zoomvtools 1.1.1

#[cfg(all(target_arch = "x86_64", feature = "avx2"))]
mod avx2;
mod rust;

#[cfg(test)]
mod tests;

use std::{
    f32::consts::PI,
    mem::{MaybeUninit, size_of},
    num::{NonZeroU8, NonZeroUsize},
};

use crate::util::{Pixel, assume_init_vec, uninit_vec};
use safefma::Fma;
use semisafe::slice::get as semisafe_get;
use semisafe::slice::get_mut as semisafe_get_mut;

#[derive(Debug, Clone)]
pub struct OverlapWindows {
    // window sizes
    nx: NonZeroUsize,
    ny: NonZeroUsize,

    overlap_9_windows: Vec<u16>,
}

impl OverlapWindows {
    const WINDOW_SCALE: f32 = 2048.0;
    const WINDOW_VARIANTS: usize = 9;

    #[must_use]
    #[inline]
    pub fn new(nx: NonZeroUsize, ny: NonZeroUsize, ox: usize, oy: usize) -> Self {
        let nx_value = nx.get();
        let ny_value = ny.get();
        let size = nx_value * ny_value;

        let (f_win1_uvx, f_win1_uvx_first, f_win1_uvx_last) =
            Self::build_axis_windows(nx_value, ox);
        let (f_win1_uvy, f_win1_uvy_first, f_win1_uvy_last) =
            Self::build_axis_windows(ny_value, oy);

        let mut overlap_9_windows: Vec<MaybeUninit<u16>> = uninit_vec(size * Self::WINDOW_VARIANTS);

        let (win_over_uvtl, rest) = overlap_9_windows.split_at_mut(size);
        let (win_over_uvtm, rest) = rest.split_at_mut(size);
        let (win_over_uvtr, rest) = rest.split_at_mut(size);
        let (win_over_uvml, rest) = rest.split_at_mut(size);
        let (win_over_uvmm, rest) = rest.split_at_mut(size);
        let (win_over_uvmr, rest) = rest.split_at_mut(size);
        let (win_over_uvbl, rest) = rest.split_at_mut(size);
        let (win_over_uvbm, win_over_uvbr) = rest.split_at_mut(size);

        for (j, ((&y_first, &y), &y_last)) in f_win1_uvy_first
            .iter()
            .zip(f_win1_uvy.iter())
            .zip(f_win1_uvy_last.iter())
            .enumerate()
        {
            let row_offset = j * nx_value;

            for (i, ((&x_first, &x), &x_last)) in f_win1_uvx_first
                .iter()
                .zip(f_win1_uvx.iter())
                .zip(f_win1_uvx_last.iter())
                .enumerate()
            {
                let idx = row_offset + i;
                semisafe_get_mut(win_over_uvtl, idx)
                    .write(Self::quantize_window(y_first * x_first));
                semisafe_get_mut(win_over_uvtm, idx).write(Self::quantize_window(y_first * x));
                semisafe_get_mut(win_over_uvtr, idx).write(Self::quantize_window(y_first * x_last));
                semisafe_get_mut(win_over_uvml, idx).write(Self::quantize_window(y * x_first));
                semisafe_get_mut(win_over_uvmm, idx).write(Self::quantize_window(y * x));
                semisafe_get_mut(win_over_uvmr, idx).write(Self::quantize_window(y * x_last));
                semisafe_get_mut(win_over_uvbl, idx).write(Self::quantize_window(y_last * x_first));
                semisafe_get_mut(win_over_uvbm, idx).write(Self::quantize_window(y_last * x));
                semisafe_get_mut(win_over_uvbr, idx).write(Self::quantize_window(y_last * x_last));
            }
        }

        // SAFETY: nested loops above initialize every slot of each split window exactly once.
        let overlap_9_windows = unsafe { assume_init_vec(overlap_9_windows) };

        Self {
            nx,
            ny,
            overlap_9_windows,
        }
    }

