hex86/asm/cat64.asm

global _start

section	.data
_start:
	call	getchar
	cmp	rax,-1
	je	.done
	call	putchar
	jmp	_start
	
.done:
	mov	rdi,rax
	mov	rax,60
	syscall

getchar:
	mov	rax,0x00
	mov	rdi,0		;stdin fd
	lea	rsi,[rel buf]
	mov	rdx,1		;count
	syscall
	
	cmp	rax,1
	jne	.getchar_fail

	mov	rax,0
	mov	al,[rel buf]
	ret

.getchar_fail:
	mov	rax,-1
	ret

putchar:
	mov	[rel buf],al

	mov	rax,0x01
	mov	rdi,1		;stdout fd
	lea	rsi,[rel buf]
	mov	rdx,1
	syscall

	ret

buf:
	db	0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00