/**
 * \file pcm/pcm_plugin.c
 * \ingroup PCM
 * \brief PCM Interface
 * \author Jaroslav Kysela <perex@perex.cz>
 * \author Abramo Bagnara <abramo@alsa-project.org>
 * \date 2000-2001
 */
/*
 *  PCM - Common plugin code
 *  Copyright (c) 2000 by Abramo Bagnara <abramo@alsa-project.org>
 *
 *
 *   This library is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Lesser General Public License as
 *   published by the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public
 *   License along with this library; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 */

/*!

\page pcm_plugins PCM (digital audio) plugins

PCM plugins extends functionality and features of PCM devices.
The plugins take care about various sample conversions, sample
copying among channels and so on.

\section pcm_plugins_slave Slave definition

The slave plugin can be specified directly with a string or the definition
can be entered inside a compound configuration node. Some restrictions can
be also specified (like static rate or count of channels).

\code
pcm_slave.NAME {
	pcm STR		# PCM name
	# or
	pcm { }		# PCM definition
	format STR	# Format or "unchanged"
	channels INT	# Count of channels or "unchanged" string
	rate INT	# Rate in Hz or "unchanged" string
	period_time INT	# Period time in us or "unchanged" string
	buffer_time INT # Buffer time in us or "unchanged" string
}
\endcode

Example:

\code
pcm_slave.slave_rate44100Hz {
	pcm "hw:0,0"
	rate 44100
}

pcm.rate44100Hz {
	type plug
	slave slave_rate44100Hz
}
\endcode

The equivalent configuration (in one compound):

\code
pcm.rate44100Hz {
	type plug
	slave {
		pcm "hw:0,0"
		rate 44100
	}
}
\endcode

*/
  
#include <limits.h>
#include "pcm_local.h"
#include "pcm_plugin.h"

#ifndef DOC_HIDDEN

static snd_pcm_sframes_t
snd_pcm_plugin_undo_read(snd_pcm_t *pcm ATTRIBUTE_UNUSED,
			 const snd_pcm_channel_area_t *res_areas ATTRIBUTE_UNUSED,
			 snd_pcm_uframes_t res_offset ATTRIBUTE_UNUSED,
			 snd_pcm_uframes_t res_size ATTRIBUTE_UNUSED,
			 snd_pcm_uframes_t slave_undo_size ATTRIBUTE_UNUSED)
{
	return -EIO;
}

static snd_pcm_sframes_t
snd_pcm_plugin_undo_write(snd_pcm_t *pcm ATTRIBUTE_UNUSED,
			  const snd_pcm_channel_area_t *res_areas ATTRIBUTE_UNUSED,
			  snd_pcm_uframes_t res_offset ATTRIBUTE_UNUSED,
			  snd_pcm_uframes_t res_size ATTRIBUTE_UNUSED,
			  snd_pcm_uframes_t slave_undo_size ATTRIBUTE_UNUSED)
{
	return -EIO;
}

snd_pcm_sframes_t
snd_pcm_plugin_undo_read_generic(snd_pcm_t *pcm ATTRIBUTE_UNUSED,
				 const snd_pcm_channel_area_t *res_areas ATTRIBUTE_UNUSED,
				 snd_pcm_uframes_t res_offset ATTRIBUTE_UNUSED,
				 snd_pcm_uframes_t res_size ATTRIBUTE_UNUSED,
				 snd_pcm_uframes_t slave_undo_size)
{
	return slave_undo_size;
}

snd_pcm_sframes_t
snd_pcm_plugin_undo_write_generic(snd_pcm_t *pcm ATTRIBUTE_UNUSED,
				  const snd_pcm_channel_area_t *res_areas ATTRIBUTE_UNUSED,
				  snd_pcm_uframes_t res_offset ATTRIBUTE_UNUSED,
				  snd_pcm_uframes_t res_size ATTRIBUTE_UNUSED,
				  snd_pcm_uframes_t slave_undo_size)
{
	return slave_undo_size;
}

