pcm_lib.c

/*
 *  Digital Audio (PCM) abstract layer
 *  Copyright (c) by Jaroslav Kysela <perex@perex.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 <linux/slab.h>
#include <linux/time.h>
#include <linux/math64.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 = new_hw_ptr;
			} else {
				runtime->silence_start = ofs;
			}
		}
		frames = runtime->buffer_size - runtime->silence_filled;
	}
	if (snd_BUG_ON(frames > runtime->buffer_size))
		return;
	if (frames == 0)
		return;
	ofs = runtime->silence_start % 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_BUG_ON(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_BUG_ON(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;
	}
}

#ifdef CONFIG_SND_PCM_XRUN_DEBUG
#define xrun_debug(substream, mask)	((substream)->pstr->xrun_debug & (mask))
#else
#define xrun_debug(substream, mask)	0
#endif

#define dump_stack_on_xrun(substream) do {		\
		if (xrun_debug(substream, 2))		\
			dump_stack();			\
	} while (0)

static void pcm_debug_name(struct snd_pcm_substream *substream,
			   char *name, size_t len)
{
	snprintf(name, len, "pcmC%dD%d%c:%d",
		 substream->pcm->card->number,
		 substream->pcm->device,
		 substream->stream ? 'c' : 'p',
		 substream->number);
}

static void xrun(struct snd_pcm_substream *substream)
{
	struct snd_pcm_runtime *runtime = substream->runtime;

	if (runtime->tstamp_mode == SNDRV_PCM_TSTAMP_ENABLE)
		snd_pcm_gettime(runtime, (struct timespec *)&runtime->status->tstamp);
	snd_pcm_stop(substream, SNDRV_PCM_STATE_XRUN);
	if (xrun_debug(substream, 1)) {
		char name[16];
		pcm_debug_name(substream, name, sizeof(name));
		snd_printd(KERN_DEBUG "XRUN: %s\n", name);
		dump_stack_on_xrun(substream);
	}
}

static 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 (pos >= runtime->buffer_size) {
		if (printk_ratelimit()) {
			char name[16];
			pcm_debug_name(substream, name, sizeof(name));
			snd_printd(KERN_ERR  "BUG: %s, pos = 0x%lx, "
				   "buffer size = 0x%lx, period size = 0x%lx\n",
				   name, pos, runtime->buffer_size,
				   runtime->period_size);
		}
		pos = 0;
	}
	pos -= pos % runtime->min_align;
	return pos;
}

static 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;
}

#define hw_ptr_error(substream, fmt, args...)				\
	do {								\
		if (xrun_debug(substream, 1)) {				\
			if (printk_ratelimit()) {			\
				snd_printd("PCM: " fmt, ##args);	\
			}						\
			dump_stack_on_xrun(substream);			\
		}							\
	} while (0)

static 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 old_hw_ptr, new_hw_ptr, hw_ptr_interrupt, hw_base;
	snd_pcm_sframes_t hdelta, delta;
	unsigned long jdelta;

	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;
	}
	hw_base = runtime->hw_ptr_base;
	new_hw_ptr = hw_base + pos;
	hw_ptr_interrupt = runtime->hw_ptr_interrupt + runtime->period_size;
	delta = new_hw_ptr - hw_ptr_interrupt;
	if (hw_ptr_interrupt >= runtime->boundary) {
		hw_ptr_interrupt -= runtime->boundary;
		if (hw_base < runtime->boundary / 2)
			/* hw_base was already lapped; recalc delta */
			delta = new_hw_ptr - hw_ptr_interrupt;
	}
	if (delta < 0) {
		delta += runtime->buffer_size;
		if (delta < 0) {
			hw_ptr_error(substream, 
				     "Unexpected hw_pointer value "
				     "(stream=%i, pos=%ld, intr_ptr=%ld)\n",
				     substream->stream, (long)pos,
				     (long)hw_ptr_interrupt);
			/* rebase to interrupt position */
			hw_base = new_hw_ptr = hw_ptr_interrupt;
			/* align hw_base to buffer_size */
			hw_base -= hw_base % runtime->buffer_size;
			delta = 0;
		} else {
			hw_base += runtime->buffer_size;
			if (hw_base >= runtime->boundary)
				hw_base = 0;
			new_hw_ptr = hw_base + pos;
		}
	}

	/* Do jiffies check only in xrun_debug mode */
	if (!xrun_debug(substream, 4))
		goto no_jiffies_check;

