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Added some HD6309 optimizations to level1's covdg.asm file. Optimization 1) added TFM clear screen Optimization 2) added TFM scroll screen One of the optimizations was copied over from the level2's covdg.asm file.
author David Ladd <drencor-xeen@users.sourceforge.net>
date Fri, 28 Jul 2017 15:42:20 -0500
parents b8c7b7fbf3c9
children
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********************************************************************
* JoyStk - Joystick Subroutine Module
*
* $Id$
*
* Ed.    Comments                                       Who YY/MM/DD
* ------------------------------------------------------------------
*   1    Created for Coyota project                     BGP 98/??/??

         nam   JoyStk
         ttl   Joystick Subroutine Module

         ifp1  
         use   defsfile
         endc  

edition  set   1

         mod   eom,name,Sbrtn+Objct,Reent+0,Joy,size

size     equ   .

name     fcs   /JoyStk/
         fcb   edition

* Joystick Read Routine
*
* Entry:
*   X  = $0000 for Right, $0001 for Left
*
* Exit:
*   2,s = param count (should be 4)
*   4,s = addr of 1st param            (joystick number)
*   6,s = size of 1st param
*   8,s = addr of 2nd param            (joystick X)
*  10,s = size of 2nd param
*  12,s = addr of 3rd param            (joystick Y)
*  14,s = size of 3rd param
*  16,s = addr of 4th param            (joystick button)
*  18,s = size of 4th param

Joy      ldd   2,s        get param count
         cmpd  #4         4 params?
         bne   error
         ldd   [4,s]      get joystick num.
* fix up joystick value
         lslb             shift left 3 times
         lslb  
         lslb  
         pshs  b
         lda   #$00       fetch X value
         bsr   JoyPoll
         std   [9,s]      save in param addr
         lda   #$08       fetch Y value
         ldb   ,s+        get joystick selector
         bsr   JoyPoll
         std   [12,s]
* get button value
         clra  
         ldb   #$FF
         stb   $FF02
         ldb   $FF00
         clr   $FF02
         comb  
         tst   [5,s]
         beq   BtnLft
         andb  #$05
         bra   BtnCnt
BtnLft   andb  #$0A
         lsrb  
BtnCnt   lsrb  
         bcc   BtnCnt2
         orb   #$01
BtnCnt2  std   [16,s]     save button
         clrb             no error
         rts   
error    coma  
         ldb   #E$IllArg
         rts   


* Joystick read routine
*
* Entry:
*   A  = value to place in $FF01 (00 for X, 08 for Y)
*   B  = value to place in $FF03 (00 for Right, 08 for Left)
*
* Exit:
*   D  = value

JoyPoll  pshs  a
         lda   $FF01
         anda  #$F7
         ora   ,s+
         sta   $FF01      select X or Y

         pshs  b
         lda   $FF03
         anda  #$F7
         ora   ,s+
         sta   $FF03      select Right or Left

* Low res binary tree search for joystick value
         lda   #$7F       DAC value
         ldb   #$40
         bra   L0122

L0117    lsrb             reset DAC offset value
         cmpb  #$01
         bhi   L0122
         lsra
         lsra
         tfr   a,b
         clra
         rts
L0122    pshs  b
         sta   $FF20
         tst   $FF00
         bpl   L012F
         adda  ,s+
         bra   L0117
L012F    suba  ,s+
         bra   L0117

         emod  
eom      equ   *
         end