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—base:scanning_the_keyboard_without_joysticks_interfere [2022-03-11 22:40] (current) – created erhan
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 +====== Scanning the keyboard without joysticks interfere ======
  
 +Converts keycode ($00-$3F) to $DC00-$DC01 values and scans without interfering from joysticks at port 1 or 2. Also keeps history, to detect key press & hold.
 +
 +<code>
 +
 +;64tass format
 +;with default $dc02 - $dc03 values ($ff and $00)
 +;taken from Platoon game, shortened and key history integrated.
 +;code to key conversion table below, from c64-wiki.com
 +
 +;to use inside irq, below code is enough :
 +; lda #$keycode
 +; jsr keyscan
 +; bcc +
 +; inc $d020
 +;+ rts 
 +
 +;$00 Inst/Del $10 5 $20 9 $30 £
 +;$01 Return $11 R $21 I $31 *
 +;$02 Crsr ←→ $12 D $22 J $32 ]
 +;$03 F7/F8 $13 6 $23 0 $33 Clr/Home
 +;$04 F1/F2 $14 C $24 M $34 R.Shift
 +;$05 F3/F4 $15 F $25 K $35 =
 +;$06 F5/F6 $16 T $26 O $36 ↑
 +;$07 Crsr ↑↓ $17 X $27 N $37 ?
 +;$08 3 $18 7 $28 + $38 1
 +;$09 W $19 Y $29 P $39 ←
 +;$0A A $1A G $2A L $3A Ctrl
 +;$0B 4 $1B 8 $2B − $3B 2
 +;$0C Z $1C B $2C > $3C Space
 +;$0D S $1D H $2D [ $3D Commodore
 +;$0E E $1E U $2E @ $3E Q
 +;$0F L.Shift $1F V $2F < $3F Run/Stop
 +
 +
 + * = $1000
 +
 + lda #$3e ;scan for key "Q"
 + jsr keyscan
 + bcc +
 + inc $d020 ;C=1, this code executed if key is pressed
 ++
 +- lda $d011
 + bpl -
 +- lda $d011
 + bmi -
 +
 + jmp $1000
 +
 +keyscan
 +; sty backy+1 ;remove comment if you need .Y preserved
 + pha
 + lsr
 + lsr
 + lsr
 + tay
 + lda row,y
 + sta $dc00
 + pla
 + and #$07
 + tay
 + lda $dc01
 + and column,y
 + bne nokey
 + lda #$ff ;key is checked 2nd time, to be sure of
 + sta $dc00 ;joy #1 and #2 are not interfering
 + lda $dc01
 + and column,y
 + beq nokey
 +
 + cmp histv ;history value ?
 + bne +
 + clc         ;case #3, key is held down. keep history & set C=0
 + bcc backy
 +
 +nokey asl ;case #1, no keypress, update history value 2x & set C=0
 + clc
 + .byte $24
 ++ sec ;case #2, key pressed&released. update history & set C=1
 + sta histv
 +
 +backy
 +; ldy #$00 ;remove comment if you need .Y preserved
 + lda #$ff
 + sta $dc00 ;set default value
 + lda #$7f
 + sta $dc01 ;set default value
 + rts
 +
 +
 +row .byte $fe,$fd,$fb,$f7,$ef,$df,$bf,$7f
 +column .byte $01,$02,$04,$08,$10,$20,$40,$80
 +histv .byte $00
 +
 +</code>
base/scanning_the_keyboard_without_joysticks_interfere.txt · Last modified: 2022-03-11 22:40 by erhan

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