C++内嵌彙編代碼(1)

#include <iostream>

using namespace std;

void Add()

{

int a, b, r;

cout << "please input two numbers" << endl;

cin>>a;

cin>>b;

cout << "input end" << endl;

int * c = & a;

__asm

{

//<将a, b 移入寄存器eax, ebx>

mov eax, c; // 将位址移入eax

mov eax, [eax]; // 将位址中的值移到eax

//mov r, eax; //将寄存器中的内容移到記憶體r中

mov ebx, b;//可以像這樣直接對ebx指派

lea eax, [eax + ebx];

mov r, eax;

//</将a, b 移入寄存器eax, ebx>

}

cout << a << " + "<< b << " = " << r << endl;

}

void AddOther()

{

int a, b, r;

cin>>a;

cin>>b;

__asm

{

//add a, b; //不正确的操作數類型

//add ->先移到寄存器中

mov eax, a;

mov ebx, b;

add eax, ebx;

mov r, eax;

}

cout << r << endl;

}

void Increase()

{

cout << "start increasing" << endl;

int a;

cin >> a;

__asm

{

inc a;

}

cout << a << endl;

cout << "end" << endl;

}

void Decrease()

{

cout << "start decreasing" << endl;

int a;

cin >> a;

__asm

{

dec a;

}

cout << a << endl;

cout << "end" << endl;

}

void Negtive()

{

cout << "negtive" << endl;

int a;

cin >> a;

__asm

{

neg a;

}

cout << a << endl;

}

void Subtract()

{

cout << "subtract" << endl;

int a, b;

cin >> a;

cin >> b;

_asm

{

mov eax, a;

mov ebx, b;

sub eax, ebx;

mov a, eax;

}

cout << a << endl;

}

void Multiply()

{

cout << "Multiply" << endl;

int a, b;

cin >> a;

cin >> b;

//mul a eax=eax*a, 結果儲存在eax中

_asm

{

mov eax, a;

mul b;

mov a, eax;

}

cout << a << endl;

}

void AddTwoNumbers(int* storehere, int number1, int number2)

{

_asm

{

mov eax,dword ptr [number1];

add eax,dword ptr [number2];

mov ecx,dword ptr [storehere];

mov dword ptr [ecx],eax;

}

}

void main( )

{

//Add();

//Increase();

//Decrease();

//Negtive();

//AddOther();

//Subtract();

//Multiply();

int a = 3;

int b = 5;

int r;

AddTwoNumbers(&r, a, b);

cout << r << endl;

system("pause");

}

shl 邏輯左移，右面補零

shl 寄存器(設數值為m)  移動位數n

則寄存器結果為2n m

#include <iostream>
int Power(int num, int power);

int main()
{
	std::cout << Power( 3, 8);
	system("pause");
	return 0;
}

int Power(int num, int power)
{
	//ECX為位寄存器,它的低位為CX，CX又可分為CH和CL
	__asm
	{
		MOV EAX, num ;
			MOV ECX, power //CL為CX的低bit
			SHL EAX, CL
	}
	// 結果儲存在EAX中
}