add test.ts

deno_test_wasm/test.ts

@@ -0,0 +1,30 @@
+const wasmCode = await Deno.readFile("./test_wasm/target/wasm32-unknown-unknown/debug/test_wasm.wasm");
+const wasmModule = new WebAssembly.Module(wasmCode);
+const wasmInstance = new WebAssembly.Instance(wasmModule);
+
+const linearMemory = wasmInstance.exports.memory;
+
+function writeString() {
+    let s = "hello world !";
+    let encoded = new TextEncoder().encode(s);
+    let ptr = wasmInstance.exports.malloc(encoded.length);
+    const mem = new Uint8Array(linearMemory.buffer, ptr);
+    for (let i = 0; i < encoded.length; i++) {
+        mem[i] = encoded[i];
+    }
+    return ptr;
+}
+
+// from https://tilman.xyz/blog/2019/12/building-webassembly-for-deno/
+function readString(memory, ptr) {
+    const mem = new Uint8Array(memory.buffer, ptr);
+    let length;
+    for (length = 0; mem[length] !== 0; length ++);
+    return new TextDecoder("utf-8").decode(new Uint8Array(mem.buffer, ptr, length));
+}
+
+let ptr = writeString();
+console.log("DECODED:\n" + readString(linearMemory, ptr) + " @" + ptr);
+
+let ptr2 = wasmInstance.exports.to_uppercase(ptr);
+console.log("DECODED:\n" + readString(linearMemory, ptr2) + " @" + ptr2);

deno_test_wasm/test_wasm/build.sh

@@ -0,0 +1 @@
+cargo build --target wasm32-unknown-unknown

deno_test_wasm/test_wasm/src/lib.rs

@@ -7,6 +7,7 @@ pub extern "C" fn malloc(len: usize) -> *mut c_char {
     s.into_raw()
 }
 
+#[no_mangle]
 pub extern "C" fn to_uppercase(ptr: *mut c_char) -> *mut c_char {
     let s = unsafe { CString::from_raw(ptr) };
     let s2 = CString::new(s.to_string_lossy().to_uppercase()).unwrap();