL(snd_pcm_hw_constraint_minmax);

static int snd_pcm_hw_rule_list(struct snd_pcm_hw_params *params,
                        struct snd_pcm_hw_rule *rule)
{
      struct snd_pcm_hw_constraint_list *list = rule->private;
      return snd_interval_list(hw_param_interval(params, rule->var), list->count, list->list, list->mask);
}           


/**
 * snd_pcm_hw_constraint_list
 * @runtime: PCM runtime instance
 * @cond: condition bits
 * @var: hw_params variable to apply the list constraint
 * @l: list
 * 
 * Apply the list of constraints to an interval parameter.
 */
int snd_pcm_hw_constraint_list(struct snd_pcm_runtime *runtime,
                         unsigned int cond,
                         snd_pcm_hw_param_t var,
                         struct snd_pcm_hw_constraint_list *l)
{
      return snd_pcm_hw_rule_add(runtime, cond, var,
                           snd_pcm_hw_rule_list, l,
                           var, -1);
}

EXPORT_SYMBOL(snd_pcm_hw_constraint_list);

static int snd_pcm_hw_rule_ratnums(struct snd_pcm_hw_params *params,
                           struct snd_pcm_hw_rule *rule)
{
      struct snd_pcm_hw_constraint_ratnums *r = rule->private;
      unsigned int num = 0, den = 0;
      int err;
      err = snd_interval_ratnum(hw_param_interval(params, rule->var),
                          r->nrats, r->rats, &num, &den);
      if (err >= 0 && den && rule->var == SNDRV_PCM_HW_PARAM_RATE) {
            params->rate_num = num;
            params->rate_den = den;
      }
      return err;
}

/**
 * snd_pcm_hw_constraint_ratnums
 * @runtime: PCM runtime instance
 * @cond: condition bits
 * @var: hw_params variable to apply the ratnums constraint
 * @r: struct snd_ratnums constriants
 */
int snd_pcm_hw_constraint_ratnums(struct snd_pcm_runtime *runtime, 
                          unsigned int cond,
                          snd_pcm_hw_param_t var,
                          struct snd_pcm_hw_constraint_ratnums *r)
{
      return snd_pcm_hw_rule_add(runtime, cond, var,
                           snd_pcm_hw_rule_ratnums, r,
                           var, -1);
}

EXPORT_SYMBOL(snd_pcm_hw_constraint_ratnums);

static int snd_pcm_hw_rule_ratdens(struct snd_pcm_hw_params *params,
                           struct snd_pcm_hw_rule *rule)
{
      struct snd_pcm_hw_constraint_ratdens *r = rule->private;
      unsigned int num = 0, den = 0;
      int err = snd_interval_ratden(hw_param_interval(params, rule->var),
                          r->nrats, r->rats, &num, &den);
      if (err >= 0 && den && rule->var == SNDRV_PCM_HW_PARAM_RATE) {
            params->rate_num = num;
            params->rate_den = den;
      }
      return err;
}

/**
 * snd_pcm_hw_constraint_ratdens
 * @runtime: PCM runtime instance
 * @cond: condition bits
 * @var: hw_params variable to apply the ratdens constraint
 * @r: struct snd_ratdens constriants
 */
int snd_pcm_hw_constraint_ratdens(struct snd_pcm_runtime *runtime, 
                          unsigned int cond,
                          snd_pcm_hw_param_t var,
                          struct snd_pcm_hw_constraint_ratdens *r)
{
      return snd_pcm_hw_rule_add(runtime, cond, var,
                           snd_pcm_hw_rule_ratdens, r,
                           var, -1);
}

EXPORT_SYMBOL(snd_pcm_hw_constraint_ratdens);

static int snd_pcm_hw_rule_msbits(struct snd_pcm_hw_params *params,
                          struct snd_pcm_hw_rule *rule)
{
      unsigned int l = (unsigned long) rule->private;
      int width = l & 0xffff;
      unsigned int msbits = l >> 16;
      struct snd_interval *i = hw_param_interval(params, SNDRV_PCM_HW_PARAM_SAMPLE_BITS);
      if (snd_interval_single(i) && snd_interval_value(i) == width)
            params->msbits = msbits;
      return 0;
}

/**
 * snd_pcm_hw_constraint_msbits
 * @runtime: PCM runtime instance
 * @cond: condition bits
 * @width: sample bits width
 * @msbits: msbits width
 */
int snd_pcm_hw_constraint_msbits(struct snd_pcm_runtime *runtime, 
                         unsigned int cond,
                         unsigned int width,
                         unsigned int msbits)
{
      unsigned long l = (msbits << 16) | width;
      return snd_pcm_hw_rule_add(runtime, cond, -1,
                            snd_pcm_hw_rule_msbits,
                            (void*) l,
                            SNDRV_PCM_HW_PARAM_SAMPLE_BITS, -1);
}

EXPORT_SYMBOL(snd_pcm_hw_constraint_msbits);

static int snd_pcm_hw_rule_step(struct snd_pcm_hw_params *params,
                        struct snd_pcm_hw_rule *rule)
{
      unsigned long step = (unsigned long) rule->private;
      return snd_interval_step(hw_param_interval(params, rule->var), 0, step);
}

