fix(engine): prevent dropped cursor motion input on Windows

1 files changed, 96 insertions, 0 deletions

diff --git a/engine/src/util.rs b/engine/src/util.rs
index 439fe9a..454a776 100644
--- a/engine/src/util.rs
+++ b/engine/src/util.rs
@@ -1,3 +1,9 @@
+use std::fmt::Debug;
+use std::mem::transmute;
+use std::sync::atomic::Ordering;
+
+use portable_atomic::AtomicU128;
+
 use crate::ecs::util::VecExt;
 
 #[derive(Debug)]
@@ -94,6 +100,96 @@ impl<T> OptionExt<T> for Option<T>
     }
 }
 
+pub struct AtomicTwoF64
+{
+    inner: AtomicU128,
+}
+
+impl AtomicTwoF64
+{
+    pub const fn new((first, second): (f64, f64)) -> Self
+    {
+        let mut bytes = [0u8; size_of::<u128>()];
+
+        bytes.copy_from_slice([first.to_ne_bytes(), second.to_ne_bytes()].as_flattened());
+
+        Self {
+            inner: AtomicU128::new(u128::from_ne_bytes(bytes)),
+        }
+    }
+
+    pub fn load(&self, order: Ordering) -> (f64, f64)
+    {
+        u128_to_two_f64(self.inner.load(order))
+    }
+
+    pub fn store(&self, values: (f64, f64), order: Ordering)
+    {
+        self.inner.store(two_f64_to_u128(values), order);
+    }
+
+    pub fn swap(&self, values: (f64, f64), order: Ordering) -> (f64, f64)
+    {
+        u128_to_two_f64(self.inner.swap(two_f64_to_u128(values), order))
+    }
+
+    pub fn compare_exchange(
+        &self,
+        current: (f64, f64),
+        new: (f64, f64),
+        success_order: Ordering,
+        failure_order: Ordering,
+    ) -> Result<(f64, f64), (f64, f64)>
+    {
+        self.inner
+            .compare_exchange(
+                two_f64_to_u128(current),
+                two_f64_to_u128(new),
+                success_order,
+                failure_order,
+            )
+            .map(|stored| u128_to_two_f64(stored))
+            .map_err(|stored| u128_to_two_f64(stored))
+    }
+}
+
+impl Debug for AtomicTwoF64
+{
+    fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result
+    {
+        let (first, second) = self.load(Ordering::Relaxed);
+
+        formatter
+            .debug_tuple("AtomicTwoF64")
+            .field(&first)
+            .field(&second)
+            .finish()
+    }
+}
+
+fn two_f64_to_u128((first, second): (f64, f64)) -> u128
+{
+    let mut bytes = [0u8; size_of::<u128>()];
+
+    bytes.copy_from_slice([first.to_ne_bytes(), second.to_ne_bytes()].as_flattened());
+
+    u128::from_ne_bytes(bytes)
+}
+
+fn u128_to_two_f64(src: u128) -> (f64, f64)
+{
+    let [first_bytes, second_bytes] = unsafe {
+        transmute::<[u8; size_of::<u128>()], [[u8; size_of::<f64>()]; 2]>(
+            src.to_ne_bytes(),
+        )
+    };
+
+    (
+        f64::from_ne_bytes(first_bytes),
+        f64::from_ne_bytes(second_bytes),
+    )
+}
+
 macro_rules! try_option {
     ($expr: expr) => {
         match $expr {