source: bootcd/isolinux/syslinux-6.03/core/writehex.inc

;; -----------------------------------------------------------------------
;;
;;   Copyright 1994-2008 H. Peter Anvin - All Rights Reserved
;;
;;   This program is free software; you can redistribute it and/or modify
;;   it under the terms of the GNU General Public License as published by
;;   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
;;   Boston MA 02111-1307, USA; either version 2 of the License, or
;;   (at your option) any later version; incorporated herein by reference.
;;
;; -----------------------------------------------------------------------

;;
;; writehex.inc
;;
;; Write hexadecimal numbers to the console
;;

;
; writehex[248]: Write a hex number in (AL, AX, EAX) to the console
;
writehex2:
                pushfd
                pushad
                rol eax,24
                mov cx,2
                jmp short writehex_common
writehex4:
                pushfd
                pushad
                rol eax,16
                mov cx,4
                jmp short writehex_common
writehex8:
                pushfd
                pushad
                mov cx,8
writehex_common:
.loop:          rol eax,4
                push eax
                and al,0Fh
                cmp al,10
                jae .high
.low:           add al,'0'
                jmp short .ischar
.high:          add al,'A'-10
.ischar:        call writechr
                pop eax
                loop .loop
                popad
                popfd
                ret