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tashtalk
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20210914

This commit is contained in:
lampmerchant 2021-09-14 12:09:31 -06:00
parent ac1499d633
commit 968f4623e7
1 changed files with 122 additions and 116 deletions
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238
firmware/one-chip.asm
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@ -259,12 +259,11 @@ Init
movlw B'11001000'
movwf INTCON
bra AwaitCommand
bra PrepForNextFrame
;entered with BSR = 2
AwaitNodeId
btfsc FLAGS,LR_FRM ;If there's been a change in incoming frame
call DealWithFrame ; regs, deal with the frame
call CheckLtReceiver ;Check for and deal with receiver activity
movf UR_LEN,W ;If there aren't yet 32 bytes in the UART
addlw -32 ; receiver queue, loop around again
btfss STATUS,C ; "
@ -375,8 +374,7 @@ AwaitNodeId
;entered with BSR = ?
AwaitCommand
movlb 2
btfsc FLAGS,LR_FRM ;If there's been a change in incoming frame
call DealWithFrame ; regs, deal with the frame
call CheckLtReceiver ;Check for and deal with receiver activity
movf UR_LEN,F ;If there's no data in the UART receiver queue,
btfsc STATUS,Z ; loop around again
bra AwaitCommand ; "
@ -394,88 +392,8 @@ AwaitCommand
bra AwaitNodeId ; that data
bra AwaitCommand ;All other commands are considered no-ops
;entered with BSR = 2
AwaitDest
btfsc FLAGS,LR_FRM ;If there's been a change in incoming frame
call DealWithFrame ; regs, deal with the frame
movf UR_LEN,F ;If there's no data in the UART receiver queue,
btfsc STATUS,Z ; loop around again
bra AwaitDest ; "
decf UR_LEN,F ;Decrement the UART receiver queue size
movlw B'11111011' ;If the pop off the queue dropped the length
btfss UR_LEN,6 ; below 64, assert CTS so the host sends us
andwf LATA,F ; data again
moviw FSR1++ ;Pop the next byte off the UART receiver queue
bcf FSR1L,7 ; "
movwf UR_DEST ;Save this byte as the loaded frame destination
;fall through
;entered with BSR = 2
AwaitSrc
btfsc FLAGS,LR_FRM ;If there's been a change in incoming frame
call DealWithFrame ; regs, deal with the frame
movf UR_LEN,F ;If there's no data in the UART receiver queue,
btfsc STATUS,Z ; loop around again
bra AwaitSrc ; "
decf UR_LEN,F ;Decrement the UART receiver queue size
movlw B'11111011' ;If the pop off the queue dropped the length
btfss UR_LEN,6 ; below 64, assert CTS so the host sends us
andwf LATA,F ; data again
moviw FSR1++ ;Pop the next byte off the UART receiver queue
bcf FSR1L,7 ; "
movwf UR_SRC ;Save this byte as the loaded frame source
;fall through
;entered with BSR = 2
AwaitType
btfsc FLAGS,LR_FRM ;If there's been a change in incoming frame
call DealWithFrame ; regs, deal with the frame
movf UR_LEN,F ;If there's no data in the UART receiver queue,
btfsc STATUS,Z ; loop around again
bra AwaitType ; "
decf UR_LEN,F ;Decrement the UART receiver queue size
movlw B'11111011' ;If the pop off the queue dropped the length
btfss UR_LEN,6 ; below 64, assert CTS so the host sends us
andwf LATA,F ; data again
moviw FSR1++ ;Pop the next byte off the UART receiver queue
bcf FSR1L,7 ; "
movwf UR_TYPE ;Save this byte as the loaded frame type
;fall through
;entered with BSR = 2
Await4th
btfsc FLAGS,LR_FRM ;If there's been a change in incoming frame
call DealWithFrame ; regs, deal with the frame
movf UR_LEN,F ;If there's no data in the UART receiver queue,
btfsc STATUS,Z ; loop around again
bra Await4th ; "
decf UR_LEN,F ;Decrement the UART receiver queue size
movlw B'11111011' ;If the pop off the queue dropped the length
btfss UR_LEN,6 ; below 64, assert CTS so the host sends us
andwf LATA,F ; data again
moviw FSR1++ ;Pop the next byte off the UART receiver queue
bcf FSR1L,7 ; "
movwf UR_4TH ;Save this byte as the loaded frame 4th byte
;fall through
;entered with BSR = 2
Await5th
btfsc FLAGS,LR_FRM ;If there's been a change in incoming frame
call DealWithFrame ; regs, deal with the frame
movf UR_LEN,F ;If there's no data in the UART receiver queue,
btfsc STATUS,Z ; loop around again
bra Await5th ; "
decf UR_LEN,F ;Decrement the UART receiver queue size
movlw B'11111011' ;If the pop off the queue dropped the length
btfss UR_LEN,6 ; below 64, assert CTS so the host sends us
andwf LATA,F ; data again
moviw FSR1++ ;Pop the next byte off the UART receiver queue
bcf FSR1L,7 ; "
movwf UR_5TH ;Save this byte as the loaded frame 5th byte
;fall through
;entered with BSR = 2
SetUpBackoffs
;entered with BSR = ?
PrepForNextFrame
movlw -3 ;If there have been more than two collisions
btfsc COL_HIST,7 ; during the last eight transmissions, left-
addlw 1 ; shift a one (up to a maximum of four) into
@ -528,42 +446,106 @@ SetUpBackoffs
movwf LBACKOFF ; backoff mask
movlw 33 ;Set attempts counter to 32 (plus one since we
movwf ATTEMPTS ; immediately decrement it)
bra AwaitCommand ;We're set for the next frame, wait for it
;entered with BSR = 2
AwaitDest
call CheckLtReceiver ;Check for and deal with receiver activity
movf UR_LEN,F ;If there's no data in the UART receiver queue,
btfsc STATUS,Z ; loop around again
bra AwaitDest ; "
decf UR_LEN,F ;Decrement the UART receiver queue size
movlw B'11111011' ;If the pop off the queue dropped the length
btfss UR_LEN,6 ; below 64, assert CTS so the host sends us
andwf LATA,F ; data again
moviw FSR1++ ;Pop the next byte off the UART receiver queue
bcf FSR1L,7 ; "
movwf UR_DEST ;Save this byte as the loaded frame destination
;fall through
;entered with BSR = 2
AwaitSrc
call CheckLtReceiver ;Check for and deal with receiver activity
movf UR_LEN,F ;If there's no data in the UART receiver queue,
btfsc STATUS,Z ; loop around again
bra AwaitSrc ; "
decf UR_LEN,F ;Decrement the UART receiver queue size
movlw B'11111011' ;If the pop off the queue dropped the length
btfss UR_LEN,6 ; below 64, assert CTS so the host sends us
andwf LATA,F ; data again
moviw FSR1++ ;Pop the next byte off the UART receiver queue
bcf FSR1L,7 ; "
movwf UR_SRC ;Save this byte as the loaded frame source
;fall through
;entered with BSR = 2
AwaitType
call CheckLtReceiver ;Check for and deal with receiver activity
movf UR_LEN,F ;If there's no data in the UART receiver queue,
btfsc STATUS,Z ; loop around again
bra AwaitType ; "
decf UR_LEN,F ;Decrement the UART receiver queue size
movlw B'11111011' ;If the pop off the queue dropped the length
btfss UR_LEN,6 ; below 64, assert CTS so the host sends us
andwf LATA,F ; data again
moviw FSR1++ ;Pop the next byte off the UART receiver queue
bcf FSR1L,7 ; "
movwf UR_TYPE ;Save this byte as the loaded frame type
;fall through
;entered with BSR = 2
Await4th
call CheckLtReceiver ;Check for and deal with receiver activity
movf UR_LEN,F ;If there's no data in the UART receiver queue,
btfsc STATUS,Z ; loop around again
bra Await4th ; "
decf UR_LEN,F ;Decrement the UART receiver queue size
movlw B'11111011' ;If the pop off the queue dropped the length
btfss UR_LEN,6 ; below 64, assert CTS so the host sends us
andwf LATA,F ; data again
moviw FSR1++ ;Pop the next byte off the UART receiver queue
bcf FSR1L,7 ; "
movwf UR_4TH ;Save this byte as the loaded frame 4th byte
;fall through
;entered with BSR = 2
Await5th
call CheckLtReceiver ;Check for and deal with receiver activity
movf UR_LEN,F ;If there's no data in the UART receiver queue,
btfsc STATUS,Z ; loop around again
bra Await5th ; "
decf UR_LEN,F ;Decrement the UART receiver queue size
movlw B'11111011' ;If the pop off the queue dropped the length
btfss UR_LEN,6 ; below 64, assert CTS so the host sends us
andwf LATA,F ; data again
moviw FSR1++ ;Pop the next byte off the UART receiver queue
bcf FSR1L,7 ; "
movwf UR_5TH ;Save this byte as the loaded frame 5th byte
bra WaitToSendCtrl ;Prepare to send as soon as possible
;entered with BSR = ?
SetTimer2
TryAgain
decf ATTEMPTS,F ;Decrement the attempts counter; if it's hit
btfsc STATUS,Z ; zero, give up trying to transmit this frame
bra GiveUp ; and if necessary drain the frame payload
movlb 0 ;XORing together the bytes of Timer1 is a cheap
movf TMR1L,W ; but reasonable way to get a 'random' number;
xorwf TMR1H,W ; AND it with the local backoff mask to get our
andwf LBACKOFF,W ; backoff value in multiples of 100us
addlw 4 ;Add 400us to this for minimum interdialog gap
movwf PR2 ;Multiply the value in WREG by 5, because
lslf WREG,W ; Timer2 will interrupt after 20us times the
lslf WREG,W ; value in PR2
addwf PR2,F ; "
decf PR2,F ; "
bsf T2CON,TMR2ON ;Activate Timer2
clrf TMR2 ;Reset Timer2
bcf PIR1,TMR2IF ;Clear the Timer2 interrupt flag
call SetTimer2 ;Set Timer2 using the local backoff mask
;fall through
;entered with BSR = 0
;entered with BSR = ?
WaitToSendCtrl
bsf INTCON,GIE ;Reenable interrupts in case they were disabled
btfsc T2CON,TMR2ON ;If Timer2 has been stopped, it means a frame
bra WTSC1 ; came in while we were waiting; handle it and
call DealWithFrame ; defer and retry
movlb 0 ;If Timer2 has been stopped, it means a frame
btfsc T2CON,TMR2ON ; came in while we were waiting; handle it and
bra WTSC1 ; defer and retry
call DealWithFrame ; "
bra Deferred ; "
WTSC1 bcf INTCON,GIE ;Disable interrupts before checking Timer2
btfss PIR1,TMR2IF ;Unless Timer2 has interrupted, loop around
bra WaitToSendCtrl ; again
btfss UR_TYPE,7 ;If the loaded frame is a control frame, just
bra WTSC2 ; go ahead and send it and then await the next
call SendControlFrame; command byte
bra AwaitCommand ; "
bra WTSC2 ; go ahead and send it and then prepare for the
call SendControlFrame; next frame
bra PrepForNextFrame; "
WTSC2 call SendRts ;If it's a data frame, send an RTS frame first
movlb 0 ;Set Timer2 to interrupt after 200us, the
movlw 9 ; maximum interframe gap
@ -579,7 +561,7 @@ WTSC2 call SendRts ;If it's a data frame, send an RTS frame first
;entered with BSR = ?
GiveUp
btfsc UR_TYPE,7 ;If loaded frame is a control frame, we already
bra AwaitCommand ; have it in full
bra PrepForNextFrame; have it in full
movlb 2 ;If loaded frame is a data frame, we need to
movf UR_4TH,W ; extract the length from the 4th and 5th bytes
andlw B'00000011' ; and drain that many characters from the UART
@ -590,9 +572,8 @@ GiveUp1 movlw -1 ;Decrement the length counter; if it was
addwf LT_LENL,F ; already zero, we're done
addwfc LT_LENH,F ; "
btfss STATUS,C ; "
bra AwaitCommand ; "
GiveUp2 btfsc FLAGS,LR_FRM ;If there's been a change in incoming frame
call DealWithFrame ; regs, deal with the frame
bra PrepForNextFrame; "
GiveUp2 call CheckLtReceiver ;Check for and deal with receiver activity
movf UR_LEN,F ;If there's no data in the UART receiver queue,
btfsc STATUS,Z ; loop around again
bra GiveUp2 ; "
@ -608,7 +589,7 @@ GiveUp2 btfsc FLAGS,LR_FRM ;If there's been a change in incoming frame
Deferred
bsf DEF_HIST,0 ;We had to defer, so note that in deferral log
bsf LBACKOFF,0 ;Expand local backoff mask if it's zero
bra SetTimer2 ;And retry
bra TryAgain ;And retry
;entered with BSR = ?
Collided
@ -616,7 +597,7 @@ Collided
lslf LBACKOFF,F ;Expand local backoff mask by one bit, up to a
bsf LBACKOFF,0 ; maximum of 0b1111
bcf LBACKOFF,4 ; "
bra SetTimer2 ;And retry
bra TryAgain ;And retry
;entered with BSR = 0
WaitForSilence
@ -629,7 +610,7 @@ WFS1 bcf INTCON,GIE ;Disable interrupts before checking Timer2
btfss PIR1,TMR2IF ;Unless Timer2 has interrupted, loop around
bra WaitForSilence ; again
call SendDataFrame ;If Timer2 has interrupted, send our broadcast
bra AwaitCommand ; frame and return to await next command
bra PrepForNextFrame; frame and return to await next frame
;entered with BSR = 0
WaitForCts
@ -638,7 +619,7 @@ WaitForCts
bra WFC1 ; came in while we were waiting; handle it
call DealWithFrame ; "
btfss FLAGS,CTS_PLS ;If the flag has been cleared, data's been sent
bra AwaitCommand ; and we can return to await a new command;
bra PrepForNextFrame; and we can return to await a new frame;
bcf FLAGS,CTS_PLS ; otherwise consider it a collision and retry
bra Collided ; "
WFC1 btfss PIR1,TMR2IF ;Unless Timer2 has interrupted, loop around
@ -649,6 +630,31 @@ WFC1 btfss PIR1,TMR2IF ;Unless Timer2 has interrupted, loop around
;;; LocalTalk Transmitter Subprograms ;;;
SetTimer2
movlb 0 ;XORing together the bytes of Timer1 is a cheap
movf TMR1L,W ; but reasonable way to get a 'random' number;
xorwf TMR1H,W ; AND it with the local backoff mask to get our
andwf LBACKOFF,W ; backoff value in multiples of 100us
addlw 4 ;Add 400us to this for minimum interdialog gap
movwf PR2 ;Multiply the value in WREG by 5, because
lslf WREG,W ; Timer2 will interrupt after 20us times the
lslf WREG,W ; value in PR2
addwf PR2,F ; "
decf PR2,F ; "
bsf T2CON,TMR2ON ;Activate Timer2
clrf TMR2 ;Reset Timer2
bcf PIR1,TMR2IF ;Clear the Timer2 interrupt flag
return
CheckLtReceiver
btfsc FLAGS,LR_FRM ;If there's been a change in incoming frame
call DealWithFrame ; regs, deal with the frame
movlb 0 ;If Timer2 has been stopped, it means there was
btfss T2CON,TMR2ON ; activity on LocalTalk bus and we need to
call SetTimer2 ; reset and restart Timer2
movlb 2 ;Callers will have had BSR set to 2
return
DealWithFrame
movlb 2
btfss FLAGS,LR_FRM ;If the incoming frame regs haven't changed,