first version, only very simple greedy packer

src/greedy_packer.rs

@@ -0,0 +1,44 @@
+use crate::lz::LzCoder;
+use crate::match_finder::MatchFinder;
+
+pub fn pack(data: &[u8]) -> Vec<u8> {
+    let match_finder = MatchFinder::new(data);
+    let mut lz = LzCoder::new();
+
+    let mut pos = 0;
+    while pos < data.len() {
+        let mut encoded_match = false;
+        if let Some(m) = match_finder.matches(pos).next() {
+            let max_offset = 1 << (m.length * 3 - 1).min(31);
+            let offset = pos - m.pos;
+            if offset < max_offset {
+                lz.encode_match(offset, m.length);
+                pos += m.length;
+                encoded_match = true;
+            }
+        }
+
+        if !encoded_match {
+            let offset = lz.last_offset();
+            if offset != 0 {
+                let length = data[pos..]
+                    .iter()
+                    .zip(data[(pos - offset)..].iter())
+                    .take_while(|(a, b)| a == b)
+                    .count();
+                if length > 0 {
+                    lz.encode_match(offset, length);
+                    pos += length;
+                    encoded_match = true;
+                }
+            }
+        }
+
+        if !encoded_match {
+            lz.encode_literal(data[pos]);
+            pos += 1;
+        }
+    }
+
+    lz.finish()
+}