void snd_pcm_plugin_init(snd_pcm_plugin_t *plugin)
{
	memset(plugin, 0, sizeof(snd_pcm_plugin_t));
	plugin->undo_read = snd_pcm_plugin_undo_read;
	plugin->undo_write = snd_pcm_plugin_undo_write;
}

static int snd_pcm_plugin_delay(snd_pcm_t *pcm, snd_pcm_sframes_t *delayp)
{
	snd_pcm_plugin_t *plugin = pcm->private_data;
	snd_pcm_sframes_t sd;
	int err = snd_pcm_delay(plugin->gen.slave, &sd);
	if (err < 0)
		return err;
        if (pcm->stream == SND_PCM_STREAM_CAPTURE &&
	    pcm->access != SND_PCM_ACCESS_RW_INTERLEAVED &&
	    pcm->access != SND_PCM_ACCESS_RW_NONINTERLEAVED) {
                sd += snd_pcm_mmap_capture_avail(pcm);
        }        

	*delayp = sd;
	return 0;
}

static int snd_pcm_plugin_prepare(snd_pcm_t *pcm)
{
	snd_pcm_plugin_t *plugin = pcm->private_data;
	int err;
	err = snd_pcm_prepare(plugin->gen.slave);
	if (err < 0)
		return err;
	*pcm->hw.ptr = 0;
	*pcm->appl.ptr = 0;
	if (plugin->init) {
		err = plugin->init(pcm);
		if (err < 0)
			return err;
	}
	return 0;
}

static int snd_pcm_plugin_reset(snd_pcm_t *pcm)
{
	snd_pcm_plugin_t *plugin = pcm->private_data;
	int err;
	err = snd_pcm_reset(plugin->gen.slave);
	if (err < 0)
		return err;
	*pcm->hw.ptr = 0;
	*pcm->appl.ptr = 0;
	if (plugin->init) {
		err = plugin->init(pcm);
		if (err < 0)
			return err;
	}
	return 0;
}

static snd_pcm_sframes_t snd_pcm_plugin_rewindable(snd_pcm_t *pcm)
{
	return snd_pcm_mmap_hw_rewindable(pcm);
}

snd_pcm_sframes_t snd_pcm_plugin_rewind(snd_pcm_t *pcm, snd_pcm_uframes_t frames)
{
	snd_pcm_plugin_t *plugin = pcm->private_data;
	snd_pcm_sframes_t n = snd_pcm_plugin_rewindable(pcm);
	snd_pcm_sframes_t sframes;

	if ((snd_pcm_uframes_t)n < frames)
		frames = n;
	if (frames == 0)
		return 0;
	
        sframes = frames;
	sframes = snd_pcm_rewind(plugin->gen.slave, sframes);
	if (sframes < 0)
		return sframes;
	snd_pcm_mmap_appl_backward(pcm, (snd_pcm_uframes_t) sframes);
	return (snd_pcm_sframes_t) sframes;
}

static snd_pcm_sframes_t snd_pcm_plugin_forwardable(snd_pcm_t *pcm)
{
	return snd_pcm_mmap_avail(pcm);
}

snd_pcm_sframes_t snd_pcm_plugin_forward(snd_pcm_t *pcm, snd_pcm_uframes_t frames)
{
	snd_pcm_plugin_t *plugin = pcm->private_data;
	snd_pcm_sframes_t n = snd_pcm_plugin_forwardable(pcm);
	snd_pcm_sframes_t sframes;

	if ((snd_pcm_uframes_t)n < frames)
		frames = n;
	if (frames == 0)
		return 0;
	
        sframes = frames;
	sframes = INTERNAL(snd_pcm_forward)(plugin->gen.slave, sframes);
	if (sframes < 0)
		return sframes;
	snd_pcm_mmap_appl_forward(pcm, (snd_pcm_uframes_t) frames);
	return (snd_pcm_sframes_t) frames;
}

static snd_pcm_sframes_t snd_pcm_plugin_write_areas(snd_pcm_t *pcm,
						    const snd_pcm_channel_area_t *areas,
						    snd_pcm_uframes_t offset,
						    snd_pcm_uframes_t size)
{
	snd_pcm_plugin_t *plugin = pcm->private_data;
	snd_pcm_t *slave = plugin->gen.slave;
	snd_pcm_uframes_t xfer = 0;
	snd_pcm_sframes_t result;
	int err;

