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C:/temp/src/j2k/QNX4/SerialPort.hpp

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#ifndef __J2K__SerialPort_HPP__
#define __J2K__SerialPort_HPP__

// Maybe optimize the cost of sift down the array
// if too much inefficient...
// By using a wrap up array.

// If clocked enough fast, then the array shouldn't grow
// higher than 3 or 4 task at a time.

// Modem Delay from 50 to 250 ms...
#define MODEM_DELAY  100

// We can stack up to 30 task in the list
// 30 x 50 ms = 1500 ms delay needed to empty the task list !
// Which means more than 30 mouse clicks in 1.5 second !
 
#define MAX_SERIAL_TASK 30

struct SerialTask_t {
  int cmd;
  int id;
  int valid;
};

class SerialPort {
public:
  // Default Constructor
  SerialPort() {
    // Elan-104 on QNX-2 COM1
    modem = open( "//2/dev/ser1", O_RDWR );
    Task  = new SerialTask_t[ MAX_SERIAL_TASK ];

    for( int i = 0; i < MAX_SERIAL_TASK; i++ ) {
      Task[i].cmd   = 0;
      Task[i].id    = 0;
      Task[i].valid = 0;
    }

    bottom  = 0;
    Waiting = 0;

    curr.cmd   = 0;
    curr.id    = 0;
    curr.valid = 0;

    TrainCmd( 96, -1 );   // Activate Serial Controller
  }

  // Destructor
  virtual ~SerialPort() {
    delete [] Task;
    TrainCmd( 97, -1 );   // Deactivate Serial Controller
  }

  void TrainCmd( int cmd, int id ) {
    buf[0] = cmd;

    if ( id > 0 ) {
      buf[1] = id;
      write( modem, &buf, 2 );    // Send TrainID
    } else {
      write( modem, &buf, 1 );    // Don't Send TrainID
    }

    Waiting = 1;
    delay( MODEM_DELAY );

    Waiting = 0;
  }

  void AddTask( int cmd, int id ) {
    if ( Waiting == 0 ) {
      TrainCmd( cmd, id );
    } else if ( bottom >= MAX_SERIAL_TASK ) {
      printf("\n*** Error: Reach the end of the array  ***  ");
      printf("\n***        Can't Add more Serial Task ! ***\n"); 
      return;        
    } else {
      ++bottom;
      Task[ bottom ].cmd   = cmd;
      Task[ bottom ].id    = id;
      Task[ bottom ].valid = 1;
    }
  }

  void ExecuteTask() {
    if ( bottom < 1 ) return;
    if ( Task[0].valid == 0 ) return;

    curr.cmd = Task[0].cmd;
    curr.id  = Task[0].id;

    for( int k = 0; k < bottom; k++ ) {
      Task[k].cmd   = Task[k+1].cmd;
      Task[k].id    = Task[k+1].id;
      Task[k].valid = Task[k+1].valid;
    }

    Task[bottom].cmd   = 0;
    Task[bottom].id    = 0;
    Task[botton].valid = 0;

    bottom--;

    curr.valid = 0;
    TrainCmd( curr.cmd, curr.id );
  }

private:
  int  modem;     // Modem File Descriptor
  char buf[3];    // Modem Output String Buffer

  SerialTask_t* Task;
  SerialTask_t  curr;
  int bottom;
  int Waiting;
};

#endif

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