I have a simple c code:
// accumulate.c
int arr[];
int accumulate(int start, int end) {
int sum = 0;
for(int i = start; i < end; i++) {
sum += arr[i];
}
return sum;
}
compile it to wasm:
$ emcc accumulate.c -O3 -s SIDE_MODULE -o accumulate.wasm
the following HTML works fine:
<!-- accumulate.html -->
<script>
const memory = new WebAssembly.Memory({
initial: 1,
});
const importObj = {
env: {
memory: memory,
__memory_base: 0,
g$arr: () => {}
}
};
(async () => {
const res = await fetch("accumulate.wasm");
const wasmFile = await res.arrayBuffer();
const module = await WebAssembly.compile(wasmFile);
const instance = await WebAssembly.instantiate(module, importObj);
const arr = new Uint32Array(memory.buffer);
for (let i = 0; i < 10; i++) {
arr[i] = i;
}
const sum = instance.exports.accumulate(0, 10);
console.log("accumulate from 0 to 10: " + sum);
})();
</script>
However, if I set memory
to shared: true
:
const memory = new WebAssembly.Memory({
initial: 1,
maximum: 1,
shared: true
});
Chrome turns out the error "LinkError: WebAssembly.instantiate(): mismatch in shared state of memory, declared = 0, imported = 1".
Now I know it is because the wasm's memory
needs to be declared as shared
.
See the issue on Emscripten