added support for literals less than 5

src/encoding/blocks/compressed.rs

@@ -13,15 +13,22 @@ fn compress_literals(literals: &[u8], writer: &mut BitWriter) {
 
  let encoder_table = huff0_encoder::HuffmanTable::build_from_data(literals);
  let mut encoder = huff0_encoder::HuffmanEncoder::new(encoder_table);
- let encoded = encoder.encode4x(literals);
 
  let (size_format, size_bits) = match literals.len() {
- 0..6 => unimplemented!("should probably just be a raw block"),
- 6..1024 => (0b01u8, 10),
+ 0..6 => (0b00u8, 10),
+ 6..1024 => (0b01, 10),
  1024..16384 => (0b10, 14),
  16384..262144 => (0b11, 18),
  _ => unimplemented!("too many literals"),
  };
+
+ let encoded;
+ if size_format == 0 {
+ encoded = encoder.encode(literals);
+ } else {
+ encoded = encoder.encode4x(literals);
+ }
+
  writer.write_bits(size_format, 2);
  writer.write_bits(literals.len() as u32, size_bits);
  writer.write_bits(encoded.len() as u32, size_bits);

src/huff0/huff0_encoder.rs

@@ -32,6 +32,7 @@ impl HuffmanEncoder {
  writer.dump()
  }
  pub fn encode4x(&mut self, data: &[u8]) -> Vec<u8> {
+ assert!(data.len() >= 4);
  let split_size = (data.len() + 3) / 4;
  let src1 = &data[..split_size];
  let src2 = &data[split_size..split_size * 2];