/**
 * snd_pcm_hw_constraint_step
 * @runtime: PCM runtime instance
 * @cond: condition bits
 * @var: hw_params variable to apply the step constraint
 * @step: step size
 */
int snd_pcm_hw_constraint_step(struct snd_pcm_runtime *runtime,
                         unsigned int cond,
                         snd_pcm_hw_param_t var,
                         unsigned long step)
{
      return snd_pcm_hw_rule_add(runtime, cond, var, 
                           snd_pcm_hw_rule_step, (void *) step,
                           var, -1);
}

EXPORT_SYMBOL(snd_pcm_hw_constraint_step);

static int snd_pcm_hw_rule_pow2(struct snd_pcm_hw_params *params, struct snd_pcm_hw_rule *rule)
{
      static int pow2_sizes[] = {
            1<<0, 1<<1, 1<<2, 1<<3, 1<<4, 1<<5, 1<<6, 1<<7,
            1<<8, 1<<9, 1<<10, 1<<11, 1<<12, 1<<13, 1<<14, 1<<15,
            1<<16, 1<<17, 1<<18, 1<<19, 1<<20, 1<<21, 1<<22, 1<<23,
            1<<24, 1<<25, 1<<26, 1<<27, 1<<28, 1<<29, 1<<30
      };
      return snd_interval_list(hw_param_interval(params, rule->var),
                         ARRAY_SIZE(pow2_sizes), pow2_sizes, 0);
}           

/**
 * snd_pcm_hw_constraint_pow2
 * @runtime: PCM runtime instance
 * @cond: condition bits
 * @var: hw_params variable to apply the power-of-2 constraint
 */
int snd_pcm_hw_constraint_pow2(struct snd_pcm_runtime *runtime,
                         unsigned int cond,
                         snd_pcm_hw_param_t var)
{
      return snd_pcm_hw_rule_add(runtime, cond, var, 
                           snd_pcm_hw_rule_pow2, NULL,
                           var, -1);
}

EXPORT_SYMBOL(snd_pcm_hw_constraint_pow2);

static void _snd_pcm_hw_param_any(struct snd_pcm_hw_params *params,
                          snd_pcm_hw_param_t var)
{
      if (hw_is_mask(var)) {
            snd_mask_any(hw_param_mask(params, var));
            params->cmask |= 1 << var;
            params->rmask |= 1 << var;
            return;
      }
      if (hw_is_interval(var)) {
            snd_interval_any(hw_param_interval(params, var));
            params->cmask |= 1 << var;
            params->rmask |= 1 << var;
            return;
      }
      snd_BUG();
}

void _snd_pcm_hw_params_any(struct snd_pcm_hw_params *params)
{
      unsigned int k;
      memset(params, 0, sizeof(*params));
      for (k = SNDRV_PCM_HW_PARAM_FIRST_MASK; k <= SNDRV_PCM_HW_PARAM_LAST_MASK; k++)
            _snd_pcm_hw_param_any(params, k);
      for (k = SNDRV_PCM_HW_PARAM_FIRST_INTERVAL; k <= SNDRV_PCM_HW_PARAM_LAST_INTERVAL; k++)
            _snd_pcm_hw_param_any(params, k);
      params->info = ~0U;
}

EXPORT_SYMBOL(_snd_pcm_hw_params_any);

/**
 * snd_pcm_hw_param_value
 * @params: the hw_params instance
 * @var: parameter to retrieve
 * @dir: pointer to the direction (-1,0,1) or NULL
 *
 * Return the value for field PAR if it's fixed in configuration space 
 *  defined by PARAMS. Return -EINVAL otherwise
 */
int snd_pcm_hw_param_value(const struct snd_pcm_hw_params *params,
                     snd_pcm_hw_param_t var, int *dir)
{
      if (hw_is_mask(var)) {
            const struct snd_mask *mask = hw_param_mask_c(params, var);
            if (!snd_mask_single(mask))
                  return -EINVAL;
            if (dir)
                  *dir = 0;
            return snd_mask_value(mask);
      }
      if (hw_is_interval(var)) {
            const struct snd_interval *i = hw_param_interval_c(params, var);
            if (!snd_interval_single(i))
                  return -EINVAL;
            if (dir)
                  *dir = i->openmin;
            return snd_interval_value(i);
      }
      return -EINVAL;
}

EXPORT_SYMBOL(snd_pcm_hw_param_value);

void _snd_pcm_hw_param_setempty(struct snd_pcm_hw_params *params,
                        snd_pcm_hw_param_t var)
{
      if (hw_is_mask(var)) {
            snd_mask_none(hw_param_mask(params, var));
            params->cmask |= 1 << var;
            params->rmask |= 1 << var;
      } else if (hw_is_interval(var)) {
            snd_interval_none(hw_param_interval(params, var));
            params->cmask |= 1 << var;
            params->rmask |= 1 << var;
      } else {
            snd_BUG();
      }
}

EXPORT_SYMBOL(_snd_pcm_hw_param_setempty);

static int _snd_pcm_hw_param_first(struct snd_pcm_hw_params *params,
                           snd_pcm_hw_param_t var)
{
      int changed;
      if (hw_is_mask(var))
            changed = snd_mask_refine_first(hw_param_mask(params, var));
      else if (hw_is_interval(var))
            changed = snd_interval_refine_first(hw_param_interval(params, var));
      else
            return -EINVAL;
      if (changed) {
            params->cmask |= 1 << var;
            params->rmask |= 1 << var;
      }
      return changed;
}


