tfmini_parser.cpp

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/**
 * @file modified from sf0x_parser.cpp
 * @author Lorenz Meier <lm@inf.ethz.ch>
 * @author Chuong Nguyen <chnguye7@asu.edu>
 * @author Ayush Gaud <ayush.gaud@gmail.com>
 *
 * Declarations of parser for the Benewake TFmini laser rangefinder series
 */

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

// #define TFMINI_DEBUG

#ifdef TFMINI_DEBUG
#include <stdio.h>

const char *parser_state[] = {
    "0_UNSYNC",
    "1_SYNC_1",
    "2_SYNC_2",
    "3_GOT_DIST_L",
    "4_GOT_DIST_H",
    "5_GOT_STRENGTH_L",
    "6_GOT_STRENGTH_H",
    "7_GOT_PRESERVED",
    "8_GOT_QUALITY"
    "9_GOT_CHECKSUM"
};
#endif

int tfmini_parse(char c, char *parserbuf, unsigned *parserbuf_index, TFMINI_PARSE_STATE *state, float *dist)
{
    int ret = -1;
    //char *end;

    switch (*state) {
    case TFMINI_PARSE_STATE::STATE6_GOT_CHECKSUM:
        if (c == 'Y') {
            *state = TFMINI_PARSE_STATE::STATE1_SYNC_1;
            parserbuf[*parserbuf_index] = c;
            (*parserbuf_index)++;

        } else {
            *state = TFMINI_PARSE_STATE::STATE0_UNSYNC;
        }

        break;

    case TFMINI_PARSE_STATE::STATE0_UNSYNC:
        if (c == 'Y') {
            *state = TFMINI_PARSE_STATE::STATE1_SYNC_1;
            parserbuf[*parserbuf_index] = c;
            (*parserbuf_index)++;
        }

        break;

    case TFMINI_PARSE_STATE::STATE1_SYNC_1:
        if (c == 'Y') {
            *state = TFMINI_PARSE_STATE::STATE1_SYNC_2;
            parserbuf[*parserbuf_index] = c;
            (*parserbuf_index)++;

        } else {
            *state = TFMINI_PARSE_STATE::STATE0_UNSYNC;
            *parserbuf_index = 0;
        }

        break;

    case TFMINI_PARSE_STATE::STATE1_SYNC_2:
        *state = TFMINI_PARSE_STATE::STATE2_GOT_DIST_L;
        parserbuf[*parserbuf_index] = c;
        (*parserbuf_index)++;

        break;

    case TFMINI_PARSE_STATE::STATE2_GOT_DIST_L:
        *state = TFMINI_PARSE_STATE::STATE2_GOT_DIST_H;
        parserbuf[*parserbuf_index] = c;
        (*parserbuf_index)++;

        break;

    case TFMINI_PARSE_STATE::STATE2_GOT_DIST_H:
        *state = TFMINI_PARSE_STATE::STATE3_GOT_STRENGTH_L;
        parserbuf[*parserbuf_index] = c;
        (*parserbuf_index)++;

        break;

    case TFMINI_PARSE_STATE::STATE3_GOT_STRENGTH_L:
        *state = TFMINI_PARSE_STATE::STATE3_GOT_STRENGTH_H;
        parserbuf[*parserbuf_index] = c;
        (*parserbuf_index)++;

        break;

    case TFMINI_PARSE_STATE::STATE3_GOT_STRENGTH_H:
        *state = TFMINI_PARSE_STATE::STATE4_GOT_RESERVED;
        parserbuf[*parserbuf_index] = c;
        (*parserbuf_index)++;

        break;

    case TFMINI_PARSE_STATE::STATE4_GOT_RESERVED:
        *state = TFMINI_PARSE_STATE::STATE5_GOT_QUALITY;
        parserbuf[*parserbuf_index] = c;
        (*parserbuf_index)++;

        break;

    case TFMINI_PARSE_STATE::STATE5_GOT_QUALITY:
        // Find the checksum
        unsigned char cksm = 0;

        for (int i = 0; i < 8; i++) {
            cksm += parserbuf[i];
        }

        if (c == cksm) {
            parserbuf[*parserbuf_index] = '\0';
            unsigned int t1 = parserbuf[2];
            unsigned int t2 = parserbuf[3];
            t2 <<= 8;
            t2 += t1;
            *dist = ((float)t2) / 100;
            *state = TFMINI_PARSE_STATE::STATE6_GOT_CHECKSUM;
            *parserbuf_index = 0;
            ret = 0;

        } else {
            *state = TFMINI_PARSE_STATE::STATE0_UNSYNC;
            *parserbuf_index = 0;
        }

        break;
    }

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

    return ret;
}