sound/core/oss/rate.c - kernel/msm - Gitiles

 /*
  *  Rate conversion Plug-In
  *  Copyright (c) 1999 by Jaroslav Kysela <perex@suse.cz>
  *
  *
  *   This library is free software; you can redistribute it and/or modify
  *   it under the terms of the GNU Library 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 Library General Public License for more details.
  *
  *   You should have received a copy of the GNU Library General Public
  *   License along with this library; if not, write to the Free Software
  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  *
  */

 #include <sound/driver.h>

 #ifdef CONFIG_SND_PCM_OSS_PLUGINS

 #include <linux/time.h>
 #include <sound/core.h>
 #include <sound/pcm.h>
 #include "pcm_plugin.h"

 #define SHIFT	11
 #define BITS	(1<<SHIFT)
 #define R_MASK	(BITS-1)

 /*
  *  Basic rate conversion plugin
  */

 struct rate_channel {
 	signed short last_S1;
 	signed short last_S2;
 };

 typedef void (*rate_f)(struct snd_pcm_plugin *plugin,
 		       const struct snd_pcm_plugin_channel *src_channels,
 		       struct snd_pcm_plugin_channel *dst_channels,
 		       int src_frames, int dst_frames);

 struct rate_priv {
 	unsigned int pitch;
 	unsigned int pos;
 	rate_f func;
 	snd_pcm_sframes_t old_src_frames, old_dst_frames;
 	struct rate_channel channels[0];
 };

 static void rate_init(struct snd_pcm_plugin *plugin)
 {
 	unsigned int channel;
 	struct rate_priv *data = (struct rate_priv *)plugin->extra_data;
 	data->pos = 0;
 	for (channel = 0; channel < plugin->src_format.channels; channel++) {
 		data->channels[channel].last_S1 = 0;
 		data->channels[channel].last_S2 = 0;
 	}
 }

 static void resample_expand(struct snd_pcm_plugin *plugin,
 			    const struct snd_pcm_plugin_channel *src_channels,
 			    struct snd_pcm_plugin_channel *dst_channels,
 			    int src_frames, int dst_frames)
 {
 	unsigned int pos = 0;
 	signed int val;
 	signed short S1, S2;
 	signed short *src, *dst;
 	unsigned int channel;
 	int src_step, dst_step;
 	int src_frames1, dst_frames1;
 	struct rate_priv *data = (struct rate_priv *)plugin->extra_data;
 	struct rate_channel *rchannels = data->channels;

 	for (channel = 0; channel < plugin->src_format.channels; channel++) {
 		pos = data->pos;
 		S1 = rchannels->last_S1;
 		S2 = rchannels->last_S2;
 		if (!src_channels[channel].enabled) {
 			if (dst_channels[channel].wanted)
 				snd_pcm_area_silence(&dst_channels[channel].area, 0, dst_frames, plugin->dst_format.format);
 			dst_channels[channel].enabled = 0;
 			continue;
 		}
 		dst_channels[channel].enabled = 1;
 		src = (signed short *)src_channels[channel].area.addr +
 			src_channels[channel].area.first / 8 / 2;
 		dst = (signed short *)dst_channels[channel].area.addr +
 			dst_channels[channel].area.first / 8 / 2;
 		src_step = src_channels[channel].area.step / 8 / 2;
 		dst_step = dst_channels[channel].area.step / 8 / 2;
 		src_frames1 = src_frames;
 		dst_frames1 = dst_frames;
 		while (dst_frames1-- > 0) {
 			if (pos & ~R_MASK) {
 				pos &= R_MASK;
 				S1 = S2;
 				if (src_frames1-- > 0) {
 					S2 = *src;
 					src += src_step;
 				}
 			}
 			val = S1 + ((S2 - S1) * (signed int)pos) / BITS;
 			if (val < -32768)
 				val = -32768;
 			else if (val > 32767)
 				val = 32767;
 			*dst = val;
 			dst += dst_step;
 			pos += data->pitch;
 		}
 		rchannels->last_S1 = S1;
 		rchannels->last_S2 = S2;
 		rchannels++;
 	}
 	data->pos = pos;
 }

