gistfile1.txt

diff --git a/index.html b/index.html
index dd19415..e015780 100644
--- a/index.html
+++ b/index.html
@@ -14,20 +14,23 @@ fetch('target/wasm32-unknown-unknown/release/wasmmem.wasm')
 
   .then(bytes => WebAssembly.instantiate(bytes, {
     env: {
-      draw: function(data_ptr, counter) {
+      draw: function(counter) {
         console.log("Called draw with counter: ", counter);
-        console.log("Called draw with ptr:", data_ptr);
 
         for(var i = 0; i < 5; i++) {
-          console.log("data[", i, "]:", rust_memory[data_ptr + i]);
+          console.log("data[", i, "]:", rust_memory[i]);
         }
       }
     }
   }))
 
   .then(results => {
-    rust_memory = new Uint8Array(results.instance.exports.memory.buffer);
     var gamestate_ptr = results.instance.exports.start();
+    var pointer = results.instance.exports.data_address(gamestate_ptr);
+    var len = results.instance.exports.data_length(gamestate_ptr);
+    console.log(pointer, len);
+    rust_memory = new Uint8Array(results.instance.exports.memory.buffer, pointer, len);
+
     console.log("Gamestate pointer:", gamestate_ptr);
 
     results.instance.exports.update(gamestate_ptr);
diff --git a/src/main.rs b/src/main.rs
index 0d2ee27..9fcc499 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,5 +1,7 @@
+use std::os::raw::c_void;
+
 extern {
-    fn draw(data: *const u8, counter: i32);
+    fn draw(counter: i32);
 }
 
 pub struct Gamestate {
@@ -13,7 +15,7 @@ impl Gamestate {
             // NOTE: changing this to `66_000` will make the web
             // client show zeros instead of the initial values set
             // here as well as in `update`.
-            data: vec![5; 65_000],
+            data: vec![5; 66_000],
             counter: 0,
         }
     }
@@ -26,6 +28,26 @@ pub fn start() -> *mut Gamestate {
     Box::into_raw(state)
 }
 
+
+#[no_mangle]
+pub extern "C" fn data_address(state_ptr: *mut Gamestate) -> *mut c_void  {
+    let mut state = unsafe { Box::from_raw(state_ptr) };
+
+    let ptr = state.data.as_mut_ptr();
+    std::mem::forget(state);
+    return ptr as *mut c_void;
+}
+
+#[no_mangle]
+pub extern "C" fn data_length(state_ptr: *mut Gamestate) -> usize {
+    let state = unsafe { Box::from_raw(state_ptr) };
+
+    let ret = state.data.len();
+    std::mem::forget(state);
+    return ret;
+
+}
+
 #[no_mangle]
 pub fn update(state_ptr: *mut Gamestate) {
     let mut state = unsafe { Box::from_raw(state_ptr) };
@@ -39,11 +61,10 @@ pub fn update(state_ptr: *mut Gamestate) {
         *num = 42 + counter as u8;
     }
 
-    let data_ptr = state.data.as_ptr();
     std::mem::forget(state);
 
     unsafe {
-        draw(data_ptr, counter)
+        draw(counter)
     }
 }