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720289b2cd
freebsd-nq/sys/dev/sound/pcm/feeder_rate.c
Ariff Abdullah 720289b2cd Update my email address, so people know where the exact / 
proper / correct place to bug me.

Approved by:	netchild (mentor)
2005-11-14 18:37:59 +00:00

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/*-
* Copyright (c) 1999 Cameron Grant <cg@FreeBSD.org>
* Copyright (c) 2003 Orion Hodson <orion@FreeBSD.org>
* Copyright (c) 2005 Ariff Abdullah <ariff@FreeBSD.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* 2005-06-11:
* ==========
*
* *New* and rewritten soft sample rate converter supporting arbitary sample
* rate, fine grained scalling/coefficients and unified up/down stereo
* converter. Most of disclaimers from orion's previous version also applied
* here, regarding with linear interpolation deficiencies, pre/post
* anti-aliasing filtering issues. This version comes with much simpler and
* tighter interface, although it works almost exactly like the older one.
*
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* *
* This new implementation is fully dedicated in memory of Cameron Grant, *
* the creator of magnificent, highly addictive feeder infrastructure. *
* *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
*
* Orion's notes:
* =============
*
* This rate conversion code uses linear interpolation without any
* pre- or post- interpolation filtering to combat aliasing. This
* greatly limits the sound quality and should be addressed at some
* stage in the future.
*
* Since this accuracy of interpolation is sensitive and examination
* of the algorithm output is harder from the kernel, th code is
* designed to be compiled in the kernel and in a userland test
* harness. This is done by selectively including and excluding code
* with several portions based on whether _KERNEL is defined. It's a
* little ugly, but exceedingly useful. The testsuite and its
* revisions can be found at:
* http://people.freebsd.org/~orion/files/feedrate/
*
* Special thanks to Ken Marx for exposing flaws in the code and for
* testing revisions.
*/
#include <dev/sound/pcm/sound.h>
#include "feeder_if.h"
SND_DECLARE_FILE("$FreeBSD$");
#define RATE_ASSERT(x, y) /* KASSERT(x,y) */
#define RATE_TRACE(x...) /* printf(x) */
MALLOC_DEFINE(M_RATEFEEDER, "ratefeed", "pcm rate feeder");
#define FEEDBUFSZ 8192
#define ROUNDHZ 25
#define RATEMIN 4000
/* 8000 * 138 or 11025 * 100 . This is insane, indeed! */
#define RATEMAX 1102500
#define MINGAIN 92
#define MAXGAIN 96
#define FEEDRATE_CONVERT_64 0
#define FEEDRATE_CONVERT_SCALE64 1
#define FEEDRATE_CONVERT_SCALE32 2
#define FEEDRATE_CONVERT_PLAIN 3
#define FEEDRATE_CONVERT_FIXED 4
#define FEEDRATE_CONVERT_OPTIMAL 5
#define FEEDRATE_CONVERT_WORST 6
#define FEEDRATE_64_MAXROLL 32
#define FEEDRATE_32_MAXROLL 16
struct feed_rate_info {
uint32_t src, dst; /* rounded source / destination rates */
uint32_t rsrc, rdst; /* original source / destination rates */
uint32_t gx, gy; /* interpolation / decimation ratio */
uint32_t alpha; /* interpolation distance */
uint32_t pos, bpos; /* current sample / buffer positions */
uint32_t bufsz; /* total buffer size */
int32_t scale, roll; /* scale / roll factor */
int16_t *buffer;
uint32_t (*convert)(struct feed_rate_info *, int16_t *, uint32_t);
};
static uint32_t
feed_convert_64(struct feed_rate_info *, int16_t *, uint32_t);
static uint32_t
feed_convert_scale64(struct feed_rate_info *, int16_t *, uint32_t);
static uint32_t
feed_convert_scale32(struct feed_rate_info *, int16_t *, uint32_t);
static uint32_t
feed_convert_plain(struct feed_rate_info *, int16_t *, uint32_t);
int feeder_rate_ratemin = RATEMIN;
int feeder_rate_ratemax = RATEMAX;
/*
* See 'Feeder Scaling Type' below..
