# -----------------------------------
# INITALIZATION PROCEDURE
# -----------------------------------

cli

# Initialize interrupt handlers.  
# IRQ0 is the data input line. IRQ1 is the button press.
lir inputhandler1
xor $at, $at
or $at, $ir
lir 1
shl $at, $ir
lir i0
sw $at, $ir

# Initialize IRQ1.
lir inputhandler2
xor $at, $at
or $at, $ir
lir 1
shl $at, $ir
lir i1
sw $at, $ir

# Jump to wait state.
lir wait
j $ir



# -----------------------------------
# DATA INPUT INTERRUPT HANDLER
# -----------------------------------
inputhandler1:
# Disable interrupts in this interrupt handler.
cli

# Load data from input port zero into $a0.
lir pi0
xor $a0, $a0
lw $a0, $ir

#Shifts the data in the display register over 4.
lir po0
lw $t1, $ir
shl $t1, 4
or $t1, $a0
lw $t1, $ir

# Load the starting number into $a1.
lir startN

# Pseudoinstruction expansion of "lw $a1, startN"
xor $at,$at
or $at,$ir
lir 1
lw $a1, $at

# Display the input number on the output port.
lir po0
sw $a0, $ir

# Go back to wait state.
lir wait
j $ir


# -----------------------------------
# BUTTON PRESS INTERRUPT HANDLER
# -----------------------------------
inputhandler2:
# Clear interrupts in this interrupt handler.
cli
# Go to main procedure.
lir main
j $ir