✨ Use a static Vec<u8> to handle shared memory

render-wasm/src/mem.rs

@@ -1,17 +1,25 @@
+static mut BUFFERU8: Option<Box<Vec<u8>>> = None;
+
 #[no_mangle]
 pub extern "C" fn alloc_bytes(len: usize) -> *mut u8 {
-    // create a new mutable buffer with capacity `len`
-    let mut buf: Vec<u8> = Vec::with_capacity(len);
-    let ptr = buf.as_mut_ptr();
-    // take ownership of the memory block and ensure the its destructor is not
-    // called when the object goes out of scope at the end of the function
-    std::mem::forget(buf);
+    // TODO: Figure out how to deal with Result<T> from Emscripten
+    if unsafe { BUFFERU8.is_some() } {
+        panic!("Bytes already allocated");
+    }
+
+    let mut buffer = Box::new(Vec::<u8>::with_capacity(len));
+    let ptr = buffer.as_mut_ptr();
+
+    unsafe { BUFFERU8 = Some(buffer) };
     return ptr;
 }
 
-pub fn free(ptr: *mut u8, len: usize) {
-    unsafe {
-        let buf = Vec::<u8>::from_raw_parts(ptr, len, len);
-        std::mem::forget(buf);
-    }
+pub fn free_bytes() {
+    let buffer = unsafe { BUFFERU8.take() }.expect("uninitialized buffer");
+    std::mem::drop(buffer);
+}
+
+pub fn buffer_ptr() -> *mut u8 {
+    let buffer = unsafe { BUFFERU8.as_mut() }.expect("uninitializied buffer");
+    buffer.as_mut_ptr()
 }