PEP 8 Assembly Language Programming Write a program to calculate the sum of the

Question

PEP 8 Assembly Language Programming

Write a program to calculate the sum of the first n integers.

Main should input an integer and then call RecSum, which is a recursive function.

Add trace tags.

The code for sum is:

if (n==0) return 0;

else return n+ RecSum(n-1);

You should test it with several different inputs. You can use the formula to check whether you are getting the correct answer.

The formula is Sum(n) = n* (n+1)/2

Note: you are not coding the formula - you need to code the recursive method.

recSum1:

BR main
num: .equate 0 ;local variable #2d
n: .equate 0;parameter #2d
retVal: .equate 2 ;#2d
main: subsp 2,i ; allocate #num
deci num, s
lda num,s
subsp 4,i ;;allocate #retVal #n
sta num,s

;call RecSum
addsp 2,i ;deallocate #n
deco 0,s ; output answer;
addsp 4,i ;deallocate #retVal #num
stop
.end

Rec Sum 2:

BR main
num: .equate 0 ;local variable #2d
n: .equate 2;parameter #2d
retVal: .equate 4 ;#2d
RecSum: lda 2,s
cpa 0,i
brgt else

br done
else: lda 1,i
done: sta retVal,s
ret0
main: subsp 2,i ; allocate #num
deci num, s
lda num,s
subsp 4,i ;;allocate #retVal #n
sta num,s

call RecSum
addsp 2,i ;deallocate #n
deco 0,s ; output answer;
addsp 4,i ;deallocate #retVal #num
stop
.end

Explanation / Answer

CODE:

.LFB0:
        .cfi_startproc
        pushq        %rbp
        .cfi_def_cfa_offset 16
        .cfi_offset 6, -16
        movq        %rsp, %rbp
        .cfi_def_cfa_register 6
        subq        $16, %rsp
        movq        %fs:40, %rax
        movq        %rax, -8(%rbp)
        xorl        %eax, %eax
        movl        $.LC0, %edi
        movl        $0, %eax
        call        printf
        leaq        -12(%rbp), %rax
        movq        %rax, %rsi
        movl        $.LC1, %edi
        movl        $0, %eax
        call        __isoc99_scanf
        movl        -12(%rbp), %eax
        movl        %eax, %edi
        call        addNumbers
        movl        %eax, %esi
        movl        $.LC2, %edi
        movl        $0, %eax
        call        printf
        movl        $0, %eax
        movq        -8(%rbp), %rdx
        xorq        %fs:40, %rdx
        je        .L3
        call        __stack_chk_fail
.L3:
        leave
        .cfi_def_cfa 7, 8
        ret
        .cfi_endproc
.LFE0:
        .size        main, .-main
        .globl        addNumbers
        .type        addNumbers, @function
addNumbers:
.LFB1:
        .cfi_startproc
        pushq        %rbp
        .cfi_def_cfa_offset 16
        .cfi_offset 6, -16
        movq        %rsp, %rbp
        .cfi_def_cfa_register 6
        subq        $16, %rsp
        movl        %edi, -4(%rbp)
        cmpl        $0, -4(%rbp)
        je        .L5
        movl        -4(%rbp), %eax
        subl        $1, %eax
        movl        %eax, %edi
        call        addNumbers
        movl        %eax, %edx
        movl        -4(%rbp), %eax
        addl        %edx, %eax
        jmp        .L6
.L5:
        movl        -4(%rbp), %eax

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