; UART0 registers

U0RBR	EQU	0xE000C000
U0THR	EQU	0xE000C000
U0IER	EQU	0xE000C004
U0IIR	EQU	0xE000C008
U0FCR	EQU	0xE000C008
U0LCR	EQU	0xE000C00C
U0LSR	EQU	0xE000C014
U0SCR	EQU	0xE000C01C
U0DLL	EQU	0xE000C000
U0DLM	EQU	0xE000C004
PINSEL0	EQU	0xE002C000

; User Initial Stack & Heap
        AREA    |.text|, CODE, READONLY

        EXPORT  __main
__main	BL	iuart0
loop	MOV	R0, #'H'
		BL	writec
		MOV	R0, #'e'
		BL	writec
		MOV	R0, #'l'
		BL	writec
		MOV	R0, #'l'
		BL	writec
		MOV	R0, #'o'
		BL	writec
		MOV	R0, #' '
		BL	writec
		MOV	R0, #'w'
		BL	writec
		MOV	R0, #'o'
		BL	writec
		MOV	R0, #'r'
		BL	writec
		MOV	R0, #'l'
		BL	writec
		MOV	R0, #'d'
		BL	writec
		MOV	R0, #'\n'
		BL	writec
		B	loop

iuart0	
	MOV	R1, #0x5   ; PINSEL0 = 0x5
	LDR	R0, =PINSEL0
	STR	R1, [R0]

	MOV	R1, #0x7	; U0FCR = 0x7
	LDR	R0, =U0FCR
	STRB	R1,[R0]
	
	MOV	R1, #0x83	; U0LCR = 0x83
	LDR	R0, =U0LCR
	STRB	R1,[R0]

	MOV	R1, #0x0f	; U0DLL = 0x0f
	LDR	R0, =U0DLL
	STRB	R1,[R0]

	MOV	R1, #0x00	; U0DLM = 0x0
	LDR	R0, =U0DLM
	STRB	R1,[R0]

	MOV	R1, #0x03	; U0LCR = 0x03
	LDR	R0, =U0LCR
	STRB	R1,[R0]
	BX	R14		; return from subroutine

writec	LDR	R1, =U0LSR
	LDRB	R1, [R1]
	TST	R1, #0x40
	BEQ	writec
	LDR	R1, =U0THR
	STRB	R0, [R1]
	BX	R14		; return from subroutine

    END