*/
static int feeder_rate_scaling = FEEDRATE_CONVERT_OPTIMAL;
static int feeder_rate_buffersize = FEEDBUFSZ & ~1;
/*
* sysctls.. I love sysctls..
*/
TUNABLE_INT("hw.snd.feeder_rate_ratemin", &feeder_rate_ratemin);
TUNABLE_INT("hw.snd.feeder_rate_ratemax", &feeder_rate_ratemin);
TUNABLE_INT("hw.snd.feeder_rate_scaling", &feeder_rate_scaling);
TUNABLE_INT("hw.snd.feeder_rate_buffersize", &feeder_rate_buffersize);
static int
sysctl_hw_snd_feeder_rate_ratemin(SYSCTL_HANDLER_ARGS)
{
int err, val;
val = feeder_rate_ratemin;
err = sysctl_handle_int(oidp, &val, sizeof(val), req);
if (val < 1 || val >= feeder_rate_ratemax)
err = EINVAL;
else
feeder_rate_ratemin = val;
return err;
}
SYSCTL_PROC(_hw_snd, OID_AUTO, feeder_rate_ratemin, CTLTYPE_INT | CTLFLAG_RW,
0, sizeof(int), sysctl_hw_snd_feeder_rate_ratemin, "I", "");
static int
sysctl_hw_snd_feeder_rate_ratemax(SYSCTL_HANDLER_ARGS)
{
int err, val;
val = feeder_rate_ratemax;
err = sysctl_handle_int(oidp, &val, sizeof(val), req);
if (val <= feeder_rate_ratemin || val > 0x7fffff)
err = EINVAL;
else
feeder_rate_ratemax = val;
return err;
}
SYSCTL_PROC(_hw_snd, OID_AUTO, feeder_rate_ratemax, CTLTYPE_INT | CTLFLAG_RW,
0, sizeof(int), sysctl_hw_snd_feeder_rate_ratemax, "I", "");
static int
sysctl_hw_snd_feeder_rate_scaling(SYSCTL_HANDLER_ARGS)
{
int err, val;
val = feeder_rate_scaling;
err = sysctl_handle_int(oidp, &val, sizeof(val), req);
/*
* Feeder Scaling Type
* ===================
*
* 1. Plain 64bit (high precision)
* 2. 64bit scaling (high precision, CPU friendly, but can
* cause gain up/down).
* 3. 32bit scaling (somehow can cause hz roundup, gain
* up/down).
* 4. Plain copy (default if src == dst. Except if src == dst,
* this is the worst / silly conversion method!).
*
* Sysctl options:-
*
* 0 - Plain 64bit - no fallback.
* 1 - 64bit scaling - no fallback.
* 2 - 32bit scaling - no fallback.
* 3 - Plain copy - no fallback.
* 4 - Fixed rate. Means that, choose optimal conversion method
* without causing hz roundup.
* 32bit scaling (as long as hz roundup does not occur),
* 64bit scaling, Plain 64bit.
* 5 - Optimal / CPU friendly (DEFAULT).
* 32bit scaling, 64bit scaling, Plain 64bit
* 6 - Optimal to worst, no 64bit arithmetic involved.
* 32bit scaling, Plain copy.