	while (size > 0) {
		snd_pcm_uframes_t frames = size;
		const snd_pcm_channel_area_t *slave_areas;
		snd_pcm_uframes_t slave_offset;
		snd_pcm_uframes_t slave_frames = ULONG_MAX;
		
		result = snd_pcm_mmap_begin(slave, &slave_areas, &slave_offset, &slave_frames);
		if (result < 0) {
			err = result;
			goto error;
		}
		if (slave_frames == 0)
			break;
		frames = plugin->write(pcm, areas, offset, frames,
				       slave_areas, slave_offset, &slave_frames);
		if (CHECK_SANITY(slave_frames > snd_pcm_mmap_playback_avail(slave))) {
			SNDMSG("write overflow %ld > %ld", slave_frames,
			       snd_pcm_mmap_playback_avail(slave));
			err = -EPIPE;
			goto error;
		}
		result = snd_pcm_mmap_commit(slave, slave_offset, slave_frames);
		if (result > 0 && (snd_pcm_uframes_t)result != slave_frames) {
			snd_pcm_sframes_t res;
			res = plugin->undo_write(pcm, slave_areas, slave_offset + result, slave_frames, slave_frames - result);
			if (res < 0) {
				err = res;
				goto error;
			}
			frames -= res;
		}
		if (result <= 0) {
			err = result;
			goto error;
		}
		snd_pcm_mmap_appl_forward(pcm, frames);
		offset += frames;
		xfer += frames;
		size -= frames;
	}
	return (snd_pcm_sframes_t)xfer;

 error:
	return xfer > 0 ? (snd_pcm_sframes_t)xfer : err;
}

static snd_pcm_sframes_t snd_pcm_plugin_read_areas(snd_pcm_t *pcm,
						   const snd_pcm_channel_area_t *areas,
						   snd_pcm_uframes_t offset,
						   snd_pcm_uframes_t size)
{
	snd_pcm_plugin_t *plugin = pcm->private_data;
	snd_pcm_t *slave = plugin->gen.slave;
	snd_pcm_uframes_t xfer = 0;
	snd_pcm_sframes_t result;
	int err;
	
	while (size > 0) {
		snd_pcm_uframes_t frames = size;
		const snd_pcm_channel_area_t *slave_areas;
		snd_pcm_uframes_t slave_offset;
		snd_pcm_uframes_t slave_frames = ULONG_MAX;
		
		result = snd_pcm_mmap_begin(slave, &slave_areas, &slave_offset, &slave_frames);
		if (result < 0) {
			err = result;
			goto error;
		}
		if (slave_frames == 0)
			break;
		frames = (plugin->read)(pcm, areas, offset, frames,
				      slave_areas, slave_offset, &slave_frames);
		if (CHECK_SANITY(slave_frames > snd_pcm_mmap_capture_avail(slave))) {
			SNDMSG("read overflow %ld > %ld", slave_frames,
			       snd_pcm_mmap_playback_avail(slave));
			err = -EPIPE;
			goto error;
		}
		result = snd_pcm_mmap_commit(slave, slave_offset, slave_frames);
		if (result > 0 && (snd_pcm_uframes_t)result != slave_frames) {
			snd_pcm_sframes_t res;
			
			res = plugin->undo_read(slave, areas, offset, frames, slave_frames - result);
			if (res < 0) {
				err = res;
				goto error;
			}
			frames -= res;
		}
		if (result <= 0) {
			err = result;
			goto error;
		}
		snd_pcm_mmap_appl_forward(pcm, frames);
		offset += frames;
		xfer += frames;
		size -= frames;
	}
	return (snd_pcm_sframes_t)xfer;

