text: /**
   * \file include/pcm_ioplug.h
   * \brief External I/O-Plugin SDK
   * \author Takashi Iwai <tiwai@suse.de>
   * \date 2005
   *
   * External I/O-Plugin SDK
   */
  
  /*
   * ALSA external PCM plugin SDK
   *
   * Copyright (c) 2005 Takashi Iwai <tiwai@suse.de>
   *
   *   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., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
   *
   */
  
  #ifndef __ALSA_PCM_IOPLUG_H
  #define __ALSA_PCM_IOPLUG_H
  
  /**
   * \defgroup PCM_IOPlug External I/O plugin SDK
   * \ingroup Plugin_SDK
   * See the \ref pcm page for more details.
   * \{
   */
  
  /** hw constraints for ioplug */
  enum {
  	SND_PCM_IOPLUG_HW_ACCESS = 0,	/**< access type */
  	SND_PCM_IOPLUG_HW_FORMAT,	/**< format */
  	SND_PCM_IOPLUG_HW_CHANNELS,	/**< channels */
  	SND_PCM_IOPLUG_HW_RATE,		/**< rate */
  	SND_PCM_IOPLUG_HW_PERIOD_BYTES,	/**< period bytes */
  	SND_PCM_IOPLUG_HW_BUFFER_BYTES,	/**< buffer bytes */
  	SND_PCM_IOPLUG_HW_PERIODS,	/**< number of periods */
  	SND_PCM_IOPLUG_HW_PARAMS	/**< max number of hw constraints */
  };
  	
  /** I/O plugin handle */
  typedef struct snd_pcm_ioplug snd_pcm_ioplug_t;
  /** Callback table of ioplug */
  typedef struct snd_pcm_ioplug_callback snd_pcm_ioplug_callback_t;
  #ifdef DOC_HIDDEN
  /* redefine typedefs for stupid doxygen */
  typedef snd_pcm_ioplug snd_pcm_ioplug_t;
  typedef snd_pcm_ioplug_callback snd_pcm_ioplug_callback_t;
  #endif
  
  /*
   * bit flags for additional conditions
   */
  #define SND_PCM_IOPLUG_FLAG_LISTED	(1<<0)		/**< list up this PCM */
  #define SND_PCM_IOPLUG_FLAG_MONOTONIC	(1<<1)		/**< monotonic timestamps */
  
  /*
   * Protocol version
   */
  #define SND_PCM_IOPLUG_VERSION_MAJOR	1	/**< Protocol major version */
  #define SND_PCM_IOPLUG_VERSION_MINOR	0	/**< Protocol minor version */
  #define SND_PCM_IOPLUG_VERSION_TINY	2	/**< Protocol tiny version */
  /**
   * IO-plugin protocol version
   */
  #define SND_PCM_IOPLUG_VERSION		((SND_PCM_IOPLUG_VERSION_MAJOR<<16) |\
  					 (SND_PCM_IOPLUG_VERSION_MINOR<<8) |\
  					 (SND_PCM_IOPLUG_VERSION_TINY))
  
  /** Handle of ioplug */
  struct snd_pcm_ioplug {
  	/**
  	 * protocol version; #SND_PCM_IOPLUG_VERSION must be filled here
  	 * before calling #snd_pcm_ioplug_create()
  	 */
  	unsigned int version;
  	/**
  	 * name of this plugin; must be filled before calling #snd_pcm_ioplug_create()
  	 */
  	const char *name;
  	unsigned int flags;	/**< SND_PCM_IOPLUG_FLAG_XXX */
  	int poll_fd;		/**< poll file descriptor */
  	unsigned int poll_events;	/**< poll events */
  	unsigned int mmap_rw;		/**< pseudo mmap mode */
  	/**
  	 * callbacks of this plugin; must be filled before calling #snd_pcm_ioplug_create()
  	 */
  	const snd_pcm_ioplug_callback_t *callback;
  	/**
  	 * private data, which can be used freely in the driver callbacks
  	 */
  	void *private_data;
  	/**
  	 * PCM handle filled by #snd_pcm_extplug_create()
  	 */
  	snd_pcm_t *pcm;
  
  	snd_pcm_stream_t stream;	/**< stream direcion; read-only */	
  	snd_pcm_state_t state;		/**< current PCM state; read-only */
  	volatile snd_pcm_uframes_t appl_ptr;	/**< application pointer; read-only */
  	volatile snd_pcm_uframes_t hw_ptr;	/**< hw pointer; read-only */
  	int nonblock;			/**< non-block mode; read-only */
  
  	snd_pcm_access_t access;	/**< access type; filled after hw_params is called */
  	snd_pcm_format_t format;	/**< PCM format; filled after hw_params is called */
  	unsigned int channels;		/**< number of channels; filled after hw_params is called */
  	unsigned int rate;		/**< rate; filled after hw_params is called */
  	snd_pcm_uframes_t period_size;	/**< period size; filled after hw_params is called */
  	snd_pcm_uframes_t buffer_size;	/**< buffer size; filled after hw_params is called */
  };
  