/**
 * snd_pcm_hw_param_first
 * @pcm: PCM instance
 * @params: the hw_params instance
 * @var: parameter to retrieve
 * @dir: pointer to the direction (-1,0,1) or NULL
 *
 * Inside configuration space defined by PARAMS remove from PAR all 
 * values > minimum. Reduce configuration space accordingly.
 * Return the minimum.
 */
int snd_pcm_hw_param_first(struct snd_pcm_substream *pcm, 
                     struct snd_pcm_hw_params *params, 
                     snd_pcm_hw_param_t var, int *dir)
{
      int changed = _snd_pcm_hw_param_first(params, var);
      if (changed < 0)
            return changed;
      if (params->rmask) {
            int err = snd_pcm_hw_refine(pcm, params);
            snd_assert(err >= 0, return err);
      }
      return snd_pcm_hw_param_value(params, var, dir);
}

EXPORT_SYMBOL(snd_pcm_hw_param_first);

static int _snd_pcm_hw_param_last(struct snd_pcm_hw_params *params,
                          snd_pcm_hw_param_t var)
{
      int changed;
      if (hw_is_mask(var))
            changed = snd_mask_refine_last(hw_param_mask(params, var));
      else if (hw_is_interval(var))
            changed = snd_interval_refine_last(hw_param_interval(params, var));
      else
            return -EINVAL;
      if (changed) {
            params->cmask |= 1 << var;
            params->rmask |= 1 << var;
      }
      return changed;
}


/**
 * snd_pcm_hw_param_last
 * @pcm: PCM instance
 * @params: the hw_params instance
 * @var: parameter to retrieve
 * @dir: pointer to the direction (-1,0,1) or NULL
 *
 * Inside configuration space defined by PARAMS remove from PAR all 
 * values < maximum. Reduce configuration space accordingly.
 * Return the maximum.
 */
int snd_pcm_hw_param_last(struct snd_pcm_substream *pcm, 
                    struct snd_pcm_hw_params *params,
                    snd_pcm_hw_param_t var, int *dir)
{
      int changed = _snd_pcm_hw_param_last(params, var);
      if (changed < 0)
            return changed;
      if (params->rmask) {
            int err = snd_pcm_hw_refine(pcm, params);
            snd_assert(err >= 0, return err);
      }
      return snd_pcm_hw_param_value(params, var, dir);
}

EXPORT_SYMBOL(snd_pcm_hw_param_last);

/**
 * snd_pcm_hw_param_choose
 * @pcm: PCM instance
 * @params: the hw_params instance
 *
 * Choose one configuration from configuration space defined by PARAMS
 * The configuration chosen is that obtained fixing in this order:
 * first access, first format, first subformat, min channels,
 * min rate, min period time, max buffer size, min tick time
 */
int snd_pcm_hw_params_choose(struct snd_pcm_substream *pcm,
                       struct snd_pcm_hw_params *params)
{
      static int vars[] = {
            SNDRV_PCM_HW_PARAM_ACCESS,
            SNDRV_PCM_HW_PARAM_FORMAT,
            SNDRV_PCM_HW_PARAM_SUBFORMAT,
            SNDRV_PCM_HW_PARAM_CHANNELS,
            SNDRV_PCM_HW_PARAM_RATE,
            SNDRV_PCM_HW_PARAM_PERIOD_TIME,
            SNDRV_PCM_HW_PARAM_BUFFER_SIZE,
            SNDRV_PCM_HW_PARAM_TICK_TIME,
            -1
      };
      int err, *v;

      for (v = vars; *v != -1; v++) {
            if (*v != SNDRV_PCM_HW_PARAM_BUFFER_SIZE)
                  err = snd_pcm_hw_param_first(pcm, params, *v, NULL);
            else
                  err = snd_pcm_hw_param_last(pcm, params, *v, NULL);
            snd_assert(err >= 0, return err);
      }
      return 0;
}

static int snd_pcm_lib_ioctl_reset(struct snd_pcm_substream *substream,
                           void *arg)
{
      struct snd_pcm_runtime *runtime = substream->runtime;
      unsigned long flags;
      snd_pcm_stream_lock_irqsave(substream, flags);
      if (snd_pcm_running(substream) &&
          snd_pcm_update_hw_ptr(substream) >= 0)
            runtime->status->hw_ptr %= runtime->buffer_size;
      else
            runtime->status->hw_ptr = 0;
      snd_pcm_stream_unlock_irqrestore(substream, flags);
      return 0;
}

static int snd_pcm_lib_ioctl_channel_info(struct snd_pcm_substream *substream,
                                void *arg)
{
      struct snd_pcm_channel_info *info = arg;
      struct snd_pcm_runtime *runtime = substream->runtime;
      int width;
      if (!(runtime->info & SNDRV_PCM_INFO_MMAP)) {
            info->offset = -1;
            return 0;
      }
      width = snd_pcm_format_physical_width(runtime->format);
      if (width < 0)
            return width;
      info->offset = 0;
      switch (runtime->access) {
      case SNDRV_PCM_ACCESS_MMAP_INTERLEAVED:
      case SNDRV_PCM_ACCESS_RW_INTERLEAVED:
            info->first = info->channel * width;
            info->step = runtime->channels * width;
            break;
      case SNDRV_PCM_ACCESS_MMAP_NONINTERLEAVED:
      case SNDRV_PCM_ACCESS_RW_NONINTERLEAVED:
      {
            size_t size = runtime->dma_bytes / runtime->channels;
            info->first = info->channel * size * 8;
            info->step = width;
            break;
      }
      default:
            snd_BUG();
            break;
      }
      return 0;
}

