From 3134af6c1994239c31bfb2aa9a2ca50976d40c53 Mon Sep 17 00:00:00 2001
From: Leo C <erbl259-lmu@yahoo.de>
Date: Fri, 19 Apr 2019 00:28:56 +0200
Subject: [PATCH] Initial XON/XOFF input control (Holm. T)

---
 cbios/ascii.180 | 61 +++++++++++++++++++++++++++++++++----------------
 cbios/ioctl.inc |  3 +++
 2 files changed, 44 insertions(+), 20 deletions(-)

diff --git a/cbios/ascii.180 b/cbios/ascii.180
index fbe193d..0a2fd6f 100644
--- a/cbios/ascii.180
+++ b/cbios/ascii.180
@@ -58,7 +58,7 @@ as1_dev:
 	db	0			;absolute device #
 	db	1			;relative device
 	db	0			;iflags
-	db	M_CREAD			;fflags
+	db	M_CREAD+M_IXOFF		;fflags
 	db	M_CS8			;cflags
 
 	db	0
@@ -108,9 +108,8 @@ asci_ioctl:
 	ld	a,b
 	cp	1
 	jr	nz,asioc_1
-	ld	a,(INIDONE)
-	and	80h
-	cp	INIDONEVAL
+	ld	a,(inidone)
+	cp	inidoneval
 	ret	z
 asioc_1:
 	push	hl
@@ -546,12 +545,12 @@ asci0_inp:
 	push	ix
 	ld	ix,s0.inbuf		;
 	call	ff_gech
-	ld	a,b
-	cp	s0.rx_len/4
-	jr	nc,a0i_1
-	bit	CRTS_IFLOW,(ix+oint.fflags)
-	jr	z,a0i_1
-	di
+	ld	a,b			;remaining chrs in buffer
+	cp	s0.rx_len/4		; < 32?
+	jr	nc,a0i_1			; no, just get char
+	bit	CRTS_IFLOW,(ix+oint.fflags)	; yes, enable RTS if needed
+	jr	z,a0i_1			; no needed
+	di				; needed, enable
 	in0	a,(cntla0)
 	and	~M_RTS0			;assert RTS
 	or	M_EFR			;don't reset error flags
@@ -569,6 +568,20 @@ asci1_inp:
 	push	ix
 	ld	ix,s1.inbuf		;
 	call	ff_gech
+	ld	a,b			; remaining chars in buffer
+	cp	s0.rx_len/4		; == 25% full?
+	jr	nz,a1i_2		; no, just get char
+	bit	IXOFF,(ix+oint.fflags)	; XON/XOFF on input?
+	jr	z,a1i_2			; no
+;	di
+a1i_1:	in0	a,(stat1)		; status reg ASCI1
+	bit	TDRE,a			; Transmitter Data Reg. empty?
+	jr	z,a1i_1			; no, wait
+	ld	a,11h			; DC1/XON
+	out0	(tdr1),a		; send out
+;	ei
+a1i_2:
+	ld	a,c			; get back the char
 	pop	ix
 	ret
 
@@ -643,7 +656,7 @@ rtxisvjmp1:
 
 	.lall
 asci_int macro	dev
-	local	rxi_2,rxi_4
+	local	rxi_2,rxi_3,rxi_4
 
 	push	ix
 rxtxi&dev&_lp0:
@@ -663,20 +676,17 @@ rxtxi&dev&_lp1:
 	res	EFR,d			;
 	out0	(cntla&dev),d
 
-	ld	c,(ix+o.in_idx)		;
+	ld	c,(ix+o.in_idx)		;input buffer pointer
 	ld	b,0
 	ld	hl,s&dev&.inbuf		;
 	add	hl,bc
 
-	in0	a,(rdr&dev)		;
+	in0	a,(rdr&dev)		;get char
 	ld	(hl),a
 					;todo: break detection
 					;todo: parity, framing overrun error
 
 	ld	e,(ix+oint.fflags)
-	bit	IXON,e
-	jr	z,rxi_2
-					;todo: test XON/XOFF
 
 rxi_2:
 
@@ -689,7 +699,7 @@ rxi_2:
 	sub	(ix+o.out_idx)		;
 	jr	z,rxtxi&dev&_lp1	;skip if buffer is full
 
-	ld	(ix+o.in_idx),c		;
+	ld	(ix+o.in_idx),c		;input buffer pointer
 
 	jr	nc,$+3			;
 	 adc	b			;
@@ -705,12 +715,23 @@ rxi_2:
 	set	RTS0,d			;RTS inactive
 	out0	(cntla&dev),d		;
    endif
+   if dev=1
+	bit	IXOFF,e
+	jr	z,rxi_4
+
+;	di
+rxi_3:	in0	a,(stat&dev)		; status reg ASCI1
+	bit	TDRE,a			; Transmitter Data Reg. empty?
+	jr	z,rxi_3			; no, wait
+	ld	a,DC3			; DC3/XOFF
+	out0	(tdr&dev),a		; send out
+;	ei
+   endif
 
 rxi_4:
-	bit	IXOFF,e
-	jr	z,rxtxi&dev&_lp1
+;	bit	IXOFF,e
+;	jr	z,rxtxi&dev&_lp1
 					;todo: send XOFF
-
 rxi&dev&_noflow:
 	jr	rxtxi&dev&_lp1
 
diff --git a/cbios/ioctl.inc b/cbios/ioctl.inc
index 8d1f303..b2797f2 100644
--- a/cbios/ioctl.inc
+++ b/cbios/ioctl.inc
@@ -102,3 +102,6 @@ TIOCM_CD	equ	010h		;DCD (data carrier detect)
 TIOCM_RI	equ	020h		;RNG (ring)
 TIOCM_DSR	equ	040h		;DSR (data set ready)
 TIOCM_OUT1	equ	080h		;
+
+DC1		equ	011h		; DC1/XON
+DC3		equ	013h		; DC3/XOFF
-- 
2.39.2