 static void resample_shrink(struct snd_pcm_plugin *plugin,
 			    const struct snd_pcm_plugin_channel *src_channels,
 			    struct snd_pcm_plugin_channel *dst_channels,
 			    int src_frames, int dst_frames)
 {
 	unsigned int pos = 0;
 	signed int val;
 	signed short S1, S2;
 	signed short *src, *dst;
 	unsigned int channel;
 	int src_step, dst_step;
 	int src_frames1, dst_frames1;
 	struct rate_priv *data = (struct rate_priv *)plugin->extra_data;
 	struct rate_channel *rchannels = data->channels;

 	for (channel = 0; channel < plugin->src_format.channels; ++channel) {
 		pos = data->pos;
 		S1 = rchannels->last_S1;
 		S2 = rchannels->last_S2;
 		if (!src_channels[channel].enabled) {
 			if (dst_channels[channel].wanted)
 				snd_pcm_area_silence(&dst_channels[channel].area, 0, dst_frames, plugin->dst_format.format);
 			dst_channels[channel].enabled = 0;
 			continue;
 		}
 		dst_channels[channel].enabled = 1;
 		src = (signed short *)src_channels[channel].area.addr +
 			src_channels[channel].area.first / 8 / 2;
 		dst = (signed short *)dst_channels[channel].area.addr +
 			dst_channels[channel].area.first / 8 / 2;
 		src_step = src_channels[channel].area.step / 8 / 2;
 		dst_step = dst_channels[channel].area.step / 8 / 2;
 		src_frames1 = src_frames;
 		dst_frames1 = dst_frames;
 		while (dst_frames1 > 0) {
 			S1 = S2;
 			if (src_frames1-- > 0) {
 				S1 = *src;
 				src += src_step;
 			}
 			if (pos & ~R_MASK) {
 				pos &= R_MASK;
 				val = S1 + ((S2 - S1) * (signed int)pos) / BITS;
 				if (val < -32768)
 					val = -32768;
 				else if (val > 32767)
 					val = 32767;
 				*dst = val;
 				dst += dst_step;
 				dst_frames1--;
 			}
 			pos += data->pitch;
 		}
 		rchannels->last_S1 = S1;
 		rchannels->last_S2 = S2;
 		rchannels++;
 	}
 	data->pos = pos;
 }

 static snd_pcm_sframes_t rate_src_frames(struct snd_pcm_plugin *plugin, snd_pcm_uframes_t frames)
 {
 	struct rate_priv *data;
 	snd_pcm_sframes_t res;

 	snd_assert(plugin != NULL, return -ENXIO);
 	if (frames == 0)
 		return 0;
 	data = (struct rate_priv *)plugin->extra_data;
 	if (plugin->src_format.rate < plugin->dst_format.rate) {
 		res = (((frames * data->pitch) + (BITS/2)) >> SHIFT);
 	} else {
 		res = (((frames << SHIFT) + (data->pitch / 2)) / data->pitch);
 	}
 	if (data->old_src_frames > 0) {
 		snd_pcm_sframes_t frames1 = frames, res1 = data->old_dst_frames;
 		while (data->old_src_frames < frames1) {
 			frames1 >>= 1;
 			res1 <<= 1;
 		}
 		while (data->old_src_frames > frames1) {
 			frames1 <<= 1;
 			res1 >>= 1;
 		}
 		if (data->old_src_frames == frames1)
 			return res1;
 	}
 	data->old_src_frames = frames;
 	data->old_dst_frames = res;
 	return res;
 }

 static snd_pcm_sframes_t rate_dst_frames(struct snd_pcm_plugin *plugin, snd_pcm_uframes_t frames)
 {
 	struct rate_priv *data;
 	snd_pcm_sframes_t res;