  /** Callback table of ioplug */
  struct snd_pcm_ioplug_callback {
  	/**
  	 * start the PCM; required
  	 */
  	int (*start)(snd_pcm_ioplug_t *io);
  	/**
  	 * stop the PCM; required
  	 */
  	int (*stop)(snd_pcm_ioplug_t *io);
  	/**
  	 * get the current DMA position; required
  	 */
  	snd_pcm_sframes_t (*pointer)(snd_pcm_ioplug_t *io);
  	/**
  	 * transfer the data; optional
  	 */
  	snd_pcm_sframes_t (*transfer)(snd_pcm_ioplug_t *io,
  				      const snd_pcm_channel_area_t *areas,
  				      snd_pcm_uframes_t offset,
  				      snd_pcm_uframes_t size);
  	/**
  	 * close the PCM; optional
  	 */
  	int (*close)(snd_pcm_ioplug_t *io);
  	/**
  	 * hw_params; optional
  	 */
  	int (*hw_params)(snd_pcm_ioplug_t *io, snd_pcm_hw_params_t *params);
  	/**
  	 * hw_free; optional
  	 */
  	int (*hw_free)(snd_pcm_ioplug_t *io);
  	/**
  	 * sw_params; optional
  	 */
  	int (*sw_params)(snd_pcm_ioplug_t *io, snd_pcm_sw_params_t *params);
  	/**
  	 * prepare; optional
  	 */
  	int (*prepare)(snd_pcm_ioplug_t *io);
  	/**
  	 * drain; optional
  	 */
  	int (*drain)(snd_pcm_ioplug_t *io);
  	/**
  	 * toggle pause; optional
  	 */
  	int (*pause)(snd_pcm_ioplug_t *io, int enable);
  	/**
  	 * resume; optional
  	 */
  	int (*resume)(snd_pcm_ioplug_t *io);
  	/**
  	 * poll descriptors count; optional
  	 */
  	int (*poll_descriptors_count)(snd_pcm_ioplug_t *io);
  	/**
  	 * poll descriptors; optional
  	 */
  	int (*poll_descriptors)(snd_pcm_ioplug_t *io, struct pollfd *pfd, unsigned int space);
  	/**
  	 * mangle poll events; optional
  	 */
  	int (*poll_revents)(snd_pcm_ioplug_t *io, struct pollfd *pfd, unsigned int nfds, unsigned short *revents);
  	/**
  	 * dump; optional
  	 */
  	void (*dump)(snd_pcm_ioplug_t *io, snd_output_t *out);
  	/**
  	 * get the delay for the running PCM; optional; since v1.0.1
  	 */
  	int (*delay)(snd_pcm_ioplug_t *io, snd_pcm_sframes_t *delayp);
  	/**
  	 * query the channel maps; optional; since v1.0.2
  	 */
  	snd_pcm_chmap_query_t **(*query_chmaps)(snd_pcm_ioplug_t *io);
  	/**
  	 * get the channel map; optional; since v1.0.2
  	 */
  	snd_pcm_chmap_t *(*get_chmap)(snd_pcm_ioplug_t *io);
  	/**
  	 * set the channel map; optional; since v1.0.2
  	 */
  	int (*set_chmap)(snd_pcm_ioplug_t *io, const snd_pcm_chmap_t *map);
  };
  
  
  int snd_pcm_ioplug_create(snd_pcm_ioplug_t *io, const char *name,
  			  snd_pcm_stream_t stream, int mode);
  int snd_pcm_ioplug_delete(snd_pcm_ioplug_t *io);
  
  /* update poll_fd and mmap_rw */
  int snd_pcm_ioplug_reinit_status(snd_pcm_ioplug_t *ioplug);
  
  /* get a mmap area (for mmap_rw only) */
  const snd_pcm_channel_area_t *snd_pcm_ioplug_mmap_areas(snd_pcm_ioplug_t *ioplug);
  
  /* clear hw_parameter setting */
  void snd_pcm_ioplug_params_reset(snd_pcm_ioplug_t *io);
  
  /* hw_parameter setting */
  int snd_pcm_ioplug_set_param_minmax(snd_pcm_ioplug_t *io, int type, unsigned int min, unsigned int max);
  int snd_pcm_ioplug_set_param_list(snd_pcm_ioplug_t *io, int type, unsigned int num_list, const unsigned int *list);
  
  /* change PCM status */
  int snd_pcm_ioplug_set_state(snd_pcm_ioplug_t *ioplug, snd_pcm_state_t state);
  
  /** \} */
  
  #endif /* __ALSA_PCM_IOPLUG_H */
  