********************************************************************
* JoyDrv - Joystick Driver for 6551/Microsoft Mouse
*
* $Id$
*
* Edt/Rev  YYYY/MM/DD  Modified by
* Comment
* ------------------------------------------------------------------
*   6      1988/??/??
* L2 Upgrade distribution version.

         nam   JoyDrv
         ttl   Joystick Driver for 6551/Microsoft Mouse

* Disassembled 98/09/09 09:50:25 by Disasm v1.6 (C) 1988 by RML

         ifp1
         use   defsfile
         use   m51.defs
         endc

tylg     set   Systm+Objct   
atrv     set   ReEnt+rev
rev      set   $00
edition  set   6

MPISlot  set   $00

         mod   eom,name,tylg,atrv,start,$FF68

name     fcs   /JoyDrv/
         fcb   edition

SlotSlct equ   MPISlot

start    lbra  Init
         lbra  Term
         lbra  SSMsBtn
         lbra  SSMsXY
         lbra  SSJoyBtn

SSJoyXY  pshs  x,b,a
         ldx   #PIA0Base
         lda   <$23,x
         ldb   <$20,x
         pshs  b,a
         anda  #$F7
         sta   <$23,x
         lda   $01,x
         ldb   $03,x
         pshs  b,a
         andb  #$F7
         lsr   $04,s
         bcs   L0043
         orb   #$08
L0043    stb   $03,x
         lda   ,s
         ora   #$08
         bsr   L0065
         std   $06,s
         lda   ,s
         anda  #$F7
         bsr   L0065
         std   $04,s
         puls  b,a
         sta   $01,x
         stb   $03,x
         puls  b,a
         stb   <$20,x
         sta   <$23,x
         puls  pc,y,x
L0065    sta   $01,x
         lda   #$7F
         ldb   #$40
         bra   L0078
L006D    lsrb  
         cmpb  #$01
         bhi   L0078
         lsra  
         lsra  
         tfr   a,b
         clra  
         rts   
L0078    pshs  b
         sta   <$20,x
         tst   ,x
         bpl   L0085
         adda  ,s+
         bra   L006D
L0085    suba  ,s+
         bra   L006D

IRQPckt  equ   *
Pkt.Flip fcb   Stat.Flp	D.Poll filp byte
Pkt.Mask fcb   Stat.Msk	D.Poll mask byte
         fcb   $01      priority
*L0089    fcb   $00
*L008A    fcb   $0f,$01

***      
* JoyDrv Initialization.
*        
* INPUT:  U = JoyDrv data area address (8 bytes)
*        
* OUTPUT:  IRQ service entry installed
*          D, X, and U registers may be altered
*        
* ERROR OUTPUT:  CC = Carry set
*                B = error code
Init     ldd   #$0007
L008F    sta   b,u
         decb
         bpl   L008F
         ldd   >M$Mem,pcr	get base hardware address
         addd  #StatReg		status register address
         leax  IRQPckt,pcr
         leay  IRQSvc,pcr
         os9   F$IRQ    
         bcs   TermExit		go report error...
         ldx   >M$Mem,pcr	get base hardware address again
         ldd   #(TIC.RTS!Cmd.DTR)*256+(DB.8!Ctl.RClk!BR.01200) [D]=command:control
         pshs  cc
         orcc  #IntMasks	disable IRQs while setting up hardware
         sta   PRstReg,x	reset 6551
         std   CmdReg,x		set command and control registers
         lda   >PIA1Base+3	get PIA CART* input control register
         anda  #$FC		clear PIA CART* control bits
         sta   >PIA1Base+3	disable PIA CART* control bits
         lda   >PIA1Base+2	clear possible pending PIA CART* FIRQ
         lda   #$01		GIME CART* IRQ enable
         ora   <D.IRQER		mask in current GIME IRQ enables
         sta   <D.IRQER		save GIME CART* IRQ enable shadow register
         sta   >IrqEnR		enable GIME CART* IRQs
         ldb   DataReg,x	ensure old error,
         ldb   StatReg,x	Rx data, and
         ldb   DataReg,x	IRQ flags
         ldb   StatReg,x	are clear
         andb  Pkt.Mask,pcr	IRQ bits still set?
         bne   InitErr		yes, go disable ACIA and return...
         lda   SlotSlct,pcr	get MPI slot select value
         bmi   InitExit		no MPI slot select, go exit...
         sta   >MPI.Slct	recover original regs, return...
InitExit puls  pc,cc

***
* JoyDrv Termination.
*
* INPUT:  U = JoyDrv data area address (8 bytes)
*
* OUTPUT:  IRQ service entry removed
*          D, X, and U registers may be altered
*
* ERROR OUTPUT:  CC = Carry set
*                B = error code
Term     pshs  cc		save regs we alter
         orcc  #IntMasks	mask IRQs while disabling ACIA
InitErr  ldx   M$Mem,pcr	get base address
         lda   #TIC.RTS!Cmd.RxIE!Cmd.DTR	disable all
         sta   CmdReg,x		ACIA IRQs
         puls  cc
         leax  StatReg,x	point to status register
         tfr   x,d		copy status register address
         ldx   #$0000		remove IRQ table entry
         leay  IRQSvc,pcr
         os9   F$IRQ    
TermExit rts   

***
* Joystick button(s) status check.
*
* INPUT:  U = JoyDrv data area address (8 bytes)
*
* OUTPUT:  B = button or "clear" status
*              button(s)     = xxxxLRLR
*          A, X, and U registers may be altered
*
* ERROR OUTPUT:  none
SSJoyBtn ldb   #$FF
         ldx   #PIA0Base
         stb   $02,x
         ldb   ,x
         comb  
         andb  #$0F
         rts   

