CSCI-4350/prj1.asm

# Declare main as a global function
.globl main 

# All program code is placed after the
# .text assembler directive
.text 		

# The label 'main' represents the starting point
main:
	la $a0, arr	         # $a0 based address of array
	li $a1, 1	           # $a1 number to be found (checked) - change the value (7) to test
	li $a2, 6	           # $a2 max array index to be checked - change the value (3) to test
  li $s0, 0            # set counter to 0
  jal lookup           # hop to lookup function
  # print out result
  li $v0, 1     # print_int syscall code = 1
  move $a0, $s0 # load integer into $ao
  syscall
  j exit               # exit out of program

# lookup (int arr[], int num, int cnt).
# arr[] = 5 2 1 4 6 3
# 1. lookup (arr, 5, 3) -> 0 (the index of ‘5’ in the array)
# 2. lookup (arr, 1, 3) -> 2 (the index of ‘1’ in the array)
# 3. lookup (arr, 7, 6) -> -1 (‘7’ is not found in the array)
# 4. lookup (arr, 4, 3) -> -1 (the last parameter indicates to check only first 3 values in the
lookup:
  addi $t0, $a2, 1     # store one higher value

  # loop to find index
  beq $s0, $t0, setoob # jump to oob function if we overrun array

  # find current array value
  addi $t1, $s0, 0     # load index into $t1
  sll $t1, $t1, 2      # multiply the offset
  add $t1, $t1, $a0    # add the offset to the base address
  lw $t2, 0($t1)       # get current array value: aka arr[$s0]

  beq $a1, $t2, setval # check if this is the value we are looking for
  addi $s0, $s0, 1     # incriment counter
  j lookup             # back to beginning of loop

# set value function
setval:
  jr $ra

# set out of bounds function
setoob:
  li $s0, -1 # index is oob, set to -1
  jr $ra     # jump back to ra in main

exit:



# All memory structures are placed after the
# .data assembler directive
.data
arr:		.word 5, 2, 1, 4, 6, 3		# change array to test
#arr:		.word 5, 2, 1, 4, 6, 3		# change array to test
str_found:	.asciiz	"found"
str_not_found:	.asciiz	"not_found"
nl: .asciiz "\n"