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Visual Studio C++ Assembly Hybrid Programming

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Visual Studio C++ Assembly Hybrid Programming

Experimental requirements

Write a subroutine in assembly language that implements the GCD recursive formula, with no requirements on the form of the inlet and outlet parameters, but with C functions to get inputs, call the assembly recursive subroutine, and display in C the results returned by the subroutine.

Visual Studio 2020 Download

Check the C++ desktop development option when downloading.

Environment Configuration

optionFile->New->Project Language SelectionC++ Selectionempty program 。

Modify the environment configuration tox86。

New in the project respond in singing Or add these two files to the project.

Right-click on the item and selectGenerate dependencies - > Generate customizationsCheck the boxmasm Options.

right click file, selectcausality。

Exclusion from generation optionclogged。

Item type optionMicrosoft Macro Assembler。

The following error occurs when compiling and running.

scanf‘: This function or variable may be using scanf_s instead

Answers to related questionsLink

This can be done in the.cpp The header of the file is added to the#define _CRT_SECURE_NO_WARNINGS 。

Code

cpp file

#define _CRT_SECURE_NO_WARNINGS
#include <>

// Declare the external assembly function
extern "C" int GCD(int a, int b); // Declare an external assembly function.

int main() {
    int a, b, result.

    // Get user input
    printf("Please enter two integers to compute their greatest common divisor: "); scanf("%d %d", &a, &b); // Get user input.
    scanf("%d %d", &a, &b);

    // Call the assembly function
    result = GCD(a, b);

    // Output the result
    printf("The greatest common divisor of the numbers %d and %d is: %d\n", a, b, result);

    return 0; }
}

asm file

.model flat, c
.code
public GCD ; Declares a function public and can be called externally.

GCD proc
    mov eax, [esp+4] ; get first parameter a (at esp+4)
    mov ebx, [esp+8] ; get second argument b (at esp+8)

gcd_loop.
    cmp ebx, 0 ; if b == 0, go to end of loop
    je gcd_done
    xor edx, edx ; clear edx to avoid interference in remainder calculation
    div ebx ; eax = eax / ebx, remainder to edx
    mov eax, ebx ; a = b
    mov ebx, edx ; b = a % b
    jmp gcd_loop

gcd_done.
    ret ; Return result is stored in eax
GCD endp

endp
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