read rle .EGA files

src/ega.rs

@@ -105,7 +105,9 @@ pub fn decode<'a>(buf: &[u8], compression: Compression, tiling: Tiling)
 
   out = match compression {
     Compression::Uncompressed => decode_uncompressed(buf),
-    Compression::Rle => unimplemented!(),
+    Compression::Rle => {
+      decode_uncompressed(&decode_rle(buf))
+    },
     Compression::Lzw => {
       let mut decoder = U4Lzw::new();
       decode_uncompressed(&decoder.decode(buf))
@@ -130,6 +132,22 @@ fn decode_uncompressed(buf: &[u8]) -> Vec<u8> {
     .collect()
 }
 
+fn decode_rle(bytes: &[u8]) -> Vec<u8> {
+  let mut out = Vec::new();
+  let mut iter = bytes.iter();
+
+  while let Some(cmd) = iter.next() {
+    match cmd {
+      &0x02 => {
+        let len = *iter.next().expect("rle missing run length") as usize;
+        out.extend(::std::iter::repeat(*iter.next().expect("rle missing run value")).take(len));
+      },
+      val => out.push(*val),
+    }
+  }
+  out
+}
+
 struct U4Lzw {
   table: Vec<RefCell<Vec<u8>>>,
   load: u16,