5 files changed, 61 insertions, 23 deletions
diff --git a/lvc/codec/Cargo.toml b/lvc/codec/Cargo.toml
index 67189bb..0c52ad2 100644
--- a/lvc/codec/Cargo.toml
+++ b/lvc/codec/Cargo.toml
@@ -4,4 +4,9 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
-rayon = "1.7.0"
+rayon = {version="1.7.0",optional = true}
+
+[features]
+default = ["parallel"]
+parallel = ["dep:rayon"]
+
diff --git a/lvc/codec/src/decode.rs b/lvc/codec/src/decode.rs
index 4830156..616b7af 100644
--- a/lvc/codec/src/decode.rs
+++ b/lvc/codec/src/decode.rs
@@ -1,38 +1,54 @@
-use crate::{debug::draw_debug, huff::read_huff, split::split, Block, Frame, Pixel, View, P2};
-use rayon::join;
+use crate::{
+    debug::draw_debug, huff::read_huff, impls::join, split::split, Block, Frame, View, P2,
+};
 use std::io::{BufReader, BufWriter, Read, Result, Write};
 
 pub fn decode(size: P2, debug: bool, input: impl Read, output: impl Write) -> Result<()> {
     let mut input = BufReader::new(input);
     let mut output = BufWriter::new(output);
+    let mut d = Decoder::new(size);
+    let mut f = Frame::new(size);
+    loop {
+        d.decode_frame(&mut input, &mut f, debug)?;
+        Frame::write(&mut output, &f)?;
+    }
+}
 
-    let mut frame = Frame::new(size);
-    let mut last_frame = Frame::new(size);
-    let mut debug_frame = if debug { Some(Frame::new(size)) } else { None };
+pub struct Decoder {
+    last_frame: Frame,
+    size: P2,
+}
 
-    let huff = true;
-    loop {
+impl Decoder {
+    pub fn new(size: P2) -> Self {
+        Self {
+            size,
+            last_frame: Frame::new(size),
+        }
+    }
+    pub fn decode_frame(
+        &mut self,
+        mut input: impl Read,
+        output: &mut Frame,
+        debug: bool,
+    ) -> Result<()> {
+        let huff = true;
         let b = if huff {
             let mut buf = vec![];
             read_huff(&mut input, &mut buf)?;
+            eprintln!("{}", buf.len());
             let mut buf = std::io::Cursor::new(&mut buf);
-            Block::read(&mut buf, View::all(size))?
+            Block::read(&mut buf, View::all(self.size))?
         } else {
-            Block::read(&mut input, View::all(size))?
+            Block::read(&mut input, View::all(self.size))?
         };
 
-        decode_block(&last_frame, &mut frame, View::all(size), &b);
-
-        if let Some(debug_frame) = &mut debug_frame {
-            debug_frame.pixels.copy_from_slice(&frame.pixels);
-            draw_debug(debug_frame, View::all(size), &b);
-            Frame::write(&mut output, &debug_frame)?;
-        } else {
-            Frame::write(&mut output, &frame)?;
+        decode_block(&self.last_frame, output, View::all(self.size), &b);
+        self.last_frame.pixels.copy_from_slice(&output.pixels); // TODO use mem::swap
+        if debug {
+            draw_debug(output, View::all(self.size), &b);
         }
-
-        last_frame.pixels.copy_from_slice(&frame.pixels); // TODO use mem::swap
-        frame.pixels.iter_mut().for_each(|e| *e = Pixel::BLACK);
+        Ok(())
     }
 }
 
diff --git a/lvc/codec/src/encode.rs b/lvc/codec/src/encode.rs
index d612daf..564b0b3 100644
--- a/lvc/codec/src/encode.rs
+++ b/lvc/codec/src/encode.rs
@@ -1,5 +1,6 @@
 use crate::diff::{diff, pixel_diff};
 use crate::huff::write_huff;
+use crate::impls::join;
 use crate::split::split;
 use crate::{decode::decode_block, Block, Frame, Pixel, Ref, View, P2};
 use std::io::{BufReader, BufWriter, Read, Write};
@@ -77,7 +78,7 @@ pub fn encode_block(last_frame: &Frame, frame: &Frame, view: View, config: &Enco
         || (view_area > 64 && attention(frame, view) > config.attention_split)
     {
         let [av, bv] = split(view);
-        let (ab, bb) = rayon::join(
+        let (ab, bb) = join(
             || Box::new(encode_block(last_frame, frame, av, config)),
             || Box::new(encode_block(last_frame, frame, bv, config)),
         );
diff --git a/lvc/codec/src/impls.rs b/lvc/codec/src/impls.rs
index 098db39..b4cc119 100644
--- a/lvc/codec/src/impls.rs
+++ b/lvc/codec/src/impls.rs
@@ -1,6 +1,19 @@
 use crate::{Frame, Pixel, Ref, View, P2};
 use std::ops::{Add, AddAssign, Index, IndexMut, Sub};
 
+#[cfg(feature = "parallel")]
+pub use rayon::join;
+#[cfg(not(feature = "parallel"))]
+pub fn join<A, B, RA, RB>(oper_a: A, oper_b: B) -> (RA, RB)
+where
+    A: FnOnce() -> RA + Send,
+    B: FnOnce() -> RB + Send,
+    RA: Send,
+    RB: Send,
+{
+    (oper_a(), oper_b())
+}
+
 impl Frame {
     pub fn export(&self, view: View) -> Vec<Pixel> {
         let mut o = vec![];
diff --git a/lvc/codec/src/lib.rs b/lvc/codec/src/lib.rs
index 5cd83b9..c764211 100644
--- a/lvc/codec/src/lib.rs
+++ b/lvc/codec/src/lib.rs
@@ -6,14 +6,17 @@ pub mod debug;
 pub mod decode;
 pub mod diff;
 pub mod encode;
+pub mod frameio;
 pub mod huff;
 pub mod impls;
 pub mod serialize;
 pub mod split;
-pub mod frameio;
 
 pub type PixelValue = i16;
 
+pub use decode::{decode, Decoder};
+pub use encode::encode;
+
 #[derive(Debug, Clone, Copy, Default, PartialEq, Eq)]
 pub struct Pixel {
     pub r: PixelValue,