There is an experimental way to do something like that, using the SIDE_MODULE option, see
https://github.com/kripken/emscripten/wiki/WebAssembly-Standalone That will create a module that can be linked, which will have very minimal import requirements. However, it will still need some imports to set up the stack etc. (ONLY_MY_CODE prevents linking in of system library code, but it does still generate a js runtime to load the wasm, which it sounds like you don't want) On Sun, Nov 5, 2017 at 7:59 AM, D Danser <danse...@gmail.com> wrote: > Hi All, > > I am investigating how to run C code as WebAssembly in the browser. > > To test it out I made a small C program: > > #include <emscripten.h> > > int EMSCRIPTEN_KEEPALIVE add2(int x, int y) { > return x+2*y; > } > > And then I compiled it using: > > emcc test.c -s WASM=1 -s ONLY_MY_CODE=1 > > This produced a file a.out.wasm which is 256 bytes (which seems > reasonable) and a file a.out.js which is 85K (which seems very large). > > Further, the a.out.wasm file has the text "add2" inside, so this seemed > promising! > > Now, having read about WebAssembly on the web I did not understand why I > would need the a.out.js file, so I went ahead and tried to use a.out.wasm > directly inspired by https://developer.mozilla.org/en-US/docs/WebAssembly/ > Loading_and_running: > > <script> > function fetchAndInstantiate(url, importObject) { > return fetch(url).then(response => > response.arrayBuffer() > ).then(bytes => > WebAssembly.instantiate(bytes, importObject) > ).then(results => > results.instance > ); > } > > importObject={} > > fetchAndInstantiate('a.out.wasm', importObject).then(function(instance) { > console.log(instance.exports._add2(2,4)); > }) > </script> > > Unfortunately this did not work - I got this error in the JavaScript > console: > > TypeError: import object field 'env' is not an Object > > Troubleshooting a bit further I tried this html: > > <script> > fetch('a.out.wasm').then(response => > response.arrayBuffer() > ).then(bytes => > WebAssembly.compile(bytes) > ).then(function(mod) { > var imports = WebAssembly.Module.imports(mod); > console.log(imports[0]); > }); > </script> > > Which gave this output: > > Object { module: "env", name: "STACKTOP", kind: "global" } > > Debugging a bit futher it seemed like the webassembly needs an env in > importObject with a bunch of values in it, including this STACKTOP. > > My questions are: > > 1) Can emscripten produce a webassembly file that does not need such > values to be set externally? > 2) If emscripten cannot, is there a recommend way to get less than 85K of > JavaScript to set reasonable values? > > I used FireFox version 56 and emscripten version 1.37.22. > > > Best, > > Christian > > -- > 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. > For more options, visit https://groups.google.com/d/optout. > -- 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. For more options, visit https://groups.google.com/d/optout.
