autocommit 2022-03-02 14:24:07 CET

src/utils/bitfield.rs

@@ -0,0 +1,28 @@
+use std::mem;
+
+const SEG_SIZE: usize = 8 * mem::size_of::<usize>();
+
+#[derive(Default)]
+pub struct Bitfield {
+    vals: Vec<usize>,
+}
+
+impl Bitfield {
+    pub fn acquire(&mut self) -> u32 {
+        for (idx, n) in self.vals.iter_mut().enumerate() {
+            if *n != 0 {
+                let pos = n.trailing_zeros();
+                *n &= !(1 << pos);
+                return (idx * SEG_SIZE) as u32 + pos;
+            }
+        }
+        self.vals.push(!1);
+        ((self.vals.len() - 1) * SEG_SIZE) as u32
+    }
+
+    pub fn release(&mut self, val: u32) {
+        let idx = val as usize / SEG_SIZE;
+        let pos = val as usize % SEG_SIZE;
+        self.vals[idx] |= 1 << pos;
+    }
+}