From: ian <ian>
Date: Thu, 29 Dec 2005 02:01:20 +0000 (+0000)
Subject: fix totally broken serial FC and RBIF handling
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ijackson/git?a=commitdiff_plain;h=ea101635f589a9cf4fa14e2363130d00ba2868ab;p=trains.git

fix totally broken serial FC and RBIF handling
---

diff --git a/detpic/program.asm b/detpic/program.asm
index 5847506..1edd9d5 100644
--- a/detpic/program.asm
+++ b/detpic/program.asm
@@ -91,6 +91,7 @@ master_interrupt_low
 	call	tick_intrl
 	call	nmra_serialrx_intrl
 	call	power_fault_intrl
+	call	serialtxfc_intrl
 	call	serialtx_intrl
 	call	points_local_intrl
 	call	i2cm_intrl
diff --git a/detpic/serout.asm b/detpic/serout.asm
index 9671861..e0835c4 100644
--- a/detpic/serout.asm
+++ b/detpic/serout.asm
@@ -3,6 +3,13 @@
 
   include common.inc
   code
+
+;======================================================================
+; QUEUEING MESSAGES FOR TRANSMISSION
+
+;----------
+addbyte_toomany panic morse_HB
+
 ;----------------------------------------
 serial_addbyte
 ;  W			byte to xmit to host	trashed
@@ -13,8 +20,8 @@ serial_addbyte
 ;
 	mov_lfsr outbuf, 0
 	mov_ff	outmsg_end, FSR0L
-	bs_f	PIR1, TXIE ; ensure we get interrupted and try to xmit
 ;...
+;----------------------------------------
 serial_addbyte_another
 ;  W			byte to xmit to host	trashed
 ;  FSR0			from _addbyte[_another]	updated for ..._another again
@@ -26,21 +33,73 @@ serial_addbyte_another
 	bc_f	FSR0L, 7
 	mov_fw	FSR0L
 	mov_wf	outmsg_end
-	cmp_fw_ifne outmsg_begin
+	xor_wfw	outmsg_begin
+	bra_z	addbyte_toomany
+	; no, we're ok:
+
+	bt_f_if1 INTCON, TXIE
+	return ; don't bother messing about if tx is already enabled
+
+; we fall through to portb_read to reenable TXIE if appropriate
+;...
+;======================================================================
+; FLOW CONTROL BY HOST OF OUR TRANSMISSIONS
+
+;...
+;----------------------------------------
+portb_read
+;
+;  W			undefined	value from PORTB
+;  TXIE			any		enabled iff host allows us to xmit
+;
+; Note that this will reenable TXIE even if the serial buffer is empty,
+; every time portb_read is called.  This doesn't matter very much
+; because the serialtx_intrl routine will disable it again straight
+; away.
+;
+	mov_fw	PORTB
+	bc_f	INTCON, RBIF
+
+	bt_w_if0  p0_rs232_fcin >> 4
+	bra	txfc_disable
+	; tx enable:
+
+	bs_f	PIR1, TXIE
 	return
-	; too many
-	panic morse_HB
+
+;----------
+txfc_disable
+	bc_f	PIR1, TXIE
+	goto	led_red ; flow control forces us not to transmit
 
 ;----------------------------------------------------------------------
-serialtx_intrl
-	bt_f_if1 INTCON, RBIF
+serialtxfc_intrl
+	bt_f_if0 INTCON, RBIF
+	return
+	; yes, it's us:
+
 	rcall	portb_read ; check flow control
+	intrl_handled_nostack
+
+;----------------------------------------------------------------------
+serialtxfc_init
+	bc_f	INTCON2, RBIP
+	bs_f	INTCON, RBIE
+	rcall	portb_read
+	pin_l	p0_rs232_fcout ; set outgoing RTS/CTS active
+	return
 
+;======================================================================
+; ACTUAL TRANSMISSION
+
+;----------------------------------------------------------------------
+serialtx_intrl
 	; are we ready to transmit ?
 	bt_f_if0 PIR1, TXIF
 	return
 	bt_f_if0 PIR1, TXIE
 	return
+	; yes, it's us:
 
 	mov_lfsr outbuf, 0
 	mov_fw	outmsg_begin
@@ -58,53 +117,32 @@ serialtx_intrl
 tx_justsent_noacknmra
 	inc_f	outmsg_begin
 	bc_f	outmsg_begin, outbuf_szln2
+	call	i2c_consider_restartread
+tx_alliswell
 	call	led_green ; we're transmitting
-	goto	i2c_consider_restartread
-
-tx_bufempty
-	; maybe we send an NMRADONE
-	mov_fw	acknmra
-	bra_nz	tx_acknmra_send
-	; nothing at all to do:
-	bc_f	PIR1, TXIE
-	goto	led_black ; we're not transmitting
+	intrl_handled_nostack
 
+;----------
 tx_acknmra_insert
 	sub_wff	acknmra ; we're acking these now
 	mov_wf	INDF0 ; write it over the message we just sent
-	goto	led_green
+	bra	tx_alliswell
 
+;----------
 tx_acknmra_send
 	sub_wff	acknmra ; we're acking these now
 	mov_wf	TXREG
-	goto	led_green
-
-;----------------------------------------
-portb_read
-;  W			undefined	value from PORTB
-	mov_fw	PORTB
-	bc_f	INTCON, RBIF
-
-	bt_w_if0  p0_rs232_fcin >> 4
-	bra	tx_fcdisable
-	; tx enable:
+	bra	tx_alliswell
 
-	bs_f	PIR1, TXIE
-	bc_f	INTCON, RBIE
-	return
-
-tx_fcdisable
+;----------
+tx_bufempty
+	; maybe we send an NMRADONE
+	mov_fw	acknmra
+	bra_nz	tx_acknmra_send
+	; nothing at all to do:
 	bc_f	PIR1, TXIE
-	bs_f	INTCON, RBIE
-	goto	led_red ; flow control forces us not to transmit
-
-;----------------------------------------------------------------------
-serialtxfc_init
-	bc_f	INTCON2, RBIP
-	bs_f	INTCON, RBIE
-	rcall	portb_read
-	pin_l	p0_rs232_fcout ; set outgoing RTS/CTS active
-	return
+	call	led_black ; we're not transmitting
+	intrl_handled_nostack
 
 ;----------------------------------------------------------------------
 serialtxbuf_init
diff --git a/detpic/serout.fin b/detpic/serout.fin
index b379166..f3a3546 100644
--- a/detpic/serout.fin
+++ b/detpic/serout.fin
@@ -1,6 +1,7 @@
   extern serial_addbyte
   extern serial_addbyte_another
   extern serialtx_intrl
+  extern serialtxfc_intrl
   extern serialtxfc_init
   extern serialtxbuf_init
   extern portb_read