#	;; echo.s

#	should be a replacement for /bin/echo ... ;-)
#

#include <asm/unistd_64.h>	


	.file	"echo.s"

	.data
_separator:
	.string " "
_eoln:
	.string "\n"

	.text
	.globl echo

#  	first argument goes into %rdi  == 1, stdout
#	second argument goes into %rsi == pointer to str1 
#       third argument goes into %rdx  == number of bytes in str1
	
	
echo:
	xor	%r10,%r10	# we'll use %r10 for our "zero" register
	
	pop	%r8		# this is argc...
	pop 	%rsi		# remove command
	dec	%r8
	jz	_finish		# check for no args left in argv

_around:
	pop	%rsi		# this is the next *argv --- could test here since you are through when this a NULL pointer!

	mov	(%rsi),%r9b     # check to see if this just an empty string (so we don't do a separator)
	cmp	%r9b,%r10b
	jz	_shortcut	# if that's just a zero byte at the beginning, skip it...
	
	mov	$1,%rdi
	call	writestr

	mov	$1,%rdi
	lea	_separator,%rsi
	call	writestr

_shortcut:	
	dec	%r8
	jnz	_around

_finish:
	mov	$1,%rdi
	lea	_eoln,%rsi
	call	writestr
	
	mov	$0, %rdi	# and exit with a zero status
	mov	$__NR_exit, %rax	# syscall = 60 is exit
	syscall