WasmEdge C SDK
The WasmEdge C API denotes an interface to embed the WasmEdge runtime into a C program. The followings are the quick start guides to working with the C APIs of WasmEdge. For the details of the WasmEdge C API, please refer to the full documentation.
The WasmEdge C API also the fundamental API for other languages’ SDK.
Quick Start Guide for the WasmEdge runner
The following is an example for running a WASM file. Assume that the WASM file fibonacci.wasm is copied into the current directory, and the C file test_wasmedge.c
is as following:
#include <wasmedge/wasmedge.h>
#include <stdio.h>
int main(int Argc, const char* Argv[]) {
/* Create the configure context and add the WASI support. */
/* This step is not necessary unless you need WASI support. */
WasmEdge_ConfigureContext *ConfCxt = WasmEdge_ConfigureCreate();
WasmEdge_ConfigureAddHostRegistration(ConfCxt, WasmEdge_HostRegistration_Wasi);
/* The configure and store context to the VM creation can be NULL. */
WasmEdge_VMContext *VMCxt = WasmEdge_VMCreate(ConfCxt, NULL);
/* The parameters and returns arrays. */
WasmEdge_Value Params[1] = { WasmEdge_ValueGenI32(32) };
WasmEdge_Value Returns[1];
/* Function name. */
WasmEdge_String FuncName = WasmEdge_StringCreateByCString("fib");
/* Run the WASM function from file. */
WasmEdge_Result Res = WasmEdge_VMRunWasmFromFile(VMCxt, Argv[1], FuncName, Params, 1, Returns, 1);
if (WasmEdge_ResultOK(Res)) {
printf("Get result: %d\n", WasmEdge_ValueGetI32(Returns[0]));
} else {
printf("Error message: %s\n", WasmEdge_ResultGetMessage(Res));
}
/* Resources deallocations. */
WasmEdge_VMDelete(VMCxt);
WasmEdge_ConfigureDelete(ConfCxt);
WasmEdge_StringDelete(FuncName);
return 0;
}
Then you can compile and run: (the 32th fibonacci number is 3524578 in 0-based index)
$ gcc test_wasmedge.c -lwasmedge_c -o test_wasmedge
$ ./test_wasmedge fibonacci.wasm
Get result: 3524578
Quick Start Guide for the WasmEdge AOT compiler
Assume that the WASM file fibonacci.wasm is copied into the current directory, and the C file test_wasmedge_compiler.c
is as following:
#include <wasmedge/wasmedge.h>
#include <stdio.h>
int main(int Argc, const char* Argv[]) {
/* Create the configure context. */
WasmEdge_ConfigureContext *ConfCxt = WasmEdge_ConfigureCreate();
/* ... Adjust settings in the configure context. */
/* Result. */
WasmEdge_Result Res;
/* Create the compiler context. The configure context can be NULL. */
WasmEdge_CompilerContext *CompilerCxt = WasmEdge_CompilerCreate(ConfCxt);
/* Compile the WASM file with input and output paths. */
Res = WasmEdge_CompilerCompile(CompilerCxt, Argv[1], Argv[2]);
if (!WasmEdge_ResultOK(Res)) {
printf("Compilation failed: %s\n", WasmEdge_ResultGetMessage(Res));
return 1;
}
WasmEdge_CompilerDelete(CompilerCxt);
WasmEdge_ConfigureDelete(ConfCxt);
return 0;
}
Then you can compile and run (the output file is fibonacci.wasm.so
):
$ gcc test_wasmedge_compiler.c -lwasmedge_c -o test_wasmedge_compiler
$ ./test_wasmedge_compiler fibonacci.wasm fibonacci.wasm.so
[2021-07-02 11:08:08.651] [info] compile start
[2021-07-02 11:08:08.653] [info] verify start
[2021-07-02 11:08:08.653] [info] optimize start
[2021-07-02 11:08:08.670] [info] codegen start
[2021-07-02 11:08:08.706] [info] compile done
The compiled-WASM file can be used as a WASM input for the WasmEdge runner. The following is the comparison of the interpreter mode and the AOT mode:
$ time ./test_wasmedge fibonacci.wasm
Get result: 5702887
real 0m2.715s
user 0m2.700s
sys 0m0.008s
$ time ./test_wasmedge fibonacci.wasm.so
Get result: 5702887
real 0m0.036s
user 0m0.022s
sys 0m0.011s