erase0.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, 0xED00        ;where this program will exist

.equ    pstr, 0x0038            ;Print string pointed to by DPTR,
.equ    erblock, 0x0067   ;PAULMON2 v2.1 req'd
.equ    call_bank1, 0x0FE0



.org    location
.db     0xA5,0xE5,0xE0,0xA5     ;signiture bytes
.db     254,'X',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 C Code Only          'X'",0
.org    location+64             ;executable code begins here


	mov     dptr, #mesg_warn
	lcall   pstr

begin1:
	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, #0x8000
	mov	a, #0x24
	lcall	erblock
	mov	dptr, #0x9000
	mov	a, #0x24
	lcall	erblock
	mov	dptr, #0xA000
	mov	a, #0x24
	lcall	erblock
	mov	dptr, #0xB000
	mov	a, #0x24
	lcall	erblock
	mov	dptr, #0xC000
	mov	a, #0x24
	lcall	erblock
	mov	dptr, #0xD000
	mov	a, #0x24
	lcall	erblock

	mov	dptr, #0xF000	;erases old (non-SIMM) version
	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, #0xE0, chk

	mov     dptr, #mesg_p
	lcall   pstr
	mov     dptr, #mesg_ok
	lcall   pstr
	ret


bad:
	mov     dptr, #mesg_p
	lcall   pstr
	mov     dptr, #mesg_er
	lcall   pstr
	ret


mesg_p:	.db	"Partial Flash Erasure, ",0
mesg_ok:.db	"OK", 13,10,13,10,0
mesg_er:.db     "Failed", 13,10,13,10,0


.org    location+256
.db     0xA5,0xE5,0xE0,0xA5     ;signiture bytes
.db     254,'Y',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 C Code and Drivers   'Y'",0
.org    location+256+64         ;executable code begins here


	mov     dptr, #mesg_warn
	lcall   pstr

	mov	dptr, #0xFF40
	lcall	call_bank1

	mov	dptr, #0x2000
	mov	a, #0x24
	lcall	erblock

	mov	dptr, #0x2000
chk2:	clr	a
	movc	a, @a+dptr
	cpl	a
	jnz	bad2
	inc	dptr
	mov	a, dpl
	jnz	chk2
	mov	a, dph
	cjne	a, #0x30, chk2
	ajmp	begin1

bad2:
	ajmp	bad



mesg_warn:
.db	13,10,"Partial Flash Erasure For Developers Only",13,10
.db	"  Users should erase with 'Z' command",13,10
.db	"  and download 'MP3PLAYER.HEX'"
.db	13,10,13,10,0