off.asm

一款MP3 Player Firmware 的原代码,非常有参考价值

; MP3 Player, Turn Off Power, http://www.pjrc.com/tech/mp3
; Copyright (c) 2000, PJRC.COM, LLC

; 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; either version 2
; of the License, or (at your option) any later version.

; This program is distributed in the hope that it will be useful,
; but WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
; GNU General Public License for more details.

; You should have received a copy of the GNU General Public License
; along with this program; if not, write to the Free Software
; Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.



.equ    location, 0xFD00        ;where this program will exist

.equ    pstr, 0x0038            ;Print string pointed to by DPTR,


.equ	call_bank1, 0x0FE0
.equ	shutdown, 0x3000 + 70


.org    location
.db     0xA5,0xE5,0xE0,0xA5     ;signiture bytes
.db     254,'Q',0,0             ;id
.db     0,0,0,0                 ;reserved
.db     0,0,0,0                 ;reserved
.db     0,0,0,0                 ;reserved
.db     0,0,0,0                 ;reserved
.db     0,0,0,0                 ;user defined
.db     255,255,255,255         ;length and checksum (255=unused)
.db     "Quit, Shut Off Power",0
.org    location+64             ;executable code begins here



begin:
	mov	dptr, #shutdown
	lcall	call_bank1
	ret