$COMPACT ROM WORD16

rom_io: DO;


DECLARE
	TOKEN			LITERALLY	'SELECTOR',
	WORD_16			LITERALLY	'WORD',
	WORD_32			LITERALLY	'DWORD',

	FALSE			LITERALLY	'00H',

	/*
	 *	Declare constants for serial channel 1.
	 */
	BASE_PORT		LITERALLY	'03F8H',
	RBR				LITERALLY	'0',	/* Receive Buffer register */
	THR				LITERALLY	'0',	/* Transmitter Holding register */
	IER				LITERALLY	'1',	/* Interrupt Enable register */
	LCR				LITERALLY	'3',	/* Line Control register */
	MCR				LITERALLY	'4',	/* Modem Control register */
	LSR				LITERALLY	'5',	/* Line Status register */
	MSR				LITERALLY	'6',	/* Modem Status register */
	DLL				LITERALLY	'0',	/* Divisor Latch Low */
	DLM				LITERALLY	'1',	/* Divisor Latch High */

	/* IER values */

	NO_INTS_ON		LITERALLY	'0',

	/* LCR values */
	
	EIGHT_BIT		LITERALLY	'3',
	DLAB			LITERALLY	'80H',	/* Divisor Latch Enable */

	/* Encoding for 9600 baud */

	BAUD_CODE_LSB	LITERALLY	'12',
	BAUD_CODE_MSB	LITERALLY	'00';



$eject


rq$A$physical$attach$device: PROCEDURE(	dev_name_p,
										file_driver,
										response_mailbox,
										exception_p) 		PUBLIC;

DECLARE
	dev_name_p			POINTER,
	file_driver			BYTE,
	response_mailbox	TOKEN,
	exception_p			POINTER,

	char				BYTE;


	/* 
	 *	Program the baud rate count.
	 */
	OUTPUT(BASE_PORT + LCR)	= DLAB;			/* Select divisor latch */
	CALL TIME(10);

	OUTPUT(BASE_PORT + DLM)	= BAUD_CODE_MSB;
	CALL TIME(10);

	OUTPUT(BASE_PORT + DLL)	= BAUD_CODE_LSB;
	CALL TIME(10);
	
	/* 
	 *	Program the USART characteristics.
	 */
	OUTPUT(BASE_PORT + LCR)	= EIGHT_BIT;	/* 8-bit no parity */
	CALL TIME(10);

	OUTPUT(BASE_PORT + IER)	= NO_INTS_ON;	/* Disable all ints */
	CALL TIME(10);

	OUTPUT(BASE_PORT + MCR) = 0;			/* Reset modem signals */
	CALL TIME(10);

	/* 
	 *	Clear all interrupt sources. 
	 */
	char = INPUT(BASE_PORT + MSR);			/* Modem status */
	CALL TIME(10);

	char = INPUT(BASE_PORT + LSR);			/* Line status */
	CALL TIME(10);

	char = INPUT(BASE_PORT + RBR);			/* Purge Rx buffer */
	CALL TIME(10);

	char = INPUT(BASE_PORT + LCR);			/* Check Line Ctrl Reg */


END rq$A$physical$attach$device;


$eject


rq$A$write: PROCEDURE(	connection_t,
						buffer_p,
						buffer_size,
						response_mailbox,
						exception_p)		PUBLIC;

DECLARE
	connection_t		TOKEN,
	buffer_p			POINTER,
	buffer_size			WORD_32,
	response_mailbox	TOKEN,
	exception_p			POINTER,

	buffer				BASED buffer_p	(1) BYTE,

	index				WORD_32;



	DO index = 0 TO buffer_size - 1;

		/* 
		 * Wait until Tx buffer is ready, then output character.
		 */
		DO WHILE (INPUT(BASE_PORT + LSR) AND 20H) <> 20H;
		END;

		OUTPUT(BASE_PORT + THR)	= buffer(index);

	END;

END rq$A$write;

END rom_io;