Emscripten is the preferred toolchain for compiling C/C code into WebAssembly and running in the browser. 1. It is recommended to use emsdk management during installation, cloning and activating the latest version through git, and configuring environment variables; 2. After writing a simple C program, use the emcc command to compile and generate .wasm or .js files; 3. If the browser has no output, you need to add the EXPORTED_FUNCTIONS parameter and ensure that the HTML has a display container; 4. Complex projects support Makefile or CMake, and can link libraries such as SDL2; 5. Debugging is recommended to add the -g parameter to retain source code information, and performance optimization should reduce the interaction between JS and Wasm, use the -O3 optimization level to avoid frequent string conversion and JS calls.
Emscripten is a powerful toolchain that allows us to compile C/C code into WebAssembly (Wasm) and then run it in the browser. If you are trying to "mov" native C/C applications to web pages, Emscripten is almost the preferred option.
Installation and configuration: Prepare your environment
Before using Emscripten, you need to install its SDK. Officially recommended to manage through emsdk , you can download and install it from GitHub.
- Download emsdk:
git clone https://github.com/emscripten-core/emsdk.git
- Go to the directory and install the latest version:
cd emsdk ./emsdk install latest ./emsdk activate latest
Don't forget to add environment variables to shell configuration files (such as .bashrc or .zshrc ):
source ./emsdk_env.sh
If you encounter the problem that the command cannot be found, it is likely that the environment variable is not loaded correctly. You can try to resource or restart the terminal.
Compile your first C program
When you are ready for the development environment, try writing a simple C program:
#include <stdio.h>
int main() {
printf("Hello from Emscripten!\n");
return 0;
}Use the following command to compile:
emcc -s WASM=1 hello.c -o hello.wasm
This generates a hello.wasm file. You can also add -o hello.js so that Emscripten will automatically generate a JS glue file for loading and running WebAssembly.
FAQ: If you don't see the output when running in the browser, remember to add -s EXPORTED_FUNCTIONS="['_main']" and make sure there is a container in <body> in the HTML page to display the stdout output.
Handle dependencies and complex projects
For projects with multiple source files or third-party libraries, Emscripten also supports standard Makefile and CMake build methods.
For example, if you have a game project that uses SDL2, you can add the corresponding flag at compile time:
emcc -s USE_SDL=2 main.c -o game.js
At this time, Emscripten will automatically link the SDL2 web implementation. This is very useful for porting desktop applications.
But pay attention to memory limitations. By default, WebAssembly uses limited memory. If your application consumes a lot of memory, you can add parameter extensions:
-s TOTAL_MEMORY=64MB
However, modern browsers generally support larger memory by default, so this parameter may not need to be set in the new version.
Debugging and performance optimization skills
Debugging WebAssembly is not as intuitive as debugging JavaScript. It is recommended that you add -g parameter to preserve debugging information when compiling:
emcc -g -s WASM=1 your_code.c -o debug.wasm
This way you can see the original C source code under the Source tab of Chrome DevTools and set breakpoints.
There are a few tips for performance:
- Try to avoid frequent interactions between JS and Wasm, because cross-language calls are costly.
- If DOM operations are not required, try to use pure computing tasks to give full play to the advantages of Wasm.
- Use
-O3or-Ofastoptimization level to improve execution efficiency.
Sometimes you will find that the program runs slower than expected, so you might as well see if it has done a lot of string conversion or frequently called JS helper functions.
Basically that's it. Emscripten's learning curve is not steep, but to really use it well, you still have to practice it a few more times and be familiar with the construction process and common pitfalls.
The above is the detailed content of Leveraging the JavaScript Emscripten Toolchain. For more information, please follow other related articles on the PHP Chinese website!
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