3 files changed, 90 insertions, 2 deletions
diff --git a/azalea-core/src/bitset.rs b/azalea-core/src/bitset.rs
index d878bbf5..41d43165 100755
--- a/azalea-core/src/bitset.rs
+++ b/azalea-core/src/bitset.rs
@@ -1,4 +1,6 @@
-use azalea_buf::McBuf;
+use std::io::{Cursor, Read, Write};
+
+use azalea_buf::{BufReadError, McBuf, McBufReadable, McBufWritable};
 
 /// Represents Java's BitSet, a list of bits.
 #[derive(Debug, Clone, PartialEq, Eq, Hash, Default, McBuf)]
@@ -105,6 +107,89 @@ impl BitSet {
     pub fn set(&mut self, bit_index: usize) {
         self.data[bit_index / 64] |= 1u64 << (bit_index % 64);
     }
+
+    /// Read a BitSet with a known length.
+    pub fn read_fixed(buf: &mut Cursor<&[u8]>, length: usize) -> Result<Self, BufReadError> {
+        let mut data = vec![0; length.div_ceil(8)];
+        buf.read_exact(&mut data)?;
+        Ok(BitSet::from(data))
+    }
+}
+
+impl From<Vec<u64>> for BitSet {
+    fn from(data: Vec<u64>) -> Self {
+        BitSet { data }
+    }
+}
+
+impl From<Vec<u8>> for BitSet {
+    fn from(data: Vec<u8>) -> Self {
+        let mut words = vec![0; data.len().div_ceil(8)];
+        for (i, byte) in data.iter().enumerate() {
+            words[i / 8] |= (*byte as u64) << ((i % 8) * 8);
+        }
+        BitSet { data: words }
+    }
+}
+
+/// A list of bits with a known fixed size.
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct FixedBitSet<const N: usize>
+where
+    [(); N.div_ceil(8)]: Sized,
+{
+    data: [u8; N.div_ceil(8)],
+}
+
+impl<const N: usize> FixedBitSet<N>
+where
+    [u8; N.div_ceil(8)]: Sized,
+{
+    pub fn new() -> Self {
+        FixedBitSet {
+            data: [0; N.div_ceil(8)],
+        }
+    }
+
+    pub fn index(&self, index: usize) -> bool {
+        (self.data[index / 8] & (1u8 << (index % 8))) != 0
+    }
+
+    pub fn set(&mut self, bit_index: usize) {
+        self.data[bit_index / 8] |= 1u8 << (bit_index % 8);
+    }
+}
+
+impl<const N: usize> McBufReadable for FixedBitSet<N>
+where
+    [u8; N.div_ceil(8)]: Sized,
+{
+    fn read_from(buf: &mut Cursor<&[u8]>) -> Result<Self, BufReadError> {
+        let mut data = [0; N.div_ceil(8)];
+        for item in data.iter_mut().take(N.div_ceil(8)) {
+            *item = u8::read_from(buf)?;
+        }
+        Ok(FixedBitSet { data })
+    }
+}
+impl<const N: usize> McBufWritable for FixedBitSet<N>
+where
+    [u8; N.div_ceil(8)]: Sized,
+{
+    fn write_into(&self, buf: &mut impl Write) -> Result<(), std::io::Error> {
+        for i in 0..N.div_ceil(8) {
+            self.data[i].write_into(buf)?;
+        }
+        Ok(())
+    }
+}
+impl<const N: usize> Default for FixedBitSet<N>
+where
+    [u8; N.div_ceil(8)]: Sized,
+{
+    fn default() -> Self {
+        Self::new()
+    }
 }
 
 #[cfg(test)]
diff --git a/azalea-core/src/game_type.rs b/azalea-core/src/game_type.rs
index 75ee0674..c4b4cf76 100755..100644
--- a/azalea-core/src/game_type.rs
+++ b/azalea-core/src/game_type.rs
@@ -1,8 +1,9 @@
 use azalea_buf::{BufReadError, McBufReadable, McBufWritable};
 use std::io::{Cursor, Write};
 
-#[derive(Hash, Copy, Clone, Debug)]
+#[derive(Hash, Copy, Clone, Debug, Default)]
 pub enum GameType {
+    #[default]
     Survival,
     Creative,
     Adventure,
diff --git a/azalea-core/src/lib.rs b/azalea-core/src/lib.rs
index 7c74bdcb..30af2448 100755
--- a/azalea-core/src/lib.rs
+++ b/azalea-core/src/lib.rs
@@ -1,6 +1,8 @@
 //! Random miscellaneous things like UUIDs that don't deserve their own crate.
 
 #![feature(int_roundings)]
+#![allow(incomplete_features)]
+#![feature(generic_const_exprs)]
 
 mod difficulty;
 pub use difficulty::*;