/**
 * snd_pcm_lib_ioctl - a generic PCM ioctl callback
 * @substream: the pcm substream instance
 * @cmd: ioctl command
 * @arg: ioctl argument
 *
 * Processes the generic ioctl commands for PCM.
 * Can be passed as the ioctl callback for PCM ops.
 *
 * Returns zero if successful, or a negative error code on failure.
 */
int snd_pcm_lib_ioctl(struct snd_pcm_substream *substream,
                  unsigned int cmd, void *arg)
{
      switch (cmd) {
      case SNDRV_PCM_IOCTL1_INFO:
            return 0;
      case SNDRV_PCM_IOCTL1_RESET:
            return snd_pcm_lib_ioctl_reset(substream, arg);
      case SNDRV_PCM_IOCTL1_CHANNEL_INFO:
            return snd_pcm_lib_ioctl_channel_info(substream, arg);
      }
      return -ENXIO;
}

EXPORT_SYMBOL(snd_pcm_lib_ioctl);

/*
 *  Conditions
 */

static void snd_pcm_system_tick_set(struct snd_pcm_substream *substream, 
                            unsigned long ticks)
{
      struct snd_pcm_runtime *runtime = substream->runtime;
      if (ticks == 0)
            del_timer(&runtime->tick_timer);
      else {
            ticks += (1000000 / HZ) - 1;
            ticks /= (1000000 / HZ);
            mod_timer(&runtime->tick_timer, jiffies + ticks);
      }
}

/* Temporary alias */
void snd_pcm_tick_set(struct snd_pcm_substream *substream, unsigned long ticks)
{
      snd_pcm_system_tick_set(substream, ticks);
}

void snd_pcm_tick_prepare(struct snd_pcm_substream *substream)
{
      struct snd_pcm_runtime *runtime = substream->runtime;
      snd_pcm_uframes_t frames = ULONG_MAX;
      snd_pcm_uframes_t avail, dist;
      unsigned int ticks;
      u_int64_t n;
      u_int32_t r;
      if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
            if (runtime->silence_size >= runtime->boundary) {
                  frames = 1;
            } else if (runtime->silence_size > 0 &&
                     runtime->silence_filled < runtime->buffer_size) {
                  snd_pcm_sframes_t noise_dist;
                  noise_dist = snd_pcm_playback_hw_avail(runtime) + runtime->silence_filled;
                  if (noise_dist > (snd_pcm_sframes_t)runtime->silence_threshold)
                        frames = noise_dist - runtime->silence_threshold;
            }
            avail = snd_pcm_playback_avail(runtime);
      } else {
            avail = snd_pcm_capture_avail(runtime);
      }
      if (avail < runtime->control->avail_min) {
            snd_pcm_sframes_t n = runtime->control->avail_min - avail;
            if (n > 0 && frames > (snd_pcm_uframes_t)n)
                  frames = n;
      }
      if (avail < runtime->buffer_size) {
            snd_pcm_sframes_t n = runtime->buffer_size - avail;
            if (n > 0 && frames > (snd_pcm_uframes_t)n)
                  frames = n;
      }
      if (frames == ULONG_MAX) {
            snd_pcm_tick_set(substream, 0);
            return;
      }
      dist = runtime->status->hw_ptr - runtime->hw_ptr_base;
      /* Distance to next interrupt */
      dist = runtime->period_size - dist % runtime->period_size;
      if (dist <= frames) {
            snd_pcm_tick_set(substream, 0);
            return;
      }
      /* the base time is us */
      n = frames;
      n *= 1000000;
      div64_32(&n, runtime->tick_time * runtime->rate, &r);
      ticks = n + (r > 0 ? 1 : 0);
      if (ticks < runtime->sleep_min)
            ticks = runtime->sleep_min;
      snd_pcm_tick_set(substream, (unsigned long) ticks);
}

void snd_pcm_tick_elapsed(struct snd_pcm_substream *substream)
{
      struct snd_pcm_runtime *runtime;
      unsigned long flags;
      
      snd_assert(substream != NULL, return);
      runtime = substream->runtime;
      snd_assert(runtime != NULL, return);

      snd_pcm_stream_lock_irqsave(substream, flags);
      if (!snd_pcm_running(substream) ||
          snd_pcm_update_hw_ptr(substream) < 0)
            goto _end;
      if (runtime->sleep_min)
            snd_pcm_tick_prepare(substream);
 _end:
      snd_pcm_stream_unlock_irqrestore(substream, flags);
}

/**
 * snd_pcm_period_elapsed - update the pcm status for the next period
 * @substream: the pcm substream instance
 *
 * This function is called from the interrupt handler when the
 * PCM has processed the period size.  It will update the current
 * pointer, set up the tick, wake up sleepers, etc.
 *
 * Even if more than one periods have elapsed since the last call, you
 * have to call this only once.
 */
void snd_pcm_period_elapsed(struct snd_pcm_substream *substream)
{
      struct snd_pcm_runtime *runtime;
      unsigned long flags;

      snd_assert(substream != NULL, return);
      runtime = substream->runtime;
      snd_assert(runtime != NULL, return);

      if (runtime->transfer_ack_begin)
            runtime->transfer_ack_begin(substream);

      snd_pcm_stream_lock_irqsave(substream, flags);
      if (!snd_pcm_running(substream) ||
          snd_pcm_update_hw_ptr_interrupt(substream) < 0)
            goto _end;

      if (substream->timer_running)
            snd_timer_interrupt(substream->timer, 1);
      if (runtime->sleep_min)
            snd_pcm_tick_prepare(substream);
 _end:
      snd_pcm_stream_unlock_irqrestore(substream, flags);
      if (runtime->transfer_ack_end)
            runtime->transfer_ack_end(substream);
      kill_fasync(&runtime->fasync, SIGIO, POLL_IN);
}

