Lab2_DeanNguyen

# --------------------------
# Name: Dean Nguyen
# Assembly language program that follows Lab2
# --------------------------

.data
.text

# define a macro to move a 32 bit address to a register

.macro MOVIA reg, addr
  movhi \reg, %hi(\addr)
  ori \reg, \reg, %lo(\addr)
.endm

# define constants
.equ Switches, 0x11020 #find the base address of Switches in the system.h file
.equ Hex0, 0x11000 #find the base address of Hex0 in the system.h file
.equ Pushbuttons, 0x11010 #find the base address of Pushbuttons in the system.h file
.equ SW0_HI, 1

#remember
# r7 = load ssd constant
# r8 = bitwise and for switches
# r9 = bitwise and for pushbuttons

# define main program
.global main

main:
   movia r2, Switches #load r2 with switches address
   movia r3, Hex0 #load r3 with hex0 address
   movia r4, Pushbuttons #load r4 with pushbuttons address
   movia r5, SSDconstants #SSDconstants is address of SSDconstants
   movi r10, SW0_HI #load r10 with SW0_HI

loop:
   ldbio r7, 0(r5) #load SSD constant in r7
   stbio r7, 0(r3) #store r7 to r3
   andi r8, r2, 1 #bit mask SW0 (0000000#)
   andi r9, r4, 2 #bit mask KEY1 (00#0)
   beq r8, r0, decrement #goes to 'decrement' if sw0 is low
   beq r8, r10, increment #goes to 'increment' if sw0 is high

decrement:
   beq r9, r0, arraysDown #goes to 'arraysDown' if key1 is pressed (active high)

increment:
   beq r9, r0, arraysUp #goes to 'arraysUp' if key1 is pressed (active high)

arraysUp:
   addi r5, r5, 4 #increment array by 1
   br loop

arraysDown:
   subi r5, r5, 4 #decrement array by 1
   br loop

SSDconstants:
   .word 64, 121, 36, 48, 25, 18, 2, 120, 0, 24 #from zero to nine

SSDend:
   .end