计算机系统基础-汇编指令学习

1.1 传送指令

push %ebp
mov %esp,%ebp
and $0xfffffff0,%esp //边界对齐指令，16字节对齐
sub $0x20,%esp
movl $0xa,0x10(%esp) //立即数10赋值给偏移量为0x10的基址寄存器esp
movl $0x9,0x14(%esp) //立即数9赋值
mov 0x10(%esp),%eax
mov %eax,0x18(%esp) //立即数10赋值给0x18(%esp)
mov 0x14(%esp),%eax
mov %eax,0x1c(%esp) //立即数9赋值给0x1c(%esp)
mov 0x1c(%esp),%eax
mov %eax,0x8(%esp) //立即数9赋值给0x8(%esp)
mov 0x18(%esp),%eax
mov %eax,0x4(%esp) //立即数10赋值给0x4(%esp)
movl $0x0,(%esp)
call 41 <main+0x41>
leave
ret

参考代码：

#include"stdio.h"

int main(){

int a,b,c,d;

a=10,b=9;

printf("评测结果：成功\n评测脚本：C\n返回结果：");//此行不在汇编代码中

//**********Begin**********

c=a;

d=b;

//**********End**********

printf("%d,%d\n",c,d);

}

1.2 传送指令

mov %esp,%ebp
and $0xfffffff0,%esp
sub $0x20,%esp
movl $0xa,0x18(%esp) //立即数10赋值给偏移量为0x18的基址寄存器esp
mov 0x18(%esp),%eax
mov %eax,0x1c(%esp)
mov 0x1c(%esp),%eax
mov %eax,0x8(%esp) //立即数10赋值给``0x8(%esp)
mov 0x18(%esp),%eax
mov %eax,0x4(%esp)
movl $0x0,(%esp)
call 31 <main+0x31>
leave
ret

参考代码：

#include"stdio.h"

int main(){

int a=10;

int b;

printf("评测结果：成功\n评测脚本：C\n返回结果：");//此行不在汇编代码中

//**********Begin********

b=a;

printf("%d,%d\n",a,b);

//**********End**********

}

2.1 加减运算指令

push %ebp
mov %esp,%ebp
and $0xfffffff0,%esp
sub $0x20,%esp movl
movl $0x6,0x10(%esp) //立即数6赋值给偏移量为0x10的基址寄存器esp
movl $0x64,0x14(%esp) //16进制立即数为100
mov 0x14(%esp),%eax
mov 0x10(%esp),%edx
sub %eax,%edx //将edx-eax的值赋值给edx
mov %edx,%eax
mov %eax,0x18(%esp) //将edx的值赋值给c
mov 0x14(%esp),%eax
mov 0x10(%esp),%edx
add %edx,%eax //将eax+edx的值赋值给edx
mov %eax,0x1c(%esp)
mov 0x1c(%esp),%eax
mov %eax,0x8(%esp) //将eax的值赋值给c
mov 0x18(%esp),%eax
mov %eax,0x4(%esp)
movl $0x0,(%esp)
call 4f <main+0x4f>
leave
ret

参考代码：

#include"stdio.h"

int main(){

int a,b,c,d;

a=6,b=100;

printf("评测结果：成功\n评测脚本：C\n返回结果：");//此行不在汇编代码中

//**********Begin**********

c=a-b;

d=a+b;

//**********End**********

printf("%d,%d\n",c,d);

}

3.1 整数的乘法指令

push %ebp
mov %esp,%ebp
and $0xfffffff0,%esp
sub $0x20,%esp
movl $0x3,0x10(%esp) //立即数3赋值给偏移量为0x10的基址寄存器esp
mov 0x10(%esp),%eax
sub $0x1,%eax //将eax的值-1赋给eax
imul 0x10(%esp),%eax //将eax与0x10(%esp)内的值相乘赋给eax
mov %eax,0x14(%esp) //赋值给b
mov 0x10(%esp),%eax
imul 0x14(%esp),%eax //将c与0x10(%esp)内的值相乘赋给eax
mov %eax,0x18(%esp) //赋给c
mov 0x18(%esp),%eax
add $0x2,%eax //d+2的值赋给eax
imul 0x10(%esp),%eax //eax与0x10(%esp)内的值相乘赋给eax
mov %eax,0x1c(%esp) //赋给d
mov 0x1c(%esp),%eax
mov %eax,0x8(%esp)//赋给d
mov 0x18(%esp),%eax
mov %eax,0x4(%esp)
movl $0x0,(%esp)
call 56 <main+0x56>
leave
ret

参考代码：

#include"stdio.h"

int main(){

int a,b,c,d;

a=3;

printf("评测结果：成功\n评测脚本：C\n返回结果：");//此行不在汇编代码中

//**********Begin**********

b=a*(a-1);

c=a*b;

d=a*(c+2);

//**********End**********

printf("%d,%d\n",c,d);

}

4.1 控制转移指令

00000000 <sum>:
0: 55 push %ebp
1: 89 e5 mov %esp,%ebp
3: 83 ec 10 sub $0x10,%esp //分配十字节空间
6: c7 45 fc 00 00 00 00 movl $0x0,-0x4(%ebp) //s =0
d: c7 45 f8 00 00 00 00 movl $0x0,-0x8(%ebp) //i =0
14: eb 18 jmp 2e <sum+0x2e>
16: 8b 45 f8 mov -0x8(%ebp),%eax //
19: 8d 14 85 00 00 00 00 lea 0x0(,%eax,4),%edx //a[i]的值赋给edx
20: 8b 45 08 mov 0x8(%ebp),%eax //
23: 01 d0 add %edx,%eax
25: 8b 00 mov (%eax),%eax
27: 01 45 fc add %eax,-0x4(%ebp) //s的值+a[i]赋给s
2a: 83 45 f8 01 addl $0x1,-0x8(%ebp) //i的值+1赋给i
2e: 8b 45 f8 mov -0x8(%ebp),%eax //i的值赋给eax
31: 3b 45 0c cmp 0xc(%ebp),%eax //比较i跟n的值；
34: 7c e0 jl 16 <sum+0x16>
36: 8b 45 fc mov -0x4(%ebp),%eax
39: c9 leave
3a: c3 ret

参考代码：

#include"stdio.h"

int sum(int a\[\],int n){

//**********Begin**********

int s = 0;

for (int i = 0;i<n; i++) {

s += a $i$ ;

}

return s;

//**********End**********

}