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#include <iostream>
#include <fstream>
#include <cstdlib>
#include <string>
#include <cinttypes>
#include "wasm.hh"
// Print a Wasm value
auto operator<<(std::ostream& out, const wasm::Val& val) -> std::ostream& {
switch (val.kind()) {
case wasm::I32: {
out << val.i32();
} break;
case wasm::I64: {
out << val.i64();
} break;
case wasm::F32: {
out << val.f32();
} break;
case wasm::F64: {
out << val.f64();
} break;
case wasm::ANYREF:
case wasm::FUNCREF: {
if (val.ref() == nullptr) {
out << "null";
} else {
out << "ref(" << val.ref() << ")";
}
} break;
}
return out;
}
// A function to be called from Wasm code.
auto print_callback(
const wasm::Val args[], wasm::Val results[]
) -> wasm::own<wasm::Trap*> {
std::cout << "Calling back..." << std::endl << "> " << args[0] << std::endl;
results[0] = args[0].copy();
return nullptr;
}
// A function closure.
auto closure_callback(
void* env, const wasm::Val args[], wasm::Val results[]
) -> wasm::own<wasm::Trap*> {
auto i = *reinterpret_cast<int*>(env);
std::cout << "Calling back closure..." << std::endl;
std::cout << "> " << i << std::endl;
results[0] = wasm::Val::i32(static_cast<int32_t>(i));
return nullptr;
}
void run() {
// Initialize.
std::cout << "Initializing..." << std::endl;
auto engine = wasm::Engine::make();
auto store_ = wasm::Store::make(engine.get());
auto store = store_.get();
// Load binary.
std::cout << "Loading binary..." << std::endl;
std::ifstream file("callback.wasm");
file.seekg(0, std::ios_base::end);
auto file_size = file.tellg();
file.seekg(0);
auto binary = wasm::vec<byte_t>::make_uninitialized(file_size);
file.read(binary.get(), file_size);
file.close();
if (file.fail()) {
std::cout << "> Error loading module!" << std::endl;
return;
}
// Compile.
std::cout << "Compiling module..." << std::endl;
auto module = wasm::Module::make(store, binary);
if (!module) {
std::cout << "> Error compiling module!" << std::endl;
return;
}
// Create external print functions.
std::cout << "Creating callback..." << std::endl;
auto print_type = wasm::FuncType::make(
wasm::vec<wasm::ValType*>::make(wasm::ValType::make(wasm::I32)),
wasm::vec<wasm::ValType*>::make(wasm::ValType::make(wasm::I32))
);
auto print_func = wasm::Func::make(store, print_type.get(), print_callback);
// Creating closure.
std::cout << "Creating closure..." << std::endl;
int i = 42;
auto closure_type = wasm::FuncType::make(
wasm::vec<wasm::ValType*>::make(),
wasm::vec<wasm::ValType*>::make(wasm::ValType::make(wasm::I32))
);
auto closure_func = wasm::Func::make(store, closure_type.get(), closure_callback, &i);
// Instantiate.
std::cout << "Instantiating module..." << std::endl;
wasm::Extern* imports[] = {print_func.get(), closure_func.get()};
auto instance = wasm::Instance::make(store, module.get(), imports);
if (!instance) {
std::cout << "> Error instantiating module!" << std::endl;
return;
}
// Extract export.
std::cout << "Extracting export..." << std::endl;
auto exports = instance->exports();
if (exports.size() == 0 || exports[0]->kind() != wasm::EXTERN_FUNC || !exports[0]->func()) {
std::cout << "> Error accessing export!" << std::endl;
return;
}
auto run_func = exports[0]->func();
// Call.
std::cout << "Calling export..." << std::endl;
wasm::Val args[] = {wasm::Val::i32(3), wasm::Val::i32(4)};
wasm::Val results[1];
if (run_func->call(args, results)) {
std::cout << "> Error calling function!" << std::endl;
return;
}
// Print result.
std::cout << "Printing result..." << std::endl;
std::cout << "> " << results[0].i32() << std::endl;
// Shut down.
std::cout << "Shutting down..." << std::endl;
}
int main(int argc, const char* argv[]) {
run();
std::cout << "Done." << std::endl;
return 0;
}
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