nasm assembler input output

[sage1130]

I want to write an assembly language program for nasm assembler which will read an integer and print the same in linux.

The program should keep reading integers until a particular integer say 50 occurs.

When 50 occurs program should not print it and exit.

But I don't know how to input integer.

Can someone explain and give the complete asm program?

Thanks

Edited April 1, 2011 by rn113008

[sage1130]

Ok I found the answer

; Author : Gareth Adams

;uses :

;nasm -f elf 1a.asm

;1a.asm name of the asm file

;ld -s -o 1a 1a.o

SECTION .text

global _start

_start:

call readchar ; Read a character into char

cmp byte [char], 0ah ; Have we reached the end of the line?

je check42 ; If so, check if 42 was entered

mov eax, buf ; Point eax at the start of the buffer

add ax, word [count] ; Add the current number of characters to eax

mov bx, [char] ; Copy the character to the bx register

mov [eax], bl ; Put the character to the end of the buffer

inc word [count] ; Increment the count (number of characters)

jmp _start ; Loop through

check42:

mov ax, word [buf] ; We're assuming the number is two digits or less

cmp ax, 3234h ; Is it 42?

je end ; If so, end

call writeln ; If not, write out the character

mov word [count], 0 ; Reset the count

jmp _start ; Loop

end:

mov eax, 01h ; sys_end

mov ebx, 00h ; Error number

int 80h ; Make sys call

readchar:

mov eax, 03h ; sys_read

mov ebx, 00h ; stdin

mov ecx, char ; Where to put the input

mov edx, 01h ; How many characters to read?

int 80h

ret

writeln:

mov eax, 04h ; sys_write

mov ebx, 01h ; stdout

mov ecx, buf ; Where to read from

mov edx, 0 ; Clear edx

mov dx, word [count] ; Copy count into the lower part of edx

int 80h

mov eax, 04h ; sys_write

mov ebx, 01h ; stdout

mov ecx, cr ; Carriage return

mov edx, 01h ; One character

int 80h

ret

SECTION .data

char db 0

count dw 0

cr db 0ah

SECTION .bss

buf resb 255

I want to write an assembly language program for nasm assembler which will read an integer and print the same in linux.

The program should keep reading integers until a particular integer say 50 occurs.

When 50 occurs program should not print it and exit.

But I don't know how to input integer.

Can someone explain and give the complete asm program?

Thanks

1a.asm.zip