//
// Data Slicer Demo, mycal labs, http://www.mycal.net

/***************************************************************************

COM Port Documentation
1st  2nd  3rd  4th  Offs. DLAB  Register
-----------------------------------------------------------------------------
3F8h 2F8h 3E8h 2E8h  +0     0   RBR  Receive Buffer Register (read only) or
                                THR  Transmitter Holding Register (write only)
3F9h 2F9h 3E9h 2E9h  +1     0   IER  Interrupt Enable Register
3F8h 2F8h 3E8h 2E8h  +0     1   DL   Divisor Latch (LSB)  These registers can
3F9h 2F9h 3E9h 2E9h  +1     1   DL   Divisor Latch (MSB)  be accessed as word
3FAh 2FAh 3EAh 2EAh  +2     x   IIR  Interrupt Identification Register (r/o) or
                                FCR  FIFO Control Register (w/o, 16550+ only)
3FBh 2FBh 3EBh 2EBh  +3     x   LCR  Line Control Register
3FCh 2FCh 3ECh 2ECh  +4     x   MCR  Modem Control Register
3FDh 2FDh 3EDh 2EDh  +5     x   LSR  Line Status Register
3FEh 2FEh 3EEh 2EEh  +6     x   MSR  Modem Status Register
3FFh 2FFh 3EFh 2EFh  +7     x   SCR  Scratch Register (16450+ and some 8250s,
                                     special use with some boards)

           80h      40h      20h      10h      08h      04h      02h      01h
Register  Bit 7    Bit 6    Bit 5    Bit 4    Bit 3    Bit 2    Bit 1    Bit 0
-------------------------------------------------------------------------------
IER         0        0        0        0      EDSSI    ELSI     ETBEI    ERBFI
IIR (r/o) FIFO en  FIFO en    0        0      IID2     IID1     IID0    pending
FCR (w/o)  - RX trigger -     0        0      DMA sel  XFres    RFres   enable
LCR       DLAB     SBR    stick par  even sel Par en  stopbits  - word length -
MCR         0        0       AFE     Loop     OUT2     OUT1     RTS     DTR
LSR       FIFOerr  TEMT     THRE     Break    FE       PE       OE      RBF
MSR       DCD      RI       DSR      CTS      DDCD     TERI     DDSR    DCTS

****************************************************************************/

#include <stdio.h>
#include "io_ports.h"

int
main ()
{

  //
  // Lets use COM1 in this example.
  //
  int base = COM1;

  //
  // Turn data slicer interface on.
  //
  open_io ();

  out_byte (base + MCR, 0x01);	// Set DTR 1 DSR 0 to power up interface

  //
  // Loop forever, polling the DSR to read the input state of the
  //  Data Slicer,  Press ctrl-break to exit loop.
  //
  while (1)
    {

      //
      // Read in MSR and check to see if CTS is lit
      //
      if (in_byte (base + MSR) & 0x10)
	printf ("1\n");
      else
	printf ("0\n");
    }
}