 error:
	return xfer > 0 ? (snd_pcm_sframes_t)xfer : err;
}


static snd_pcm_sframes_t
snd_pcm_plugin_writei(snd_pcm_t *pcm, const void *buffer, snd_pcm_uframes_t size)
{
	snd_pcm_channel_area_t areas[pcm->channels];
	snd_pcm_areas_from_buf(pcm, areas, (void*)buffer);
	return snd_pcm_write_areas(pcm, areas, 0, size, 
				   snd_pcm_plugin_write_areas);
}

static snd_pcm_sframes_t
snd_pcm_plugin_writen(snd_pcm_t *pcm, void **bufs, snd_pcm_uframes_t size)
{
	snd_pcm_channel_area_t areas[pcm->channels];
	snd_pcm_areas_from_bufs(pcm, areas, bufs);
	return snd_pcm_write_areas(pcm, areas, 0, size,
				   snd_pcm_plugin_write_areas);
}

static snd_pcm_sframes_t
snd_pcm_plugin_readi(snd_pcm_t *pcm, void *buffer, snd_pcm_uframes_t size)
{
	snd_pcm_channel_area_t areas[pcm->channels];
	snd_pcm_areas_from_buf(pcm, areas, buffer);
	return snd_pcm_read_areas(pcm, areas, 0, size,
				  snd_pcm_plugin_read_areas);
}

static snd_pcm_sframes_t
snd_pcm_plugin_readn(snd_pcm_t *pcm, void **bufs, snd_pcm_uframes_t size)
{
	snd_pcm_channel_area_t areas[pcm->channels];
	snd_pcm_areas_from_bufs(pcm, areas, bufs);
	return snd_pcm_read_areas(pcm, areas, 0, size,
				  snd_pcm_plugin_read_areas);
}

static snd_pcm_sframes_t
snd_pcm_plugin_mmap_commit(snd_pcm_t *pcm,
			   snd_pcm_uframes_t offset ATTRIBUTE_UNUSED,
			   snd_pcm_uframes_t size)
{
	snd_pcm_plugin_t *plugin = pcm->private_data;
	snd_pcm_t *slave = plugin->gen.slave;
	const snd_pcm_channel_area_t *areas;
	snd_pcm_uframes_t appl_offset;
	snd_pcm_sframes_t slave_size;
	snd_pcm_sframes_t xfer;
	int err;

	if (pcm->stream == SND_PCM_STREAM_CAPTURE) {
		snd_pcm_mmap_appl_forward(pcm, size);
		return size;
	}
	slave_size = snd_pcm_avail_update(slave);
	if (slave_size < 0)
		return slave_size;
	areas = snd_pcm_mmap_areas(pcm);
	appl_offset = snd_pcm_mmap_offset(pcm);
	xfer = 0;
	while (size > 0 && slave_size > 0) {
		snd_pcm_uframes_t frames = size;
		snd_pcm_uframes_t cont = pcm->buffer_size - appl_offset;
		const snd_pcm_channel_area_t *slave_areas;
		snd_pcm_uframes_t slave_offset;
		snd_pcm_uframes_t slave_frames = ULONG_MAX;
		snd_pcm_sframes_t result;

		result = snd_pcm_mmap_begin(slave, &slave_areas, &slave_offset, &slave_frames);
		if (result < 0) {
			err = result;
			goto error;
		}
		if (frames > cont)
			frames = cont;
		frames = plugin->write(pcm, areas, appl_offset, frames,
				       slave_areas, slave_offset, &slave_frames);
		result = snd_pcm_mmap_commit(slave, slave_offset, slave_frames);
		if (result > 0 && (snd_pcm_uframes_t)result != slave_frames) {
			snd_pcm_sframes_t res;
			
			res = plugin->undo_write(pcm, slave_areas, slave_offset + result, slave_frames, slave_frames - result);
			if (res < 0) {
				err = res;
				goto error;
			}
			frames -= res;
		}
		if (result <= 0) {
			err = result;
			goto error;
		}
		snd_pcm_mmap_appl_forward(pcm, frames);
		if (frames == cont)
			appl_offset = 0;
		else
			appl_offset += result;
		size -= frames;
		slave_size -= frames;
		xfer += frames;
	}
	if (CHECK_SANITY(size)) {
		SNDMSG("short commit: %ld", size);
		return -EPIPE;
	}
	return xfer;

