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pcm_lib.c
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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Digital Audio (PCM) abstract layer
* Copyright (c) by Jaroslav Kysela <perex@perex.cz>
* Abramo Bagnara <abramo@alsa-project.org>
*/
#include <linux/slab.h>
#include <linux/sched/signal.h>
#include <linux/time.h>
#include <linux/math64.h>
#include <linux/export.h>
#include <sound/core.h>
#include <sound/control.h>
#include <sound/tlv.h>
#include <sound/info.h>
#include <sound/pcm.h>
#include <sound/pcm_params.h>
#include <sound/timer.h>
#include "pcm_local.h"
#ifdef CONFIG_SND_PCM_XRUN_DEBUG
#define CREATE_TRACE_POINTS
#include "pcm_trace.h"
#else
#define trace_hwptr(substream, pos, in_interrupt)
#define trace_xrun(substream)
#define trace_hw_ptr_error(substream, reason)
#define trace_applptr(substream, prev, curr)
#endif
static int fill_silence_frames(struct snd_pcm_substream *substream,
snd_pcm_uframes_t off, snd_pcm_uframes_t frames);
static inline void update_silence_vars(struct snd_pcm_runtime *runtime,
snd_pcm_uframes_t ptr,
snd_pcm_uframes_t new_ptr)
{
snd_pcm_sframes_t delta;
delta = new_ptr - ptr;
if (delta == 0)
return;
if (delta < 0)
delta += runtime->boundary;
if ((snd_pcm_uframes_t)delta < runtime->silence_filled)
runtime->silence_filled -= delta;
else
runtime->silence_filled = 0;
runtime->silence_start = new_ptr;
}
/*
* 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;
int err;
if (runtime->silence_size < runtime->boundary) {
snd_pcm_sframes_t noise_dist;
snd_pcm_uframes_t appl_ptr = READ_ONCE(runtime->control->appl_ptr);
update_silence_vars(runtime, runtime->silence_start, appl_ptr);
/* initialization outside pointer updates */
if (new_hw_ptr == ULONG_MAX)
new_hw_ptr = runtime->status->hw_ptr;
/* get hw_avail with the boundary crossing */
noise_dist = appl_ptr - new_hw_ptr;
if (noise_dist < 0)
noise_dist += runtime->boundary;
/* total noise distance */
noise_dist += 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 {
/*
* This filling mode aims at free-running mode (used for example by dmix),
* which doesn't update the application pointer.
*/
snd_pcm_uframes_t hw_ptr = runtime->status->hw_ptr;
if (new_hw_ptr == ULONG_MAX) {
/*
* Initialization, fill the whole unused buffer with silence.
*
* Usually, this is entered while stopped, before data is queued,
* so both pointers are expected to be zero.
*/
snd_pcm_sframes_t avail = runtime->control->appl_ptr - hw_ptr;
if (avail < 0)
avail += runtime->boundary;
/*
* In free-running mode, appl_ptr will be zero even while running,
* so we end up with a huge number. There is no useful way to
* handle this, so we just clear the whole buffer.
*/
runtime->silence_filled = avail > runtime->buffer_size ? 0 : avail;
runtime->silence_start = hw_ptr;
} else {
/* Silence the just played area immediately */
update_silence_vars(runtime, hw_ptr, new_hw_ptr);
}
/*
* In this mode, silence_filled actually includes the valid
* sample data from the user.
