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List:       linux-audio-dev
Subject:    Re: [linux-audio-dev] HOw to create an ALSA out port
From:       Pedro Lopez-Cabanillas <pedro.lopez.cabanillas () gmail ! com>
Date:       2005-07-25 16:55:38
Message-ID: 200507251855.38252.pedro.lopez.cabanillas () gmail ! com
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On Monday 25 July 2005, Jens M Andreasen wrote:
> On Mon, 2005-07-25 at 00:50 +0200, Christoph Eckert wrote:
> > I only need to write sysex data which are kept in a character
> > array. Is there a possibility to easily
> > * connect to a certain port of a device (the Midisport control
> > port)
> > * send the contents of the array to this port
[...]
> Let's see if not someone will post the alsa version ... soon.

I hope the attached program to be simple enough to be useful in your context.

Compile it with:
	$ gcc -o amsgsysex -l asound amsgsysex.c

Use it with;
	$ amsgsysex 64:1

Regards,
Pedro


["amsgsysex.c" (text/x-csrc)]

/*
 *  Copyright (C) 2005 Pedro Lopez-Cabanillas <plcl@users.sf.net>
 *
 *  This program sends a sysex MIDI message to an ALSA sequencer port
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2 as
 *  published by the Free Software Foundation.
 *
 *  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 General Public License for more details.
 */

#include <alsa/asoundlib.h>

unsigned char msg_gmreset[] =
    { 0xf0, 0x7e, 0x7f, 0x09, 0x01, 0xf7 };

char *port_address = NULL;
int port_out_id;
snd_seq_t *seq_handle;

void send_event(snd_seq_event_t *ev)
{
	int err;
	snd_seq_ev_set_source(ev, port_out_id);
	snd_seq_ev_set_subs(ev);
	snd_seq_ev_set_direct(ev);
	if ((err = snd_seq_event_output_direct(seq_handle, ev)) < 0) {
		fprintf(stderr, "error %i at send_event (%s)\n", err, snd_strerror(err));
		exit(EXIT_FAILURE);
	}
	snd_seq_drain_output(seq_handle);
}

void send_syx_event(unsigned char *data, int len)
{
	snd_seq_event_t ev;
	snd_seq_ev_clear(&ev);
	snd_seq_ev_set_sysex(&ev, len, data);
	send_event(&ev);
}

int main(int argc, char *argv[])
{
	snd_seq_addr_t dest;

	if (argc > 1) {
		port_address = argv[1];
	} else {
		fprintf(stderr, "Usage: amsgsysex SEQUENCER_PORT\n");
		return EXIT_FAILURE;
	}

	if (snd_seq_open(&seq_handle, "default", SND_SEQ_OPEN_OUTPUT, 0) < 0) {
		fprintf(stderr, "Error opening ALSA sequencer.\n");
		exit(EXIT_FAILURE);
	}
	snd_seq_set_client_name(seq_handle, "client name");
	if ((port_out_id = snd_seq_create_simple_port(seq_handle, "output port name",
		SND_SEQ_PORT_CAP_READ|SND_SEQ_PORT_CAP_SUBS_READ,
		SND_SEQ_PORT_TYPE_APPLICATION)) < 0) {
			fprintf(stderr, "Error creating sequencer port.\n");
 			exit(EXIT_FAILURE);
	}
	if (snd_seq_parse_address(seq_handle, &dest, port_address) < 0) {
		fprintf(stderr, "invalid destination address %s\n", port_address);
		return EXIT_FAILURE;
	}
	if (snd_seq_connect_to(seq_handle, port_out_id, dest.client, dest.port) < 0) {
		fprintf(stderr, "invalid connection to %d:%d (%s)\n", dest.client, dest.port, port_address);
		return EXIT_FAILURE;
	}
	send_syx_event(&msg_gmreset[0], sizeof(msg_gmreset));
	snd_seq_close(seq_handle);
	return EXIT_SUCCESS;
}


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