Question

In assembler code must be a gcd.s file

So I here is the C code I have written originally for the program. My question is how do I convert it to assembly code?

// C code below

#include

//this function swaps given integers

void swap(int*a,int*b)

{

    int temp=*a;

    *a=*b;

    *b=temp;

}

//this function returns gcd of a and b

int gcd(int a,int b)

{

    if(a

    swap(&a,&b);

    int r=a%b;

    if(r==0)

    return b;

    return gcd(b,r);

}

int main()

{

    int first,second;

    printf("Enter first positive integer: ");

    scanf("%d",&first);

    printf("Enter second positive integer: ");

    scanf("%d",&second);

    printf("The GCD is %d",gcd(first,second));

}

Original instructions

The Euclidean algorithm is a way to find the greatest common divisor of two positive integers, a and b. First let me show the computations for a=210 and b=45.

Divide 210 by 45, and get the result 4 with remainder 30, so 210=4·45+30.

Divide 45 by 30, and get the result 1 with remainder 15, so 45=1·30+15.

Divide 30 by 15, and get the result 2 with remainder 0, so 30=2·15+0.

The greatest common divisor of 210 and 45 is 15.

Formal description of the Euclidean algorithm

Input Two positive integers, a and b.

Output The greatest common divisor, g, of a and b.

Internal computation

1. If a<b, exchange a and b.

2. Divide a by b and get the remainder, r. If r=0, report b as the GCD of a and b.

3. Replace a by b and replace b by r. Return to the previous step.

Your assignment is to write an assembler code (gcd.s) that asks the user two positive numbers and calculates their greatest common denominator.

For example, you program should produce the following outputs:

Enter first positive integer: 6

Enter second positive integer: 8

The GCD is 2

Answer 1

""

First make sure we got gcc compiler in your system then save your file has filename.c,

Now go to the command prompt and enter gcc -S filename.c then press enter

then a file named filename.s will be created in the same folder where your c file is

""

   .file   "help.c"
   .text
   .globl   swap
   .def   swap;   .scl   2;   .type   32;   .endef
   .seh_proc   swap
swap:
   pushq   %rbp
   .seh_pushreg   %rbp
   movq   %rsp, %rbp
   .seh_setframe   %rbp, 0
   subq   $16, %rsp
   .seh_stackalloc   16
   .seh_endprologue
   movq   %rcx, 16(%rbp)
   movq   %rdx, 24(%rbp)
   movl   $0, -4(%rbp)
   movq   16(%rbp), %rax
   movl   (%rax), %eax
   movl   %eax, -4(%rbp)
   movq   24(%rbp), %rax
   movl   (%rax), %edx
   movq   16(%rbp), %rax
   movl   %edx, (%rax)
   movq   24(%rbp), %rax
   movl   -4(%rbp), %edx
   movl   %edx, (%rax)
   nop
   addq   $16, %rsp
   popq   %rbp
   ret
   .seh_endproc
   .globl   gcd
   .def   gcd;   .scl   2;   .type   32;   .endef
   .seh_proc   gcd
gcd:
   pushq   %rbp
   .seh_pushreg   %rbp
   movq   %rsp, %rbp
   .seh_setframe   %rbp, 0
   subq   $48, %rsp
   .seh_stackalloc   48
   .seh_endprologue
   movl   %ecx, 16(%rbp)
   movl   %edx, 24(%rbp)
   movl   $0, -4(%rbp)
   movl   16(%rbp), %edx
   movl   24(%rbp), %eax
   cmpl   %eax, %edx
   jle   .L3
   leaq   24(%rbp), %rax
   movq   %rax, %rdx
   leaq   16(%rbp), %rcx
   call   swap
.L3:
   movl   16(%rbp), %eax
   movl   24(%rbp), %ecx
   cltd
   idivl   %ecx
   movl   %edx, -4(%rbp)
   cmpl   $0, -4(%rbp)
   jne   .L4
   movl   24(%rbp), %eax
   jmp   .L5
.L4:
   movl   24(%rbp), %eax
   movl   -4(%rbp), %edx
   movl   %eax, %ecx
   call   gcd
.L5:
   addq   $48, %rsp
   popq   %rbp
   ret
   .seh_endproc
   .def   __main;   .scl   2;   .type   32;   .endef
   .section .rdata,"dr"
   .align 8
.LC0:
   .ascii "Enter first positive integer: \0"
.LC1:
   .ascii "%d\0"
   .align 8
.LC2:
   .ascii "Enter second positive integer: \0"
.LC3:
   .ascii "The GCD is %d\0"
   .text
   .globl   main
   .def   main;   .scl   2;   .type   32;   .endef
   .seh_proc   main
main:
   pushq   %rbp
   .seh_pushreg   %rbp
   movq   %rsp, %rbp
   .seh_setframe   %rbp, 0
   subq   $48, %rsp
   .seh_stackalloc   48
   .seh_endprologue
   call   __main
   movl   $0, -4(%rbp)
   movl   $0, -8(%rbp)
   leaq   .LC0(%rip), %rcx
   call   printf
   leaq   -4(%rbp), %rax
   movq   %rax, %rdx
   leaq   .LC1(%rip), %rcx
   call   scanf
   leaq   .LC2(%rip), %rcx
   call   printf
   leaq   -8(%rbp), %rax
   movq   %rax, %rdx
   leaq   .LC1(%rip), %rcx
   call   scanf
   movl   -8(%rbp), %edx
   movl   -4(%rbp), %eax
   movl   %eax, %ecx
   call   gcd
   movl   %eax, %edx
   leaq   .LC3(%rip), %rcx
   call   printf
   movl   $0, %eax
   addq   $48, %rsp
   popq   %rbp
   ret
   .seh_endproc
   .ident   "GCC: (tdm64-1) 5.1.0"
   .def   printf;   .scl   2;   .type   32;   .endef
   .def   scanf;   .scl   2;   .type   32;   .endef

--->happy coding