fn transpose_square_1()

in math/src/fft/concurrent.rs [179:198]

• 18 lines of code
• 4 McCabe index (conditional complexity)

fn transpose_square_1<T>(matrix: &mut [T], size: usize) {
    debug_assert_eq!(matrix.len(), size * size);
    if size % 2 != 0 {
        unimplemented!("odd sizes are not supported");
    }

    // iterate over upper-left triangle, working in 2x2 blocks
    for row in (0..size).step_by(2) {
        let i = row * size + row;
        matrix.swap(i + 1, i + size);
        for col in (row..size).step_by(2).skip(1) {
            let i = row * size + col;
            let j = col * size + row;
            matrix.swap(i, j);
            matrix.swap(i + 1, j + size);
            matrix.swap(i + size, j + 1);
            matrix.swap(i + size + 1, j + size + 1);
        }
    }
}