snow.cpp

#include <unistd.h>
#include <string.h>
#include <stdio.h>
#include <fcntl.h>
 

class LinuxFile
{
private:
   int m_Handle;
 
public:
    LinuxFile(const char *pFile, int flags = O_RDWR)
    {
        m_Handle = open(pFile, flags);
    }
 
    ~LinuxFile()
    {
       if (m_Handle != -1)
            close(m_Handle);
    }
 
    size_t Write(const void *pBuffer, size_t size)
    {
        return write(m_Handle, pBuffer, size);
    }
 
    size_t Read(void *pBuffer, size_t size)
    {
        return read(m_Handle, pBuffer, size);
    }
 
    size_t Write(const char *pText)
    {
        return Write(pText, strlen(pText));
    }
 
    size_t Write(int number)
    {
        char szNum[32];
        snprintf(szNum, sizeof(szNum), "%d", number);
        return Write(szNum);
    }
};
 
class LinuxGPIOExporter
{
protected:
   int m_Number;
 
public:
    LinuxGPIOExporter(int number)
        : m_Number(number)
    {
        LinuxFile("/sys/class/gpio/export", O_WRONLY).Write(number);
    }
 
    ~LinuxGPIOExporter()
    {
        LinuxFile("/sys/class/gpio/unexport", O_WRONLY).Write(m_Number);
    }
};
 
class LinuxGPIO : public LinuxGPIOExporter
{
public:
    LinuxGPIO(int number)
        : LinuxGPIOExporter(number)
    {
    }
 
   void SetValue(bool value)
    {
        char szFN[128];
        snprintf(szFN, sizeof(szFN), "/sys/class/gpio/gpio%d/value", m_Number);
        LinuxFile(szFN).Write(value ? "1" : "0");
    }
 
   void SetDirection(bool isOutput)
    {
       char szFN[128];
        snprintf(szFN, sizeof(szFN), 
           "/sys/class/gpio/gpio%d/direction", m_Number);
        LinuxFile(szFN).Write(isOutput ? "out" : "in");
    }
};


class Led { 
  public:
    void snowled()
    {
      LinuxGPIO gpio23(23);
      gpio23.SetDirection(true);
      bool on = true;
      
      for (;;)
      {
          printf("Switchingg %s the LED...\n", on ? "on" : "off");
          gpio23.SetValue(on);
          on = !on;
          sleep(1);
          
      }
    }
};





extern "C" {
    Led* Led_new(){ return new Led(); }
    void Led_snowled(Led* led){ led->snowled(); }
}