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base:c_1351_standard_mouse_routine [2015-04-17 04:30] (current)
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 +====== C= 1351 Standard Mouse Driver ======
  
 +The code is modified from it's original format to KickAssembler format by TWW
 +
 +The routine alters $d000 & $d001. It shuldn'​t be too hard to modify it.
 +
 +There are some enhancments possible as well. Self calibration and even limiting the returned alteration to a signed byte since the movements never exceeds 6 bits...
 +
 +The rest of the routine should speak for itself...
 +
 +<​code>​
 +
 +.var iirq    = $0314
 +.var vic     = $d000
 +.var sid     = $d400
 +.var potx    = sid+$19
 +.var poty    = sid+$1a
 +.var vicdata = $d000         // basics copy of vic register image
 +.var xpos    = vicdata+$00 ​  // low order xposition
 +.var ypos    = vicdata+$01 ​  // y position
 +.var xposmsb = vicdata+$10 ​  // bit 0 is high order x position
 +
 +    lda potx  // get delta values for x
 +    lsr  //CCS64 fix (remove for other emus/real HW)
 +    ldy opotx
 +    jsr movchk
 +    sty opotx
 +
 +    clc  // modify low order xposition
 +    adc xpos
 +    sta xpos
 +    txa
 +    adc #$00
 +    and #%00000001
 +    eor xposmsb
 +    sta xposmsb
 +
 +    lda poty  // get delta value for y
 +    lsr  //CCS64 fix (remove for other emus/real HW)
 +    ldy opoty
 +    jsr movchk
 +    sty opoty
 +
 +    sec  // modify y position ( decrease y for increase in pot )
 +    eor #$ff
 +    adc ypos
 +    sta ypos
 +    dec $01
 +    rts
 +//​==================================================
 +// movchk
 +//       ​entry ​  y = old value of pot register
 +//               a = currrent value of pot register
 +//       ​exit ​   y = value to use for old value
 +//               x,a = delta value for position
 +//​==================================================
 +movchk:
 +    sty oldvalue
 +    sta NewValue
 +    ldx #0
 +
 +    sec
 +    sbc oldvalue
 +    and #%01111111
 +    cmp #%01000000
 +    bcs !+
 +    lsr
 +    beq !Slutt+
 +    ldy NewValue
 +    rts
 +
 +!:  ora #%11000000
 +    cmp #$ff
 +    beq !Slutt+
 +    sec
 +    ror
 +    ldx #$ff
 +    ldy NewValue
 +    rts
 +!Slutt:
 +    lda #0
 +    rts
 +opotx: .byte $00
 +opoty: .byte $00
 +</​code>​
base/c_1351_standard_mouse_routine.txt ยท Last modified: 2015-04-17 04:30 (external edit)