Question

A.7 [5] Using SPIM, write and test a program that reads in three integers and prints out the sum of the largest two of the three. Use the SPIM system calls described on pages A-43 and A-45. You can break ties arbitrarily.

Short answer

The required code:

.data

Str1: .asciiz

Str2: .asciiz

Str3: .asciiz

.text

main:

la $t0, X lw $s0, 0($t0) addi $t1, $0, 0 li $t1, 0

li $a0,0

loop: bge $t0, 8 End_Loop bgt X($t1), $s0, Set_Max_number bgt X($t2), $s1, Set_Max_number addi $t1, $t1, 4 addi $t0, $t0, 1Set_Max_number: move $s0, X($t1) move $s1, X($t2) j loopEnd_Loop: li $v0, 1 addi $s2, $s0, $s1 li $v0,1

syscall

Step-by-step solution

Define the concept.

• The MIPS instruction “la” is used for loading the address.
• The MIPS instruction “li” is used for loading immediately.
• The “branch-on-equal (beq)” is a decision-making instruction in MIPS assembly language. The purpose of using this MIPS assembly instruction “beq reg1, reg2 Label” is going to the statement “Label” if the value of “reg1” is equal to the “reg2”.
• One of the MIPS instructions is “add $t3 $t4 $t5” for add where $t3 = $t4 + $t5.
• One of the MIPS instruction is “addi $t3 $t4 1” “$t4” is the source register, “$t3” is the destination register, and “1” is the immediate value. The purpose of using it for add immediately
• One of the MIPS instructions “bgt Rsrc1, Src2, label” is used for Branching on greater than the conditional branch to the instruction at the mentioned- statement “label” if the register “Rsrc1” contents are greater than the register “Src2” content.

And another kind of the MIPS instruction “bge Rsrc1, Src2, label” is used for Branching on greater than the equal conditional branch to the instruction at the mentioned- statement “label” if the register “Rsrc1” contents are greater than the register “Src2” content.

Determine the calculation.

The required code:

.data //this is the data section

Str1: .asciiz "Please enter a number:"

Str2: .asciiz "Please enter a number:"

Str3: .asciiz "Please enter a number:"

Str4: .asciiz "The Sum :"

.text

main:

la $t0, X

lw $s0, 0($t0) //for initialize the first value in array into Max

addi $t1, $0, 0 //Sets the counter to 0

li $t1, 0 //Index for the array of the three user given numbers

li $a0,0 //sum = 0

loop:

bge $t0, 8 End_Loop

bgt X($t1), $s0, Set_Max_number

bgt X($t2), $s1, Set_Max_number

addi $t1, $t1, 4 //Increases the index for the array of given three numbers

addi $t0, $t0, 1 // the counter is increamented

Set_Max_number:

move $s0, X($t1) // set the first greatest number among three numbers

move $s1, X($t2) // set the second greatest number among three numbers

j loop

End_Loop:

li $v0, 1 addi $s2, $s0, $s1 //add the two greatest number

li $v0,1 //print the sum of the two greatest number

syscall

The output of the program:

Please enter a number: 2

Please enter a number: 5

Please enter a number:3

The Sum :8