struct LossLess: Make Rav1dFrameHeader_segmentation::lossless a bit array.

Author: kkysen

include/dav1d/headers.rs

@@ -2096,6 +2096,48 @@ pub struct Dav1dFrameHeader_segmentation {
     pub qidx: [u8; DAV1D_MAX_SEGMENTS as usize],
 }
 
+/// Like a `[bool; RAV1D_MAX_SEGMENTS as usize]`,
+/// but the [`bool`]s are compressed into the bits of the [`u8`].
+#[derive(Clone, Copy, Default)]
+pub struct LossLess {
+    bits: u8,
+}
+
+impl LossLess {
+    pub const fn empty() -> Self {
+        Self { bits: 0 }
+    }
+
+    pub const fn get(&self, index: u8) -> bool {
+        const { assert!(u8::BITS >= RAV1D_MAX_SEGMENTS as _) };
+        self.bits & (1 << index) != 0
+    }
+
+    pub const fn all(&self) -> bool {
+        self.bits == ((1u64 << RAV1D_MAX_SEGMENTS) - 1) as u8
+    }
+
+    pub const fn to_array(&self) -> [bool; RAV1D_MAX_SEGMENTS as usize] {
+        let mut a = [false; RAV1D_MAX_SEGMENTS as usize];
+        let mut i = 0;
+        while i < RAV1D_MAX_SEGMENTS {
+            a[i as usize] = self.get(i);
+            i += 1;
+        }
+        a
+    }
+
+    pub fn from_array(a: [bool; RAV1D_MAX_SEGMENTS as usize]) -> Self {
+        let mut this = Self::empty();
+        let mut i = 0;
+        while i < RAV1D_MAX_SEGMENTS {
+            this.bits |= (a[i as usize] as u8) << i;
+            i += 1;
+        }
+        this
+    }
+}
+
 #[derive(Clone, Default)]
 #[repr(C)]
 pub struct Rav1dFrameHeader_segmentation {
@@ -2104,8 +2146,7 @@ pub struct Rav1dFrameHeader_segmentation {
     pub temporal: u8,
     pub update_data: u8,
     pub seg_data: Rav1dSegmentationDataSet,
-    /// TODO compress `[bool; 8]` into `u8`.
-    pub lossless: [bool; RAV1D_MAX_SEGMENTS as usize],
+    pub lossless: LossLess,
     pub qidx: [u8; RAV1D_MAX_SEGMENTS as usize],
 }
 
@@ -2126,7 +2167,7 @@ impl From<Dav1dFrameHeader_segmentation> for Rav1dFrameHeader_segmentation {
             temporal,
             update_data,
             seg_data: seg_data.into(),
-            lossless: lossless.map(|e| e != 0),
+            lossless: LossLess::from_array(lossless.map(|e| e != 0)),
             qidx,
         }
     }
@@ -2149,7 +2190,7 @@ impl From<Rav1dFrameHeader_segmentation> for Dav1dFrameHeader_segmentation {
             temporal,
             update_data,
             seg_data: seg_data.into(),
-            lossless: lossless.map(|e| e as u8),
+            lossless: lossless.to_array().map(|e| e as u8),
             qidx,
         }
     }

src/decode.rs

@@ -798,7 +798,7 @@ fn read_vartx_tree(
     let frame_hdr = &***f.frame_hdr.as_ref().unwrap();
     let txfm_mode = frame_hdr.txfm_mode;
     let uvtx;
-    if b.skip == 0 && (frame_hdr.segmentation.lossless[b.seg_id as usize] || max_ytx == TX_4X4) {
+    if b.skip == 0 && (frame_hdr.segmentation.lossless.get(b.seg_id) || max_ytx == TX_4X4) {
         uvtx = TX_4X4;
         max_ytx = uvtx;
         if txfm_mode == Rav1dTxfmMode::Switchable {
@@ -1683,7 +1683,7 @@ fn decode_b(
         let uv_angle;
         let cfl_alpha;
         if has_chroma {
-            let cfl_allowed = if frame_hdr.segmentation.lossless[b.seg_id as usize] {
+            let cfl_allowed = if frame_hdr.segmentation.lossless.get(b.seg_id) {
                 cbw4 == 1 && cbh4 == 1
             } else {
                 (cfl_allowed_mask & (1 << bs as u8)) != 0
@@ -1882,7 +1882,7 @@ fn decode_b(
 
         let frame_hdr = f.frame_hdr();
 
-        let tx = if frame_hdr.segmentation.lossless[b.seg_id as usize] {
+        let tx = if frame_hdr.segmentation.lossless.get(b.seg_id) {
             b.uvtx = TX_4X4;
             b.uvtx
         } else {
@@ -3075,7 +3075,7 @@ fn decode_b(
             let tx_split = [tx_split0 as u16, tx_split1];
             let mut ytx = max_ytx;
             let mut uvtx = b.uvtx;
-            if frame_hdr.segmentation.lossless[b.seg_id as usize] {
+            if frame_hdr.segmentation.lossless.get(b.seg_id) {
                 ytx = TX_4X4;
                 uvtx = TX_4X4;
             }

src/obu.rs

@@ -7,6 +7,7 @@ use crate::include::dav1d::data::Rav1dData;
 use crate::include::dav1d::dav1d::Rav1dDecodeFrameType;
 use crate::include::dav1d::headers::DRav1d;
 use crate::include::dav1d::headers::Dav1dSequenceHeader;
+use crate::include::dav1d::headers::LossLess;
 use crate::include::dav1d::headers::Rav1dAdaptiveBoolean;
 use crate::include::dav1d::headers::Rav1dChromaSamplePosition;
 use crate::include::dav1d::headers::Rav1dColorPrimaries;
@@ -1195,7 +1196,7 @@ fn parse_segmentation(
             quant.yac
         }
     });
-    let lossless = array::from_fn(|i| qidx[i] == 0 && delta_lossless);
+    let lossless = LossLess::from_array(array::from_fn(|i| qidx[i] == 0 && delta_lossless));
     Ok(Rav1dFrameHeader_segmentation {
         enabled,
         update_map,
@@ -2001,7 +2002,7 @@ fn parse_frame_hdr(
     let tiling = parse_tiling(seqhdr, &size, &debug, gb)?;
     let quant = parse_quant(seqhdr, &debug, gb);
     let segmentation = parse_segmentation(state, primary_ref_frame, &refidx, &quant, &debug, gb)?;
-    let all_lossless = segmentation.lossless.iter().all(|&it| it);
+    let all_lossless = segmentation.lossless.all();
     let delta = parse_delta(&quant, allow_intrabc, &debug, gb);
     let loopfilter = parse_loopfilter(
         state,

src/recon.rs

@@ -524,7 +524,7 @@ fn decode_coefs<BD: BitDepth>(
     let ts = &f.ts[ts];
     let chroma = plane != 0;
     let frame_hdr = &***f.frame_hdr.as_ref().unwrap();
-    let lossless = frame_hdr.segmentation.lossless[b.seg_id as usize];
+    let lossless = frame_hdr.segmentation.lossless.get(b.seg_id);
     let t_dim = &dav1d_txfm_dimensions[tx as usize];
     let dbg = dbg_block_info && plane != 0 && false;