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| author | Miquel Sabaté Solà <msabate@suse.com> | 2024-04-02 23:49:52 +0200 |
|---|---|---|
| committer | Miquel Sabaté Solà <mikisabate@gmail.com> | 2025-02-04 21:04:36 +0100 |
| commit | 3c6a583190b827c0e88e535d486a4f191ee255c0 (patch) | |
| tree | fd21f0c22dbd7e340a53dcb8fad1f4e8c07c73bc /scroll | |
| parent | 1d1f08646352df00977a88adb99e04d54e4dfd5d (diff) | |
| download | code.nes-3c6a583190b827c0e88e535d486a4f191ee255c0.tar.gz code.nes-3c6a583190b827c0e88e535d486a4f191ee255c0.zip | |
Add a way to safely read from controllers
First of all, move some reading utilities into the new `shared`
directory, so controllers can be read by more than one example. Second,
even if we keep the example on `basics/input.s` simple, let's provide a
safe alternative for the other examples.
Signed-off-by: Miquel Sabaté Solà <msabate@suse.com>
Diffstat (limited to 'scroll')
| -rw-r--r-- | scroll/include/joypad.s | 63 |
1 files changed, 0 insertions, 63 deletions
diff --git a/scroll/include/joypad.s b/scroll/include/joypad.s deleted file mode 100644 index 8711c28..0000000 --- a/scroll/include/joypad.s +++ /dev/null @@ -1,63 +0,0 @@ -.segment "CODE" - -;;; -;; Joypad controller code. The following memory addresses are reserved: $21-$23. -;; -;; Memory address $21 is used for internal purposes, whereas $22 and $23 contain -;; the bitmask of the buttons that are pressed from each controller. -;;; - -.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 |