***
* Mouse button(s) status check.
*
* INPUT:  U = JoyDrv data area address (8 bytes)
*        
* OUTPUT:  B = button or "clear" status
*              button(s)     = xxxxLRLR
*              clear         = 10000000
*              shift-clear   = 11000000
*          A, X, and U registers may be altered
*
* ERROR OUTPUT:  none
SSMsBtn  lda   ,u			get byte at ,U
         clrb  				clear B
         bita  #$20			A %00100000 bit clear?
         beq   L010E			branch if so
         orb   #$03			else set OR B with %00000011
L010E    bita  #$10			A %00010000 bit clear?
         beq   L0114			branch if so
         orb   #$0C			else set OR B with %11000000
L0114    tfr   b,a			move B to A
         anda  #$FA			AND A with %11111010
         pshs  a			save A
         andb  #$05			AND B with %00000101
         orb   7,u			OR B with ????
         leax  <L0134,pcr
         lda   b,x
         anda  #$0A
         sta   7,u
         ldb   b,x
         andb  #$85
         bpl   L0131
         ldb   2,u
         andb  #$C0
L0131    orb   ,s+
         rts   
L0134    fdb   $0003,$0003,$0806,$0206,$8002,$0002,$0806,$0a06

***
* Joystick/Mouse XY coordinate read.
* 
* INPUT:  A = side flag (1 = right, 2 = left)
*         Y = resolution (0 = low, 1 = high)
*         U = JoyDrv data area address (8 bytes)
* 
* OUTPUT:  X = horizontal coordinate (left edge = 0)
*              low resolution = 0 to 63 
*              high resolution = 0 to HResMaxX
*          Y = vertical coordinate (top edge = 0)
*              low resolution = 0 to 63
*              high resolution = 0 to HResMaxY
*          D and U registers may be altered
*        
* ERROR OUTPUT:  none           
SSMsXY   pshs  cc
         orcc  #IntMasks
         ldx   3,u
         ldd   5,u
         lsra  
         rorb  
         tfr   d,y
         puls  pc,cc

***      
* Mouse IRQ service routine.
*        
* INPUT:  A = flipped and masked device status byte 
*         U = mouse data area address
*
* OUTPUT:  updated serial mouse data
*          CC Carry clear
*          D, X, Y, and U registers may be altered
*
* ERROR OUTPUT:  none
IRQSvc   ldx   M$Mem,pcr
         bita  #Stat.Err	any error(s)?
         beq   ChkRDRF		no, go check Rx data
         ldb   DataReg,x	read Rx data register to clear error flags
L015C    lda   2,u		get current button and Rx data counter
         anda  #^%00000111	clear Rx data counter
L0160    sta   2,u		reset Rx mouse data counter to wait for sync...
IRQExit  clrb  			clear carry to mark IRQ serviced
         rts   

ChkRDRF  bita  #Stat.RxF	Rx data?
         beq   IRQExit		no, but this branch should never be taken...
         ldb   DataReg,x	get Rx data
         lda   2,u		get button status and Rx counter
         anda  #%00000111	waiting for sync with mouse data?
         bne   L017A        branch if counter is not zero
         bitb  #$40         OR Rx data with $40
         beq   IRQExit      exit if 0
L0174    stb   a,u          else save B at a,u
         inc   2,u          and increment counter
         clrb  
         rts   
L017A    bitb  #$40         OR Rx data with $40
         bne   L015C        if set, reset data counter
         cmpa  #$02         is this third byte?
         bcs   L0174        branch if less than
         ldx   #HResMaxY*2
         pshs  x            save on stack
         lda   ,u           get first byte of mouse packet
         lsra               shift right
         lsra               and again
         leax  5,u          point to X to CrntYPos,u
         bsr   L01A9        process
         ldd   ,u           get first and second byte of mouse packet
         ldx   #HResMaxX    get max X value        
         stx   ,s           save on stack in place of earlier X
         leax  3,u          point X to CrntXPos,u
         bsr   L01A9        process
         leas  $02,s        restore stack
         lda   #$80
         ldx   3,u          get CrntXPos,u
         cmpx  #320     
         bcc   L0160        branch if equal
         ora   #192
         bra   L0160
L01A9    lslb  
         lslb  
         lsra  
         rorb  
         lsra  
         rorb  
         sex   			sign extend mouse packet's 2nd XY offset ([D] = -128 to +127)
         pshs  d		save it temporarily...
         bpl   PosAdjst		go de-sensitize positive "ballistic" XY offset
         orb   #%00000111	if -8<XYoffset<0, no "ballistic" response
         addd  #$0001		"fix" negative offset "ballistic" response
         bra   RShiftD		go calculate "ballistic" offset
PosAdjst andb  #%11111000	if 0<XYoffset<8, no "ballistic" response
RShiftD  asra  			calculate 50% of XY offset
         rorb  			for "ballistic" response.
         addd  ,s++		add original XY offset total, clean up stack
         addd  ,x		add mouse's current XY position
         bpl   CheckPos		zero or positive XY position, go check it...
         clra  			set minimum XY position
         clrb
CheckPos cmpd  2,s		past maximum XY position?
         bls   SavePos		no, go save it...
         ldd   $02,s		get maximum XY position
SavePos  std   ,x		save new XY position
         rts   

         emod
eom      equ   *
         end