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Currently midi capable programs can control midi hardware, but
cannot cooperate with other programs.  The aim of this change is
to allow any program to send midi data to other programs as they
were midi hardware. For instance, this change should solve the
longstanding problem of using a midi sequencer with software
synthesizers. More precisely:

 - new midicat(1) utility (actually hardlink to aucat(1)).
   it creates software midi thru boxes, allowing programs
   to send midi messages to other programs as they were
   midi(4) hardware.

 - new midi api in libsndio (see mio_open(3)), to access
   midi(4) devices and midicat(1) sockets in a uniform way.

 - new device naming scheme <service>:<unit>[.<option>],
   common to audio and midi.

 - new sndio(7) manual describing concepts and naming

The current audio device naming still works, but people having
scripts or configuration files containing device names could read
the sndio(7) man page and slowly start updating device names.

discussed with jakemsr@ and deraadt@, help form jmc@

/*	$OpenBSD: aproc.h,v 1.17 2009/07/25 08:44:27 ratchov Exp $	*/
/*
 * Copyright (c) 2008 Alexandre Ratchov <alex@caoua.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
#ifndef APROC_H
#define APROC_H

#include <sys/queue.h>

#include "aparams.h"
#include "file.h"

struct abuf;
struct aproc;
struct file;

struct aproc_ops {
	/*
	 * Name of the ops structure, ie type of the unit.
	 */
	char *name;

	/*
	 * The state of the given input abuf changed (eg. an input block
	 * is ready for processing). This function must get the block
	 * from the input, process it and remove it from the buffer.
	 *
	 * Processing the block will result in a change of the state of
	 * OTHER buffers that are attached to the aproc (eg. the output
	 * buffer was filled), thus this routine MUST notify ALL aproc
	 * structures that are waiting on it; most of the time this
	 * means just calling abuf_flush() on the output buffer.
	 */
	int (*in)(struct aproc *, struct abuf *);

	/*
	 * The state of the given output abuf changed (eg. space for a
	 * new output block was made available) so processing can
	 * continue.  This function must process more input in order to
	 * fill the output block.
	 *
	 * Producing a block will result in the change of the state of
	 * OTHER buffers that are attached to the aproc, thus this
	 * routine MUST notify ALL aproc structures that are waiting on
	 * it; most of the time this means calling abuf_fill() on the
	 * source buffers.
	 *
	 * Before filling input buffers (using abuf_fill()), this
	 * routine must ALWAYS check for eof condition, and if needed,
	 * handle it appropriately and call abuf_hup() to free the input
	 * buffer.
	 */
	int (*out)(struct aproc *, struct abuf *);

	/*
	 * The input buffer is empty and we can no more receive data
	 * from it. The buffer will be destroyed as soon as this call
	 * returns so the abuf pointer will stop being valid after this
	 * call returns. There's no need to drain the buffer because the
	 * in() call-back was just called before.
	 *
	 * If this call reads and/or writes data on other buffers,
	 * abuf_flush() and abuf_fill() must be called appropriately.
	 */
	void (*eof)(struct aproc *, struct abuf *);

	/*
	 * The output buffer can no more accept data (it should be
	 * considered as full). After this function returns, it will be
	 * destroyed and the "abuf" pointer will be no more valid.
	 */
	void (*hup)(struct aproc *, struct abuf *);

	/*
	 * A new input was connected.
	 */
	void (*newin)(struct aproc *, struct abuf *);

	/*
	 * A new output was connected
	 */
	void (*newout)(struct aproc *, struct abuf *);

	/*
	 * Real-time record position changed (for input buffer),
	 * by the given amount of _frames_
	 */
	void (*ipos)(struct aproc *, struct abuf *, int);

	/*
	 * Real-time play position changed (for output buffer),
	 * by the given amount of _frames_
	 */
	void (*opos)(struct aproc *, struct abuf *, int);

	/*
	 * destroy the aproc, called just before to free the
	 * aproc structure
	 */
	void (*done)(struct aproc *);
};

/*
 * The aproc structure represents a simple audio processing unit; they are
 * interconnected by abuf structures and form a kind of "circuit". The circuit
 * cannot have loops.
 */
struct aproc {
	char *name;				/* for debug purposes */
	struct aproc_ops *ops;			/* call-backs */
	LIST_HEAD(, abuf) ibuflist;		/* list of inputs */
	LIST_HEAD(, abuf) obuflist;		/* list of outputs */
	unsigned refs;				/* extern references */
	union {					/* follow type-specific data */
		struct {			/* file/device io */
			struct file *file;	/* file to read/write */
		} io;
		struct {
#define MIX_DROP	1
#define MIX_AUTOQUIT	2
			unsigned flags;		/* bit mask of above */
			unsigned idle;		/* frames since idleing */
			int lat;		/* current latency */
			int maxlat;		/* max latency allowed*/
		} mix;
		struct {
#define SUB_DROP	1
#define SUB_AUTOQUIT	2
			unsigned idle;		/* frames since idleing */
			unsigned flags;		/* bit mask of above */
			int lat;		/* current latency */
			int maxlat;		/* max latency allowed*/
		} sub;
		struct {
#define RESAMP_NCTX	2
			unsigned ctx_start;
			short ctx[NCHAN_MAX * RESAMP_NCTX];
			unsigned iblksz, oblksz;
			int diff;
			int idelta, odelta;	/* remainder of resamp_[io]pos */
		} resamp;
		struct {
			short ctx[NCHAN_MAX];
		} cmap;
		struct {
			int bfirst;		/* bytes to skip at startup */
			unsigned bps;		/* bytes per sample */
			unsigned shift;		/* shift to get 32bit MSB */
			int sigbit;		/* sign bits to XOR */
			int bnext;		/* to reach the next byte */
			int snext;		/* to reach the next sample */
		} conv;
		struct {
			struct abuf *owner;	/* current input stream */
			struct timo timo;	/* timout for throtteling */
		} thru;
	} u;
};

struct aproc *aproc_new(struct aproc_ops *, char *);
void aproc_del(struct aproc *);
void aproc_setin(struct aproc *, struct abuf *);
void aproc_setout(struct aproc *, struct abuf *);
int aproc_depend(struct aproc *, struct aproc *);

struct aproc *rpipe_new(struct file *);
int rpipe_in(struct aproc *, struct abuf *);
int rpipe_out(struct aproc *, struct abuf *);
void rpipe_done(struct aproc *);
void rpipe_eof(struct aproc *, struct abuf *);
void rpipe_hup(struct aproc *, struct abuf *);

struct aproc *wpipe_new(struct file *);
void wpipe_done(struct aproc *);
int wpipe_in(struct aproc *, struct abuf *);
int wpipe_out(struct aproc *, struct abuf *);
void wpipe_eof(struct aproc *, struct abuf *);
void wpipe_hup(struct aproc *, struct abuf *);

struct aproc *mix_new(char *, int);
struct aproc *sub_new(char *, int);
struct aproc *resamp_new(char *, unsigned, unsigned);
struct aproc *cmap_new(char *, struct aparams *, struct aparams *);
struct aproc *enc_new(char *, struct aparams *);
struct aproc *dec_new(char *, struct aparams *);

void mix_pushzero(struct aproc *);
void mix_setmaster(struct aproc *);
void mix_clear(struct aproc *);
void sub_clear(struct aproc *);

#endif /* !defined(APROC_H) */