*/
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->silence_filled) % runtime->buffer_size;
do {
transfer = ofs + frames > runtime->buffer_size ? runtime->buffer_size - ofs : frames;
err = fill_silence_frames(substream, ofs, transfer);
snd_BUG_ON(err < 0);
runtime->silence_filled += transfer;
frames -= transfer;
ofs = 0;
} while (frames > 0);
snd_pcm_dma_buffer_sync(substream, SNDRV_DMA_SYNC_DEVICE);
}
#ifdef CONFIG_SND_DEBUG
void snd_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);
}
EXPORT_SYMBOL(snd_pcm_debug_name);
#endif
#define XRUN_DEBUG_BASIC (1<<0)
#define XRUN_DEBUG_STACK (1<<1) /* dump also stack */
#define XRUN_DEBUG_JIFFIESCHECK (1<<2) /* do jiffies check */
#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, XRUN_DEBUG_STACK)) \
dump_stack(); \
} while (0)
/* call with stream lock held */
void __snd_pcm_xrun(struct snd_pcm_substream *substream)
{
struct snd_pcm_runtime *runtime = substream->runtime;
trace_xrun(substream);
if (runtime->tstamp_mode == SNDRV_PCM_TSTAMP_ENABLE) {
struct timespec64 tstamp;
snd_pcm_gettime(runtime, &tstamp);
runtime->status->tstamp.tv_sec = tstamp.tv_sec;
runtime->status->tstamp.tv_nsec = tstamp.tv_nsec;
}
snd_pcm_stop(substream, SNDRV_PCM_STATE_XRUN);
if (xrun_debug(substream, XRUN_DEBUG_BASIC)) {
char name[16];
snd_pcm_debug_name(substream, name, sizeof(name));
pcm_warn(substream->pcm, "XRUN: %s\n", name);
dump_stack_on_xrun(substream);
}
}
#ifdef CONFIG_SND_PCM_XRUN_DEBUG
#define hw_ptr_error(substream, in_interrupt, reason, fmt, args...) \
do { \
trace_hw_ptr_error(substream, reason); \
if (xrun_debug(substream, XRUN_DEBUG_BASIC)) { \
pr_err_ratelimited("ALSA: PCM: [%c] " reason ": " fmt, \
(in_interrupt) ? 'Q' : 'P', ##args); \
dump_stack_on_xrun(substream); \
} \
} while (0)
#else /* ! CONFIG_SND_PCM_XRUN_DEBUG */
#define hw_ptr_error(substream, fmt, args...) do { } while (0)
#endif
int snd_pcm_update_state(struct snd_pcm_substream *substream,
struct snd_pcm_runtime *runtime)
{
snd_pcm_uframes_t avail;
avail = snd_pcm_avail(substream);
if (avail > runtime->avail_max)
runtime->avail_max = avail;
if (runtime->state == SNDRV_PCM_STATE_DRAINING) {
if (avail >= runtime->buffer_size) {
snd_pcm_drain_done(substream);
return -EPIPE;
}
} else {
if (avail >= runtime->stop_threshold) {
__snd_pcm_xrun(substream);
return -EPIPE;
}
}
if (runtime->twake) {
if (avail >= runtime->twake)
wake_up(&runtime->tsleep);
} else if (avail >= runtime->control->avail_min)
wake_up(&runtime->sleep);
return 0;
}
static void update_audio_tstamp(struct snd_pcm_substream *substream,
struct timespec64 *curr_tstamp,
struct timespec64 *audio_tstamp)
{
struct snd_pcm_runtime *runtime = substream->runtime;
u64 audio_frames, audio_nsecs;
struct timespec64 driver_tstamp;
if (runtime->tstamp_mode != SNDRV_PCM_TSTAMP_ENABLE)
return;
if (!(substream->ops->get_time_info) ||
(runtime->audio_tstamp_report.actual_type ==
SNDRV_PCM_AUDIO_TSTAMP_TYPE_DEFAULT)) {
/*
* provide audio timestamp derived from pointer position
* add delay only if requested
*/
audio_frames = runtime->hw_ptr_wrap + runtime->status->hw_ptr;
if (runtime->audio_tstamp_config.report_delay) {
if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
audio_frames -= runtime->delay;
else
audio_frames += runtime->delay;
}
audio_nsecs = div_u64(audio_frames * 1000000000LL,
runtime->rate);
*audio_tstamp = ns_to_timespec64(audio_nsecs);
}
if (runtime->status->audio_tstamp.tv_sec != audio_tstamp->tv_sec ||
runtime->status->audio_tstamp.tv_nsec != audio_tstamp->tv_nsec) {
runtime->status->audio_tstamp.tv_sec = audio_tstamp->tv_sec;
runtime->status->audio_tstamp.tv_nsec = audio_tstamp->tv_nsec;
runtime->status->tstamp.tv_sec = curr_tstamp->tv_sec;
runtime->status->tstamp.tv_nsec = curr_tstamp->tv_nsec;
}
/*
* re-take a driver timestamp to let apps detect if the reference tstamp
* read by low-level hardware was provided with a delay
*/
snd_pcm_gettime(substream->runtime, &driver_tstamp);
runtime->driver_tstamp = driver_tstamp;
}
static int snd_pcm_update_hw_ptr0(struct snd_pcm_substream *substream,
unsigned int in_interrupt)
{
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 hdelta, delta;
unsigned long jdelta;
unsigned long curr_jiffies;
struct timespec64 curr_tstamp;
struct timespec64 audio_tstamp;
int crossed_boundary = 0;
old_hw_ptr = runtime->status->hw_ptr;
/*
* group pointer, time and jiffies reads to allow for more
* accurate correlations/corrections.
