VICE.js

Versatile Commodore Emulator for JavaScript

JavaScript port of VICE 2.4 using Emscripten.

Browser	Version	Status	Note
Firefox	39	:)	ok
Chrome	43	:
IE	11	:(	broken

Examples

###c64 basic

<!doctype html>
<html lang="en-us">
    <body>
        <!-- the canvas *must not* have any border or padding, or mouse coords will be wrong -->
        <canvas  id="canvas" style="border: 0px none;"></canvas>
        <script type="text/javascript" >
            var Module = {
                arguments: ['+sound'],
                canvas: document.getElementById('canvas'),
            };
        </script>
        <script type="text/javascript" src="js/x64.js"></script>
    </body>
</html>

###auto-run a D64 disk image

<!doctype html>
<html lang="en-us">
    <body>
        <!-- the canvas *must not* have any border or padding, or mouse coords will be wrong -->
        <canvas  id="canvas" style="border: 0px none;"></canvas>
        <script type="text/javascript" >

            function audioDetected() {
                return (typeof Audio === 'function' && new Audio().mozSetup === 'function') ||
                    (typeof AudioContext === 'function') ||
                    (typeof webkitAudioContext === 'function');
            }

            function loadFiles() {
                var base64EncodedFile = '...';
                FS.createDataFile('/', 'disk-image.d64', window.atob(base64EncodedFile), true, true);
            }

            var viceArguments = ['-autostart', 'disk-image.d64'].concat(
                audioDetected() ? ['-soundsync', 0, '-soundrate', 22050, '-soundfragsize', 2] : ['-sound']
            );

            var Module = {
                preRun: [loadFiles],
                arguments: viceArguments,
                canvas: document.getElementById('canvas'),
            };

        </script>
        <script type="text/javascript" src="js/x64.js"></script>
    </body>
</html>

###send keyboard commands

<!doctype html>
<html lang="en-us">
    <body>
        <!-- the canvas *must not* have any border or padding, or mouse coords will be wrong -->
        <canvas  id="canvas" style="border: 0px none;"></canvas>
        <p><button onmousedown="sendSpaceKeyPressedCode()" onmouseup="sendSpaceKeyReleasedCode()">space bar</button></p>
        <script type="text/javascript" >

            var C64_SPACE_KEY_CODE = 32;

            function sendSpaceKeyPressedCode() {
                Module.ccall('keyboard_key_pressed', 'undefined', ['number'], [C64_SPACE_KEY_CODE]);  
            }

            function sendSpaceKeyReleasedCode() {
                Module.ccall('keyboard_key_released', 'undefined', ['number'], [C64_SPACE_KEY_CODE]);
            }

            var Module = {
                arguments: ['+sound'],
                canvas: document.getElementById('canvas'),
            };
            
        </script>
        <script type="text/javascript" src="js/x64.js"></script>
    </body>
</html>

Best Configuration Options

async mode:

soundfragsize 2 -soundrate 22050 -soundsync 0

sync mode:

soundfragsize 2 -soundrate 22050 -soundsync 0 -ntsc
ntsc is important because browser requestAnimationFame is going to deliver 60 fps which means less cpu time is wasted during vsync delay

Development

###How to find key codes

in /vice/src/arch/sdl/kbd.c # sdlkbd_press()
this line prints key codes to console when key is pressed

fprintf(stderr, "%s: %i (%s),%i\n",__func__,key,SDL_GetKeyName(key),mod);

activate by compiling vice with SDL_DEBUG flag

Resources

C64 Wiki
Commodore 64 keyboard matrix layout
COMMODORE 64 ROGRAMMER'S REFERENCE GUIDE
Commodore Manuals
Coroutines in C
requestAnimationFrame setting fps
SDL 1.2 to 2.0 Migration Guide
VICE Manual
VICE options

Tasks

try using worker thread (emcc --proxy-to-worker)
- initial tests show +10% perf in Chrome, but missing SDL Audio
- discuss proxy-to-worker
- discuss web audio & web workers
- nice callback pattern for web workers
- Proxy SDL Audio
  - \vice\src\sounddrv\soundsdl.c
  - \emscripten\src\library_sdl.js
    - line 1636 creates Audio object
  - \emscripten\src\proxyWorker.js
  - \emscripten\src\proxyClient.js
  - Native audio classes shim proxy option: Create proxies for each Audio class and simply define these classes in proxyWorker.js.
    - proxyClient will feature detect available Audio classes and send this info the proxyWorker
    - proxyWorker will implement Audio classes based on features detected by proxyClient
    - Conclusions
      - A large API needs to be proxied, lots of different Classes some vary by browser.
      - Managing all the audio object proxies (createBufferSource, createBuffer) is complicated.
      - Need to track references to proxied objects.
      - Determining when to free objects can be difficult.
      - postMessage communication would be chatty.
  - Proxy SDL_*Audio C functions
    - Seperate C code from Web Audio API's
      - Re-factor pushAudio function to use data arrays instead of a pointer to heap
    - Copy Web Audio parts of SDL_*Audio functions to proxyClient
    - Detect proxyClient in library_sdl and invoke proxy versions of SDL_*Audio functions
    - Conclusions
      - Code duplication, some code from SDL_*Audio functions exist in both library_sdl and proxyClient
      - extra data copy required by pushAudio function
        
        current process
        
        copy data from heap directly into Web Audio buffers $expensive
        
        new worker process
        
        copy data from heap into ArrayBuffer $expensive
        
        transfer ownership of data to browser thread
        
        copy data into Web Audio buffers $expensive
    - Issues
      - SDL init is synchronous so if there's a problem in the browser context part, worker does not know.
        
        Possible solution is to feature detect Web Audio and send the info to worker ahead of time so it can make a better SDL init process.
      - Sound buffer overflows if tab goes to background, probably caused by request animation frame slowing down browser thread but worker is still at full speed.
      - Sound clicks, weird timing
    - Use function addRunDependency(id) instead of custom waitForAudioFeatures logic.
    - Test with \emscripten\tests\sdl_audio_beep.cpp
      - ./emcc -O2 --minify 0 -s DISABLE_EXCEPTION_CATCHING=0 -o audio-beep.html --proxy-to-worker --closure 1 tests/sdl_audio_beep.cpp
    - proxy-dependency-bug
      - ./emcc tests/hello_world_sdl.cpp -o hello.html --proxy-to-worker --post-js hello_world_dependencies.js
file issue for Emscripten with patch
- Chrome has a console in web worker context so detect it before over-writing @ proxyWorker.js line ~81

self.console = self.console || {
  log: function(x) {
    Module.printErr(x);
  }
};

add other computers
- VIC-20
fix vice menu ui (F12)

sloanlance/vice.js

VICE.js

Examples

Best Configuration Options

Development

Resources

Tasks