 error:
	return xfer > 0 ? xfer : err;
}

static snd_pcm_sframes_t snd_pcm_plugin_avail_update(snd_pcm_t *pcm)
{
	snd_pcm_plugin_t *plugin = pcm->private_data;
	snd_pcm_t *slave = plugin->gen.slave;
	snd_pcm_sframes_t slave_size;
	int err;

	slave_size = snd_pcm_avail_update(slave);
	if (pcm->stream == SND_PCM_STREAM_CAPTURE &&
	    pcm->access != SND_PCM_ACCESS_RW_INTERLEAVED &&
	    pcm->access != SND_PCM_ACCESS_RW_NONINTERLEAVED)
		goto _capture;
        *pcm->hw.ptr = *slave->hw.ptr;
        return slave_size;
 _capture:
 	{
		const snd_pcm_channel_area_t *areas;
		snd_pcm_uframes_t xfer, hw_offset, size;
		
		xfer = snd_pcm_mmap_capture_avail(pcm);
		size = pcm->buffer_size - xfer;
		areas = snd_pcm_mmap_areas(pcm);
		hw_offset = snd_pcm_mmap_hw_offset(pcm);
		while (size > 0 && slave_size > 0) {
			snd_pcm_uframes_t frames = size;
			snd_pcm_uframes_t cont = pcm->buffer_size - hw_offset;
			const snd_pcm_channel_area_t *slave_areas;
			snd_pcm_uframes_t slave_offset;
			snd_pcm_uframes_t slave_frames = ULONG_MAX;
			snd_pcm_sframes_t result;
			/* As mentioned in the ALSA API (see pcm/pcm.c:942):
			 * The function #snd_pcm_avail_update()
			 * have to be called before any mmap begin+commit operation.
			 * Otherwise the snd_pcm_areas_copy will not called a second time.
			 * But this is needed, if the ring buffer wrap is reached and
			 * there is more data available.
			 */
			slave_size = snd_pcm_avail_update(slave);
			result = snd_pcm_mmap_begin(slave, &slave_areas, &slave_offset, &slave_frames);
			if (result < 0) {
				err = result;
				goto error;
			}
			if (frames > cont)
				frames = cont;
			frames = (plugin->read)(pcm, areas, hw_offset, frames,
					      slave_areas, slave_offset, &slave_frames);
			result = snd_pcm_mmap_commit(slave, slave_offset, slave_frames);
			if (result > 0 && (snd_pcm_uframes_t)result != slave_frames) {
				snd_pcm_sframes_t res;
				
				res = plugin->undo_read(slave, areas, hw_offset, frames, slave_frames - result);
				if (res < 0) {
					err = res;
					goto error;
				}
				frames -= res;
			}
			if (result <= 0) {
				err = result;
				goto error;
			}
			snd_pcm_mmap_hw_forward(pcm, frames);
			if (frames == cont)
				hw_offset = 0;
			else
				hw_offset += frames;
			size -= frames;
			slave_size -= slave_frames;
			xfer += frames;
		}
		return (snd_pcm_sframes_t)xfer;

	error:
		return xfer > 0 ? (snd_pcm_sframes_t)xfer : err;
	}
}

static int snd_pcm_plugin_status(snd_pcm_t *pcm, snd_pcm_status_t * status)
{
	snd_pcm_plugin_t *plugin = pcm->private_data;
	snd_pcm_sframes_t err;

	/* sync with the latest hw and appl ptrs */
	snd_pcm_plugin_avail_update(pcm);

	err = snd_pcm_status(plugin->gen.slave, status);
	if (err < 0)
		return err;
	status->appl_ptr = *pcm->appl.ptr;
	status->hw_ptr = *pcm->hw.ptr;
	return 0;
}

