load_mixer_file.cpp

Go to the documentation of this file.

/****************************************************************************
 *
 *   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
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/**
 * @file mixer_load.c
 *
 * Programmable multi-channel mixer library.
 */

#include <string.h>
#include <stdio.h>
#include <ctype.h>

#include "mixer_load.h"

int load_mixer_file(const char *fname, char *buf, unsigned maxlen)
{
    FILE *fp;
    char line[120];

    /* open the mixer definition file */
    fp = fopen(fname, "r");

    if (fp == nullptr) {
        printf("file not found\n");
        return -1;
    }

    /* 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) == nullptr) {
            break;
        }

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

        /* compact whitespace in the buffer */
        char *t, *f;

        for (f = line; *f != '\0'; f++) {
            /* scan for space characters */
            if (*f == ' ') {
                /* look for additional spaces */
                t = f + 1;

                while (*t == ' ') {
                    t++;
                }

                if (*t == '\0') {
                    /* strip trailing whitespace */
                    *f = '\0';

                } else if (t > (f + 1)) {
                    memmove(f + 1, t, strlen(t) + 1);
                }
            }
        }

        /* if the line is too long to fit in the buffer, bail */
        if ((strlen(line) + strlen(buf) + 1) >= maxlen) {
            printf("line too long\n");
            fclose(fp);
            return -1;
        }

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

    fclose(fp);
    return 0;
}