 	snd_assert(plugin != NULL, return -ENXIO);
 	if (frames == 0)
 		return 0;
 	data = (struct rate_priv *)plugin->extra_data;
 	if (plugin->src_format.rate < plugin->dst_format.rate) {
 		res = (((frames << SHIFT) + (data->pitch / 2)) / data->pitch);
 	} else {
 		res = (((frames * data->pitch) + (BITS/2)) >> SHIFT);
 	}
 	if (data->old_dst_frames > 0) {
 		snd_pcm_sframes_t frames1 = frames, res1 = data->old_src_frames;
 		while (data->old_dst_frames < frames1) {
 			frames1 >>= 1;
 			res1 <<= 1;
 		}
 		while (data->old_dst_frames > frames1) {
 			frames1 <<= 1;
 			res1 >>= 1;
 		}
 		if (data->old_dst_frames == frames1)
 			return res1;
 	}
 	data->old_dst_frames = frames;
 	data->old_src_frames = res;
 	return res;
 }

 static snd_pcm_sframes_t rate_transfer(struct snd_pcm_plugin *plugin,
 			     const struct snd_pcm_plugin_channel *src_channels,
 			     struct snd_pcm_plugin_channel *dst_channels,
 			     snd_pcm_uframes_t frames)
 {
 	snd_pcm_uframes_t dst_frames;
 	struct rate_priv *data;

 	snd_assert(plugin != NULL && src_channels != NULL && dst_channels != NULL, return -ENXIO);
 	if (frames == 0)
 		return 0;
 #ifdef CONFIG_SND_DEBUG
 	{
 		unsigned int channel;
 		for (channel = 0; channel < plugin->src_format.channels; channel++) {
 			snd_assert(src_channels[channel].area.first % 8 == 0 &&
 				   src_channels[channel].area.step % 8 == 0,
 				   return -ENXIO);
 			snd_assert(dst_channels[channel].area.first % 8 == 0 &&
 				   dst_channels[channel].area.step % 8 == 0,
 				   return -ENXIO);
 		}
 	}
 #endif

 	dst_frames = rate_dst_frames(plugin, frames);
 	if (dst_frames > dst_channels[0].frames)
 		dst_frames = dst_channels[0].frames;
 	data = (struct rate_priv *)plugin->extra_data;
 	data->func(plugin, src_channels, dst_channels, frames, dst_frames);
 	return dst_frames;
 }

 static int rate_action(struct snd_pcm_plugin *plugin,
 		       enum snd_pcm_plugin_action action,
 		       unsigned long udata)
 {
 	snd_assert(plugin != NULL, return -ENXIO);
 	switch (action) {
 	case INIT:
 	case PREPARE:
 		rate_init(plugin);
 		break;
 	default:
 		break;
 	}
 	return 0;	/* silenty ignore other actions */
 }

 int snd_pcm_plugin_build_rate(struct snd_pcm_substream *plug,
 			      struct snd_pcm_plugin_format *src_format,
 			      struct snd_pcm_plugin_format *dst_format,
 			      struct snd_pcm_plugin **r_plugin)
 {
 	int err;
 	struct rate_priv *data;
 	struct snd_pcm_plugin *plugin;

 	snd_assert(r_plugin != NULL, return -ENXIO);
 	*r_plugin = NULL;

 	snd_assert(src_format->channels == dst_format->channels, return -ENXIO);
 	snd_assert(src_format->channels > 0, return -ENXIO);
 	snd_assert(src_format->format == SNDRV_PCM_FORMAT_S16, return -ENXIO);
 	snd_assert(dst_format->format == SNDRV_PCM_FORMAT_S16, return -ENXIO);
 	snd_assert(src_format->rate != dst_format->rate, return -ENXIO);

 	err = snd_pcm_plugin_build(plug, "rate conversion",
 				   src_format, dst_format,
 				   sizeof(struct rate_priv) +
 				   src_format->channels * sizeof(struct rate_channel),
 				   &plugin);
 	if (err < 0)
 		return err;
 	data = (struct rate_priv *)plugin->extra_data;
 	if (src_format->rate < dst_format->rate) {
 		data->pitch = ((src_format->rate << SHIFT) + (dst_format->rate >> 1)) / dst_format->rate;
 		data->func = resample_expand;
 	} else {
 		data->pitch = ((dst_format->rate << SHIFT) + (src_format->rate >> 1)) / src_format->rate;
 		data->func = resample_shrink;
 	}
 	data->pos = 0;
 	rate_init(plugin);
 	data->old_src_frames = data->old_dst_frames = 0;
 	plugin->transfer = rate_transfer;
 	plugin->src_frames = rate_src_frames;
 	plugin->dst_frames = rate_dst_frames;
 	plugin->action = rate_action;
 	*r_plugin = plugin;
 	return 0;
 }

