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Linux assembler syntax
Assembly language programming under DOS / Windows, these are the Intel style assembly code. But in the Unix and Linux systems, greater use of format or AT & T, the two have very different styles for Intel, we configure our environment on syntax
Installation NASM
$ sudo apt-get install nasm
New hello.asm file
; Hello.asm
sectionTop .data; data segment declaration
msg db "Hello, world!" , 0xA; to the output string
len equ $ - msg; wordlength
section .text; declaration code segment
Global _start; designated entry function
_start :; string displayed on the screen
mov edx, len; three parameters: string length
mov ecx, msg; two parameters: the string to display
mov ebx, 1; a parameter: the file descriptor (stdout)
mov eax, 4; system call number (SYS_WRITE)
int 0x80; call the kernel function
; exit the program
mov ebx, 0; one parameter: the exit code
mov eax, 1; system call number (sys_exit)
int 0x80; calls the kernel function
Compile
NASM uses a parser written manually, so execution speed much faster than GAS, more importantly, it uses the Intel assembler syntax can be used to compile assembler with Intel syntax written
nasm -f elf64 hello.asm # 32位改成 elf32 产生hello.o
link
The assembler generates object code is not run directly on the computer, it must be processed to generate executable code linker.
ld -s -o hello hello.o
run
./hello #屏幕上打印出 "Hello,world"
