diff options
Diffstat (limited to 'include')
| -rw-r--r-- | include/joypad.s | 39 |
1 files changed, 20 insertions, 19 deletions
diff --git a/include/joypad.s b/include/joypad.s index cc15d02..784bb81 100644 --- a/include/joypad.s +++ b/include/joypad.s @@ -9,17 +9,18 @@ BUTTON_LEFT = 1 << 1 BUTTON_RIGHT = 1 << 0 - ;; Port addresses for controllers. - m_joypad1 = $4016 - ;; m_joypad2 = $4017 + ;; Port address for starting the latch process for both controllers and + ;; reading from Joypad 1. The second Joypad can be accessed by reading from + ;; $4017, which means that functions down below will simply use an indexed + ;; load with the proper value on the index register (i.e. +1). + m_joypad = $4016 ;; The previous reading from the latest read controller. - zp_prev = $21 + zp_prev = $21 - ;; After running a `read_*` function these two variables will contain the - ;; given result. - zp_buttons1 = $22 - zp_buttons2 = $23 + ;; After running a `read_*` function this variable will contain the given + ;; result. + zp_buttons = $22 ;;; ;; Safely read a controller via a re-read algorithm the joypad as indexed by @@ -35,11 +36,11 @@ ;; Mario Bros. 3, it should work for us too :P). Otherwise there is the ;; algorithm via OAM DMA, but it sure is tricky. @reread: - lda Joypad::zp_buttons1, x + lda Joypad::zp_buttons tay jsr Joypad::unsafe_read_x tya - cmp Joypad::zp_buttons1, x + cmp Joypad::zp_buttons bne @reread rts @@ -52,26 +53,26 @@ .proc unsafe_read_x ;; Start the latch process. lda #$01 - sta Joypad::m_joypad1 - sta Joypad::zp_buttons1, x ; Bit as a guard for the loop below. + sta Joypad::m_joypad + sta Joypad::zp_buttons ; Bit as a guard for the loop below. lsr - sta Joypad::m_joypad1 + sta Joypad::m_joypad ;; Now the joypad is ready to accept reads. @loop: - lda Joypad::m_joypad1, x + lda Joypad::m_joypad, x and #%00000011 ; Ignore bits other than controller. cmp #$01 ; Set carry if and only if nonzero. - rol Joypad::zp_buttons1, x ; Carry -> bit 0; bit 7 -> Carry + rol Joypad::zp_buttons ; Carry -> bit 0; bit 7 -> Carry bcc @loop rts .endproc .endscope -;; Shortcut for reading the joypad from the first player safely. -.macro READ_JOYPAD1 - ldx #$00 - lda Joypad::zp_buttons1 +;; Shortcut for reading the joypad indexed by 'x' (0 for controller 1; 1 for +;; controller 2). +.macro READ_JOYPAD_X + lda Joypad::zp_buttons sta Joypad::zp_prev jsr Joypad::read_x .endmacro |