Question

lhere are two progang questions for yon ito do. Please submit two s oram les Tn tho Settings menu of SPIM set Bare Machine OFF, Allow Pseudo Instructions ON, Exception Handler ON, Delayed Branches ON, Delayed Loads ON and Mapped IO OFF 1. (5 points) Sum of Integers Write a program to calculate 1 +2+3++n and then print the sum out. n is entered by the user. So if the user enters 10, your program will calculate 1+2+3+ +10 which is equal to 55. The user dialog will look something like this: Console Enter a positive integer n: 10 The sum of of the first n integers is: 55

Answer 1

The key here is to use the formula for sum of n natural number,

$1+2+3+... + n = \frac{n(n+1)}{2}$

Below is a code which uses this formula:

.data

inputPrompt: .asciiz "Enter a positive integer n: "

resultStr: .asciiz "The sum of the first n integers is: "

.text

.globl main

main:

li $v0, 4 # syscall 4 (print_str)

la $a0, inputPrompt # argument: string

syscall # print the string

# System call for user input

li $v0, 5 # 5 is for read integer

syscall

# Copy this to temp 0 register

move $t0, $v0

# Create another copy in t1 with value $v0+1

addi $t1, $v0, 1

# n*(n+1)

mult    $t0, $t1            # $t0 * $t1 = Hi and Lo registers

mflo    $t2                 # copy Lo to $t2, thus result is in $t2

addi $t3, $0, 2    # Move 2 to $t3, for dividing n*(n+1)

div     $t2, $t3            # $t2 / $t3

mflo    $t2                 # $t2 = floor($t2 / $t3), result is in $t2

# Print out the output text

li $v0, 4 # 4 for printing string

la $a0, resultStr # Location of string to print in $a0

syscall

# Print out the result

li $v0, 1 # 1 for printing integer

move $a0, $t2 # Integer to print in $a0

syscall

jr $ra # return to caller

Screenshots:

Result: