From: ian <ian>
Date: Wed, 21 Dec 2005 13:49:16 +0000 (+0000)
Subject: switch nmra timer ISR to use FSR2 and reserve FSR2 for it
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ijackson/git?a=commitdiff_plain;h=0c836807c1c6488d6d70ecd74ef5f3e5af66aea8;p=trains.git

switch nmra timer ISR to use FSR2 and reserve FSR2 for it
---

diff --git a/detpic/common.inc b/detpic/common.inc
index d842960..663741b 100644
--- a/detpic/common.inc
+++ b/detpic/common.inc
@@ -33,7 +33,7 @@ clock equ -1
 ;   PCLATH		Low ISR			Not used
 ;   t_dolocal		Low ISR			High ISR
 ;   FSR1		Low ISR			High ISR (detect[1])
-;   FSR2		Low ISR			High ISR (detect[1])
+;   FSR2		High ISR (nmra)		High ISR (detect[1])
 ;
 ; Trashed	May be trashed by any routine anywhere.  Saved
 ;		during every ISR entry/exit.
@@ -68,7 +68,9 @@ clock equ -1
 ; saves that register for the benefit of its callers.
 ;
 ;  [1]	FSR1 and FSR2 on slave pics are reserved exclusively for the
-;	I2C response and detection code (detect.asm), after det_slave_init.
+;	I2C response and detection code (detect.asm), after
+;	detect_slave_init.  Likewise FSR2 is reserved exclusively
+;	for the NMRA output ISR after nmra_init.
 ;
 ; General-purpose hardware allocation:
 ;
diff --git a/detpic/nmra-stream.asm b/detpic/nmra-stream.asm
index 6ff993a..695b18d 100644
--- a/detpic/nmra-stream.asm
+++ b/detpic/nmra-stream.asm
@@ -27,7 +27,7 @@ nextaction	equ	6	; bit 6: change polarity on next interrupt y/n
  ; nmractrl is a bitmask, and only the bits above are used
 
 fromserial	res	1	; from-serial buffer location (in buffer bank)
-totrack		res	1	; to-track buffer location (in buffer bank)
+totrack		equ	FSR2L	; to-track buffer location (in buffer bank)
 totrackbit	res	1	; bit location of pointer within byte
  ;
  ; buffers are each 16 bytes (this is hardwired)
@@ -142,6 +142,7 @@ nmra_init
 ; initialise buffers (for bank 5, for nmra from-serial/to-track buffers)
 
 	mov_lw	bufferpage
+	mov_wf	FSR2H
 
 	clr_fa	nmractrl  	; for bits relevant to control of nmra stream
 	clr_fa	fromserial  	; for loc'n of write-from-usart ptr in buffers
@@ -351,13 +352,8 @@ read_from_buffer
 ; set na=cb=bit value, advance bit (i.e. rotate transmitbit right), 
 ; check if bit7, if so, advance byte, return
 
- fixme save and restore FSR1
- fixme check other to-be-saved stuff ??
 	debug 	'p'
-	mov_ff	totrack,FSR1L		; set low byte of IND1 pointer
-	mov_lw	bufferpage
-	mov_wfa	FSR1H  			; set high byte of IND1 pointer
-	mov_ff	INDF1,WREG
+	mov_ff	INDF2, WREG
 	and_wfwa totrackbit    		; select bit to be transmitted
 
 	bra_z	zero_bit_to_track 
@@ -403,17 +399,14 @@ advance_pointer
 
 ; currently on bit 7 of the byte, after having read rest of byte to
 ; track; check whether it is 1 or 0
-	mov_ff	totrack,FSR1L	
-	mov_lw	bufferpage
-	mov_wfa	FSR1H  		
 
 ; if set, move to next buffer
-	bt_fa_if1 INDF1,7  
+	bt_fa_if1 INDF2,7  
 	call	advance_read_buffer
 
 ; if not set, move to next byte of samebuffer (increment totrack)
 ; (will be on bit 7 at this point anyway so no need to change totrackbit)
-	bt_fa_if0 INDF1,7  
+	bt_fa_if0 INDF2,7  
 	inc_fa	totrack    
 	return