EXPORT_SYMBOL(snd_pcm_period_elapsed);

static int snd_pcm_lib_write_transfer(struct snd_pcm_substream *substream,
                              unsigned int hwoff,
                              unsigned long data, unsigned int off,
                              snd_pcm_uframes_t frames)
{
      struct snd_pcm_runtime *runtime = substream->runtime;
      int err;
      char __user *buf = (char __user *) data + frames_to_bytes(runtime, off);
      if (substream->ops->copy) {
            if ((err = substream->ops->copy(substream, -1, hwoff, buf, frames)) < 0)
                  return err;
      } else {
            char *hwbuf = runtime->dma_area + frames_to_bytes(runtime, hwoff);
            snd_assert(runtime->dma_area, return -EFAULT);
            if (copy_from_user(hwbuf, buf, frames_to_bytes(runtime, frames)))
                  return -EFAULT;
      }
      return 0;
}
 
typedef int (*transfer_f)(struct snd_pcm_substream *substream, unsigned int hwoff,
                    unsigned long data, unsigned int off,
                    snd_pcm_uframes_t size);

static snd_pcm_sframes_t snd_pcm_lib_write1(struct snd_pcm_substream *substream, 
                                  unsigned long data,
                                  snd_pcm_uframes_t size,
                                  int nonblock,
                                  transfer_f transfer)
{
      struct snd_pcm_runtime *runtime = substream->runtime;
      snd_pcm_uframes_t xfer = 0;
      snd_pcm_uframes_t offset = 0;
      int err = 0;

      if (size == 0)
            return 0;
      if (size > runtime->xfer_align)
            size -= size % runtime->xfer_align;

      snd_pcm_stream_lock_irq(substream);
      switch (runtime->status->state) {
      case SNDRV_PCM_STATE_PREPARED:
      case SNDRV_PCM_STATE_RUNNING:
      case SNDRV_PCM_STATE_PAUSED:
            break;
      case SNDRV_PCM_STATE_XRUN:
            err = -EPIPE;
            goto _end_unlock;
      case SNDRV_PCM_STATE_SUSPENDED:
            err = -ESTRPIPE;
            goto _end_unlock;
      default:
            err = -EBADFD;
            goto _end_unlock;
      }

      while (size > 0) {
            snd_pcm_uframes_t frames, appl_ptr, appl_ofs;
            snd_pcm_uframes_t avail;
            snd_pcm_uframes_t cont;
            if (runtime->sleep_min == 0 && runtime->status->state == SNDRV_PCM_STATE_RUNNING)
                  snd_pcm_update_hw_ptr(substream);
            avail = snd_pcm_playback_avail(runtime);
            if (((avail < runtime->control->avail_min && size > avail) ||
               (size >= runtime->xfer_align && avail < runtime->xfer_align))) {
                  wait_queue_t wait;
                  enum { READY, SIGNALED, ERROR, SUSPENDED, EXPIRED, DROPPED } state;
                  long tout;

                  if (nonblock) {
                        err = -EAGAIN;
                        goto _end_unlock;
                  }

                  init_waitqueue_entry(&wait, current);
                  add_wait_queue(&runtime->sleep, &wait);
                  while (1) {
                        if (signal_pending(current)) {
                              state = SIGNALED;
                              break;
                        }
                        set_current_state(TASK_INTERRUPTIBLE);
                        snd_pcm_stream_unlock_irq(substream);
                        tout = schedule_timeout(10 * HZ);
                        snd_pcm_stream_lock_irq(substream);
                        if (tout == 0) {
                              if (runtime->status->state != SNDRV_PCM_STATE_PREPARED &&
                                  runtime->status->state != SNDRV_PCM_STATE_PAUSED) {
                                    state = runtime->status->state == SNDRV_PCM_STATE_SUSPENDED ? SUSPENDED : EXPIRED;
                                    break;
                              }
                        }
                        switch (runtime->status->state) {
                        case SNDRV_PCM_STATE_XRUN:
                        case SNDRV_PCM_STATE_DRAINING:
                              state = ERROR;
                              goto _end_loop;
                        case SNDRV_PCM_STATE_SUSPENDED:
                              state = SUSPENDED;
                              goto _end_loop;
                        case SNDRV_PCM_STATE_SETUP:
                              state = DROPPED;
                              goto _end_loop;
                        default:
                              break;
                        }
                        avail = snd_pcm_playback_avail(runtime);
                        if (avail >= runtime->control->avail_min) {
                              state = READY;
                              break;
                        }
                  }
                   _end_loop:
                  remove_wait_queue(&runtime->sleep, &wait);