 #endif
	/*
	* Rate conversion Plug-In
	* Copyright (c) 1999 by Jaroslav Kysela <perex@suse.cz>
	*
	*
	* This library is free software; you can redistribute it and/or modify
	* it under the terms of the GNU Library 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 Library General Public License for more details.
	*
	* You should have received a copy of the GNU Library General Public
	* License along with this library; if not, write to the Free Software
	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	*
	*/

	#include <sound/driver.h>

	#ifdef CONFIG_SND_PCM_OSS_PLUGINS

	#include <linux/time.h>
	#include <sound/core.h>
	#include <sound/pcm.h>
	#include "pcm_plugin.h"

	#define SHIFT 11
	#define BITS (1<<SHIFT)
	#define R_MASK (BITS-1)

	/*
	* Basic rate conversion plugin
	*/

	struct rate_channel {
	signed short last_S1;
	signed short last_S2;
	};

	typedef void (rate_f)(struct snd_pcm_plugin plugin,
	const struct snd_pcm_plugin_channel *src_channels,
	struct snd_pcm_plugin_channel *dst_channels,
	int src_frames, int dst_frames);

	struct rate_priv {
	unsigned int pitch;
	unsigned int pos;
	rate_f func;
	snd_pcm_sframes_t old_src_frames, old_dst_frames;
	struct rate_channel channels[0];
	};

	static void rate_init(struct snd_pcm_plugin *plugin)
	{
	unsigned int channel;
	struct rate_priv data = (struct rate_priv )plugin->extra_data;
	data->pos = 0;
	for (channel = 0; channel < plugin->src_format.channels; channel++) {
	data->channels[channel].last_S1 = 0;
	data->channels[channel].last_S2 = 0;
	}
	}

	static void resample_expand(struct snd_pcm_plugin *plugin,
	const struct snd_pcm_plugin_channel *src_channels,
	struct snd_pcm_plugin_channel *dst_channels,
	int src_frames, int dst_frames)
	{
	unsigned int pos = 0;
	signed int val;
	signed short S1, S2;
	signed short src, dst;
	unsigned int channel;
	int src_step, dst_step;
	int src_frames1, dst_frames1;
	struct rate_priv data = (struct rate_priv )plugin->extra_data;
	struct rate_channel *rchannels = data->channels;

	for (channel = 0; channel < plugin->src_format.channels; channel++) {
	pos = data->pos;
	S1 = rchannels->last_S1;
	S2 = rchannels->last_S2;
	if (!src_channels[channel].enabled) {
	if (dst_channels[channel].wanted)
	snd_pcm_area_silence(&dst_channels[channel].area, 0, dst_frames, plugin->dst_format.format);
	dst_channels[channel].enabled = 0;
	continue;
	}
	dst_channels[channel].enabled = 1;
	src = (signed short *)src_channels[channel].area.addr +
	src_channels[channel].area.first / 8 / 2;
	dst = (signed short *)dst_channels[channel].area.addr +
	dst_channels[channel].area.first / 8 / 2;
	src_step = src_channels[channel].area.step / 8 / 2;
	dst_step = dst_channels[channel].area.step / 8 / 2;
	src_frames1 = src_frames;
	dst_frames1 = dst_frames;
	while (dst_frames1-- > 0) {
	if (pos & ~R_MASK) {
	pos &= R_MASK;
	S1 = S2;
	if (src_frames1-- > 0) {
	S2 = *src;
	src += src_step;
	}
	}
	val = S1 + ((S2 - S1) * (signed int)pos) / BITS;
	if (val < -32768)
	val = -32768;
	else if (val > 32767)
	val = 32767;
	*dst = val;
	dst += dst_step;
	pos += data->pitch;
	}
	rchannels->last_S1 = S1;
	rchannels->last_S2 = S2;
	rchannels++;
	}
	data->pos = pos;
	}