*/
if (val < FEEDRATE_CONVERT_64 || val > FEEDRATE_CONVERT_WORST)
err = EINVAL;
else
feeder_rate_scaling = val;
return err;
}
SYSCTL_PROC(_hw_snd, OID_AUTO, feeder_rate_scaling, CTLTYPE_INT | CTLFLAG_RW,
0, sizeof(int), sysctl_hw_snd_feeder_rate_scaling, "I", "");
static int
sysctl_hw_snd_feeder_rate_buffersize(SYSCTL_HANDLER_ARGS)
{
int err, val;
val = feeder_rate_buffersize;
err = sysctl_handle_int(oidp, &val, sizeof(val), req);
/*
* Don't waste too much kernel space
*/
if (val < 2 || val > 65536)
err = EINVAL;
else
feeder_rate_buffersize = val & ~1;
return err;
}
SYSCTL_PROC(_hw_snd, OID_AUTO, feeder_rate_buffersize, CTLTYPE_INT | CTLFLAG_RW,
0, sizeof(int), sysctl_hw_snd_feeder_rate_buffersize, "I", "");
static void
feed_speed_ratio(uint32_t x, uint32_t y, uint32_t *gx, uint32_t *gy)
{
uint32_t w, src = x, dst = y;
while (y != 0) {
w = x % y;
x = y;
y = w;
}
*gx = src / x;
*gy = dst / x;
}
static void
feed_scale_roll(uint32_t dst, int32_t *scale, int32_t *roll, int32_t max)
{
int64_t k, tscale;
int32_t j, troll;
*scale = *roll = -1;
for (j = MAXGAIN; j >= MINGAIN; j -= 3) {
for (troll = 0; troll < max; troll++) {
tscale = (1 << troll) / dst;
k = (tscale * dst * 100) >> troll;
if (k > j && k <= 100) {
*scale = tscale;
*roll = troll;
return;
}
}
}
}
static int
feed_get_best_coef(uint32_t *src, uint32_t *dst, uint32_t *gx, uint32_t *gy,
int32_t *scale, int32_t *roll)
{
uint32_t tsrc, tdst, sscale, dscale;
int32_t tscale, troll;
int i, j, hzmin, hzmax;
*scale = *roll = -1;
for (i = 0; i < 2; i++) {
hzmin = (ROUNDHZ * i) + 1;
hzmax = hzmin + ROUNDHZ;
for (j = hzmin; j < hzmax; j++) {
tsrc = *src - (*src % j);
tdst = *dst;
if (tsrc < 1 || tdst < 1)
goto coef_failed;
feed_speed_ratio(tsrc, tdst, &sscale, &dscale);
feed_scale_roll(dscale, &tscale, &troll,
FEEDRATE_32_MAXROLL);
if (tscale != -1 && troll != -1) {
*src = tsrc;
*gx = sscale;
*gy = dscale;
*scale = tscale;
*roll = troll;
return j;
}
}
for (j = hzmin; j < hzmax; j++) {
tsrc = *src - (*src % j);
tdst = *dst - (*dst % j);
if (tsrc < 1 || tdst < 1)
goto coef_failed;
feed_speed_ratio(tsrc, tdst, &sscale, &dscale);
feed_scale_roll(dscale, &tscale, &troll,
FEEDRATE_32_MAXROLL);
if (tscale != -1 && troll != -1) {
*src = tsrc;
*dst = tdst;
*gx = sscale;
*gy = dscale;
*scale = tscale;
*roll = troll;
return j;
}
}
for (j = hzmin; j < hzmax; j++) {
tsrc = *src;
tdst = *dst - (*dst % j);
if (tsrc < 1 || tdst < 1)
goto coef_failed;
feed_speed_ratio(tsrc, tdst, &sscale, &dscale);
feed_scale_roll(dscale, &tscale, &troll,
FEEDRATE_32_MAXROLL);
if (tscale != -1 && troll != -1) {
*src = tsrc;
*dst = tdst;
*gx = sscale;
*gy = dscale;
*scale = tscale;
*roll = troll;
return j;
}
}
}
coef_failed:
feed_speed_ratio(*src, *dst, gx, gy);
feed_scale_roll(*gy, scale, roll, FEEDRATE_32_MAXROLL);
return 0;
}
static void
feed_rate_reset(struct feed_rate_info *info)
{
info->scale = -1;
info->roll = -1;
info->src = info->rsrc;
info->dst = info->rdst;
info->gx = 0;
info->gy = 0;
}
static int
feed_rate_setup(struct pcm_feeder *f)
{
struct feed_rate_info *info = f->data;
int r = 0;
info->pos = 2;
info->bpos = 4;
info->alpha = 0;
feed_rate_reset(info);
if (info->src == info->dst) {
/*
* No conversion ever needed. Just do plain copy.