    #[must_use]
    fn build_axis_windows(length: usize, overlap: usize) -> (Vec<f32>, Vec<f32>, Vec<f32>) {
        let overlap = overlap.min(length);

        let mut window = vec![1.0; length];
        let mut window_first = vec![1.0; length];
        let mut window_last = vec![1.0; length];

        if overlap == 0 {
            return (window, window_first, window_last);
        }

        let overlap_f = overlap as f32;
        let length_f = length as f32;
        let denominator = overlap_f * 2.0;

        for i in 0..overlap {
            let phase = (i as f32 - overlap_f + 0.5) / denominator;
            let value = Self::cosine_squared(phase);
            *semisafe_get_mut(&mut window, i) = value;
            *semisafe_get_mut(&mut window_last, i) = value;
        }

        for i in length - overlap..length {
            let phase = (i as f32 - length_f + overlap_f + 0.5) / denominator;
            let value = Self::cosine_squared(phase);
            *semisafe_get_mut(&mut window, i) = value;
            *semisafe_get_mut(&mut window_first, i) = value;
        }

        (window, window_first, window_last)
    }

    #[must_use]
    fn cosine_squared(value: f32) -> f32 {
        let cosine = (PI * value).cos();
        cosine * cosine
    }

    #[must_use]
    fn quantize_window(value: f32) -> u16 {
        value.fma(Self::WINDOW_SCALE, 0.5) as u16
    }

    #[must_use]
    const fn size(&self) -> usize {
        self.nx.get() * self.ny.get()
    }

    #[must_use]
    #[inline]
    pub fn get_window(&self, i: usize) -> &[u16] {
        let size = self.size();
        semisafe_get(&self.overlap_9_windows, (size * i)..)
    }
}

pub type OverlapsFn = unsafe fn(
    dest: *mut u8,
    dest_stride_bytes: NonZeroUsize,
    src: *const u8,
    src_stride_bytes: NonZeroUsize,
    window: *const u16,
    window_stride: NonZeroUsize,
);

