hex2a.he

#
# HEX2 for Linux-i386-ELF
#
# Copyright (C) 2001, Edmund GRIMLEY EVANS <edmundo@rano.org>
#

# Elf32_Ehdr
  7f 45 4c 46 01 01 01	# e_ident
  00 00 00 00 00 00 00 00 00
  02 00			# e_type
  03 00			# e_machine
  01 00 00 00		# e_version
  25 82 04 08	#!	# e_entry = 0x08048000 + len(ehdr) + len(phdr)
  34 00 00 00		# e_phoff = len(ehdr)
  00 00 00 00		# e_shoff
  00 00 00 00		# e_flags
  34 00			# e_ehsize = len(ehdr)
  20 00			# e_phentsize = len(phdr)
  01 00			# e_phnum
  00 00			# e_shentsize
  00 00			# e_shnum
  00 00			# e_shstrndx

# Elf32_Phdr
  01 00 00 00		# p_type
  00 00 00 00		# p_offset
  00 80 04 08		# p_vaddr = 0x08048000
  00 80 04 08		# p_paddr = 0x08048000
  44 02 00 00	#!	# p_filesz = len(ehdr) + len(phdr) + len(prog)
  44 02 00 00	#!	# p_memsz = len(ehdr) + len(phdr) + len(prog)
  07 00 00 00		# p_flags
  00 10 00 00		# p_align

# A stackless implementation of exit(42), for debugging:
# 31 c0 40 b3 2a cd 80

# pos: # 0x08048054
	00 00 00 00
# label: # 0x08048058
	00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
	00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
	00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
	00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
	00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
	00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
	00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
	00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
	00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
	00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
	00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
	00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
	00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
	00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
	00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
	00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
	00 00 00

# getchar:
	6a 00			# push	$0x0
	31 db			# xor	%ebx,%ebx
	89 e1			# mov	%esp,%ecx
	89 da			# mov	%ebx,%edx
	42			# inc	%edx
	b8 03 00 00 00		# mov	$0x3,%eax
	cd 80			# int	$0x80
	85 c0			# test	%eax,%eax
	74 02			# je	exit
	58			# pop	%eax
	c3			# ret

# exit:
	31 c0			# xor	%eax,%eax
	89 c3			# mov	%eax,%ebx
	40			# inc	%eax
	cd 80			# int	$0x80

# gethex:
	e8 de ff ff ff		# call	getchar
	83 f8 20		# cmp	$0x20,%eax
	7e f6			# jle	gethex
	83 f8 23		# cmp	$0x23,%eax
	75 0c			# jne	.l1

# .loop:
	e8 cf ff ff ff		# call	getchar
	83 f8 0a		# cmp	$0xa,%eax
	75 f6			# jne	.loop
	eb e5			# jmp	gethex

# .l1:
	83 f8 2e		# cmp	$0x2e,%eax
	75 19			# jne	.l2
	e8 be ff ff ff		# call	getchar
	25 ff 00 00 00		# and	$0xff,%eax
	05 58 80 04 08		# add	label,%eax
	8b 1d 54 80 04 08	# mov	pos,%ebx
	89 18			# mov	%ebx,(%eax)
	eb c7			# jmp	gethex

# .l2:
	83 f8 30		# cmp	$0x30,%eax
	7c 09			# jl	.l3
	83 f8 3a		# cmp	$0x3a,%eax
	7d 04			# jge	.l3
	83 e8 30		# sub	$0x30,%eax
	c3			# ret

# .l3:
	83 f8 61		# cmp	$0x61,%eax
	7c 09			# jl	.l4
	83 f8 67		# cmp	$0x67,%eax
	7d 04			# jge	.l4
	83 e8 57		# sub	$0x57,%eax
	c3			# ret

# .l4:
	25 ff 00 00 00		# and	$0xff,%eax
	05 58 80 04 08		# add	label,%eax
	8b 18			# mov	(%eax),%ebx
	a1 54 80 04 08		# mov	pos,%eax
	83 c0 04		# add	$0x4,%eax
	a3 54 80 04 08		# mov	%eax,pos
	29 c3			# sub	%eax,%ebx
	89 d8			# mov	%ebx,%eax
	50			# push	%eax
	e8 24 00 00 00		# call	putchar
	58			# pop	%eax
	c1 f8 08		# sar	$0x8,%eax
	50			# push	%eax
	e8 1a 00 00 00		# call	putchar
	58			# pop	%eax
	c1 f8 10		# sar	$0x10,%eax
	50			# push	%eax
	e8 10 00 00 00		# call	putchar
	58			# pop	%eax
	c1 f8 18		# sar	$0x18,%eax
	50			# push	%eax
	e8 06 00 00 00		# call	putchar
	58			# pop	%eax
	e9 64 ff ff ff		# jmp	gethex

# putchar:
	31 db			# xor	%ebx,%ebx
	43			# inc	%ebx
	8d 4c 24 04		# lea	0x4(%esp,1),%ecx
	89 da			# mov	%ebx,%edx
	b8 04 00 00 00		# mov	$0x4,%eax
	cd 80			# int	$0x80
	c3			# ret

# _start:
	e8 4e ff ff ff		# call	gethex
	c1 e0 04		# shl	$0x4,%eax
	50			# push	%eax
	e8 45 ff ff ff		# call	gethex
	01 04 24		# add	%eax,(%esp,1)
	ff 05 54 80 04 08	# incl	0x0
	e8 d3 ff ff ff		# call	putchar
	58			# pop	%eax
	eb e1			# jmp	_start