crtsi.s

基于51的单片机的PPP协议实现

;	C STARTUP FOR MC68HC08
;	WITH AUTOMATIC DATA INITIALISATION
;	Copyright (c) 1995 by COSMIC Software
;
	xref	_main, __memory, __idesc__, __stack
	xdef	_exit, __stext
;
	switch	.bss
__sbss:
	switch	.text
__stext:
	ldhx	#__stack	; initialize stack pointer
	txs
	ldhx	#__idesc__	; descriptor address
	lda	1,x		; save start
	psha			; address of
	lda	0,x		; prom data
	psha
	aix	#2		; skip address
ibcl:
	lda	0,x		; test flag byte
	beq	zbss		; no more segment
	lda	4,x		; compute length
	sub	2,sp		; of segment
	psha
	lda	3,x
	sbc	2,sp
	tst	1,sp		; if LSB nul,
	beq	ok		; keep it
	inca			; else increment MSB
ok:
	psha
	lda	2,x		; destination address
	psha			; on the stack
	lda	1,x
	psha
	pshx			; and save
	pshh			; pointer
dbcl:
	ldx	7,sp		; load source pointer
	pshx
	ldx	9,sp
	inc	9,sp		; increment pointer
	bne	oks
	inc	8,sp
oks:
	pulh
	lda	0,x		; load byte
	ldx	3,sp		; load source pointer
	pshx
	ldx	5,sp
	inc	5,sp		; increment pointer
	bne	okd
	inc	4,sp
okd:
	pulh
	sta	0,x		; store byte
	dbnz	6,sp,dbcl	; count LSB
	dbnz	5,sp,dbcl	; count MSB
	pulh			; reload pointer
	pulx
	aix	#5		; next descriptor
	ais	#4		; cleanup stack
	bra	ibcl		; and loop
zbss:
	ais	#2		; remove pointer
	ldhx	#__sbss		; start of bss
	bra	loop		; start loop
zbcl:
	clr	0,x		; clear byte
	aix	#1		; next byte
loop:
	cphx	#__memory	; up to the end
	bne	zbcl		; and loop
prog:
	jsr	_main		; execute main
_exit:
	bra	_exit		; and stay here
;
	end