1 files changed, 135 insertions, 0 deletions
diff --git a/static/blog/input.s b/static/blog/input.s
new file mode 100644
index 0000000..56ccee5
--- /dev/null
+++ b/static/blog/input.s
@@ -0,0 +1,135 @@
+.ROMBANKMAP
+BANKSTOTAL  2
+BANKSIZE    $4000
+BANKS       1
+BANKSIZE    $2000
+BANKS       1
+.ENDRO
+
+.MEMORYMAP
+DEFAULTSLOT  0
+SLOTSIZE     $4000
+SLOT 0       $C000
+SLOTSIZE     $2000
+SLOT 1       $0000
+.ENDME
+
+.ENUM $00
+sleeping     DB
+color        DB
+frame_count  DB
+.ENDE
+
+  .bank 0 slot 0
+  .org $0000
+RESET:
+  SEI
+  CLD
+  LDX #$FF
+  TXS
+  INX
+  STX $2000.w
+  STX $2001.w
+  STX $4010.w
+  LDX #$40
+  STX $4017.w
+
+vblankwait1:
+  BIT $2002
+  BPL vblankwait1
+
+clrmem:
+  LDA #$00
+  STA $0000, x
+  STA $0100, x
+  STA $0300, x
+  STA $0400, x
+  STA $0500, x
+  STA $0600, x
+  STA $0700, x
+  LDA #$FE
+  STA $0200, x
+  INX
+  BNE clrmem
+
+  LDA #%10000001
+  STA color
+
+vblankwait2:
+  BIT $2002
+  BPL vblankwait2
+
+  LDA #%10000000
+  STA $2000
+
+loop:
+  INC sleeping
+wait_for_vblank_end:
+  LDA sleeping
+  BNE wait_for_vblank_end
+
+  ; controller 1 latch
+  LDA #$01
+  STA $4016
+  LDA #$00
+  STA $4016
+
+  ; controller 1 clock, reading the state of the A button
+  LDA $4016
+  AND #%00000001
+  BNE change_color
+  JMP loop_end
+  ; reading the rest of the buttons is unnecessary, so we don't do it
+
+change_color:
+  LDA #$00
+  STA frame_count
+  LDX color
+  CPX #%10000001
+  BEQ turn_green
+  CPX #%01000001
+  BEQ turn_red
+
+turn_blue:
+  LDA #%10000001
+  STA color
+  JMP loop_end
+turn_green:
+  LDA #%01000001
+  STA color
+  JMP loop_end
+turn_red:
+  LDA #%00100001
+  STA color
+
+loop_end:
+  JMP loop
+
+NMI:
+  PHA
+  TXA
+  PHA
+  TYA
+  PHA
+
+  LDA color
+  STA $2001
+
+  LDA #$00
+  STA sleeping
+  PLA
+  TAY
+  PLA
+  TAX
+  PLA
+
+  RTI
+
+  .orga $FFFA
+  .dw NMI
+  .dw RESET
+  .dw 0
+
+  .bank 1 slot 1
+  .org $0000
+  .incbin "sprites.chr"