int snd_pcm_plugin_may_wait_for_avail_min(snd_pcm_t *pcm,
					  snd_pcm_uframes_t avail)
{
	if (pcm->stream == SND_PCM_STREAM_CAPTURE &&
	    pcm->access != SND_PCM_ACCESS_RW_INTERLEAVED &&
	    pcm->access != SND_PCM_ACCESS_RW_NONINTERLEAVED) {
		/* mmap access on capture device already consumes data from
		 * slave in avail_update operation. Entering snd_pcm_wait after
		 * having already consumed some fragments leads to waiting for
		 * too long time, as slave will unnecessarily wait for avail_min
		 * condition reached again. To avoid unnecessary wait times we
		 * adapt the avail_min threshold on slave dynamically. Just
		 * modifying slave->avail_min as a shortcut and lightweight
		 * solution does not work for all slave plugin types and in
		 * addition it will not propagate the change through all
		 * downstream plugins, so we have to use the sw_params API.
		 * note: reading fragmental parts from slave will only happen
		 * in case
		 * a) the slave can provide contineous hw_ptr between periods
		 * b) avail_min does not match one slave_period
		 */
		snd_pcm_plugin_t *plugin = pcm->private_data;
		snd_pcm_t *slave = plugin->gen.slave;
		snd_pcm_uframes_t needed_slave_avail_min;
		snd_pcm_sframes_t available;

		/* update, as it might have changed. This will also call
		 * avail_update on slave and also can return error
		 */
		available = snd_pcm_avail_update(pcm);
		if (available < 0)
			return 0;

		if ((snd_pcm_uframes_t)available >= pcm->avail_min)
			/* don't wait at all. As we can't configure avail_min
			 * of slave to 0 return here
			 */
			return 0;

		needed_slave_avail_min = pcm->avail_min - available;
		if (slave->avail_min != needed_slave_avail_min) {
			snd_pcm_sw_params_t *swparams;
			snd_pcm_sw_params_alloca(&swparams);
			/* pray that changing sw_params while running is
			 * properly implemented in all downstream plugins...
			 * it's legal but not commonly used.
			 */
			snd_pcm_sw_params_current(slave, swparams);
			/* snd_pcm_sw_params_set_avail_min() restricts setting
			 * to >= period size. This conflicts at least with our
			 * dshare patch which allows combining multiple periods
			 * or with slaves which return hw postions between
			 * periods -> set directly in sw_param structure
			 */
			swparams->avail_min = needed_slave_avail_min;
			snd_pcm_sw_params(slave, swparams);
		}
		avail = available;
	}
	return snd_pcm_generic_may_wait_for_avail_min(pcm, avail);
}

const snd_pcm_fast_ops_t snd_pcm_plugin_fast_ops = {
	.status = snd_pcm_plugin_status,
	.state = snd_pcm_generic_state,
	.hwsync = snd_pcm_generic_hwsync,
	.delay = snd_pcm_plugin_delay,
	.prepare = snd_pcm_plugin_prepare,
	.reset = snd_pcm_plugin_reset,
	.start = snd_pcm_generic_start,
	.drop = snd_pcm_generic_drop,
	.drain = snd_pcm_generic_drain,
	.pause = snd_pcm_generic_pause,
	.rewindable = snd_pcm_plugin_rewindable,
	.rewind = snd_pcm_plugin_rewind,
	.forwardable = snd_pcm_plugin_forwardable,
	.forward = snd_pcm_plugin_forward,
	.resume = snd_pcm_generic_resume,
	.link = snd_pcm_generic_link,
	.link_slaves = snd_pcm_generic_link_slaves,
	.unlink = snd_pcm_generic_unlink,
	.writei = snd_pcm_plugin_writei,
	.writen = snd_pcm_plugin_writen,
	.readi = snd_pcm_plugin_readi,
	.readn = snd_pcm_plugin_readn,
	.avail_update = snd_pcm_plugin_avail_update,
	.mmap_commit = snd_pcm_plugin_mmap_commit,
	.htimestamp = snd_pcm_generic_htimestamp,
	.poll_descriptors_count = snd_pcm_generic_poll_descriptors_count,
	.poll_descriptors = snd_pcm_generic_poll_descriptors,
	.poll_revents = snd_pcm_generic_poll_revents,
	.may_wait_for_avail_min = snd_pcm_plugin_may_wait_for_avail_min,
};

#endif
