#include "ns16550.h"

@ this module implements the elementary serial I/O operations

	.text
	.code	32
	.global	serial_out
serial_out:
	ldr	r1, =uart_base
	ldr	r2, [r1]
1:	ldrb	r3, [r2, #NS16550_LSR]
	tst	r3, #NS16550_LSR_THRE
	beq	1b
	strb	r0, [r2, #NS16550_THR]
	bx	lr

	.global	serial_in_poll
serial_in_poll:
	ldr	r1, =uart_base
	ldr	r2, [r1]
	ldrb	r3, [r2, #NS16550_LSR]
	tst	r3, #NS16550_LSR_DR
	mvneq	r0, #1
	bxeq	lr
	ldrb	r0, [r2, #NS16550_RBR]
	bx	lr