                  switch (state) {
                  case ERROR:
                        err = -EPIPE;
                        goto _end_unlock;
                  case SUSPENDED:
                        err = -ESTRPIPE;
                        goto _end_unlock;
                  case SIGNALED:
                        err = -ERESTARTSYS;
                        goto _end_unlock;
                  case EXPIRED:
                        snd_printd("playback write error (DMA or IRQ trouble?)\n");
                        err = -EIO;
                        goto _end_unlock;
                  case DROPPED:
                        err = -EBADFD;
                        goto _end_unlock;
                  default:
                        break;
                  }
            }
            if (avail > runtime->xfer_align)
                  avail -= avail % runtime->xfer_align;
            frames = size > avail ? avail : size;
            cont = runtime->buffer_size - runtime->control->appl_ptr % runtime->buffer_size;
            if (frames > cont)
                  frames = cont;
            snd_assert(frames != 0, snd_pcm_stream_unlock_irq(substream); return -EINVAL);
            appl_ptr = runtime->control->appl_ptr;
            appl_ofs = appl_ptr % runtime->buffer_size;
            snd_pcm_stream_unlock_irq(substream);
            if ((err = transfer(substream, appl_ofs, data, offset, frames)) < 0)
                  goto _end;
            snd_pcm_stream_lock_irq(substream);
            switch (runtime->status->state) {
            case SNDRV_PCM_STATE_XRUN:
                  err = -EPIPE;
                  goto _end_unlock;
            case SNDRV_PCM_STATE_SUSPENDED:
                  err = -ESTRPIPE;
                  goto _end_unlock;
            default:
                  break;
            }
            appl_ptr += frames;
            if (appl_ptr >= runtime->boundary)
                  appl_ptr -= runtime->boundary;
            runtime->control->appl_ptr = appl_ptr;
            if (substream->ops->ack)
                  substream->ops->ack(substream);

            offset += frames;
            size -= frames;
            xfer += frames;
            if (runtime->status->state == SNDRV_PCM_STATE_PREPARED &&
                snd_pcm_playback_hw_avail(runtime) >= (snd_pcm_sframes_t)runtime->start_threshold) {
                  err = snd_pcm_start(substream);
                  if (err < 0)
                        goto _end_unlock;
            }
            if (runtime->sleep_min &&
                runtime->status->state == SNDRV_PCM_STATE_RUNNING)
                  snd_pcm_tick_prepare(substream);
      }
 _end_unlock:
      snd_pcm_stream_unlock_irq(substream);
 _end:
      return xfer > 0 ? (snd_pcm_sframes_t)xfer : err;
}

snd_pcm_sframes_t snd_pcm_lib_write(struct snd_pcm_substream *substream, const void __user *buf, snd_pcm_uframes_t size)
{
      struct snd_pcm_runtime *runtime;
      int nonblock;

      snd_assert(substream != NULL, return -ENXIO);
      runtime = substream->runtime;
      snd_assert(runtime != NULL, return -ENXIO);
      snd_assert(substream->ops->copy != NULL || runtime->dma_area != NULL, return -EINVAL);
      if (runtime->status->state == SNDRV_PCM_STATE_OPEN)
            return -EBADFD;

      nonblock = !!(substream->f_flags & O_NONBLOCK);

      if (runtime->access != SNDRV_PCM_ACCESS_RW_INTERLEAVED &&
          runtime->channels > 1)
            return -EINVAL;
      return snd_pcm_lib_write1(substream, (unsigned long)buf, size, nonblock,
                          snd_pcm_lib_write_transfer);
}

EXPORT_SYMBOL(snd_pcm_lib_write);

static int snd_pcm_lib_writev_transfer(struct snd_pcm_substream *substream,
                               unsigned int hwoff,
                               unsigned long data, unsigned int off,
                               snd_pcm_uframes_t frames)
{
      struct snd_pcm_runtime *runtime = substream->runtime;
      int err;
      void __user **bufs = (void __user **)data;
      int channels = runtime->channels;
      int c;
      if (substream->ops->copy) {
            snd_assert(substream->ops->silence != NULL, return -EINVAL);
            for (c = 0; c < channels; ++c, ++bufs) {
                  if (*bufs == NULL) {
                        if ((err = substream->ops->silence(substream, c, hwoff, frames)) < 0)
                              return err;
                  } else {
                        char __user *buf = *bufs + samples_to_bytes(runtime, off);
                        if ((err = substream->ops->copy(substream, c, hwoff, buf, frames)) < 0)
                              return err;
                  }
            }
      } else {
            /* default transfer behaviour */
            size_t dma_csize = runtime->dma_bytes / channels;
            snd_assert(runtime->dma_area, return -EFAULT);
            for (c = 0; c < channels; ++c, ++bufs) {
                  char *hwbuf = runtime->dma_area + (c * dma_csize) + samples_to_bytes(runtime, hwoff);
                  if (*bufs == NULL) {
                        snd_pcm_format_set_silence(runtime->format, hwbuf, frames);
                  } else {
                        char __user *buf = *bufs + samples_to_bytes(runtime, off);
                        if (copy_from_user(hwbuf, buf, samples_to_bytes(runtime, frames)))
                              return -EFAULT;
                  }
            }
      }
      return 0;
}
 
snd_pcm_sframes_t snd_pcm_lib_writev(struct snd_pcm_substream *substream,
                             void __user **bufs,
                             snd_pcm_uframes_t frames)
{
      struct snd_pcm_runtime *runtime;
      int nonblock;

      snd_assert(substream != NULL, return -ENXIO);
      runtime = substream->runtime;
      snd_assert(runtime != NULL, return -ENXIO);
      snd_assert(substream->ops->copy != NULL || runtime->dma_area != NULL, return -EINVAL);
      if (runtime->status->state == SNDRV_PCM_STATE_OPEN)
            return -EBADFD;

      nonblock = !!(substream->f_flags & O_NONBLOCK);

      if (runtime->access != SNDRV_PCM_ACCESS_RW_NONINTERLEAVED)
            return -EINVAL;
      return snd_pcm_lib_write1(substream, (unsigned long)bufs, frames,
                          nonblock, snd_pcm_lib_writev_transfer);
}