*/
info->convert = feed_convert_plain;
info->gx = 1;
info->gy = 1;
} else {
switch (feeder_rate_scaling) {
case FEEDRATE_CONVERT_64:
feed_speed_ratio(info->src, info->dst,
&info->gx, &info->gy);
info->convert = feed_convert_64;
break;
case FEEDRATE_CONVERT_SCALE64:
feed_speed_ratio(info->src, info->dst,
&info->gx, &info->gy);
feed_scale_roll(info->gy, &info->scale,
&info->roll, FEEDRATE_64_MAXROLL);
if (info->scale == -1 || info->roll == -1)
return -1;
info->convert = feed_convert_scale64;
break;
case FEEDRATE_CONVERT_SCALE32:
r = feed_get_best_coef(&info->src, &info->dst,
&info->gx, &info->gy, &info->scale,
&info->roll);
if (r == 0)
return -1;
info->convert = feed_convert_scale32;
break;
case FEEDRATE_CONVERT_PLAIN:
feed_speed_ratio(info->src, info->dst,
&info->gx, &info->gy);
info->convert = feed_convert_plain;
break;
case FEEDRATE_CONVERT_FIXED:
r = feed_get_best_coef(&info->src, &info->dst,
&info->gx, &info->gy, &info->scale,
&info->roll);
if (r != 0 && info->src == info->rsrc &&
info->dst == info->rdst)
info->convert = feed_convert_scale32;
else {
/* Fallback */
feed_rate_reset(info);
feed_speed_ratio(info->src, info->dst,
&info->gx, &info->gy);
feed_scale_roll(info->gy, &info->scale,
&info->roll, FEEDRATE_64_MAXROLL);
if (info->scale != -1 && info->roll != -1)
info->convert = feed_convert_scale64;
else
info->convert = feed_convert_64;
}
break;
case FEEDRATE_CONVERT_OPTIMAL:
r = feed_get_best_coef(&info->src, &info->dst,
&info->gx, &info->gy, &info->scale,
&info->roll);
if (r != 0)
info->convert = feed_convert_scale32;
else {
/* Fallback */
feed_rate_reset(info);
feed_speed_ratio(info->src, info->dst,
&info->gx, &info->gy);
feed_scale_roll(info->gy, &info->scale,
&info->roll, FEEDRATE_64_MAXROLL);
if (info->scale != -1 && info->roll != -1)
info->convert = feed_convert_scale64;
else
info->convert = feed_convert_64;
}
break;
case FEEDRATE_CONVERT_WORST:
r = feed_get_best_coef(&info->src, &info->dst,
&info->gx, &info->gy, &info->scale,
&info->roll);
if (r != 0)
info->convert = feed_convert_scale32;
else {
/* Fallback */
feed_rate_reset(info);
feed_speed_ratio(info->src, info->dst,
&info->gx, &info->gy);
info->convert = feed_convert_plain;
}
break;
default:
return -1;
break;
}
/* No way! */
if (info->gx == 0 || info->gy == 0)
return -1;
/*
* No need to interpolate/decimate, just do plain copy.
* This probably caused by Hz roundup.
*/
if (info->gx == info->gy)
info->convert = feed_convert_plain;
}
return 0;
}
static int
feed_rate_set(struct pcm_feeder *f, int what, int value)
{
struct feed_rate_info *info = f->data;
if (value < feeder_rate_ratemin || value > feeder_rate_ratemax)
return -1;
switch (what) {
case FEEDRATE_SRC:
info->rsrc = value;
break;
case FEEDRATE_DST:
info->rdst = value;
break;
default:
return -1;
}
return feed_rate_setup(f);
}
static int
feed_rate_get(struct pcm_feeder *f, int what)
{
struct feed_rate_info *info = f->data;
/*
* Return *real* src/dst rate.
*/
switch (what) {
case FEEDRATE_SRC:
return info->rsrc;
case FEEDRATE_DST:
return info->rdst;
default:
return -1;
}
return -1;
}
static int
feed_rate_init(struct pcm_feeder *f)
{
struct feed_rate_info *info;
info = malloc(sizeof(*info), M_RATEFEEDER, M_NOWAIT | M_ZERO);
if (info == NULL)
return ENOMEM;
/*
* bufsz = sample from last cycle + conversion space
*/
info->bufsz = 2 + feeder_rate_buffersize;
info->buffer = malloc(sizeof(*info->buffer) * info->bufsz,
M_RATEFEEDER, M_NOWAIT | M_ZERO);
if (info->buffer == NULL) {
free(info, M_RATEFEEDER);
return ENOMEM;
}
info->rsrc = DSP_DEFAULT_SPEED;
info->rdst = DSP_DEFAULT_SPEED;
f->data = info;
return feed_rate_setup(f);
}
static int
feed_rate_free(struct pcm_feeder *f)
{
struct feed_rate_info *info = f->data;
if (info) {
if (info->buffer)
free(info->buffer, M_RATEFEEDER);
free(info, M_RATEFEEDER);
}
f->data = NULL;
return 0;
}
static uint32_t
feed_convert_64(struct feed_rate_info *info, int16_t *dst, uint32_t max)
{
int64_t x, alpha, distance;
uint32_t ret;
int32_t pos, bpos, gx, gy;
int16_t *src;
/*
* Plain, straight forward 64bit arith. No bit-magic applied here.
