diff --git a/README.md b/README.md index 1c43436db..b7c0518a3 100644 --- a/README.md +++ b/README.md @@ -4,22 +4,22 @@ DOSBox ported to Emscripten About ----- -[DOSBox](http://www.dosbox.com/) is an open source DOS emulator designed for -running old games. [Emscripten](https://github.com/kripken/emscripten) -compiles C/C++ code to JavaScript. This is a version of DOSBox which can be -compiled with Emscripten to run in a web browser. It allows running old DOS -games and other DOS programs in a web browser. +[DOSBox](https://www.dosbox.com/) is an open source +[DOS](https://en.wikipedia.org/wiki/DOS) emulator designed for +running games. [Emscripten](https://emscripten.org/) compiles code to +JavaScript and [WebAssembly](https://webassembly.org/). This is a version of +DOSBox which can be compiled with Emscripten to run in a web browser. It allows +running old DOS games and other DOS programs in a web browser. DOSBox is distributed under the GNU General Public License. See the -[COPYING file](https://github.com/dreamlayers/em-dosbox/blob/em-dosbox-0.74/COPYING) -for more information. +[COPYING file](COPYING) for more information. Status ------ Em-DOSBox runs most games successfully in web browsers. Although DOSBox has not been fully re-structured for running as an Emscripten main loop, most -functionality is available thanks to emterpreter sync. A few programs can +functionality is available thanks to Emscripten Asyncify. A few programs can still run into problems due to paging exceptions. Other issues @@ -27,24 +27,24 @@ Other issues * Game save files are written into the Emscripten file system, which is by default an in-memory file system. Saved games will be lost when you close - the web page. + the web page. It is possible to interface other JavaScript code with the + Emscripten file system to address this issue. * Compiling in Windows is not supported. The build process requires a Unix-like environment due to use of GNU Autotools. See Emscripten [issue 2208](https://github.com/kripken/emscripten/issues/2208). * Emscripten [issue 1909](https://github.com/kripken/emscripten/issues/1909) used to make large switch statements highly inefficient. It seems fixed now, but V8 JavaScript Engine [issue -2275](http://code.google.com/p/v8/issues/detail?id=2275) prevents large switch +2275](https://bugs.chromium.org/p/v8/issues/detail?id=2275) prevents large switch statements from being optimized. Because of this, the simple, normal and prefetch cores are automatically transformed. Case statements for x86 instructions become functions, and an array of function pointers is used instead of the switch statements. The `--enable-funarray` configure option controls this and defaults to yes. -* The same origin policy prevents access to data files when running via a -file:// URL in some browsers. Use a web server such as -`python -m SimpleHTTPServer` instead. +* Most web browsers prevent access to other files when using `file://` URLs. +Use a web server such as `python -m http.server` instead. * In Firefox, ensure that -[dom.max\_script\_run\_time](http://kb.mozillazine.org/Dom.max_script_run_time) +[dom.max\_script\_run\_time](https://kb.mozillazine.org/Dom.max_script_run_time) is set to a reasonable value that will allow you to regain control in case of a hang. * Firefox may use huge amounts of memory when starting asm.js builds which have @@ -55,19 +55,26 @@ DOSBox can only give full precision when running on an x86 CPU. Compiling --------- -Use the latest stable version of Emscripten (from the master branch). For +This code retains the ability to build a normal version of DOSBox, for +running as an ordinary computer application. These instructions are focused +on how to build using Emscripten, for running in a web browser. + +Use the latest stable version of Emscripten. For more information see the the -[Emscripten installation instructions](https://kripken.github.io/emscripten-site/docs/getting_started/downloads.html). +[Emscripten installation instructions](https://emscripten.org/docs/getting_started/downloads.html). Em-DOSBox depends on bug fixes and new features found in recent versions of Emscripten. Some Linux distributions have packages with old versions, which should not be used. First, create `./configure` by running `./autogen.sh`. Then configure with `emconfigure ./configure` and build with `make`. -This will create `src/dosbox.js` which contains DOSBox and `src/dosbox.html`, -a web page for use as a template by the packager. These cannot be used as-is. -You need to provide DOSBox with files to run and command line arguments for -running them. +DOSBox will be contained in `src/dosbox.js`, and if WebAssembly is enabled +(the default), `src/dosbox.wasm`. Also, `src/dosbox.html` will be created, +which is a simple web page that provides an interface to DOSBox. You can +customize it or use DOSBox in your own web page. If you built with Asyncify +enabled (the default), you can open `src/dosbox.html` via a web server, and +run DOSBox. Without Asyncify DOSBox won't work like that, and you need to add +files to run. See below for information on "Running DOS Programs". This branch supports SDL 2 and uses it by default. Emscripten will automatically fetch SDL 2 from Emscripten Ports and build it. Use of `make -j` @@ -78,39 +85,30 @@ To use a different pre-built copy of Emscripten SDL 2, specify a path as in `emconfigure ./configure --with-sdl2=/path/to/SDL-emscripten`. To use SDL 1, give a `--with-sdl2=no` or `--without-sdl2` argument to `./configure`. -Emscripten emterpreter sync is used by default. This enables more DOSBox -features to work, but requires an Emscripten version after 1.29.4 and may -cause a small performance penalty. To disable use of emterpreter sync, -add the `--disable-sync` argument to `./configure`. When sync is used, -the Emscripten -[memory initialization file](https://kripken.github.io/emscripten-site/docs/optimizing/Optimizing-Code.html#memory-initialization) -is enabled, which means `dosbox.html.mem` needs to be in the same folder as -`dosbox.js`. The memory initialization file is large. Serve it in compressed -format to save bandwidth. - -WebAssembly ------------ - -[WebAssembly](https://github.com/kripken/emscripten/wiki/WebAssembly) is a -binary format which is meant to be a more efficient replacement for asm.js. -To build to WebAssembly instead of asm.js, the `-s WASM=1` option needs to -be added to the final `emcc` link command. There is no need to rebuild the -object files. You can do this using the `--enable-wasm` option when running -`./configure`. Since WebAssembly is still under very active development, use -the latest incoming Emscripten and browser development builds like -[Firefox Nightly](https://nightly.mozilla.org/) and -[Chrome Canary](https://www.google.com/chrome/browser/canary.html). - -Building with WebAssembly changes the dosbox.html file. Files packaged -using a dosbox.html without WebAssembly will not work with a WebAssembly -build. +Emscripten [Asyncify](https://emscripten.org/docs/porting/asyncify.html) is +used by default. This enables more DOSBox features to work, and only causes +a very small performance penalty. + +If building with Emscripten versions between 1.29.4 and 1.39.17, you could +try using Emterpreter Sync instead of Asyncify. This is depreciated, worse +than Asyncify and not recommended. Such builds create a memory initialization +file `src/dosbox.html.mem` needs to be in the same folder as `dosbox.js`. The +memory initialization file is large. Serve it in compressed format to save +bandwidth. Running DOS Programs -------------------- -To run DOS programs, you need to provide a suitable web page, load files into -the Emscripten file system, and give command line arguments to DOSBox. The -simplest method is by using the included packager tools. +When compiled using Asyncify, you can interactively load files. In DOSBox, +first use `mount c: /` and `c:` commands to provide a space for new files. +Then use the `wget` command to retrieve files from the same web server. +You can use relative URLs, simply providing file names to load files from +the same directory as the HTML page. + +If not using Asyncify, or generally, for convenience, you can create web pages +which run particular games. Such a page needs to load files into the Emscripten +file system and give command line arguments to DOSBox. The simplest method is +by using the included packager tools. The normal packager tool is `src/packager.py`, which runs the Emscripten packager. It requires `dosbox.html`, which is created when building Em-DOSBox. @@ -121,7 +119,7 @@ as `repackager.py`. The following instructions assume use of the normal packager. If using repackager, replace `packager.py` with `repackager.py`. You need -[Python 2](https://www.python.org/downloads/) to run either packager. +[Python 3](https://www.python.org/downloads/) to run either packager. If you have a single DOS executable such as `Gwbasic.exe`, place it in the same `src` directory as `packager.py` and package it using: @@ -132,12 +130,12 @@ This creates `gwbasic.html` and `gwbasic.data`. Placing those in the same directory as `dosbox.js` and viewing `gwbasic.html` will run the program in a web browser: -Some browsers have a same origin policy that prevents access to the required +Most browsers prevent access to the required data files while using `file://` URLs. To get around this you can use Python's -built in Really Simple HTTP Server and point the browser to +built in HTTP server and point the browser to [http://localhost:8000](http://localhost:8000). -```python -m SimpleHTTPServer 8000``` +```python -m http.server 8000``` If you need to package a collection of DOS files. Place all the files in a single directory and package that directory with the executable specified. For @@ -150,13 +148,13 @@ Again, place the created `stryker.html` and `stryker.data` files in the same directory as `dosbox.js` and view `stryker.html` to run the game in browser. You can also include a [DOSBox -configuration](http://www.dosbox.com/wiki/Dosbox.conf) file that will be +configuration](https://www.dosbox.com/wiki/Dosbox.conf) file that will be acknowledged by the emulator to modify any speed, audio or graphic settings. Simply include a `dosbox.conf` text file in the package directory before you run `./packager.py`. To attempt to run Major Stryker in CGA graphics mode, you would create the -configuration file `/src/major_stryker/dosbox.conf` and include this body of +configuration file `src/major_stryker/dosbox.conf` and include this body of text: ``` @@ -172,7 +170,7 @@ Credits ------- Most of the credit belongs to the -[DOSBox crew](http://www.dosbox.com/crew.php). +[DOSBox crew](https://www.dosbox.com/crew.php). They created DOSBox and made it compatible with a wide variety of DOS games. [Ismail Khatib](https://github.com/CeRiAl) got DOSBox to compile with Emscripten, but didn't get it to work.