hex86/asm/cat.asm

global _start

section	.data
getchar:
	mov	eax,0x03
	mov	ebx,0		;stdin fd
	mov	ecx,buf
	mov	edx,1		;count
	int	0x80
	
	cmp	eax,1
	jne	.getchar_fail
	
	mov	eax,[buf]
	ret

.getchar_fail:
	mov	eax,-1
	ret

putchar:
	mov	[buf],eax

	mov	eax,0x04
	mov	ebx,1		;stdout fd
	mov	ecx,buf
	mov	edx,1
	int	0x80

	ret

_start:
	call	getchar
	cmp	eax,-1
	je	.done
	call	putchar
	jmp	_start
	
.done:
	mov	ebx,eax
	mov	eax,0x01
	int	0x80

buf:
	db	0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff