This gist is part of my article “Emscripten’s embind”.
Build it with
$ emcc -s EXTRA_EXPORTED_RUNTIME_METHODS='["cwrap"]' -O3 nobind.cpp
or
$ docker run --rm -v $(pwd):/src trzeci/emscripten emcc -s EXTRA_EXPORTED_RUNTIME_METHODS='["cwrap"]' -O3 nobind.cpp
License Apache-2.0
| /** | |
| * Copyright 2018 Google Inc. All Rights Reserved. | |
| * Licensed under the Apache License, Version 2.0 (the "License"); | |
| * you may not use this file except in compliance with the License. | |
| * You may obtain a copy of the License at | |
| * http://www.apache.org/licenses/LICENSE-2.0 | |
| * Unless required by applicable law or agreed to in writing, software | |
| * distributed under the License is distributed on an "AS IS" BASIS, | |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
| * See the License for the specific language governing permissions and | |
| * limitations under the License. | |
| */ | |
| #include <emscripten.h> | |
| #include <stdint.h> | |
| #include <stdlib.h> | |
| #include <string> | |
| extern "C" | |
| EMSCRIPTEN_KEEPALIVE | |
| double add(double a, double b) { | |
| return a b; | |
| } | |
| extern "C" | |
| EMSCRIPTEN_KEEPALIVE | |
| const char* exclaim(char* message) { | |
| std::string *input = new std::string(message); | |
| return (*input "!").c_str(); | |
| } | |
| extern "C" | |
| EMSCRIPTEN_KEEPALIVE | |
| int mymalloc(int size) { | |
| return (int)malloc(size); | |
| } | |
| extern "C" | |
| EMSCRIPTEN_KEEPALIVE | |
| void myfree(int p) { | |
| free((void *)p); | |
| } |
| <script src="/a.out.js"></script> | |
| <script> | |
| Module.onRuntimeInitialized = _ => { | |
| const api = { | |
| add: Module.cwrap('add', 'number', ['number', 'number']), | |
| exclaim: Module.cwrap('exclaim', 'number', ['number']), | |
| malloc: Module.cwrap('mymalloc', 'number', ['number']), | |
| free: Module.cwrap('myfree', '', ['number']) | |
| }; | |
| function add(a, b) { | |
| return api.add(a, b); | |
| } | |
| function exclaim(str) { | |
| const utf8 = new TextEncoder('utf-8').encode(str); | |
| const p = api.malloc(utf8.byteLength); | |
| Module.HEAP8.set(utf8, p); | |
| const p2 = api.exclaim(p); | |
| const resultView = new Uint8Array(Module.HEAP8.buffer, p2, utf8.byteLength 1); | |
| return new TextDecoder('utf-8').decode(resultView); | |
| } | |
| console.log(add(22, 20)); | |
| console.log(exclaim('Hello World')); | |
| }; | |
| </script> |
@beaufortfrancois Habit. Removed it.
@surma Thank you for sharing the example. Your blogs related to WebAssembly are useful and knowledgeable.
Related to this example, I have one doubt.
In file nobind.html, and in function exclaim(str), memory pointed by p and p2 should be freed after the usage. Otherwise, there will be memory leak. Is that correct ?
@surma Why
async?