text: #ifndef SIMPLEGPIO_HPP_
  #define SIMPLEGPIO_HPP_
  
   /****************************************************************
   * Constants
   ****************************************************************/
  
  #define SYSFS_GPIO_DIR "/sys/class/gpio"
  #define POLL_TIMEOUT (3 * 1000) /* 3 seconds */
  #define MAX_BUF 64
  
  enum PIN_DIRECTION{
  	INPUT_PIN=0,
  	OUTPUT_PIN=1
  };
  
  enum PIN_VALUE{
  	LOW=0,
  	HIGH=1
  };
  
  /****************************************************************
   * gpio_export
   ****************************************************************/
  int gpio_export(unsigned int gpio);
  int gpio_unexport(unsigned int gpio);
  int gpio_set_dir(unsigned int gpio, PIN_DIRECTION out_flag);
  int gpio_set_value(unsigned int gpio, PIN_VALUE value);
  int gpio_get_value(unsigned int gpio, unsigned int *value);
  int gpio_set_edge(unsigned int gpio, char *edge);
  int gpio_fd_open(unsigned int gpio);
  int gpio_fd_close(int fd);
  
  #endif /* SIMPLEGPIO_HPP_ */
  
  