EXPORT_SYMBOL(snd_pcm_lib_writev);

static int snd_pcm_lib_read_transfer(struct snd_pcm_substream *substream, 
                             unsigned int hwoff,
                             unsigned long data, unsigned int off,
                             snd_pcm_uframes_t frames)
{
      struct snd_pcm_runtime *runtime = substream->runtime;
      int err;
      char __user *buf = (char __user *) data + frames_to_bytes(runtime, off);
      if (substream->ops->copy) {
            if ((err = substream->ops->copy(substream, -1, hwoff, buf, frames)) < 0)
                  return err;
      } else {
            char *hwbuf = runtime->dma_area + frames_to_bytes(runtime, hwoff);
            snd_assert(runtime->dma_area, return -EFAULT);
            if (copy_to_user(buf, hwbuf, frames_to_bytes(runtime, frames)))
                  return -EFAULT;
      }
      return 0;
}

static snd_pcm_sframes_t snd_pcm_lib_read1(struct snd_pcm_substream *substream,
                                 unsigned long data,
                                 snd_pcm_uframes_t size,
                                 int nonblock,
                                 transfer_f transfer)
{
      struct snd_pcm_runtime *runtime = substream->runtime;
      snd_pcm_uframes_t xfer = 0;
      snd_pcm_uframes_t offset = 0;
      int err = 0;

      if (size == 0)
            return 0;
      if (size > runtime->xfer_align)
            size -= size % runtime->xfer_align;

      snd_pcm_stream_lock_irq(substream);
      switch (runtime->status->state) {
      case SNDRV_PCM_STATE_PREPARED:
            if (size >= runtime->start_threshold) {
                  err = snd_pcm_start(substream);
                  if (err < 0)
                        goto _end_unlock;
            }
            break;
      case SNDRV_PCM_STATE_DRAINING:
      case SNDRV_PCM_STATE_RUNNING:
      case SNDRV_PCM_STATE_PAUSED:
            break;
      case SNDRV_PCM_STATE_XRUN:
            err = -EPIPE;
            goto _end_unlock;
      case SNDRV_PCM_STATE_SUSPENDED:
            err = -ESTRPIPE;
            goto _end_unlock;
      default:
            err = -EBADFD;
            goto _end_unlock;
      }

      while (size > 0) {
            snd_pcm_uframes_t frames, appl_ptr, appl_ofs;
            snd_pcm_uframes_t avail;
            snd_pcm_uframes_t cont;
            if (runtime->sleep_min == 0 && runtime->status->state == SNDRV_PCM_STATE_RUNNING)
                  snd_pcm_update_hw_ptr(substream);
            __draining:
            avail = snd_pcm_capture_avail(runtime);
            if (runtime->status->state == SNDRV_PCM_STATE_DRAINING) {
                  if (avail < runtime->xfer_align) {
                        err = -EPIPE;
                        goto _end_unlock;
                  }
            } else if ((avail < runtime->control->avail_min && size > avail) ||
                     (size >= runtime->xfer_align && avail < runtime->xfer_align)) {
                  wait_queue_t wait;
                  enum { READY, SIGNALED, ERROR, SUSPENDED, EXPIRED, DROPPED } state;
                  long tout;

                  if (nonblock) {
                        err = -EAGAIN;
                        goto _end_unlock;
                  }

                  init_waitqueue_entry(&wait, current);
                  add_wait_queue(&runtime->sleep, &wait);
                  while (1) {
                        if (signal_pending(current)) {
                              state = SIGNALED;
                              break;
                        }
                        set_current_state(TASK_INTERRUPTIBLE);
                        snd_pcm_stream_unlock_irq(substream);
                        tout = schedule_timeout(10 * HZ);
                        snd_pcm_stream_lock_irq(substream);
                        if (tout == 0) {
                              if (runtime->status->state != SNDRV_PCM_STATE_PREPARED &&
                                  runtime->status->state != SNDRV_PCM_STATE_PAUSED) {
                                    state = runtime->status->state == SNDRV_PCM_STATE_SUSPENDED ? SUSPENDED : EXPIRED;
                                    break;
                              }
                        }
                        switch (runtime->status->state) {
                        case SNDRV_PCM_STATE_XRUN:
                              state = ERROR;
                              goto _end_loop;
                        case SNDRV_PCM_STATE_SUSPENDED:
                              state = SUSPENDED;
                              goto _end_loop;
                        case SNDRV_PCM_STATE_DRAINING:
                              goto __draining;
                        case SNDRV_PCM_STATE_SETUP:
                              state = DROPPED;
                              goto _end_loop;
                        default:
                              break;
                        }
                        avail = snd_pcm_capture_avail(runtime);
                        if (avail >= runtime->control->avail_min) {
                              state = READY;
                              break;
                        }
                  }
                   _end_loop:
                  remove_wait_queue(&runtime->sleep, &wait);