#[must_use]
#[inline]
pub fn select_overlaps<T: Pixel>(width: NonZeroUsize, height: NonZeroUsize) -> OverlapsFn {
    #[cfg(all(target_arch = "x86_64", feature = "avx2"))]
    if crate::util::has_avx2() {
        match (size_of::<T>(), width.get(), height.get()) {
            // PERF: Equivalent to scalar on test machine
            (1, 2, 2) => return avx2::overlaps_u8::<2, 2>,
            (1, 2, 4) => return avx2::overlaps_u8::<2, 4>,
            // PERF: Equivalent to scalar on test machine
            (1, 4, 2) => return avx2::overlaps_u8::<4, 2>,
            (1, 4, 4) => return avx2::overlaps_u8::<4, 4>,
            (1, 4, 8) => return avx2::overlaps_u8::<4, 8>,
            // TODO: 60% slower than scalar on test machine
            #[cfg(feature = "experimental")]
            (1, 8, 1) => return avx2::overlaps_u8::<8, 1>,
            #[cfg(feature = "experimental")]
            (1, 8, 2) => return avx2::overlaps_u8::<8, 2>,
            #[cfg(feature = "experimental")]
            (1, 8, 4) => return avx2::overlaps_u8::<8, 4>,
            #[cfg(feature = "experimental")]
            (1, 8, 8) => return avx2::overlaps_u8::<8, 8>,
            #[cfg(feature = "experimental")]
            (1, 8, 16) => return avx2::overlaps_u8::<8, 16>,
            // PERF: equivalent to scalar on test machine
            (1, 16, 1) => return avx2::overlaps_u8::<16, 1>,
            (1, 16, 2) => return avx2::overlaps_u8::<16, 2>,
            (1, 16, 4) => return avx2::overlaps_u8::<16, 4>,
            (1, 16, 8) => return avx2::overlaps_u8::<16, 8>,
            (1, 16, 16) => return avx2::overlaps_u8::<16, 16>,
            (1, 16, 32) => return avx2::overlaps_u8::<16, 32>,
            // PERF: 80% faster than scalar on test machine
            (1, 32, 8) => return avx2::overlaps_u8::<32, 8>,
            (1, 32, 16) => return avx2::overlaps_u8::<32, 16>,
            (1, 32, 32) => return avx2::overlaps_u8::<32, 32>,
            (1, 32, 64) => return avx2::overlaps_u8::<32, 64>,
            // PERF: 20% slower than scalar on test machine
            (1, 64, 16) => return avx2::overlaps_u8::<64, 16>,
            (1, 64, 32) => return avx2::overlaps_u8::<64, 32>,
            (1, 64, 64) => return avx2::overlaps_u8::<64, 64>,
            (1, 64, 128) => return avx2::overlaps_u8::<64, 128>,
            // PERF: 3-10% faster than scalar on test machine
            (1, 128, 32) => return avx2::overlaps_u8::<128, 32>,
            (1, 128, 64) => return avx2::overlaps_u8::<128, 64>,
            (1, 128, 128) => return avx2::overlaps_u8::<128, 128>,
            // PERF: Equivalent to scalar on test machine
            (2, 2, 2) => return avx2::overlaps_u16::<2, 2>,
            (2, 2, 4) => return avx2::overlaps_u16::<2, 4>,
            // PERF: Equivalent to scalar on test machine
            (2, 4, 2) => return avx2::overlaps_u16::<4, 2>,
            (2, 4, 4) => return avx2::overlaps_u16::<4, 4>,
            (2, 4, 8) => return avx2::overlaps_u16::<4, 8>,
            // TODO: 40% slower than scalar on test machine
            #[cfg(feature = "experimental")]
            (2, 8, 1) => return avx2::overlaps_u16::<8, 1>,
            #[cfg(feature = "experimental")]
            (2, 8, 2) => return avx2::overlaps_u16::<8, 2>,
            #[cfg(feature = "experimental")]
            (2, 8, 4) => return avx2::overlaps_u16::<8, 4>,
            #[cfg(feature = "experimental")]
            (2, 8, 8) => return avx2::overlaps_u16::<8, 8>,
            #[cfg(feature = "experimental")]
            (2, 8, 16) => return avx2::overlaps_u16::<8, 16>,
            // PERF: 3% faster than scalar on test machine
            (2, 16, 1) => return avx2::overlaps_u16::<16, 1>,
            (2, 16, 2) => return avx2::overlaps_u16::<16, 2>,
            (2, 16, 4) => return avx2::overlaps_u16::<16, 4>,
            (2, 16, 8) => return avx2::overlaps_u16::<16, 8>,
            (2, 16, 16) => return avx2::overlaps_u16::<16, 16>,
            (2, 16, 32) => return avx2::overlaps_u16::<16, 32>,
            // PERF: 75% faster than scalar on test machine
            (2, 32, 8) => return avx2::overlaps_u16::<32, 8>,
            (2, 32, 16) => return avx2::overlaps_u16::<32, 16>,
            (2, 32, 32) => return avx2::overlaps_u16::<32, 32>,
            (2, 32, 64) => return avx2::overlaps_u16::<32, 64>,
            // TODO: 30% slower than scalar on test machine
            #[cfg(feature = "experimental")]
            (2, 64, 16) => return avx2::overlaps_u16::<64, 16>,
            #[cfg(feature = "experimental")]
            (2, 64, 32) => return avx2::overlaps_u16::<64, 32>,
            #[cfg(feature = "experimental")]
            (2, 64, 64) => return avx2::overlaps_u16::<64, 64>,
            #[cfg(feature = "experimental")]
            (2, 64, 128) => return avx2::overlaps_u16::<64, 128>,
            // TODO: 30% slower than scalar on test machine
            #[cfg(feature = "experimental")]
            (2, 128, 32) => return avx2::overlaps_u16::<128, 32>,
            #[cfg(feature = "experimental")]
            (2, 128, 64) => return avx2::overlaps_u16::<128, 64>,
            #[cfg(feature = "experimental")]
            (2, 128, 128) => return avx2::overlaps_u16::<128, 128>,
            _ => {
                // fallthrough
            }
        };
    }

