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;;; TODO: safe read
.scope Joypad
;; Button masks.
BUTTON_A = 1 << 7
BUTTON_B = 1 << 6
BUTTON_SELECT = 1 << 5
BUTTON_START = 1 << 4
BUTTON_UP = 1 << 3
BUTTON_DOWN = 1 << 2
BUTTON_LEFT = 1 << 1
BUTTON_RIGHT = 1 << 0
;; Port addresses for controllers.
JOYPAD1 = $4016
JOYPAD2 = $4017
;; We keep all the information from controller from mainly two variables:
;; m_buttons1 and m_buttons2; containing respectively the buttons pressed
;; for this frame for both controllers. The m_inv_buttons ($21) is an
;; internal variable and should not be used for anything outside of this
;; usage.
m_inv_buttons = $21
m_buttons1 = $22
m_buttons2 = $23
;; READ_CONTROLLER reads the input from the controller mapped into the given
;; port, and saves the state into the given `buttons` address.
;; Implementation taken from NESHacker's example of smb3-like movement.
.macro READ_CONTROLLER port, buttons
lda m_inv_buttons
tay
lda #1
sta port
sta m_inv_buttons
lsr
sta port
:
lda port
lsr
rol m_inv_buttons
bcc :-
tya
eor m_inv_buttons
and m_inv_buttons
sta buttons
.endmacro
;; read sets the values for m_buttons1 and m_buttons2 as read from both
;; controllers.
.proc read
READ_CONTROLLER JOYPAD1, m_buttons1
READ_CONTROLLER JOYPAD2, m_buttons2
rts
.endproc
.endscope
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