将下面的代码保存为asm.s文件:
.section .data
data_items: #These are the data items
.long 3,67,34,222,45,75,54,34,44,33,22,11,66,0
.section .text
.globl _start
_start:
movl $0, %edi # move 0 into the index register
movl data_items(,%edi,4), %eax # load the first byte of data
movl %eax, %ebx # since this is the first item, %eax is
# the biggest
start_loop: # start loop
cmpl $0, %eax # check to see if we've hit the end
je loop_exit
incl %edi # load next value
movl data_items(,%edi,4), %eax
cmpl %ebx, %eax # compare values
jle start_loop # jump to loop beginning if the new
# one isn't bigger
movl %eax, %ebx # move the value as the largest
jmp start_loop # jump to loop beginning
loop_exit:
# %ebx is the status code for the _exit system call
# and it already has the maximum number
movl $1, %eax #1 is the _exit() syscall
int $0x80
在Linux终端中编译这段代码:
$as asm.s -o asm.o //编译这段汇编代码
$ld asm.o -o asm //链接编译代码为可执行程序
$ ./asm //执行程序
如何在Linux查看自己写的程序的汇编代码?
有两种方法:
1、gcc -S temp.c 这样会生成temp.s的汇编文件
2、$ gcc temp.c -g
$ objdump -dS a.out