sf0x_parser.cpp

Go to the documentation of this file.

/****************************************************************************
 *
 *   Copyright (c) 2014 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 sf0x_parser.cpp
 * @author Lorenz Meier <lm@inf.ethz.ch>
 *
 * Driver for the Lightware SF0x laser rangefinder series
 */

#include "sf0x_parser.h"
#include <string.h>
#include <stdlib.h>

//#define SF0X_DEBUG

#ifdef SF0X_DEBUG
#include <stdio.h>

const char *parser_state[] = {
    "0_UNSYNC",
    "1_SYNC",
    "2_GOT_DIGIT0",
    "3_GOT_DOT",
    "4_GOT_DIGIT1",
    "5_GOT_DIGIT2",
    "6_GOT_CARRIAGE_RETURN"
};
#endif

int sf0x_parser(char c, char *parserbuf, unsigned *parserbuf_index, enum SF0X_PARSE_STATE *state, float *dist)
{
    int ret = -1;
    char *end;

    switch (*state) {
    case SF0X_PARSE_STATE0_UNSYNC:
        if (c == '\n') {
            *state = SF0X_PARSE_STATE1_SYNC;
            (*parserbuf_index) = 0;
        }

        break;

    case SF0X_PARSE_STATE1_SYNC:
        if (c >= '0' && c <= '9') {
            *state = SF0X_PARSE_STATE2_GOT_DIGIT0;
            parserbuf[*parserbuf_index] = c;
            (*parserbuf_index)++;
        }

        break;

    case SF0X_PARSE_STATE2_GOT_DIGIT0:
        if (c >= '0' && c <= '9') {
            *state = SF0X_PARSE_STATE2_GOT_DIGIT0;
            parserbuf[*parserbuf_index] = c;
            (*parserbuf_index)++;

        } else if (c == '.') {
            *state = SF0X_PARSE_STATE3_GOT_DOT;
            parserbuf[*parserbuf_index] = c;
            (*parserbuf_index)++;

        } else {
            *state = SF0X_PARSE_STATE0_UNSYNC;
        }

        break;

    case SF0X_PARSE_STATE3_GOT_DOT:
        if (c >= '0' && c <= '9') {
            *state = SF0X_PARSE_STATE4_GOT_DIGIT1;
            parserbuf[*parserbuf_index] = c;
            (*parserbuf_index)++;

        } else {
            *state = SF0X_PARSE_STATE0_UNSYNC;
        }

        break;

    case SF0X_PARSE_STATE4_GOT_DIGIT1:
        if (c >= '0' && c <= '9') {
            *state = SF0X_PARSE_STATE5_GOT_DIGIT2;
            parserbuf[*parserbuf_index] = c;
            (*parserbuf_index)++;

        } else {
            *state = SF0X_PARSE_STATE0_UNSYNC;
        }

        break;

    case SF0X_PARSE_STATE5_GOT_DIGIT2:
        if (c == '\r') {
            *state = SF0X_PARSE_STATE6_GOT_CARRIAGE_RETURN;

        } else {
            *state = SF0X_PARSE_STATE0_UNSYNC;
        }

        break;

    case SF0X_PARSE_STATE6_GOT_CARRIAGE_RETURN:
        if (c == '\n') {
            parserbuf[*parserbuf_index] = '\0';
            *dist = strtod(parserbuf, &end);
            *state = SF0X_PARSE_STATE1_SYNC;
            *parserbuf_index = 0;
            ret = 0;

        } else {
            *state = SF0X_PARSE_STATE0_UNSYNC;
        }

        break;
    }

#ifdef SF0X_DEBUG
    printf("state: SF0X_PARSE_STATE%s\n", parser_state[*state]);
#endif

    return ret;
}