px4_autopilot/apps/systemcmds/mixer/mixer.c

/****************************************************************************
 *
 *   Copyright (C) 2012 PX4 Development Team. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name PX4 nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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/**
 * @file mixer.c
 *
 * Mixer utility.
 */

#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <ctype.h>
#include <nuttx/compiler.h>

#include <systemlib/err.h>
#include <drivers/drv_mixer.h>
#include <uORB/topics/actuator_controls.h>

__EXPORT int mixer_main(int argc, char *argv[]);

static void	usage(const char *reason) noreturn_function;
static void	load(const char *devname, const char *fname) noreturn_function;

int
mixer_main(int argc, char *argv[])
{
	if (argc < 2)
		usage("missing command");

	if (!strcmp(argv[1], "load")) {
		if (argc < 4)
			usage("missing device or filename");

		load(argv[2], argv[3]);
	}

	usage("unrecognised command");
}

static void
usage(const char *reason)
{
	if (reason)
		fprintf(stderr, "%s\n", reason);

	fprintf(stderr, "usage:\n");
	fprintf(stderr, "  mixer load <device> <filename>\n");
	/* XXX other useful commands? */
	exit(1);
}

static void
load(const char *devname, const char *fname)
{
	int		dev;
	FILE		*fp;
	char		line[80];
	char		buf[512];

	/* open the device */
	if ((dev = open(devname, 0)) < 0)
		err(1, "can't open %s\n", devname);

	/* reset mixers on the device */
	if (ioctl(dev, MIXERIOCRESET, 0))
		err(1, "can't reset mixers on %s", devname);

	/* open the mixer definition file */
	fp = fopen(fname, "r");
	if (fp == NULL)
		err(1, "can't open %s", fname);

	/* read valid lines from the file into a buffer */
	buf[0] = '\0';
	for (;;) {

		/* get a line, bail on error/EOF */
		line[0] = '\0';
		if (fgets(line, sizeof(line), fp) == NULL)
			break;

		/* if the line doesn't look like a mixer definition line, skip it */
		if ((strlen(line) < 2) || !isupper(line[0]) || (line[1] != ':'))
			continue;

		/* XXX an optimisation here would be to strip extra whitespace */

		/* if the line is too long to fit in the buffer, bail */
		if ((strlen(line) + strlen(buf) + 1) >= sizeof(buf))
			break;

		/* add the line to the buffer */
		strcat(buf, line);
	}

	/* XXX pass the buffer to the device */
	int ret = ioctl(dev, MIXERIOCLOADBUF, (unsigned long)buf);

	if (ret < 0)
		err(1, "error loading mixers from %s", fname);
	exit(0);
}