PX4-Autopilot/src/drivers/sf0x/sf0x_parser.cpp

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/**
 * @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;

	unsigned len = strlen(parserbuf);
	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;
}