#	;; ls.s
#

#
#

#include <asm/unistd_32.h>

	.file	"ls.s"

	.data
argc:
	.long	0
argv:
	.long	0	# location of the current argument

fd:
	.long	0
	
dirname:
	.string "/usr/lib"
open_flags:
	.quad	00200000
#	.quad	O_DIRECTORY | O_RDONLY
eoln:
	.string "\n"
separator:
	.string " "

	.align	4
direntries:
	.space	4096,0

bytes_received:
	.long	0

	.text
	.global	ls

ls:
	# walk through arglist, see if you can open files...
	
	nop
	pop     argc 		
	pop	%eax

	dec	argc
	jz	_finish

_nextarg:
	pop	%ebx		# load directory name into %rdi
	mov	open_flags,%ecx
	mov	$__NR_open,%eax
	int	$0x80

	cmp	$0,%eax
	jl	_next

	# save the file descriptor in fd (%r15)
	mov	%eax,fd
	lea	direntries,%r14
	# clear %r8 - %r9
#	xor	%r8,%r8		# going to use this to walk direntries
	xor	%rsi,%rsi
#	xor	%r9,%r9		# going to calculate offset to next dirent
	xor	%rdi,%rdi
#	xor	%r10,%r10	# going to use save how many bytes did we receive from getdents

_read_entries:
	mov 	fd,%ebx		# recover file descriptor from %r15
	lea	direntries,%ecx	# point %rsi at direntries
	mov	$4096,%edx
	mov	$__NR_getdents,%eax
	int	$0x80

	cmp	$0,%eax
	jle	_finish

	mov	%eax,bytes_received
	call	_process_entries

	# close the file descriptor...
	mov	%r15,%rdi
	mov	$__NR_close,%rax
	int	$0x80

_next:	
	dec	%r13
	jnz	_nextarg

_finish:	
	mov	$0,%rdi	# and exit with a zero status
	mov	$__NR_exit,%rax	# syscall = 60 is exit
	int	$0x80

#
#  process_entries
#
#
#	we have been handed a block of entries in 'direntries'
#
#       step through each one, and call appropriate handler for
#	each individual one...
#

_process_entries:
	lea	direntries,%rsi	# %rsi has the current dirent
_around:	
	call	_entry_raw
	# is there a next?
	mov	16(%rsi),%rdiw	# okay, %rdiw has distance to next
	add	%rdi,%rsi

	mov	%rsi,%r12	# check to see if we have processed all bytes...
	sub	%r14,%r12	# %r14 should have value of direntries
	cmp	%r10,%r12
	jl	_around

	ret
	
#
#   entry_raw
#	
#	this is the most basic handler --> all that it does is send an
#	entry out to stdout
#

_entry_raw:
	mov	$1,%ebx
	lea	18(%rsi),%ecx
	call	writestr
	mov	$1,%ebx
	lea	eoln,%ecx
	call	writestr
	ret