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README.md

About

An emulator for the (Super) CHIP-8 VM, a target for many classic games.

Blog post.

Installation

Install manually or via Quelpa for the time being.

Usage

You may want to customize chip8-keys to a keymap fitting your keyboard. Given the default value of chip8-keys-qwerty, the hex keypad is mapped to the following keys:

Other customizables of interest are chip8-speed-factor (amount of cycles executed on each timer run) and chip8-key-timeout (number of seconds a key is considered pressed after an event).

To boot up a ROM, type M-x chip8-emulate RET <path/to/rom> RET.

There's a basic set of controls for the emulator, p toggles between play/pause, Q pauses before quitting the window and g resets the currently playing ROM.

Sound emulation

Unfortunately it's hard to play sounds in Emacs in a cross-platform and non-blocking way, for this reason this emulator defaults to printing a "beep" message whenever the game sounds the buzzer. The following hack allows you to play a sound, provided you are on a Linux system with mpv installed:

(defvar my-chip8-mpv-fifo (expand-file-name "/path/to/mpv-fifo")
(defvar my-chip8-beep-file (expand-file-name "/path/to/beep.ogg"))

(defun my-chip8-make-fifo ()
  (shell-command-to-string (concat "mkfifo " my-chip8-mpv-fifo)))

(defun my-chip8-write-to-fifo (string)
  (with-temp-buffer
    (insert string)
    (write-region (point-min) (point-max) my-chip8-mpv-fifo nil 'nomessage)))

(defun my-chip8-beep-start ()
  (my-chip8-write-to-fifo "set pause no\n"))

(defun my-chip8-beep-stop ()
  (my-chip8-write-to-fifo "set pause yes\n"))

(defvar my-chip8-mpv-process nil)

(defun my-chip8-start-mpv ()
  (setq my-chip8-mpv-process
        (start-process "mpv" "*mpv*" "mpv"
                       "--loop" "--pause" "--input-file"
                       my-chip8-mpv-fifo my-chip8-beep-file)))

(defun my-chip8-mode-hook ()
  (when my-chip8-mpv-process
    (stop-process my-chip8-mpv-process))
  (my-chip8-make-fifo)
  (my-chip8-start-mpv))

(add-hook 'chip8-mode-hook 'my-chip8-mode-hook)

(setq chip8-beep-start-function 'my-chip8-beep-start)
(setq chip8-beep-stop-function 'my-chip8-beep-stop)

Debugging

Customize chip8-debug to enable logging of currently executed commands to a *CHIP-8 debug* buffer.

Bugs

Make sure to attach a copy of the problematic ROM and the debug log to your email.