From: ian <ian>
Date: Sun, 25 Dec 2005 16:56:39 +0000 (+0000)
Subject: abolish lasttelldone in favour of acknmra
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ijackson/git?a=commitdiff_plain;h=74bf865d4a1cd0f395ac002bdee100ad1f180df2;p=trains.git

abolish lasttelldone in favour of acknmra
---

diff --git a/detpic/morse.messages b/detpic/morse.messages
index 96592f6..550f8bc 100644
--- a/detpic/morse.messages
+++ b/detpic/morse.messages
@@ -28,6 +28,7 @@ HW	::t			; host sent message which was too long
 HO				; host RS232 read overrun
 HF				; host RS232 framing error
 HN				; host sent too much NMRA - buffers full
+HM				; host sent too much NMRA - ack count overflow
 HB				; data for host overran buffer
 
 # Regarding communications by master with slaves
diff --git a/detpic/nmra-stream.asm b/detpic/nmra-stream.asm
index 89a8588..4bd54b5 100644
--- a/detpic/nmra-stream.asm
+++ b/detpic/nmra-stream.asm
@@ -29,7 +29,6 @@ nextaction	equ	6	; bit 6: change polarity on next interrupt y/n
 fromserial	res	1	; from-serial buffer location (in buffer bank)
 totrack		equ	FSR2L	; to-track buffer location (in buffer bank)
 totrackbit	res	1	; bit location of pointer within byte
-lasttelldone	res	1	; last nmra msg we've told host we've finished
  ;
  ; buffers are each 16 bytes (this is hardwired)
  ; and there are four of them starting at 0x500, 0x510, 0x520, 0x530.
@@ -48,18 +47,15 @@ lasttelldone	res	1	; last nmra msg we've told host we've finished
  ; because there is no nmra data at all then totrack points to the
  ; start of the same buffer as fromserial
  ;
- ; lasttelldone points to the last buffer whose complete transmission
- ; we've reported to the host.
- ;
  ; We maintain the following properties, notionally:
  ;
- ;  lasttelldone <= totrack <= fromserial < lasttelldone
+ ;  totrack <= fromserial < totrack
  ;
- ;              /             \            \
- ;             '               \            `- equal would mean overrun
- ;  equal if we have            \
- ;  told the host about our      `- equal if we have nothing but
- ;  current buffer state             idle to trasmit
+ ;            \            \
+ ;             \            `- equal would mean overrun
+ ;              \
+ ;               `- equal if we have nothing but
+ ;                   idle to trasmit
  ;
 
 bufferpage	equ	5
@@ -235,7 +231,7 @@ nmra_serialrx_intrl
 serial_receive_done
 	intrl_handled_nostack
 
-receive_too_much_nmra		panic	morse_HW
+receive_too_much_nmra		panic	morse_HN
 receive_message_too_long	panic	morse_HW
 
 ; *** I *think* the interrupt bit is cleared by reading out of RCREG
@@ -261,12 +257,6 @@ advance_write_buffer
 					;  where BB is this buffer
 					;   and CC is next buffer
 
-	; we have to check our proposed new value for fromserial
-	; against totrack before we store it in fromserial;
-	; otherwise there's the possibility that we will store
-	; the new value, and then the high-priority ISR will
-	; interrupt us and advance totrack onto the buffer we've
-	; just filled, fooling us into thinking we've overrun.
 	xor_wfw	totrack			; W =		0?DD????
 	and_lw	0x30			;		..DD....
 	bra_z	receive_too_much_nmra	; where DD is (fromserial buffer)
@@ -440,9 +430,12 @@ advance_read_buffer
 	bc_fa	totrack,6
 	debug 	'9'	; write 'v' to serial port
 
-	bs_f	flags, flags_tellnmra	; ensure we tell
-	bs_f	PIE1, TXIE		;  host to send us more
+	inc_f	acknmra
+	bs_f	PIE1, TXIE	; ensure we tell host to send us more
+	bt_f_if0 acknmra, 2
 	return
+	; oops:
+	panic	morse_HM
 
 
 
diff --git a/detpic/variables.asm b/detpic/variables.asm
index 18681e3..90db760 100644
--- a/detpic/variables.asm
+++ b/detpic/variables.asm
@@ -9,8 +9,8 @@ idloc1		res	1	; from 2nd idlocs byte; bit 7 is master:
 idloc1_master	equ	7
 idloc1_boarddet	equ	6
 
+acknmra		res	1	; must tell host about NMRA buffer state
 flags		res	1	; miscellaneous state flags
-flags_tellnmra	equ	7	; must tell host about NMRA buffer state
 
 t		res	1	; general temporary
 u		res	1	; general temporary (another)