    match (size_of::<T>(), width.get(), height.get()) {
        (1, 2, 2) => rust::overlaps_u8::<2, 2>,
        (1, 2, 4) => rust::overlaps_u8::<2, 4>,
        (1, 4, 2) => rust::overlaps_u8::<4, 2>,
        (1, 4, 4) => rust::overlaps_u8::<4, 4>,
        (1, 4, 8) => rust::overlaps_u8::<4, 8>,
        (1, 8, 1) => rust::overlaps_u8::<8, 1>,
        (1, 8, 2) => rust::overlaps_u8::<8, 2>,
        (1, 8, 4) => rust::overlaps_u8::<8, 4>,
        (1, 8, 8) => rust::overlaps_u8::<8, 8>,
        (1, 8, 16) => rust::overlaps_u8::<8, 16>,
        (1, 16, 1) => rust::overlaps_u8::<16, 1>,
        (1, 16, 2) => rust::overlaps_u8::<16, 2>,
        (1, 16, 4) => rust::overlaps_u8::<16, 4>,
        (1, 16, 8) => rust::overlaps_u8::<16, 8>,
        (1, 16, 16) => rust::overlaps_u8::<16, 16>,
        (1, 16, 32) => rust::overlaps_u8::<16, 32>,
        (1, 32, 8) => rust::overlaps_u8::<32, 8>,
        (1, 32, 16) => rust::overlaps_u8::<32, 16>,
        (1, 32, 32) => rust::overlaps_u8::<32, 32>,
        (1, 32, 64) => rust::overlaps_u8::<32, 64>,
        (1, 64, 16) => rust::overlaps_u8::<64, 16>,
        (1, 64, 32) => rust::overlaps_u8::<64, 32>,
        (1, 64, 64) => rust::overlaps_u8::<64, 64>,
        (1, 64, 128) => rust::overlaps_u8::<64, 128>,
        (1, 128, 32) => rust::overlaps_u8::<128, 32>,
        (1, 128, 64) => rust::overlaps_u8::<128, 64>,
        (1, 128, 128) => rust::overlaps_u8::<128, 128>,
        (2, 2, 2) => rust::overlaps_u16::<2, 2>,
        (2, 2, 4) => rust::overlaps_u16::<2, 4>,
        (2, 4, 2) => rust::overlaps_u16::<4, 2>,
        (2, 4, 4) => rust::overlaps_u16::<4, 4>,
        (2, 4, 8) => rust::overlaps_u16::<4, 8>,
        (2, 8, 1) => rust::overlaps_u16::<8, 1>,
        (2, 8, 2) => rust::overlaps_u16::<8, 2>,
        (2, 8, 4) => rust::overlaps_u16::<8, 4>,
        (2, 8, 8) => rust::overlaps_u16::<8, 8>,
        (2, 8, 16) => rust::overlaps_u16::<8, 16>,
        (2, 16, 1) => rust::overlaps_u16::<16, 1>,
        (2, 16, 2) => rust::overlaps_u16::<16, 2>,
        (2, 16, 4) => rust::overlaps_u16::<16, 4>,
        (2, 16, 8) => rust::overlaps_u16::<16, 8>,
        (2, 16, 16) => rust::overlaps_u16::<16, 16>,
        (2, 16, 32) => rust::overlaps_u16::<16, 32>,
        (2, 32, 8) => rust::overlaps_u16::<32, 8>,
        (2, 32, 16) => rust::overlaps_u16::<32, 16>,
        (2, 32, 32) => rust::overlaps_u16::<32, 32>,
        (2, 32, 64) => rust::overlaps_u16::<32, 64>,
        // FIXME: 64 and 128 widths have serious regressions when compiled with znver4
        (2, 64, 16) => rust::overlaps_u16::<64, 16>,
        (2, 64, 32) => rust::overlaps_u16::<64, 32>,
        (2, 64, 64) => rust::overlaps_u16::<64, 64>,
        (2, 64, 128) => rust::overlaps_u16::<64, 128>,
        (2, 128, 32) => rust::overlaps_u16::<128, 32>,
        (2, 128, 64) => rust::overlaps_u16::<128, 64>,
        (2, 128, 128) => rust::overlaps_u16::<128, 128>,
        _ => panic!("unsupported block size for overlaps: {}x{}", width, height),
    }
}

pub type ToPixelsFn = unsafe fn(
    dest: *mut u8,
    dest_stride_bytes: NonZeroUsize,
    src: *const u8,
    src_stride_bytes: NonZeroUsize,
    width: NonZeroUsize,
    height: NonZeroUsize,
    bits_per_sample: NonZeroU8,
);

#[must_use]
#[inline]
pub fn select_to_pixels<T: Pixel>() -> ToPixelsFn {
    match size_of::<T>() {
        1 => rust::to_pixels_u16_to_u8,
        2 => rust::to_pixels_u32_to_u16,
        _ => unreachable!(),
    }
}