clab/c/ex1.c

#include <stdio.h>


/**
 * This file aims to help understanding calling conventions made by gcc
 * Arch: x86_64
 *
 * The conclusions here are only valid for gcc compilers
 */

/***
 * Calling convention intel x86
 * movl eax, 0
 *
 * Calling convention arm arch64
 * empty preamble
 */
int f00()
{
	return 7;
}

void fl(char* str){
	printf("%s",str);
}

/***
 * Calling convention intel x86
 * movl eax, 0
 *
 * Calling convention arm arch64
 * empty preamble
 */
char f01()
{
	return 0;
}

/**
 * Calling convention intel x86
 * movl edi, a -> f1(edi)
 *
 * Calling convention arm arch64
 *
 * subtract 16 bytes in the stack for arguments
 * fetch from sp -12 (12=-16+4)
 *
 */

int f1(int a)
{
	return a + 1;
}



/**
 * Calling convention intel x86
 * movl edi, a -> f1(edi)
 *
 * Calling convention arm arch64
 *
 * subtract 16 bytes in the stack for arguments
 * fetch from sp -8 (12=-16+8)
 *
 */
long f1l(long a)
{
	return a+1;
}

/**
 * Calling convention
 * movl esi, b
 * movl edi, a
 * f(edi,esi)
 */
int f2(int a, int b)
{
	return a + b;
}

/**
 * Calling convention
 * movl    	edx, c
 * movl    	esi, b
 * movl		edi, a
 */
int f3(int a, int b, int c)
{
	return a + b - c;
}

/**
 * Calling convention
 *
 * movl		ecx, d
 * movl    	edx, c
 * movl    	esi, b
 * movl		edi, a
 */
int f4(int a, int b, int c, int d)
{
	return (a + b) - (c + d);
}

/**
 * Calling convention
 *
 * movl		r8d, e
 * movl		ecx, d
 * movl    	edx, c
 * movl    	esi, b
 * movl		edi, a
 */
int f5(int a, int b, int c, int d, int e)
{
	return (a + b) - (c + d) + e;
}

/**
 * Calling convention
 *
 * movl		r9d, f
 * movl		r8d, e
 * movl		ecx, d
 * movl    	edx, c
 * movl    	esi, b
 * movl		edi, a
 */
int f6(int a, int b, int c, int d, int e, int f)
{
	int sum1 = a + b + c;
	int sum2 = d + e + f;
	int mult = sum1 * sum2;
	return mult;
}

/**
 * Calling convention
 *
 * push		h
 * movl		r9d, f
 * movl		r8d, e
 * movl		ecx, d
 * movl    	edx, c
 * movl    	esi, b
 * movl		edi, a
 *
 * Note: After the call we will have
 * addq		rsp 8 --> Revert the push into stack operation of size long
 */
int f7(int a, int b, int c, int d, int e, int f, int h)
{
	return a + b - c + d - e + f - h;
}

/**
 * Calling convention
 *
 * push		j
 * push		h
 * movl		r9d, f
 * movl		r8d, e
 * movl		ecx, d
 * movl    	edx, c
 * movl    	esi, b
 * movl		edi, a
 *
 * Note: After the call we have
 * addq		rsp 16 --> Revert the two push into stack operations (by size long)
 */
int f8(int a, int b, int c, int d, int e, int f, int h, int j)
{
	return a + b + c - d - e - f - h + j;
}

long fl0(long int a)
{
	return a * a;
}

int main()
{
	fl("Hello Master");
	f00();
	f01();
	f1(1);
	f1l(1);
	f2(1, 2);
	f3(1, 2, 3);
	f4(1, 2, 3, 4);
	f5(1, 2, 3, 4, 5);
	f6(1, 2, 3, 4, 5, 6);
	f7(1, 2, 3, 4, 5, 6, 7);
	f8(1, 2, 3, 4, 5, 6, 7, 8);

	fl0(10L);
	return 0;
}