Started KeySet type

src/lib.rs

@@ -82,6 +82,56 @@ impl InterruptConfig {
     }
 }
 
+#[derive(Clone, Copy)]
+pub struct KeySet(u128);
+
+impl KeySet {
+    fn contains(&self, key_number: u8) -> bool {
+        (self.0 & (1 << key_number)) != 0
+    }
+}
+
+impl core::ops::Not for KeySet {
+    type Output = KeySet;
+
+    fn not(self) -> Self::Output {
+        KeySet(!self.0)
+    }
+}
+
+pub struct KeySetIter {
+    key_set: KeySet,
+    shift: u8,
+}
+
+impl core::iter::Iterator for KeySetIter {
+    type Item = u8;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let next_shift = self.key_set.0.trailing_zeros() as u8 + 1;
+        if next_shift >= 128 {
+            return None;
+        }
+
+        self.key_set.0 >>= next_shift;
+        self.shift += next_shift;
+
+        Some(self.shift - 1)
+    }
+}
+
+impl core::iter::IntoIterator for KeySet {
+    type Item = u8;
+
+    type IntoIter = KeySetIter;
+
+    fn into_iter(self) -> Self::IntoIter {
+        KeySetIter {
+            key_set: self,
+            shift: 0
+        }
+    }
+}
 
 impl<I2C: embedded_hal::i2c::I2c> TCA8418<I2C> {
     pub fn new(