;license:MIT
;(c) 2018 by 4am
;
!cpu 6502
!to "build/FX/FOURSQUARE",plain
*=$6000

         lda   #<@coords
         sta   $FE
         lda   #>@coords
         sta   $FF
         ldy   #$00
@loop1
         lda   ($FE),y
         bpl   @copy
         lda   #$18
         jsr   WaitForKeyWithTimeout
         bmi   @exit
         bpl   @next                 ; always branches
@copy
         tax
         iny
         lda   ($fe),y
         tay
         txa
         jsr   HGRBlockToWhite
@next
         inc   $FE
         bne   +
         inc   $FF
+        inc   $FE
         bne   +
         inc   $FF
+        ldy   #$00
         lda   ($FE),y
         cmp   #$80
         bne   @loop1

@loop2
         dec   $FE
         lda   $FE
         cmp   #$FF
         bne   +
         dec   $FF
+        dec   $FE
         lda   $FE
         cmp   #$FF
         bne   +
         dec   $FF
+        ldy   #$00
         lda   ($FE),y
         cmp   #$80
         beq   @exit
         lda   ($FE),y
         bpl   @copy2
         lda   #$18
         jsr   WaitForKeyWithTimeout
         bmi   @exit
         bpl   @loop2                ; always branches
@copy2
         tax
         iny
         lda   ($fe),y
         tay
         txa
         jsr   HGRBlockCopy
         beq   @loop2                ; always branches
@exit    rts

         !byte $80,$80
@coords
         !source "src/fx/fx.hgr.foursquare.data.a"
         !byte $80
         !source "src/wait.a"
         !source "src/fx/fx.hgr.common.a"