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nasm例子

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nasm例子

assembly_nasm_example.asm

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section .data
	text db "Hello, world!",10

section .text
	global _start

_start:
	mov rax, 1
	mov rdi, 1
	mov rsi, text
	mov rdx, 14
	syscall

	mov rax, 60
	mov rdi, 0
	syscall

try_sasm_3.asm

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SECTION .data                           
    msg     db  'Hello World!', 0Ah     ; 换行Windows, dos用0Dh和0Ah; Unix和Linux舍去0Dh, 只用0Ah

SECTION .text                            
global  _main
_main:
    mov     ebp, esp; for correct debugging
    mov     eax, msg         
    call    strlen           
    
    mov     edx, eax         
    mov     ecx, msg         
    mov     ebx, 1           
    mov     eax, 4           ; SYS_WRITE  4
    int     80h              

    mov     ebx, 0           
    mov     eax, 1           ; SYS_EXIT  1
    int     80h              
    
    
strlen:                      
    push    ebx              ; find strlen of msg
    mov     ebx, eax         
    
nextchar:                    
    cmp     byte [eax], 0    ; \0
    jz      finished         ; finished
    inc     eax              
    jmp     nextchar         ; nextchar
    
finished:
    sub     eax, ebx         ; strlen: eax = eax - ebx
    pop     ebx              
    ret

try_sasm_4.asm

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;-------------------Hello World Program(include)--------------------
; nasm -f elf helloworld-inc.asm
; ld -m elf_i386 helloworld-inc.o -o helloworld-inc
; ./helloworld-inc
;-------------------------------------------------------------------

SECTION .data                            
    msg1    db  'Hello World!', 0Ah, 0h  ; 换行Windows, dos用0Dh和0Ah; Unix和Linux舍去0Dh, 只用0Ah
    msg2    db  'Hello NASM!', 0Ah, 0h   
    
SECTION .text                            
global  _main

_main:
    mov     eax, msg1           
    call    sprint              ; sprint

    mov     eax, msg2
    call    sprint

    call    quit                ; exit


;-------------------Hello World Program(include)--------------------
;-------------------------------------------------------------------


;------------------------------------------
; int slen(String message)
slen:
    push    ebx
    mov     ebx, eax

nextchar:
    cmp     byte [eax], 0
    jz      finished
    inc     eax
    jmp     nextchar

finished:
    sub     eax, ebx
    pop     ebx
    ret

;------------------------------------------
; void sprint(String message)
sprint:
    push    edx
    push    ecx
    push    ebx
    push    eax
    call    slen            ; slen

    mov     edx, eax
    pop     eax

    mov     ecx, eax
    mov     ebx, 1
    mov     eax, 4
    int     80h

    pop     ebx
    pop     ecx
    pop     edx
    ret

;------------------------------------------
; void exit()
quit:
    mov     ebx, 0
    mov     eax, 1
    int     80h
    ret

try_sasm_5

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section	.text
   global _main   ;must be declared for linker (ld)
	
_main:
   mov   ebp, esp ;for correct debugging ;tell linker entry point
   mov	edx, 9	;message length
   mov	ecx, stars;message to write
   mov	ebx, 1	;file descriptor (stdout)
   mov	eax, 4	;system call number (sys_write)
   int	0x80		;call kernel

   mov	eax, 1	;system call number (sys_exit)
   int	0x80		;call kernel

section	.data
stars   times 9 db '*'