NES Power Pad

ReadController1:
  LDA buttons1Lo
  STA buttons1Lo_old   ;save last frame's joypad button states

  LDA buttons1Hi
  STA buttons1Hi_old   ;save last frame's joypad button states

  LDA #$01
  STA $4016
  LDA #$00
  STA $4016
  LDX #$08
ReadController1Loop:
  LDA $4016
  LSR A            ; bit0 -> Carry
  LSR A            ; bit1 -> Carry
  LSR A            ; bit2 -> Carry
  LSR A            ; bit3 -> Carry
  ROL buttons1Lo     ; bit3 <- Carry
  LSR A            ; bit4 -> Carry
  ROL buttons1Hi     ; bit4 <- Carry
  DEX
  BNE ReadController1Loop

  LDA buttons1Lo_old ;what was pressed last frame.  EOR to flip all the bits to find ...
  EOR #$FF    ;what was not pressed last frame
  AND buttons1Lo ;what is pressed this frame
  STA buttons1Lo_pressed ;stores off-to-on transitions

  LDA buttons1Hi_old ;what was pressed last frame.  EOR to flip all the bits to find ...
  EOR #$FF    ;what was not pressed last frame
  AND buttons1Hi ;what is pressed this frame
  STA buttons1Hi_pressed ;stores off-to-on transitions
  RTS


handle_input:
Read2:
  LDA buttons1Lo_pressed      ; power pad button 2
  AND #%10000000
  BEQ Read2Done

Read2Done:


Read1:
  LDA buttons1Lo_pressed     ; power pad button 1
  AND #%01000000
  BEQ Read1Done

Read1Done:


Read5:
  LDA buttons1Lo_pressed     ; power pad button 5
  AND #%00100000
  BEQ Read5Done

Read5Done:


Read9:
  LDA buttons1Lo_pressed     ; power pad button 9
  AND #%00010000
  BEQ Read9Done

Read9Done:


Read6:
  LDA buttons1Lo_pressed     ; power pad button 6
  AND #%00001000
  BEQ Read6Done

Read6Done:


Read10:
  LDA buttons1Lo_pressed     ; power pad button 10
  AND #%00000100
  BEQ Read10Done

Read10Done:


Read11:
  LDA buttons1Lo_pressed     ; power pad button 11
  AND #%00000010
  BEQ Read11Done

Read11Done:


Read7:
  LDA buttons1Lo_pressed     ; power pad button 7
  AND #%00000001
  BEQ Read7Done

Read7Done:


Read4:
  LDA buttons1Hi_pressed     ; power pad button 4
  AND #%10000000
  BEQ Read4Done


Read4Done:


Read3:
  LDA buttons1Hi_pressed     ; power pad button 3
  AND #%01000000
  BEQ Read3Done

Read3Done:


Read12:
  LDA buttons1Hi_pressed     ; power pad button 12
  AND #%00100000
  BEQ Read12Done

Read12Done:


Read8:
  LDA buttons1Hi_pressed     ; power pad button 8
  AND #%00010000
  BEQ Read8Done

Read8Done:

  RTI