Question

PLEASE USE VERY BASIC REGISTERS AND CODE TO DO THE FOLLOWING

Objectives:

-write assembly language programs to:
            -define a recursive procedure/function and call it.
            -use syscall operations to display integers and strings on the console window
            -use syscall operations to read integers from the keyboard.

Assignment Description:

Implement a MIPS assembly language program that defines "main", and "function1" procedures.

The function1 is recursive and should be defined as:

function1(n) = (2*n)+9                      if n <= 5

             = function1(n-2) + n*function1(n-3) - 2*n    otherwise.

The main asks a user to enter an integer for n and calls the function1 by passing the n value, then prints the result. If your program causes an infinite loop, press Control and 'C' keys at the same time to stop it.  Name your source code file assignment7.s.

C program that will ask a user to enter an integer, calls the fuction1, and prints the returned value from the function1.

// The function1 is a recursive procedure/function defined by:
// function1(n) = (2*n)+9 if n <= 5
//              =  function1(n-2) + n*function1(n-3) - 2*n  otherwise.

int function1(int n)
{
    if (n <= 5)
     {
        int ans1 = (2*n)+9;
        return ans1;
    }
    else
     {
        int ans1 = function1(n-2) + n*function1(n-3) - 2*n;
        return ans1;
     }
}

// The main calls function1 by entering an integer given by a user.
void main()
{
    int ans, n;

    printf("Enter an integer:\n");

    // read an integer from user and store it in "n"
    scanf("%d", &n);

    ans = function1(n);

    // print out the solution computed by function 1
    printf("The solution is: %d\n", ans);

    return;
}

The following is a sample output (user input is in bold):

Enter an integer:
8
The solution is: 231

Answer 1

ANSWER:

.data

            #declare the strings

            prompt1: .asciiz "Enter an integer: "

            message1: .asciiz "The solution is: "

            next_line: .asciiz " "

.text

#############################################

# Procedure main

# Description: The main calls function1 by entering an integer given by a user.

# parameters:

# return value: $v0

# registers to be used: $a0, $v0, and $v1

#############################################

main:

            #Print "Enter an integer: "

            la $a0, prompt1

            li $v0, 4

            syscall

            #read the integer input from the user

            #$v0 = user input

            li $v0, 5

            syscall

            #move the input value to $a0

            move $a0, $v0

            #Adjust sp/ store ra

            addi $sp, $sp, -4

            sw $ra, 0($sp)

            #call the function

            #jump and link function1 and $a0 is passed as parameter

            jal function1

            #Adjust sp/ load ra  

            lw $ra, 0($sp)

            addi $sp, $sp, 4

            #save return value from function1

            move $v1, $v0

            #Print "The solution is:"

            la $a0, message1

            li $v0, 4

            syscall

            #print the results

            move $a0, $v1

            li $v0, 1

            syscall

            #print new line

            la $a0, next_line

            li $v0, 4

            syscall

            #end program

            li $v0, 10

            syscall

################################################

# Procedure function1

# Description: The function1 is a recursive procedure defined by:

#                                                          function1(n) = (3*n)-5 if n <= 3

#                                               = (n-1)*function1(n-1) + function1(n-2) - n otherwise.

# parameters: $a0

# return value: $v0

# registers to be used:$v1,$s1,$t0,$t4,$v1,$zero

################################################

function1:

            #Save $ra, $a0, $s1, and $v1 on the stack

            addi $sp, $sp, -16

            sw $ra, 0($sp)

            sw $a0, 4($sp)

            sw $v1, 8($sp)

            sw $s1, 12($sp)

            #check if $a0 <4.If yes, then return 3*n-5

            #otherwise go to else

            slti $t0, $a0, 4

            beq $t0, $zero, else

            mul $a0,$a0,3#find 3*n

            sub $a0,$a0,5#find 3*n-5

            move $v0, $a0 #return 3*n-5

            #jump to return label

            j return

else:

            #store the input value(n) in $v1

            move $v1, $a0

            #find ($a0 - 1)

            sub $a0, $a0, 1

            jal function1 #int function1($a0 - 1)                 

            sub $s2, $v1,1 #$s2= n-1

            mul $s1,$s2,$v0#$s1=(n-1) * function1 ($a0 - 1)

            #find ($a0 - 2)

            sub $a0, $a0, 1

            #int function1 ($a0 - 2)

            jal function1

            #$t4 = function1 ($a0 - 2)-n

            sub $t4,$v0,$v1

            #$v0=(n-1) * function1 ($a0 - 1)+function1 ($a0 - 2)-n

            add $v0, $s1,$t4

return:

            #load the $ra, $a0, $s1, and $v1 from the stack

            lw $s1, 12 ($sp)

            lw $v1, 8 ($sp)

            lw $a0, 4 ($sp)

            lw $ra, 0 ($sp)

            addi $sp, $sp, 16

            #return to main function

            jr $ra

Sample output:

Mars Messages Run iO Enter an integer: The solution is: 7842 program is finished running Enter an integer: The solution is: 35 program is finished running Enter an integer: The solution is: 9 program is finished running Enter an integer: The solution is: -2 program is finished running Enter an integer: Clear he solution is: 63823 - program is finished running