use warnings;
use strict;

use Config;
my $ccflags .= $Config{ccflags} . " -l wiringPi";
use Inline ('C' => 'END', ccflags => $ccflags);
#use Inline 'C';

my $dht_pin = 4;
my $err_pin = 1;
my $temp_limit = 65.0;
my $warn_pin = 6;

my $ret = read_temp($dht_pin, $err_pin, $temp_limit, $warn_pin);

print "$ret\n";

cleanup($dht_pin, $err_pin, $warn_pin);

__END__
__C__

#include <wiringPi.h>
#include "dht11.h"
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>

#define MAXTIMINGS	85

float read_temp(int dhtPin, int tempErrPin, float tempErrLimit, int tempWarnPin)
{
    int dht11_dat[5] = { 0, 0, 0, 0, 0 };

	uint8_t laststate	= HIGH;
	uint8_t counter		= 0;
	uint8_t j		= 0, i;
	float	f; /* fahrenheit */

	dht11_dat[0] = dht11_dat[1] = dht11_dat[2] = dht11_dat[3] = dht11_dat[4] = 0;
	
    /* pull pin down for 18 milliseconds */
	pinMode(dhtPin, OUTPUT);
	digitalWrite(dhtPin, LOW );
	delay( 18 );
	/* then pull it up for 40 microseconds */
	digitalWrite(dhtPin, HIGH );
	delayMicroseconds( 40 );
	/* prepare to read the pin */
	pinMode(dhtPin, INPUT );

	/* detect change and read data */
	for ( i = 0; i < MAXTIMINGS; i++ )
	{
		counter = 0;
		while ( digitalRead( dhtPin ) == laststate )
		{
			counter++;
			delayMicroseconds( 1 );
			if ( counter == 255 )
			{
				break;
			}
		}
		laststate = digitalRead( dhtPin );

		if ( counter == 255 )
			break;

		/* ignore first 3 transitions */
		if ( (i >= 4) && (i % 2 == 0) )
		{
			/* shove each bit into the storage bytes */
			dht11_dat[j / 8] <<= 1;
			if ( counter > 16 )
				dht11_dat[j / 8] |= 1;
			j++;
		}
	}

	/*
	 * check we read 40 bits (8bit x 5 ) + verify checksum in the last byte
	 * print it out if data is good
	 */
	if ( (j >= 40) &&
	     (dht11_dat[4] == ( (dht11_dat[0] + dht11_dat[1] + dht11_dat[2] + dht11_dat[3]) & 0xFF) ) )
	{
		f = dht11_dat[2] * 9. / 5. + 32;

        // debugging
        // printf("f: %.1f: warn: %.1f\n", f, tempErrLimit);
        // printf("warnPin: %d\n", tempWarnPin);

        int warn = 0;

        if (tempErrPin > -1)
        {
            pinMode(tempErrPin, OUTPUT);

            if (f > tempErrLimit)
            {
                warn = 1;
                digitalWrite(tempErrPin, HIGH);

                if (tempWarnPin > -1)
                {
                    pinMode(tempWarnPin, OUTPUT);
                    digitalWrite(tempWarnPin, HIGH);
                }
            } 
            else
            {
                digitalWrite(tempErrPin, LOW);
            }
        }
    
		/*
         * printf( "Humidity = %d.%d %% Temperature = %d.%d *C (%.1f *F)\n",
	     * dht11_dat[0], dht11_dat[1], dht11_dat[2], dht11_dat[3], f );
         */

        if (warn > 0)
        {
            return f;
        }
        else
        {
            return 0.0;
        }
	}
}

int cleanup(int dhtPin, int tempErrPin, int tempWarnPin)
{
    digitalWrite(dhtPin, LOW);
    pinMode(dhtPin, INPUT);

    digitalWrite(tempErrPin, LOW);
    pinMode(tempErrPin, INPUT);

    digitalWrite(tempWarnPin, LOW);
    pinMode(tempWarnPin, INPUT);

	return(0);
}