; xutil.z - xmodem utilities

.incl	"c:xmodem"

.extern	initx			; set up an xmodem file transfer
initx:
	ld	hl,xabort
	ld	(abortf),hl	; set the abort function
	ld	hl,xmstr
	jp	initsc		; just set up screen with 'Xmodem' string
.dseg
xmstr:	db	'Xmodem\0'
.cseg

.extern	xmflgs			; parse flags for an xmodem send
xmflgs:
	call	clrflg
	ld	a,1
	ld	(crcmod),a	; but set crc flag
xmflp:	ld	a,(hl)
	or	0x20
	cp	0x20
	ret	z		; return on end of string or space
	inc	hl
	cp	'b'		; 'b' - modem7 batch
	jr	nz,noxmb
	ld	(mdm7b),a	; set modem7 batch flag
	xor	a
	ld	(ymdmb),a	; clear ymodem batch (can't have both)
	jr	xmflp
noxmb:	cp	'y'		; 'y' - ymodem batch
	jr	nz,noxmy
	ld	(ymdmb),a	; set ymodem batch flag
	xor	a
	ld	(mdm7b),a	; clear modem7 batch (can't have both)
	jr	xmflp
noxmy:	cp	'k'		; 'k' - 1K packets
	jr	nz,noxmk
	ld	(longpk),a	; set the flag
	jr	xmflp
noxmk:	cp	'q'		; 'q' - quiet value
	jr	nz,noxmq
	ex	de,hl
	ld	hl,qcount
	inc	(hl)		; bump the count
	ex	de,hl
	jr	xmflp
noxmq:	cp	'a'		; 'a' - alarm
	jr	nz,noxma
	ld	(beep),a	; set flag to beep on completion
	jr	xmflp
noxma:	xor	'c'		; 'c' - checksum mode
	jr	nz,xmflp
	ld	(crcmod),a	; set to checksum
	jr	xmflp

.extern	updcrc			; update crc with value in a
updcrc:
	ld	c,a		; save byte in c
	call	dou1
dou1:	ld	hl,chksum
	ld	a,c
	rrca
	rrca
	rrca
	rrca
	ld	c,a
	xor	a
	rld
	inc	hl
	rld
	xor	c
	and	0x0f
	add	a,a
	push	hl
	ld	l,a
	ld	h,0
	ld	de,crctab + 1
	add	hl,de
	ex	de,hl
	pop	hl
	ld	a,(de)
	dec	de
	xor	(hl)
	ld	(hl),a
	dec	hl
	ld	a,(de)
	xor	(hl)
	ld	(hl),a
	ret

.extern	can3			; send 5 CAN's to far end to force it to stop
can3:				; used to be three, but with Zmodem systems
	ld	b,5		; sometimes more are needed
can3lp:	push	bc
	ld	a,CAN
	call	modopc
	pop	bc
	djnz	can3lp
	ret

.extern	chkcan			; called when we get a CAN - checks for a
chkcan:				; second right behind it
	call	gettc3		; wait 3 seconds
	cp	CAN
	ret	nz		; no - didn't get one
	call	diag
	db	'Cancelled by remote\0'
	xor	a
	ret

.extern	rnresp			; beef about failure of far end to respond
rnresp:
	call	diag
	db	'Remote not responding\0'
	ret

.extern	cvtnib			; convert a nibble at the bottom of a to a
cvtnib:				; character
	and	0x0f		; get just the bits we want
	add	a,'0'
	cp	'9' + 1		; check if it's a digit ok
	ret	c		; yes - return as is
	add	a,0x27		; else conver to a letter
	ret

xabort:	call	gettc3
	jr	nc,xabort	; let the line cool down
	call	can3
	jp	dabort

.useg
.extern	olp
olp:	ds	1
.extern	attmps
attmps:	ds	1
.extern	closeo
closeo:	ds	1
.extern	fatal
fatal:	ds	1
.extern	errorf
errorf:	ds	1
.extern	batch
batch:	ds	1
.extern	secip
secip:	ds	1
.extern	eotc
eotc:	ds	1
.extern	openfl		; \
openfl:	ds	1	;  \ Bound
.extern	sectnm		;  /
sectnm:	ds	2	; /
.extern	bufsiz
bufsiz:	ds	2
.extern	chksum
chksum:	ds	2

.extern	expsec
expsec:	ds	2
.extern	sntsec
sntsec:	ds	2
.extern	xbuff
.extern	packet
xbuff:
packet:
	ds	1024

.dseg
crctab:
	dw	0x0000, 0x1021
	dw	0x2042, 0x3063
	dw	0x4084, 0x50a5
	dw	0x60c6, 0x70e7
	dw	0x8108, 0x9129
	dw	0xa14a, 0xb16b
	dw	0xc18c, 0xd1ad
	dw	0xe1ce, 0xf1ef