working single line with drop arrow key write

2024-11-21 14:31:12 +00:00 · 2018-02-04 19:21:35 -05:00 · 2018-02-04 19:21:35 -05:00 · f68a7a36c4
commit f68a7a36c4
parent 5aa31dfafe
1 changed files with 47 additions and 3 deletions
--- a/src/main.S
+++ b/src/main.S
@ -36,13 +36,42 @@ inloop      clc
            bit   #%1
            bmi   keybranch
            jmp   inloop
-
 keybranch   jsr   keydown
            jmp   inloop

 keydown     nop
-            stal  $000400,X
-            ldal  $00C010
+            cmp   #$8B        ; up
+            beq   up
+            cmp   #$8A        ; down
+            beq   down
+            cmp   #$88        ; left
+            beq   left
+            cmp   #$95        ; right
+            beq   right
+            jmp   dispchar
+
+up          nop
+            jmp   rtsout
+down        nop
+            jmp   rtsout
+
+left        clc
+            cpx   #0
+            beq   rtsout
+            dex
+            jmp   rtsout
+
+right       clc
+            cpx   #39
+            beq   rtsout
+            inx
+            jmp   rtsout
+
+dispchar    stal  $000400,X
+            jmp   rtsout
+
+rtsout      ldal  $00C010
+            lda   #0
            rts

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@ -187,6 +216,21 @@ brkboi      brk



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