	/* Skip the jiffies check for hardwares with BATCH flag.
	 * Such hardware usually just increases the position at each IRQ,
	 * thus it can't give any strange position.
	 */
	if (runtime->hw.info & SNDRV_PCM_INFO_BATCH)
		goto no_jiffies_check;
	hdelta = new_hw_ptr - old_hw_ptr;
	if (hdelta < runtime->delay)
		goto no_jiffies_check;
	hdelta -= runtime->delay;
	jdelta = jiffies - runtime->hw_ptr_jiffies;
	if (((hdelta * HZ) / runtime->rate) > jdelta + HZ/100) {
		delta = jdelta /
			(((runtime->period_size * HZ) / runtime->rate)
								+ HZ/100);
		hw_ptr_error(substream,
			     "hw_ptr skipping! [Q] "
			     "(pos=%ld, delta=%ld, period=%ld, "
			     "jdelta=%lu/%lu/%lu)\n",
			     (long)pos, (long)hdelta,
			     (long)runtime->period_size, jdelta,
			     ((hdelta * HZ) / runtime->rate), delta);
		hw_ptr_interrupt = runtime->hw_ptr_interrupt +
				   runtime->period_size * delta;
		if (hw_ptr_interrupt >= runtime->boundary)
			hw_ptr_interrupt -= runtime->boundary;
		/* rebase to interrupt position */
		hw_base = new_hw_ptr = hw_ptr_interrupt;
		/* align hw_base to buffer_size */
		hw_base -= hw_base % runtime->buffer_size;
		delta = 0;
	}
 no_jiffies_check:
	if (delta > runtime->period_size + runtime->period_size / 2) {
		hw_ptr_error(substream,
			     "Lost interrupts? "
			     "(stream=%i, delta=%ld, intr_ptr=%ld)\n",
			     substream->stream, (long)delta,
			     (long)hw_ptr_interrupt);
		/* rebase hw_ptr_interrupt */
		hw_ptr_interrupt =
			new_hw_ptr - new_hw_ptr % runtime->period_size;
	}
	runtime->hw_ptr_interrupt = hw_ptr_interrupt;

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

	if (runtime->status->hw_ptr == new_hw_ptr)
		return 0;

	runtime->hw_ptr_base = hw_base;
	runtime->status->hw_ptr = new_hw_ptr;
	runtime->hw_ptr_jiffies = jiffies;
	if (runtime->tstamp_mode == SNDRV_PCM_TSTAMP_ENABLE)
		snd_pcm_gettime(runtime, (struct timespec *)&runtime->status->tstamp);

	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, hw_base;
	snd_pcm_sframes_t delta;
	unsigned long jdelta;

	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;
	}
	hw_base = runtime->hw_ptr_base;
	new_hw_ptr = hw_base + pos;

	delta = new_hw_ptr - old_hw_ptr;
	jdelta = jiffies - runtime->hw_ptr_jiffies;
	if (delta < 0) {
		delta += runtime->buffer_size;
		if (delta < 0) {
			hw_ptr_error(substream, 
				     "Unexpected hw_pointer value [2] "
				     "(stream=%i, pos=%ld, old_ptr=%ld, jdelta=%li)\n",
				     substream->stream, (long)pos,
				     (long)old_hw_ptr, jdelta);
			return 0;
		}
		hw_base += runtime->buffer_size;
		if (hw_base >= runtime->boundary)
			hw_base = 0;
		new_hw_ptr = hw_base + pos;
	}
	/* Do jiffies check only in xrun_debug mode */
	if (!xrun_debug(substream, 4))
		goto no_jiffies_check;
	if (delta < runtime->delay)
		goto no_jiffies_check;
	delta -= runtime->delay;
	if (((delta * HZ) / runtime->rate) > jdelta + HZ/100) {
		hw_ptr_error(substream,
			     "hw_ptr skipping! "
			     "(pos=%ld, delta=%ld, period=%ld, jdelta=%lu/%lu)\n",
			     (long)pos, (long)delta,
			     (long)runtime->period_size, jdelta,
			     ((delta * HZ) / runtime->rate));
		return 0;
	}
 no_jiffies_check:
	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&
	    runtime->silence_size > 0)
		snd_pcm_playback_silence(substream, new_hw_ptr);

	if (runtime->status->hw_ptr == new_hw_ptr)
		return 0;

	runtime->hw_ptr_base = hw_base;
	runtime->status->hw_ptr = new_hw_ptr;
	runtime->hw_ptr_jiffies = jiffies;
	if (runtime->tstamp_mode == SNDRV_PCM_TSTAMP_ENABLE)
		snd_pcm_gettime(runtime, (struct timespec *)&runtime->status->tstamp);

	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_BUG_ON(!n);
		*r = 0;
		return UINT_MAX;
	}
	n = div_u64_rem(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;
	if (snd_BUG_ON(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)
{
	if (snd_BUG_ON(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)
{
	if (snd_BUG_ON(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;

	if (!count) {
		i->empty = 1;
		return -EINVAL;
	}
        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);