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diff --git a/docs/emscripten.txt b/docs/emscripten.txt new file mode 100644 index 00000000000..dbc8bd5ad48 --- /dev/null +++ b/docs/emscripten.txt @@ -0,0 +1,60 @@ +Compiling MAME to JavaScript via Emscripten +=========================================== + +First, download and install Emscripten by following the instructions at the +official site: + +https://kripken.github.io/emscripten-site/docs/getting_started/downloads.html + +Once Emscripten has been installed, it should be possible to compile MAME +out-of-the-box using Emscripten's 'emmake' tool. Because a full MAME compile is +too large to load into a web browser at once, you will want to use the SOURCES +parameter to compile only a subset of the project, e.g. (in the mame directory): + +emmake make SUBTARGET=pacmantest SOURCES=src/mame/drivers/pacman.cpp + +The SOURCES parameter should have the path to at least one driver .cpp file. +The make process will attempt to locate and include all dependencies necessary +to produce a complete build including the specified driver(s). However, +sometimes it is necessary to manually specify additional files (using commas) if +this process misses something. E.g.: + +emmake make SUBTARGET=apple2e SOURCES=src/mame/drivers/apple2e.cpp,src/mame/machine/applefdc.cpp + +The value of the SUBTARGET parameter serves only to differentiate multiple +builds and need not be set to any specific value. + +Other make parameters can also be used, e.g. -j for multithreaded compilation. + +When the compilation reaches the emcc phase, you may see a number of "unresolved +symbol" warnings. At the moment, this is expected for OpenGL-related functions +such as glPointSize. Any others may indicate that an additional dependency file +needs to be specified in the SOURCES list. Unfortunately this process is not +automated and you will need to search the source tree to locate the files +supplying the missing symbols. You may also be able to get away with ignoring +the warnings if the code path referencing them is not used at run-time. + +If all goes well, a .js file will be output to the current directory. This file +cannot be run by itself, but requires an HTML loader to provide it with a canvas +to output to and pass in command-line parameters. The Emularity project provides +such a loader: + +https://github.com/db48x/emularity + +There are example .html files in that repository which can be edited to point +to your newly compiled MAME js filename and pass in whatever parameters you +desire. You will then need to place all of the following on a web server: + +* The compiled MAME .js file +* The .js files from the Emularity package (loader.js, browserfs.js, etc.) +* A .zip file with the ROMs for the MAME driver you would like to run (if any) +* Any software files you would like to run with the MAME driver +* An Emularity loader .html modified to point to all of the above + +You need to use a web server instead of opening the local files directly due to +security restrictions in modern web browsers. + +If the result fails to run, you can open the Web Console in your browser to see +any error output which may have been produced (e.g. missing or incorrect ROM +files). A "ReferenceError: foo is not defined" error most likely indicates that +a needed source file was omitted from the SOURCES list. |