                  switch (state) {
                  case ERROR:
                        err = -EPIPE;
                        goto _end_unlock;
                  case SUSPENDED:
                        err = -ESTRPIPE;
                        goto _end_unlock;
                  case SIGNALED:
                        err = -ERESTARTSYS;
                        goto _end_unlock;
                  case EXPIRED:
                        snd_printd("capture read error (DMA or IRQ trouble?)\n");
                        err = -EIO;
                        goto _end_unlock;
                  case DROPPED:
                        err = -EBADFD;
                        goto _end_unlock;
                  default:
                        break;
                  }
            }
            if (avail > runtime->xfer_align)
                  avail -= avail % runtime->xfer_align;
            frames = size > avail ? avail : size;
            cont = runtime->buffer_size - runtime->control->appl_ptr % runtime->buffer_size;
            if (frames > cont)
                  frames = cont;
            snd_assert(frames != 0, snd_pcm_stream_unlock_irq(substream); return -EINVAL);
            appl_ptr = runtime->control->appl_ptr;
            appl_ofs = appl_ptr % runtime->buffer_size;
            snd_pcm_stream_unlock_irq(substream);
            if ((err = transfer(substream, appl_ofs, data, offset, frames)) < 0)
                  goto _end;
            snd_pcm_stream_lock_irq(substream);
            switch (runtime->status->state) {
            case SNDRV_PCM_STATE_XRUN:
                  err = -EPIPE;
                  goto _end_unlock;
            case SNDRV_PCM_STATE_SUSPENDED:
                  err = -ESTRPIPE;
                  goto _end_unlock;
            default:
                  break;
            }
            appl_ptr += frames;
            if (appl_ptr >= runtime->boundary)
                  appl_ptr -= runtime->boundary;
            runtime->control->appl_ptr = appl_ptr;
            if (substream->ops->ack)
                  substream->ops->ack(substream);

            offset += frames;
            size -= frames;
            xfer += frames;
            if (runtime->sleep_min &&
                runtime->status->state == SNDRV_PCM_STATE_RUNNING)
                  snd_pcm_tick_prepare(substream);
      }
 _end_unlock:
      snd_pcm_stream_unlock_irq(substream);
 _end:
      return xfer > 0 ? (snd_pcm_sframes_t)xfer : err;
}

snd_pcm_sframes_t snd_pcm_lib_read(struct snd_pcm_substream *substream, void __user *buf, snd_pcm_uframes_t size)
{
      struct snd_pcm_runtime *runtime;
      int nonblock;
      
      snd_assert(substream != NULL, return -ENXIO);
      runtime = substream->runtime;
      snd_assert(runtime != NULL, return -ENXIO);
      snd_assert(substream->ops->copy != NULL || runtime->dma_area != NULL, return -EINVAL);
      if (runtime->status->state == SNDRV_PCM_STATE_OPEN)
            return -EBADFD;

      nonblock = !!(substream->f_flags & O_NONBLOCK);
      if (runtime->access != SNDRV_PCM_ACCESS_RW_INTERLEAVED)
            return -EINVAL;
      return snd_pcm_lib_read1(substream, (unsigned long)buf, size, nonblock, snd_pcm_lib_read_transfer);
}

EXPORT_SYMBOL(snd_pcm_lib_read);

static int snd_pcm_lib_readv_transfer(struct snd_pcm_substream *substream,
                              unsigned int hwoff,
                              unsigned long data, unsigned int off,
                              snd_pcm_uframes_t frames)
{
      struct snd_pcm_runtime *runtime = substream->runtime;
      int err;
      void __user **bufs = (void __user **)data;
      int channels = runtime->channels;
      int c;
      if (substream->ops->copy) {
            for (c = 0; c < channels; ++c, ++bufs) {
                  char __user *buf;
                  if (*bufs == NULL)
                        continue;
                  buf = *bufs + samples_to_bytes(runtime, off);
                  if ((err = substream->ops->copy(substream, c, hwoff, buf, frames)) < 0)
                        return err;
            }
      } else {
            snd_pcm_uframes_t dma_csize = runtime->dma_bytes / channels;
            snd_assert(runtime->dma_area, return -EFAULT);
            for (c = 0; c < channels; ++c, ++bufs) {
                  char *hwbuf;
                  char __user *buf;
                  if (*bufs == NULL)
                        continue;

                  hwbuf = runtime->dma_area + (c * dma_csize) + samples_to_bytes(runtime, hwoff);
                  buf = *bufs + samples_to_bytes(runtime, off);
                  if (copy_to_user(buf, hwbuf, samples_to_bytes(runtime, frames)))
                        return -EFAULT;
            }
      }
      return 0;
}
 
snd_pcm_sframes_t snd_pcm_lib_readv(struct snd_pcm_substream *substream,
                            void __user **bufs,
                            snd_pcm_uframes_t frames)
{
      struct snd_pcm_runtime *runtime;
      int nonblock;

      snd_assert(substream != NULL, return -ENXIO);
      runtime = substream->runtime;
      snd_assert(runtime != NULL, return -ENXIO);
      snd_assert(substream->ops->copy != NULL || runtime->dma_area != NULL, return -EINVAL);
      if (runtime->status->state == SNDRV_PCM_STATE_OPEN)
            return -EBADFD;

      nonblock = !!(substream->f_flags & O_NONBLOCK);
      if (runtime->access != SNDRV_PCM_ACCESS_RW_NONINTERLEAVED)
            return -EINVAL;
      return snd_pcm_lib_read1(substream, (unsigned long)bufs, frames, nonblock, snd_pcm_lib_readv_transfer);
}

EXPORT_SYMBOL(snd_pcm_lib_readv);

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