;; ito.asm Input to Output
;; version 0.0.2a
;;
;; Copyright 2016 Kevin G. Austin
;;
;; Licensed under the Apache License, Version 2.0 (the "License");
;; you may not use this file except in compliance with the License.
;; You may obtain a copy of the License at
;; 
;;     http://www.apache.org/licenses/LICENSE-2.0
;; 
;; Unless required by applicable law or agreed to in writing, software
;; distributed under the License is distributed on an "AS IS" BASIS,
;; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
;; See the License for the specific language governing permissions and
;; limitations under the License.
;;
;; to build :
;; For 32 bit Linux systems
;; nasm -f elf ito.asm && ld -s ito.o -o ito
;; For 64 bit Linux systems
;; nasm -f elf64 ito.asm && ld -s ito.o -o ito
;;
;; Uncomment the next line for 32 bit systems
;; BITS 32
;; Uncomment the next line for 64 bit systems
;; BITS 64


section .bss
		charbufr:	resb	1		; reserve 1 byte buffer

section .text

		global _start

_start:		

;; Loop once for each char of output.

charloop:

		mov	eax, 3				; syscall 3 = read
		mov	bl, 0				; 0 = stdin
		mov	ecx, charbufr			; pointer to char buffer
		mov	dl, 1				; read 1 char
		int	0x80				; syscall
		or	eax, eax			; test return
		jle	short done			; <= 0 means done

		mov	eax, 4				; syscall 4 = write
		mov	bl, 1				; 1 = stdout
		mov	ecx, charbufr			; pointer to char buffer
		mov	dl, 1				; write 1 char
		int	0x80				; syscall
		or	eax, eax			; test return
		jg	short charloop			; > 0 means success so loop

done:
		xor	eax, eax			; clear eax
		inc	eax				; set syscall to exit (= 1)
		int	0x80				; syscall