Hi, I quickly cobbled together a "simplest possible sample" for calling a C function from JS here:
https://github.com/floooh/emsc-interop-demo This is running in the browser though and it's a bit quick'n'dirty, but it should get you started at least for your own experimentations. The important things are the EMSCRIPTEN_KEEPALIVE annotation in the hello.c file, and the underscore in front of the addc() function call in Javascript in shell.html. If you cannot annotate the original source files with EMSCRIPTEN_KEEPALIVE, you can also provide the C functions names to make visible to Javascript with a compiler option instead, see here: https://emscripten.org/docs/getting_started/FAQ.html#why-do-functions-in-my-c-c-source-code-vanish-when-i-compile-to-javascript-and-or-i-get-no-functions-to-process I prefer to work with simple C-APIs instead of C++ APIs, because with C-APIs you can (more or less) call the functions directly from Javascript instead of creating a "language binding" between C++ and Javascript interfaces. For this, emscripten has a tool called "embind" (which adds a whole new level of complexity and more things that can break, but I guess that's personal opinion heh). There are some caveats with non-trivial function arguments (for instance pointers to data on the WASM heap), maybe embind makes this case easier, don't know. In any case, here's the embind documentation: https://emscripten.org/docs/porting/connecting_cpp_and_javascript/embind.html Hope this helps! On Wednesday, 14 April 2021 at 02:43:49 UTC+2 HJ wrote: > I am a beginner and I'm sure all the information is there, but I am > struggling to get even a basic example working. I can run the tutorial > example, but I can't get anything for the following: > > I have converted some MATLAB .m script files to C (MATLAB can convert to C > or CPP. I've tried both C and CPP in the below information.) > > MATLAB has 1 function per 1 file, so now I have two .c files with one c > function in each. > > I've run emcc to convert .c to .js > When I look in the a.out.js and search for "myfunct", all I see for my > function is the following and I'm not sure how to call it in my js main > program: > > /** @type {function(...*):?} */ var _myFunc = Module["_myFunc"] = > createExportWrapper("myFunc"); > > I've played around with many different command line parameters that I've > found on various Q&A forums, but still can't figure out how to create such > that there is a function called "myFunc" that I can call from my other js > files (actually typescript, but just assume js for this.) > > This code will be run on the server side, node.js, and not on a browser. > Backend code that will call these converted MATLAB functions to generate > data. > > It would be nice to have an example from beginning to end (I've been > searching and searching, but I only find answers that will say things like, > "You just need to use the xxxx option", but there is more to the puzzle > that I am missing. > > It seems like the examples on emscripten site are all self contained: you > build and run them, but no example of how to convert a function and how to > integrate it (call it) from other js code. I have read the many options, > but again I am not sure exactly what to do. I've also read the comments in > the produced js file about creating a module and searched, but I am not > sure how to define a module for a function. > > - What are the emcc parameters do I use? > - Can I convert just this one function or do I need to have a main() > that calls it? > - Once converted, it looks like I need to define a module for > "myfunc", but I am not sure how it is defined, when to define, do I add > after into the .js? > - What about using the WASM=0 option to only produce js and no WASM. > Maybe that is a route to take? (I tried and it produced some different > code > in .js, but i'm still stuck on what to do with it. > > I created the below simple function that takes a double and returns a > double for trying this. If anyone can show me the steps with this or any > HelloWorld that takes a parameter and returns it would be greatly > appreciated. (or even more complex example.) > > Thank helping this newbie! :-) > > *myFunc.c:* > > #include "myfunc.h" > double myfunc(double myInt) { > return myInt + 50.0; > } > > *myFunc.h:* > > #ifndef MYFUNC_H > #define MYFUNC_H > > /* Include Files */ > #include "rtwtypes.h" > #include <stddef.h> > #include <stdlib.h> > > #ifdef __cplusplus > extern "C" { > #endif > > /* Function Declarations */ > extern double myFunc(double myInt); > > #ifdef __cplusplus > } > #endif > > #endif > -- You received this message because you are subscribed to the Google Groups "emscripten-discuss" group. To unsubscribe from this group and stop receiving emails from it, send an email to emscripten-discuss+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/emscripten-discuss/3556d977-ec57-4f18-9086-745b925529e5n%40googlegroups.com.
