start adding bit storage

4 files changed, 155 insertions, 1 deletions

diff --git a/.gitignore b/.gitignore
index ad9bfc78..364ea72c 100755
--- a/.gitignore
+++ b/.gitignore
@@ -3,3 +3,6 @@
 flamegraph.svg
 perf.data
 perf.data.old
+
+# TODO: remove this after chunk-decoding is merged
+/login.txt
diff --git a/azalea-world/src/bit_storage.rs b/azalea-world/src/bit_storage.rs
new file mode 100644
index 00000000..b2202e48
--- /dev/null
+++ b/azalea-world/src/bit_storage.rs
@@ -0,0 +1,149 @@
+use std::{error::Error, fmt};
+
+// this is from minecraft's code
+// yeah idk either
+const MAGIC: [(i32, i32, i32); 64] = [
+    (-1, -1, 0),
+    (-2147483648, 0, 0),
+    (1431655765, 1431655765, 0),
+    (-2147483648, 0, 1),
+    (858993459, 858993459, 0),
+    (715827882, 715827882, 0),
+    (613566756, 613566756, 0),
+    (-2147483648, 0, 2),
+    (477218588, 477218588, 0),
+    (429496729, 429496729, 0),
+    (390451572, 390451572, 0),
+    (357913941, 357913941, 0),
+    (330382099, 330382099, 0),
+    (306783378, 306783378, 0),
+    (286331153, 286331153, 0),
+    (-2147483648, 0, 3),
+    (252645135, 252645135, 0),
+    (238609294, 238609294, 0),
+    (226050910, 226050910, 0),
+    (214748364, 214748364, 0),
+    (204522252, 204522252, 0),
+    (195225786, 195225786, 0),
+    (186737708, 186737708, 0),
+    (178956970, 178956970, 0),
+    (171798691, 171798691, 0),
+    (165191049, 165191049, 0),
+    (159072862, 159072862, 0),
+    (153391689, 153391689, 0),
+    (148102320, 148102320, 0),
+    (143165576, 143165576, 0),
+    (138547332, 138547332, 0),
+    (-2147483648, 0, 4),
+    (130150524, 130150524, 0),
+    (126322567, 126322567, 0),
+    (122713351, 122713351, 0),
+    (119304647, 119304647, 0),
+    (116080197, 116080197, 0),
+    (113025455, 113025455, 0),
+    (110127366, 110127366, 0),
+    (107374182, 107374182, 0),
+    (104755299, 104755299, 0),
+    (102261126, 102261126, 0),
+    (99882960, 99882960, 0),
+    (97612893, 97612893, 0),
+    (95443717, 95443717, 0),
+    (93368854, 93368854, 0),
+    (91382282, 91382282, 0),
+    (89478485, 89478485, 0),
+    (87652393, 87652393, 0),
+    (85899345, 85899345, 0),
+    (84215045, 84215045, 0),
+    (82595524, 82595524, 0),
+    (81037118, 81037118, 0),
+    (79536431, 79536431, 0),
+    (78090314, 78090314, 0),
+    (76695844, 76695844, 0),
+    (75350303, 75350303, 0),
+    (74051160, 74051160, 0),
+    (72796055, 72796055, 0),
+    (71582788, 71582788, 0),
+    (70409299, 70409299, 0),
+    (69273666, 69273666, 0),
+    (68174084, 68174084, 0),
+    (-2147483648, 0, 5),
+];
+
+/// A compact list of integers with the given number of bits per entry.
+pub struct BitStorage {
+    data: Vec<u64>,
+    bits: u32,
+    mask: u64,
+    size: u32,
+    values_per_long: u8,
+    divide_mul: i32,
+    divide_add: i32,
+    divide_shift: i32,
+}
+
+#[derive(Debug)]
+pub enum BitStorageError {
+    InvalidLength { got: usize, expected: usize },
+}
+impl fmt::Display for BitStorageError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            BitStorageError::InvalidLength { got, expected } => write!(
+                f,
+                "Invalid length given for storage, got: {}, but expected: {}",
+                got, expected
+            ),
+        }
+    }
+}
+impl Error for BitStorageError {}
+
+impl BitStorage {
+    /// Create a new BitStorage with the given number of bits per entry.
+    /// `size` is the number of entries in the BitStorage.
+    pub fn new(bits: u32, size: u32, data: Option<Vec<u64>>) -> Result<Self, BitStorageError> {
+        let values_per_long = 64 / bits;
+        let magic_index = values_per_long - 1;
+        let (divide_mul, divide_add, divide_shift) = MAGIC[magic_index as usize];
+        let calculated_length = (size + values_per_long - 1) / values_per_long;
+
+        let mask = (1 << bits) - 1;
+
+        let using_data = if let Some(data) = data {
+            if data.len() != calculated_length as usize {
+                return Err(BitStorageError::InvalidLength {
+                    got: data.len(),
+                    expected: calculated_length as usize,
+                });
+            }
+            data
+        } else {
+            vec![0; calculated_length as usize]
+        };
+
+        Ok(BitStorage {
+            data: using_data,
+            bits,
+            mask,
+            size,
+            values_per_long: values_per_long as u8,
+            divide_mul,
+            divide_add,
+            divide_shift,
+        })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_wikivg_example() {
+        let data = [
+            1, 2, 2, 3, 4, 4, 5, 6, 6, 4, 8, 0, 7, 4, 3, 13, 15, 16, 9, 14, 10, 12, 0, 2,
+        ];
+        let expected_compact: [u64; 2] = [0x0020863148418841, 0x01018A7260F68C87];
+        let storage = BitStorage::new(5, 10, None).unwrap();
+    }
+}
diff --git a/azalea-world/src/lib.rs b/azalea-world/src/lib.rs
index ea7798f8..54961401 100644
--- a/azalea-world/src/lib.rs
+++ b/azalea-world/src/lib.rs
@@ -1,7 +1,9 @@
+mod bit_storage;
 mod palette;
 
 use azalea_core::ChunkPos;
 use azalea_protocol::mc_buf::{McBufReadable, McBufWritable};
+pub use bit_storage::BitStorage;
 use palette::PalettedContainer;
 use std::{
     io::{Read, Write},
diff --git a/bot/src/main.rs b/bot/src/main.rs
index 6a2d5959..504c8d41 100644
--- a/bot/src/main.rs
+++ b/bot/src/main.rs
@@ -5,7 +5,7 @@ async fn main() {
     println!("Hello, world!");
 
     // let address = "95.111.249.143:10000";
-    let address = "172.23.192.1:59152";
+    let address = "172.23.192.1:65163";
     // let response = azalea_client::ping::ping_server(&address.try_into().unwrap())
     //     .await
     //     .unwrap();