Ass2.asm

.eqv IN_ADRESS_HEXA_KEYBOARD 0xFFFF0012
 
.data
Message: .asciiz "Oh my god. Someone's presed a button.\n"
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# MAIN Procedure
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.text
main:
	#---------------------------------------------------------
	# Enable interrupts you expect
	#---------------------------------------------------------
	# Enable the interrupt of Keyboard matrix 4x4 of Digital Lab Sim
	li $t1, IN_ADRESS_HEXA_KEYBOARD
	li $t3, 0x80 # bit 7 of = 1 to enable interrupt
	sb $t3, 0($t1)
	#---------------------------------------------------------
	# No-end loop, main program, to demo the effective of interrupt
	#---------------------------------------------------------
Loop: 	nop
	nop
	b Loop # Wait for interrupt
end_main:
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# GENERAL INTERRUPT SERVED ROUTINE for all interrupts
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.ktext 0x80000180
	#--------------------------------------------------------
	# Processing
	#--------------------------------------------------------
IntSR: 	addi $v0, $zero, 4 # show message
	la $a0, Message
	syscall
	#--------------------------------------------------------
	# Evaluate the return address of main routine
	# epc <= epc + 4
	#--------------------------------------------------------
 
next_pc:mfc0 $at, $14 # $at <= Coproc0.$14 = Coproc0.epc
	addi $at, $at, 4 # $at = $at + 4 (next instruction)
	mtc0 $at, $14 # Coproc0.$14 = Coproc0.epc <= $at
return: eret # Return from exception