; Joypad Test Cartridge (U) zero-page aliases - Pass 2
; Semantic names for addresses with observed usage patterns; ZpXX names for
; addresses whose role is not yet uniquely determined.

VramPtrLo           = $00 ; VRAM write pointer low byte (indirect, used by VramWriteLoop/VramWrite)
VramPtrHi           = $01 ; VRAM write pointer high byte (indirect)
VramLen             = $02 ; VRAM write data length counter
PpuScrollX          = $03 ; PPU horizontal scroll value (latched to $2005)
Zp04                = $04 ; Temporary zero-page storage
RetAddrTempLo       = $05 ; Return address temp low byte (used by RetAddrUpdate)
RetAddrTempHi       = $06 ; Return address temp high byte (used by RetAddrUpdate)
Zp0D                = $0D ; Temporary zero-page storage
PpuMaskShadow       = $0E ; PPUMASK shadow register (bits cleared for sprite/bg)
PpuScrollY          = $0EC ; PPU vertical scroll value (latched to $2005)
PpuScrollX_Init     = $0ED ; PPU horizontal scroll value written during init
PpuMaskValue        = $0EE ; PPUMASK value written during init (also shadow)
PpuCtrlShadow       = $EF ; PPUCTRL shadow register (NMI bit cleared via and #$7F)
VramToggleFlag      = $CF ; Flag toggled each frame (asl/rol at $C095-$C09D)
NmiFlagByte         = $E0 ; Flag cleared during NMI ($CD0F)

; Controller / button state (indexed by button number via $4E,X)
JoyBtnStateBase     = $4E ; Base address for indexed button states ($4E,X)
JoyBtnState_P1_A    = $4E ; Player 1 button A state/timer
JoyBtnState_P1_B    = $4F ; Player 1 button B state/timer
JoyBtnState_P1_Select = $50 ; Player 1 select state/timer (if used)
JoyBtnState_P1_Start = $51 ; Player 1 start state/timer
JoyBtnState_P1_Up   = $52 ; Player 1 up state/timer
FrameCounterLo      = $53 ; Frame counter low byte (incremented each frame)
FrameCounterHi      = $54 ; Frame counter high byte
JoyBtnTimer_P1_Down = $55 ; Player 1 down button timer
JoyBtnTimer_P1_Left = $56 ; Player 1 left button timer
JoyBtnTimer_P1_Right = $57 ; Player 1 right button timer
JoyBtnTimer_P1_Start2 = $5C ; Player 1 start timer (second instance)
JoyBtnTimer_P1_A2   = $61 ; Player 1 button A timer (second instance)
JoyBtnTimer_P2_Down = $5E ; Player 2 down button timer
JoyBtnTimer_P2_Left = $59 ; Player 2 left button timer
JoyBtnTimer_P2_Right = $64 ; Player 2 right button timer
JoyBtnTimer_P2_A    = $5F ; Player 2 button A timer
JoyBtnTimer_P2_B    = $5A ; Player 2 button B timer

; Generic zero-page aliases (role not yet uniquely determined)
Zp60                = $60 ; Temporary zero-page storage
Zp65                = $65 ; Temporary zero-page storage
Zp66                = $66 ; Temporary zero-page storage
Zp68                = $68 ; Temporary zero-page storage
Zp69                = $69 ; Temporary zero-page storage