rfid.c

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/* -- Includes -- */
/* system libraries */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>  /* String function definitions */
#include <unistd.h>  /* UNIX standard function definitions */
#include <sys/time.h>
#include <sys/select.h>
/* project libraries */
#include "config.h"
#include "def.h"
#include "serialport.h"
#include "rfid.h"

/* -- Defines -- */

/* -- Functions -- */

rfid_t *rfid_open(char *device_path)
{
    // RFID structure
    rfid_t *rfids = (rfid_t *) malloc(sizeof(rfid_t));

    // Open serial port
    rfids->sps = serialport_open(device_path);
    // Configure serial port
    serialport_config(rfids->sps, 2400);

    return rfids;
}

int rfid_close(rfid_t *rfids)
{
    int res;

    // Close serial port
    res = serialport_close(rfids->sps);
    // Free memory
    free(rfids);

    return res;
}

int rfid_read_locked(rfid_t *rfids)
{
    char buffer[32];
    char *bufptr;           // Current char in buffer
    int  nbytes, tbytes;    // Number of bytes read

    // Read characters into buffer until we get a CR or NL
    bufptr = buffer;


    while ((nbytes = (int)read(rfids->sps->descriptor, bufptr, 1)) > 0)
    {
        // Wait for start byte -> "NL"
        if(*bufptr == '\n') {
            //printf("__NL");
            tbytes = 0;
        }
        // If "CR" received then check if 10 bytes collected if yes -> finished
        else if(*bufptr == '\r') {
            //printf("CR");
            *bufptr = '\0';
            if (tbytes == 10) {
                break;
            }
        }
        // Collect bytes
        else {
            //printf("%s : %d\n",buffer,tbytes);
            // Check overflow
            if (tbytes < 11) {
                tbytes += nbytes;
                bufptr += nbytes;
            }
            else
            {
                break;
            }
        }
    }

    //Copy ID to structure
    strncpy(rfids->last_id, buffer, 11);


    return 0;
}

int rfid_read(rfid_t *rfids)
{
    char buffer[32];
    char *bufptr;           // Current char in buffer
    int  nbytes, tbytes, n;    // Number of bytes read

    // Prepare select()
    struct timeval tv;
    tv.tv_sec = 0;
    tv.tv_usec = 200000;
    fd_set infds;
    FD_ZERO(&infds);
    FD_SET(rfids->sps->descriptor, &infds);

    struct timeval tv2;
    tv2.tv_sec = 0;
    tv2.tv_usec = 10000;
    fd_set infds2;
    FD_ZERO(&infds2);
    FD_SET(rfids->sps->descriptor, &infds2);

    // Read characters into buffer until we get a CR or NL
    bufptr = buffer;

    if((n = select(rfids->sps->descriptor + 1, &infds2, NULL, NULL, &tv2)) > 0)
    {
        //while((n = select(rfids->sps.descriptor + 1, &infds, NULL, NULL, &tv)) > 0)
        while ((nbytes = (int)read(rfids->sps->descriptor, bufptr, 1)) > 0)
        {
            //nbytes = (int)read(rfids->sps.descriptor, bufptr, 1);
            
            // Wait for start byte -> "NL"
            if(*bufptr == '\n') {
                tbytes = 0;
            }
            // If "CR" received then check if 10 bytes collected if yes -> finished
            else if(*bufptr == '\r') {
                *bufptr = '\0';
                if (tbytes == 10) {
                    strncpy(rfids->id, buffer, 11);
                    strncpy(rfids->last_id, buffer, 11);

                    // Flush input buffer
                    //printf("FLUSHED: %d\n", serialport_flush_input(rfids->sps));

                    return 0;
                }
            }
            // Collect bytes
            else {
                //printf("%s : %d\n",buffer,tbytes);
                // Check overflow
                if (tbytes < 11) {
                    tbytes += nbytes;
                    bufptr += nbytes;
                }
                else
                {
                    break;
                }
            }
        }
    }
    else
    {
        //Copy ID to structure
        strncpy(rfids->id, s_CONFIG_RFID_EMPTY_TAG, 11);
    }


    return 0;
}