	static void resample_shrink(struct snd_pcm_plugin *plugin,
	const struct snd_pcm_plugin_channel *src_channels,
	struct snd_pcm_plugin_channel *dst_channels,
	int src_frames, int dst_frames)
	{
	unsigned int pos = 0;
	signed int val;
	signed short S1, S2;
	signed short src, dst;
	unsigned int channel;
	int src_step, dst_step;
	int src_frames1, dst_frames1;
	struct rate_priv data = (struct rate_priv )plugin->extra_data;
	struct rate_channel *rchannels = data->channels;

	for (channel = 0; channel < plugin->src_format.channels; ++channel) {
	pos = data->pos;
	S1 = rchannels->last_S1;
	S2 = rchannels->last_S2;
	if (!src_channels[channel].enabled) {
	if (dst_channels[channel].wanted)
	snd_pcm_area_silence(&dst_channels[channel].area, 0, dst_frames, plugin->dst_format.format);
	dst_channels[channel].enabled = 0;
	continue;
	}
	dst_channels[channel].enabled = 1;
	src = (signed short *)src_channels[channel].area.addr +
	src_channels[channel].area.first / 8 / 2;
	dst = (signed short *)dst_channels[channel].area.addr +
	dst_channels[channel].area.first / 8 / 2;
	src_step = src_channels[channel].area.step / 8 / 2;
	dst_step = dst_channels[channel].area.step / 8 / 2;
	src_frames1 = src_frames;
	dst_frames1 = dst_frames;
	while (dst_frames1 > 0) {
	S1 = S2;
	if (src_frames1-- > 0) {
	S1 = *src;
	src += src_step;
	}
	if (pos & ~R_MASK) {
	pos &= R_MASK;
	val = S1 + ((S2 - S1) * (signed int)pos) / BITS;
	if (val < -32768)
	val = -32768;
	else if (val > 32767)
	val = 32767;
	*dst = val;
	dst += dst_step;
	dst_frames1--;
	}
	pos += data->pitch;
	}
	rchannels->last_S1 = S1;
	rchannels->last_S2 = S2;
	rchannels++;
	}
	data->pos = pos;
	}

	static snd_pcm_sframes_t rate_src_frames(struct snd_pcm_plugin *plugin, snd_pcm_uframes_t frames)
	{
	struct rate_priv *data;
	snd_pcm_sframes_t res;

	snd_assert(plugin != NULL, return -ENXIO);
	if (frames == 0)
	return 0;
	data = (struct rate_priv *)plugin->extra_data;
	if (plugin->src_format.rate < plugin->dst_format.rate) {
	res = (((frames * data->pitch) + (BITS/2)) >> SHIFT);
	} else {
	res = (((frames << SHIFT) + (data->pitch / 2)) / data->pitch);
	}
	if (data->old_src_frames > 0) {
	snd_pcm_sframes_t frames1 = frames, res1 = data->old_dst_frames;
	while (data->old_src_frames < frames1) {
	frames1 >>= 1;
	res1 <<= 1;
	}
	while (data->old_src_frames > frames1) {
	frames1 <<= 1;
	res1 >>= 1;
	}
	if (data->old_src_frames == frames1)
	return res1;
	}
	data->old_src_frames = frames;
	data->old_dst_frames = res;
	return res;
	}

	static snd_pcm_sframes_t rate_dst_frames(struct snd_pcm_plugin *plugin, snd_pcm_uframes_t frames)
	{
	struct rate_priv *data;
	snd_pcm_sframes_t res;

