csu3_am335x/EVSE/GPL/mosquitto-2.0.13/examples/temperature_conversion/temperature_conversion.cpp

#include <cstdio>
#include <cstring>

#include "temperature_conversion.h"
#include <mosquittopp.h>

mqtt_tempconv::mqtt_tempconv(const char *id, const char *host, int port) : mosquittopp(id)
{
	int keepalive = 60;

	/* Connect immediately. This could also be done by calling
	 * mqtt_tempconv->connect(). */
	connect(host, port, keepalive);
};

mqtt_tempconv::~mqtt_tempconv()
{
}

void mqtt_tempconv::on_connect(int rc)
{
	printf("Connected with code %d.\n", rc);
	if(rc == 0){
		/* Only attempt to subscribe on a successful connect. */
		subscribe(NULL, "temperature/celsius");
	}
}

void mqtt_tempconv::on_message(const struct mosquitto_message *message)
{
	double temp_celsius, temp_fahrenheit;
	char buf[51];

	if(!strcmp(message->topic, "temperature/celsius")){
		memset(buf, 0, 51*sizeof(char));
		/* Copy N-1 bytes to ensure always 0 terminated. */
		memcpy(buf, message->payload, 50*sizeof(char));
		temp_celsius = atof(buf);
		temp_fahrenheit = temp_celsius*9.0/5.0 + 32.0;
		snprintf(buf, 50, "%f", temp_fahrenheit);
		publish(NULL, "temperature/fahrenheit", strlen(buf), buf);
	}
}

void mqtt_tempconv::on_subscribe(int mid, int qos_count, const int *granted_qos)
{
	printf("Subscription succeeded.\n");
}