*/
ret = 0;
alpha = info->alpha;
gx = info->gx;
gy = info->gy;
pos = info->pos;
bpos = info->bpos;
src = info->buffer;
for (;;) {
if (alpha < gx) {
alpha += gy;
pos += 2;
if (pos == bpos)
break;
} else {
alpha -= gx;
distance = gy - alpha;
x = (alpha * src[pos - 2]) + (distance * src[pos]);
dst[ret++] = x / gy;
x = (alpha * src[pos - 1]) + (distance * src[pos + 1]);
dst[ret++] = x / gy;
if (ret == max)
break;
}
}
info->alpha = alpha;
info->pos = pos;
return ret;
}
static uint32_t
feed_convert_scale64(struct feed_rate_info *info, int16_t *dst, uint32_t max)
{
int64_t x, alpha, distance;
uint32_t ret;
int32_t pos, bpos, gx, gy, roll;
int16_t *src;
/*
* 64bit scaling.
*/
ret = 0;
roll = info->roll;
alpha = info->alpha * info->scale;
gx = info->gx * info->scale;
gy = info->gy * info->scale;
pos = info->pos;
bpos = info->bpos;
src = info->buffer;
for (;;) {
if (alpha < gx) {
alpha += gy;
pos += 2;
if (pos == bpos)
break;
} else {
alpha -= gx;
distance = gy - alpha;
x = (alpha * src[pos - 2]) + (distance * src[pos]);
dst[ret++] = x >> roll;
x = (alpha * src[pos - 1]) + (distance * src[pos + 1]);
dst[ret++] = x >> roll;
if (ret == max)
break;
}
}
info->alpha = alpha / info->scale;
info->pos = pos;
return ret;
}
static uint32_t
feed_convert_scale32(struct feed_rate_info *info, int16_t *dst, uint32_t max)
{
uint32_t ret;
int32_t x, pos, bpos, gx, gy, alpha, roll, distance;
int16_t *src;
/*
* 32bit scaling.
*/
ret = 0;
roll = info->roll;
alpha = info->alpha * info->scale;
gx = info->gx * info->scale;
gy = info->gy * info->scale;
pos = info->pos;
bpos = info->bpos;
src = info->buffer;
for (;;) {
if (alpha < gx) {
alpha += gy;
pos += 2;
if (pos == bpos)
break;
} else {
alpha -= gx;
distance = gy - alpha;
x = (alpha * src[pos - 2]) + (distance * src[pos]);
dst[ret++] = x >> roll;
x = (alpha * src[pos - 1]) + (distance * src[pos + 1]);
dst[ret++] = x >> roll;
if (ret == max)
break;
}
}
info->alpha = alpha / info->scale;
info->pos = pos;
return ret;
}
static uint32_t
feed_convert_plain(struct feed_rate_info *info, int16_t *dst, uint32_t max)
{
uint32_t ret;
int32_t pos, bpos, gx, gy, alpha;
int16_t *src;
/*
* Plain copy.
*/
ret = 0;
gx = info->gx;
gy = info->gy;
alpha = info->alpha;
pos = info->pos;
bpos = info->bpos;
src = info->buffer;
for (;;) {
if (alpha < gx) {
alpha += gy;
pos += 2;
if (pos == bpos)
break;
} else {
alpha -= gx;
dst[ret++] = src[pos];
dst[ret++] = src[pos + 1];
if (ret == max)
break;
}
}
info->pos = pos;
info->alpha = alpha;
return ret;
}
static int32_t
feed_rate(struct pcm_feeder *f, struct pcm_channel *c, uint8_t *b,
uint32_t count, void *source)
{
struct feed_rate_info *info = f->data;
uint32_t i;
int32_t fetch, slot;
int16_t *dst = (int16_t *)b;
/*
* This loop has been optimized to generalize both up / down
* sampling without causing missing samples or excessive buffer
* feeding.
