fn read_residual_data()

in image/src/codecs/webp/vp8.rs [1463:1538]

• 57 lines of code
• 20 McCabe index (conditional complexity)

    fn read_residual_data(&mut self, mb: &MacroBlock, mbx: usize, p: usize) -> [i32; 384] {
        let sindex = mb.segmentid as usize;
        let mut blocks = [0i32; 384];
        let mut plane = if mb.luma_mode == LumaMode::B { 3 } else { 1 };

        if plane == 1 {
            let complexity = self.top[mbx].complexity[0] + self.left.complexity[0];
            let mut block = [0i32; 16];
            let dcq = self.segment[sindex].y2dc;
            let acq = self.segment[sindex].y2ac;
            let n = self.read_coefficients(&mut block, p, plane, complexity as usize, dcq, acq);

            self.left.complexity[0] = if n { 1 } else { 0 };
            self.top[mbx].complexity[0] = if n { 1 } else { 0 };

            transform::iwht4x4(&mut block);

            for k in 0usize..16 {
                blocks[16 * k] = block[k];
            }

            plane = 0;
        }

        for y in 0usize..4 {
            let mut left = self.left.complexity[y + 1];
            for x in 0usize..4 {
                let i = x + y * 4;
                let block = &mut blocks[i * 16..i * 16 + 16];

                let complexity = self.top[mbx].complexity[x + 1] + left;
                let dcq = self.segment[sindex].ydc;
                let acq = self.segment[sindex].yac;

                let n = self.read_coefficients(block, p, plane, complexity as usize, dcq, acq);

                if block[0] != 0 || n {
                    transform::idct4x4(block);
                }

                left = if n { 1 } else { 0 };
                self.top[mbx].complexity[x + 1] = if n { 1 } else { 0 };
            }

            self.left.complexity[y + 1] = left;
        }

        plane = 2;

        for &j in &[5usize, 7usize] {
            for y in 0usize..2 {
                let mut left = self.left.complexity[y + j];

                for x in 0usize..2 {
                    let i = x + y * 2 + if j == 5 { 16 } else { 20 };
                    let block = &mut blocks[i * 16..i * 16 + 16];

                    let complexity = self.top[mbx].complexity[x + j] + left;
                    let dcq = self.segment[sindex].uvdc;
                    let acq = self.segment[sindex].uvac;

                    let n = self.read_coefficients(block, p, plane, complexity as usize, dcq, acq);
                    if block[0] != 0 || n {
                        transform::idct4x4(block);
                    }

                    left = if n { 1 } else { 0 };
                    self.top[mbx].complexity[x + j] = if n { 1 } else { 0 };
                }

                self.left.complexity[y + j] = left;
            }
        }

        blocks
    }