thermometer/thermometer.cpp

This example shows a fictional thermometer.

The Makefile for this sample is the following:

CXX = g++

# We enable the c++0x flag, plus we define the NDS3_DLL preprocessor macro.
CXXFLAGS = -std=c++0x -Wall -Wextra -pedantic -fPIC -pthread -DNDS3_DLL

# Flags passed to gcc during linking
LINK = -shared -fPIC -Wl,-as-needed

# Name of our device library
TARGET = libthermometer.so
 
# We specify that we depend on NDS3
LIBS = -lnds3
 
# We assume that all the .cpp files are in the src folder
SRCS = thermometer.cpp

OBJS = $(SRCS:.cpp=.o)
# Rules for building
$(TARGET): $(OBJS)
    $(CXX) $(LINK) -o $@ $^ $(LIBS)

.PHONY: clean
clean:
    $(RM) $(TARGET) $(OBJS)

The code shows a simple delegate function that is called each time the control system wants to read the temperature.

#include <nds3/nds.h>
#include <iostream>

// This class declares our device in the contructor and supplies the functionalities to support it
class Thermometer
{
private:
    nds::PVDelegateIn<double> m_thermometerPiniPV;

public:

    // Constructor. Here we setup the device structure
    Thermometer(nds::Factory &factory,
                const std::string &deviceName,
                const nds::namedParameters_t &parameters) :
    m_thermometerPiniPV(nds::PVDelegateIn<double>("TemperaturePINI", std::bind(&Thermometer::getTempRandom, 
                                                                             this, 
                                                                             std::placeholders::_1, 
                                                                             std::placeholders::_2)))
    {
        nds::Port rootNode(deviceName);
        rootNode.addChild(nds::PVDelegateIn<double>("Temperature", std::bind(&Thermometer::getTemperature, 
                                                                             this, 
                                                                             std::placeholders::_1, 
                                                                             std::placeholders::_2)));

    m_thermometerPiniPV.processAtInit(1);
    rootNode.addChild(m_thermometerPiniPV);

        rootNode.initialize(this, factory);
    }

    void getTemperature(timespec* pTimestamp, double* pValue)
    {
        *pValue = 10; // It is always cold in here
    std::cout << "Temperature #1: " << *pValue << std::endl;
    }

    void getTempRandom(timespec* pTimestamp, double* pValue)
    {
        *pValue = 35; // It is always hot right there
    std::cout << "Temperature #2 (pini): " << *pValue << std::endl;
    }
};

// If we want to load our device support dynamically then we have to compile it
//  as a dynamic module and we have to provide the functions to allocate it,
//  deallocate it and retrieve its name
NDS_DEFINE_DRIVER(Thermometer, Thermometer)