*/
RATE_ASSERT(count >= 4 && count % 4 == 0,
("%s: Count size not byte integral\n", __func__));
count >>= 1;
slot = (((info->gx * (count >> 1)) + info->gy - info->alpha - 1) / info->gy) << 1;
/*
* Optimize buffer feeding aggresively to ensure calculated slot
* can be fitted nicely into available buffer free space, hence
* avoiding multiple feeding.
*/
if (info->pos != 2 && info->bpos - info->pos == 2 &&
info->bpos + slot > info->bufsz) {
/*
* Copy last unit sample and its previous to
* beginning of buffer.
*/
info->buffer[0] = info->buffer[info->pos - 2];
info->buffer[1] = info->buffer[info->pos - 1];
info->buffer[2] = info->buffer[info->pos];
info->buffer[3] = info->buffer[info->pos + 1];
info->pos = 2;
info->bpos = 4;
}
RATE_ASSERT(slot >= 0, ("%s: Negative Slot: %d\n",
__func__, slot));
i = 0;
for (;;) {
for (;;) {
fetch = info->bufsz - info->bpos;
RATE_ASSERT(fetch >= 0,
("%s: Buffer overrun: %d > %d\n",
__func__, info->bpos, info->bufsz));
if (slot < fetch)
fetch = slot;
if (fetch > 0) {
RATE_ASSERT(fetch % 2 == 0,
("%s: Fetch size not sample integral\n",
__func__));
fetch = FEEDER_FEED(f->source, c,
(uint8_t *)(info->buffer + info->bpos),
fetch << 1, source);
if (fetch == 0)
break;
RATE_ASSERT(fetch % 4 == 0,
("%s: Fetch size not byte integral\n",
__func__));
fetch >>= 1;
info->bpos += fetch;
slot -= fetch;
RATE_ASSERT(slot >= 0,
("%s: Negative Slot: %d\n", __func__,
slot));
if (slot == 0)
break;
if (info->bpos == info->bufsz)
break;
} else
break;
}
if (info->pos == info->bpos) {
RATE_ASSERT(info->pos == 2,
("%s: EOF while in progress\n", __func__));
break;
}
RATE_ASSERT(info->pos <= info->bpos,
("%s: Buffer overrun: %d > %d\n", __func__,
info->pos, info->bpos));
RATE_ASSERT(info->pos < info->bpos,
("%s: Zero buffer!\n", __func__));
RATE_ASSERT((info->bpos - info->pos) % 2 == 0,
("%s: Buffer not sample integral\n", __func__));
i += info->convert(info, dst + i, count - i);
RATE_ASSERT(info->pos <= info->bpos,
("%s: Buffer overrun: %d > %d\n",
__func__, info->pos, info->bpos));
if (info->pos == info->bpos) {
/*
* End of buffer cycle. Copy last unit sample
* to beginning of buffer so next cycle can
* interpolate using it.
*/
info->buffer[0] = info->buffer[info->pos - 2];
info->buffer[1] = info->buffer[info->pos - 1];
info->bpos = 2;
info->pos = 2;
}
if (i == count)
break;
}
return i << 1;
}
static struct pcm_feederdesc feeder_rate_desc[] = {
{FEEDER_RATE, AFMT_S16_LE | AFMT_STEREO, AFMT_S16_LE | AFMT_STEREO, 0},
{0, 0, 0, 0},
};
static kobj_method_t feeder_rate_methods[] = {
KOBJMETHOD(feeder_init, feed_rate_init),
KOBJMETHOD(feeder_free, feed_rate_free),
KOBJMETHOD(feeder_set, feed_rate_set),
KOBJMETHOD(feeder_get, feed_rate_get),
KOBJMETHOD(feeder_feed, feed_rate),
{0, 0}
};
FEEDER_DECLARE(feeder_rate, 2, NULL);
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