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64 lines
2.0 KiB
64 lines
2.0 KiB
5 years ago
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# Declare main as a global function
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.globl main
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# All program code is placed after the
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# .text assembler directive
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.text
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# The label 'main' represents the starting point
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main:
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la $a0, arr # $a0 based address of array
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li $a1, 1 # $a1 number to be found (checked) - change the value (7) to test
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li $a2, 6 # $a2 max array index to be checked - change the value (3) to test
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li $s0, 0 # set counter to 0
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jal lookup # hop to lookup function
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# print out result
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li $v0, 1 # print_int syscall code = 1
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move $a0, $s0 # load integer into $ao
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syscall
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j exit # exit out of program
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# lookup (int arr[], int num, int cnt).
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# arr[] = 5 2 1 4 6 3
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# 1. lookup (arr, 5, 3) -> 0 (the index of ‘5’ in the array)
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# 2. lookup (arr, 1, 3) -> 2 (the index of ‘1’ in the array)
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# 3. lookup (arr, 7, 6) -> -1 (‘7’ is not found in the array)
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# 4. lookup (arr, 4, 3) -> -1 (the last parameter indicates to check only first 3 values in the
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lookup:
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addi $t0, $a2, 1 # store one higher value
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# loop to find index
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beq $s0, $t0, setoob # jump to oob function if we overrun array
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# find current array value
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addi $t1, $s0, 0 # load index into $t1
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sll $t1, $t1, 2 # multiply the offset
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add $t1, $t1, $a0 # add the offset to the base address
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lw $t2, 0($t1) # get current array value: aka arr[$s0]
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beq $a1, $t2, setval # check if this is the value we are looking for
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addi $s0, $s0, 1 # incriment counter
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j lookup # back to beginning of loop
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# set value function
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setval:
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jr $ra
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# set out of bounds function
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setoob:
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li $s0, -1 # index is oob, set to -1
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jr $ra # jump back to ra in main
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exit:
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# All memory structures are placed after the
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# .data assembler directive
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.data
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arr: .word 5, 2, 1, 4, 6, 3 # change array to test
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#arr: .word 5, 2, 1, 4, 6, 3 # change array to test
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str_found: .asciiz "found"
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str_not_found: .asciiz "not_found"
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nl: .asciiz "\n"
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