1 files changed, 76 insertions, 0 deletions
diff --git a/bv1/codec/src/decode.rs b/bv1/codec/src/decode.rs
new file mode 100644
index 0000000..616b7af
--- /dev/null
+++ b/bv1/codec/src/decode.rs
@@ -0,0 +1,76 @@
+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)?;
+    }
+}
+
+pub struct Decoder {
+    last_frame: Frame,
+    size: P2,
+}
+
+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(self.size))?
+        } else {
+            Block::read(&mut input, View::all(self.size))?
+        };
+
+        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);
+        }
+        Ok(())
+    }
+}
+
+pub fn decode_block(last_frame: &Frame, frame: &mut Frame, view: View, block: &Block) {
+    match block {
+        Block::Lit(pxs) => frame.import(view, &pxs),
+        Block::Split(a, b) => {
+            let [av, bv] = split(view);
+            let (frame1, frame2) =
+                unsafe { (&mut *(frame as *mut Frame), &mut *(frame as *mut Frame)) };
+            join(
+                || decode_block(last_frame, frame1, av, &a),
+                || decode_block(last_frame, frame2, bv, &b),
+            );
+        }
+        Block::Ref(r) => {
+            for y in view.a.y..view.b.y {
+                for x in view.a.x..view.b.x {
+                    let p = P2 { x, y };
+                    frame[p] = last_frame[p + r.pos_off] + r.color_off
+                }
+            }
+        }
+    }
+}