erase1.asm

一款MP3 Player Firmware 的原代码,非常有参考价值

; MP3 Player, Main Program Erase, 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.


; this little utility adds a quick and easy command to the
; board (press 'X') to erase just the program (player.hex),
; so when working on the firmware, you can press 'X' and the
; download just the main program instead of all the data.
; This speeds things up quite a bit.


.equ    location, 0xFF00        ;where this program will exist

.equ    erblock, 0x0067   ;PAULMON2 v2.1 req'd

.equ    return_addr, 0x0FF0     ;jump here to return to caller in bank0


.org    location
.db     0xA5,0xE5,0xE0,0xA5     ;signiture bytes
.db     35,255,0,0              ;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     "Erase Driver Code",0
.org    location+64             ;executable code begins here


	mov	dptr, #0x2000
	mov	a, #0x24
	lcall	erblock
	mov	dptr, #0x3000
	mov	a, #0x24
	lcall	erblock
	mov	dptr, #0x4000
	mov	a, #0x24
	lcall	erblock
	mov	dptr, #0x5000
	mov	a, #0x24
	lcall	erblock
	mov	dptr, #0x6000
	mov	a, #0x24
	lcall	erblock
	mov	dptr, #0x7000
	mov	a, #0x24
	lcall	erblock



	mov	dptr, #0x3000
chk:	clr	a
	movc	a, @a+dptr
	cpl	a
	jnz	bad
	inc	dptr
	mov	a, dpl
	jnz	chk
	mov	a, dph
	cjne	a, #0x80, chk
	clr	c
	ljmp	return_addr

bad:
	setb	c
	ljmp	return_addr