* The values are stored at the end of this routine after
* corrections for hw_ptr position
*/
pos = substream->ops->pointer(substream);
curr_jiffies = jiffies;
if (runtime->tstamp_mode == SNDRV_PCM_TSTAMP_ENABLE) {
if ((substream->ops->get_time_info) &&
(runtime->audio_tstamp_config.type_requested != SNDRV_PCM_AUDIO_TSTAMP_TYPE_DEFAULT)) {
substream->ops->get_time_info(substream, &curr_tstamp,
&audio_tstamp,
&runtime->audio_tstamp_config,
&runtime->audio_tstamp_report);
/* re-test in case tstamp type is not supported in hardware and was demoted to DEFAULT */
if (runtime->audio_tstamp_report.actual_type == SNDRV_PCM_AUDIO_TSTAMP_TYPE_DEFAULT)
snd_pcm_gettime(runtime, &curr_tstamp);
} else
snd_pcm_gettime(runtime, &curr_tstamp);
}
if (pos == SNDRV_PCM_POS_XRUN) {
__snd_pcm_xrun(substream);
return -EPIPE;
}
if (pos >= runtime->buffer_size) {
if (printk_ratelimit()) {
char name[16];
snd_pcm_debug_name(substream, name, sizeof(name));
pcm_err(substream->pcm,
"invalid position: %s, pos = %ld, buffer size = %ld, period size = %ld\n",
name, pos, runtime->buffer_size,
runtime->period_size);
}
pos = 0;
}
pos -= pos % runtime->min_align;
trace_hwptr(substream, pos, in_interrupt);
hw_base = runtime->hw_ptr_base;
new_hw_ptr = hw_base + pos;
if (in_interrupt) {
/* we know that one period was processed */
/* delta = "expected next hw_ptr" for in_interrupt != 0 */
delta = runtime->hw_ptr_interrupt + runtime->period_size;
if (delta > new_hw_ptr) {
/* check for double acknowledged interrupts */
hdelta = curr_jiffies - runtime->hw_ptr_jiffies;
if (hdelta > runtime->hw_ptr_buffer_jiffies/2 + 1) {
hw_base += runtime->buffer_size;
if (hw_base >= runtime->boundary) {
hw_base = 0;
crossed_boundary++;
}
new_hw_ptr = hw_base + pos;
goto __delta;
}
}
}
/* new_hw_ptr might be lower than old_hw_ptr in case when */
/* pointer crosses the end of the ring buffer */
if (new_hw_ptr < old_hw_ptr) {
hw_base += runtime->buffer_size;
if (hw_base >= runtime->boundary) {
hw_base = 0;
crossed_boundary++;
}
new_hw_ptr = hw_base + pos;
}
__delta:
delta = new_hw_ptr - old_hw_ptr;
if (delta < 0)
delta += runtime->boundary;
if (runtime->no_period_wakeup) {
snd_pcm_sframes_t xrun_threshold;
/*
* Without regular period interrupts, we have to check
* the elapsed time to detect xruns.
*/
jdelta = curr_jiffies - runtime->hw_ptr_jiffies;
if (jdelta < runtime->hw_ptr_buffer_jiffies / 2)
goto no_delta_check;
hdelta = jdelta - delta * HZ / runtime->rate;
xrun_threshold = runtime->hw_ptr_buffer_jiffies / 2 + 1;
while (hdelta > xrun_threshold) {
delta += runtime->buffer_size;
hw_base += runtime->buffer_size;
if (hw_base >= runtime->boundary) {
hw_base = 0;
crossed_boundary++;
}
new_hw_ptr = hw_base + pos;
hdelta -= runtime->hw_ptr_buffer_jiffies;
}
goto no_delta_check;
}
/* something must be really wrong */
if (delta >= runtime->buffer_size + runtime->period_size) {
hw_ptr_error(substream, in_interrupt, "Unexpected hw_ptr",
"(stream=%i, pos=%ld, new_hw_ptr=%ld, old_hw_ptr=%ld)\n",
substream->stream, (long)pos,
(long)new_hw_ptr, (long)old_hw_ptr);
return 0;
}
/* Do jiffies check only in xrun_debug mode */
if (!xrun_debug(substream, XRUN_DEBUG_JIFFIESCHECK))
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 = delta;
if (hdelta < runtime->delay)
goto no_jiffies_check;
hdelta -= runtime->delay;
jdelta = curr_jiffies - runtime->hw_ptr_jiffies;
if (((hdelta * HZ) / runtime->rate) > jdelta + HZ/100) {
delta = jdelta /
(((runtime->period_size * HZ) / runtime->rate)
+ HZ/100);
/* move new_hw_ptr according jiffies not pos variable */
new_hw_ptr = old_hw_ptr;
hw_base = delta;
/* use loop to avoid checks for delta overflows */
/* the delta value is small or zero in most cases */
while (delta > 0) {
new_hw_ptr += runtime->period_size;
if (new_hw_ptr >= runtime->boundary) {
new_hw_ptr -= runtime->boundary;
crossed_boundary--;
}
delta--;
}
/* align hw_base to buffer_size */
hw_ptr_error(substream, in_interrupt, "hw_ptr skipping",
"(pos=%ld, delta=%ld, period=%ld, jdelta=%lu/%lu/%lu, hw_ptr=%ld/%ld)\n",
