;Mouse Control Assembly Language Routines for Commander x16 computer

        SUBROUTINE _MOUSE

;Mouse Mode Constants for MCNFG Routine
MHIDE   EQU $00     ;Hide Mouse
MSHOW   EQU $01     ;Show Mouse
MCSTM   EQU $FF     ;Show Mouse - Custom Sprite

;Mouse Button Bitmasks
MBLEFT  EQU $01     ;Left Mouse Button
MBMIDL  EQU $04     ;Middle Mouse Button
MBRGHT  EQU $02     ;Right Mouse Button

;Mouse Scaling Constants
;Specific to the X16
MSNONE  EQU $00     ;Do Not Change Resolution
MSLOW   EQU $02     ;Low Resolution (320x240)
MSHIGH  EQU $01     ;High Resolution (640x480)

;Mouse Status Variables
MOUSEX  EQU $02   ;Mouse X Position (ABI Register R0)
MOUSEY  EQU $04   ;Mouse Y Position (ABI Register R1)
MOUSEB  EQU $06   ;Mouse Button Status (ABI Register R2L)

;Kernal Internal Mouse Variables
MOUSEV  EQU $A021   ;Valid for Kernal Version R37

;mcnfg(mode) - Configure Mouse
;Args: A = Mode
;Affects: X,Y
;Returns: A = Result Code: $00 = Success
MCNFG:   LDX #MSLOW     ;Set Scale for 320x240 Screen
MCNFGS:  JSR $FF68  ;Kernal mouse_config Routine
         LDA #0     ;Return Success
         RTS

;mread() - Read Mouse
;Sets: MOUSEX, MOUSEY, MOUSEB
;Affects: X
;Returns: A = Result Code: $00 = Success
MREAD:  LDX #MOUSEX ;Set Data Address
        JSR $FF6B   ;Execute Kernal mouse_get Routine
        STA MOUSEB  ;Store Mouse Button Status
        LDA #0      ;Return Success
        RTS

;mscan() - Scan Mouse
;Retrieves mouse state for subsequent mread()
;This is called during the default interrupt
;handler so should only be called if the interrupt
;routine is entirey replaced.
MSCAN   EQU $FF71   ;Aliased to Kernal mouse_scan routine