	snd_assert(plugin != NULL, return -ENXIO);
	if (frames == 0)
	return 0;
	data = (struct rate_priv *)plugin->extra_data;
	if (plugin->src_format.rate < plugin->dst_format.rate) {
	res = (((frames << SHIFT) + (data->pitch / 2)) / data->pitch);
	} else {
	res = (((frames * data->pitch) + (BITS/2)) >> SHIFT);
	}
	if (data->old_dst_frames > 0) {
	snd_pcm_sframes_t frames1 = frames, res1 = data->old_src_frames;
	while (data->old_dst_frames < frames1) {
	frames1 >>= 1;
	res1 <<= 1;
	}
	while (data->old_dst_frames > frames1) {
	frames1 <<= 1;
	res1 >>= 1;
	}
	if (data->old_dst_frames == frames1)
	return res1;
	}
	data->old_dst_frames = frames;
	data->old_src_frames = res;
	return res;
	}

	static snd_pcm_sframes_t rate_transfer(struct snd_pcm_plugin *plugin,
	const struct snd_pcm_plugin_channel *src_channels,
	struct snd_pcm_plugin_channel *dst_channels,
	snd_pcm_uframes_t frames)
	{
	snd_pcm_uframes_t dst_frames;
	struct rate_priv *data;

	snd_assert(plugin != NULL && src_channels != NULL && dst_channels != NULL, return -ENXIO);
	if (frames == 0)
	return 0;
	#ifdef CONFIG_SND_DEBUG
	{
	unsigned int channel;
	for (channel = 0; channel < plugin->src_format.channels; channel++) {
	snd_assert(src_channels[channel].area.first % 8 == 0 &&
	src_channels[channel].area.step % 8 == 0,
	return -ENXIO);
	snd_assert(dst_channels[channel].area.first % 8 == 0 &&
	dst_channels[channel].area.step % 8 == 0,
	return -ENXIO);
	}
	}
	#endif

	dst_frames = rate_dst_frames(plugin, frames);
	if (dst_frames > dst_channels[0].frames)
	dst_frames = dst_channels[0].frames;
	data = (struct rate_priv *)plugin->extra_data;
	data->func(plugin, src_channels, dst_channels, frames, dst_frames);
	return dst_frames;
	}

	static int rate_action(struct snd_pcm_plugin *plugin,
	enum snd_pcm_plugin_action action,
	unsigned long udata)
	{
	snd_assert(plugin != NULL, return -ENXIO);
	switch (action) {
	case INIT:
	case PREPARE:
	rate_init(plugin);
	break;
	default:
	break;
	}
	return 0; /* silenty ignore other actions */
	}

	int snd_pcm_plugin_build_rate(struct snd_pcm_substream *plug,
	struct snd_pcm_plugin_format *src_format,
	struct snd_pcm_plugin_format *dst_format,
	struct snd_pcm_plugin **r_plugin)
	{
	int err;
	struct rate_priv *data;
	struct snd_pcm_plugin *plugin;

	snd_assert(r_plugin != NULL, return -ENXIO);
	*r_plugin = NULL;

	snd_assert(src_format->channels == dst_format->channels, return -ENXIO);
	snd_assert(src_format->channels > 0, return -ENXIO);
	snd_assert(src_format->format == SNDRV_PCM_FORMAT_S16, return -ENXIO);
	snd_assert(dst_format->format == SNDRV_PCM_FORMAT_S16, return -ENXIO);
	snd_assert(src_format->rate != dst_format->rate, return -ENXIO);

	err = snd_pcm_plugin_build(plug, "rate conversion",
	src_format, dst_format,
	sizeof(struct rate_priv) +
	src_format->channels * sizeof(struct rate_channel),
	&plugin);
	if (err < 0)
	return err;
	data = (struct rate_priv *)plugin->extra_data;
	if (src_format->rate < dst_format->rate) {
	data->pitch = ((src_format->rate << SHIFT) + (dst_format->rate >> 1)) / dst_format->rate;
	data->func = resample_expand;
	} else {
	data->pitch = ((dst_format->rate << SHIFT) + (src_format->rate >> 1)) / src_format->rate;
	data->func = resample_shrink;
	}
	data->pos = 0;
	rate_init(plugin);
	data->old_src_frames = data->old_dst_frames = 0;
	plugin->transfer = rate_transfer;
	plugin->src_frames = rate_src_frames;
	plugin->dst_frames = rate_dst_frames;
	plugin->action = rate_action;
	*r_plugin = plugin;
	return 0;
	}

	#endif