(long)pos, (long)hdelta,
(long)runtime->period_size, jdelta,
((hdelta * HZ) / runtime->rate), hw_base,
(unsigned long)old_hw_ptr,
(unsigned long)new_hw_ptr);
/* reset values to proper state */
delta = 0;
hw_base = new_hw_ptr - (new_hw_ptr % runtime->buffer_size);
}
no_jiffies_check:
if (delta > runtime->period_size + runtime->period_size / 2) {
hw_ptr_error(substream, in_interrupt,
"Lost interrupts?",
"(stream=%i, delta=%ld, new_hw_ptr=%ld, old_hw_ptr=%ld)\n",
substream->stream, (long)delta,
(long)new_hw_ptr,
(long)old_hw_ptr);
}
no_delta_check:
if (runtime->status->hw_ptr == new_hw_ptr) {
runtime->hw_ptr_jiffies = curr_jiffies;
update_audio_tstamp(substream, &curr_tstamp, &audio_tstamp);
return 0;
}
if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&
runtime->silence_size > 0)
snd_pcm_playback_silence(substream, new_hw_ptr);
if (in_interrupt) {
delta = new_hw_ptr - runtime->hw_ptr_interrupt;
if (delta < 0)
delta += runtime->boundary;
delta -= (snd_pcm_uframes_t)delta % runtime->period_size;
runtime->hw_ptr_interrupt += delta;
if (runtime->hw_ptr_interrupt >= runtime->boundary)
runtime->hw_ptr_interrupt -= runtime->boundary;
}
runtime->hw_ptr_base = hw_base;
runtime->status->hw_ptr = new_hw_ptr;
runtime->hw_ptr_jiffies = curr_jiffies;
if (crossed_boundary) {
snd_BUG_ON(crossed_boundary != 1);
runtime->hw_ptr_wrap += runtime->boundary;
}
update_audio_tstamp(substream, &curr_tstamp, &audio_tstamp);
return snd_pcm_update_state(substream, runtime);
}
/* CAUTION: call it with irq disabled */
int snd_pcm_update_hw_ptr(struct snd_pcm_substream *substream)
{
return snd_pcm_update_hw_ptr0(substream, 0);
}
/**
* 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,
const 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_set_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) {
*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.
*
* Return: Positive if the value is changed, zero if it's not changed, or a
* negative error code.
*/
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)
{
const unsigned int last_max = i->max;
if (snd_BUG_ON(snd_interval_empty(i)))
return -EINVAL;
if (snd_interval_single(i))
return 0;
i->max = i->min;
if (i->openmin)
i->max++;
/* only exclude max value if also excluded before refine */
i->openmax = (i->openmax && i->max >= last_max);
return 1;
}
static int snd_interval_refine_last(struct snd_interval *i)
{
const unsigned int last_min = i->min;
if (snd_BUG_ON(snd_interval_empty(i)))
return -EINVAL;
if (snd_interval_single(i))
return 0;
i->min = i->max;
if (i->openmax)
i->min--;
/* only exclude min value if also excluded before refine */
i->openmin = (i->openmin && i->min <= last_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
*
* Return: Positive if the value is changed, zero if it's not changed, or a
* negative error code.
*/
int snd_interval_ratnum(struct snd_interval *i,
unsigned int rats_count, const struct snd_ratnum *rats,
unsigned int *nump, unsigned int *denp)
{
unsigned int best_num, best_den;
int best_diff;
unsigned int k;
struct snd_interval t;
int err;
unsigned int result_num, result_den;
int result_diff;
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_up(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 (diff < 0)
diff = -diff;
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);
result_num = best_num;
result_diff = best_diff;
result_den = 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_down(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 (diff < 0)
diff = -diff;
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 (best_diff * result_den < result_diff * best_den) {
result_num = best_num;
result_den = best_den;
}
if (nump)
*nump = result_num;
if (denp)
*denp = result_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
*
* Return: Positive if the value is changed, zero if it's not changed, or a
* negative error code.
*/
static int snd_interval_ratden(struct snd_interval *i,
unsigned int rats_count,
const 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);