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#![feature(slice_as_chunks)]
#![feature(portable_simd)]

pub fn convert_via_overwriting(bgra: &[u8; 16]) -> [u8; 12] {
    let bgra = bgra.as_chunks::<4>().0;
    let mut padded_rgb = [0; 13];
    for i in (0..4).rev() {
        let pixel = u32::from_be_bytes(bgra[i]);
        padded_rgb[i*3..][..4].copy_from_slice(&pixel.to_le_bytes());
    }

let mut rgb = [0; 12];
    rgb.copy_from_slice(&padded_rgb[1..]);
    rgb
}

pub fn convert_via_shifting(bgra: &[u8; 16]) -> [u8; 12] {
    let bgra = bgra.as_chunks().0;
    let mut buffer = 0_u128;
    for bgra in bgra.iter().cloned().rev() {
        buffer <<= 24;
        buffer |= u128::from(u32::from_be_bytes(bgra) >> 8);
    }
    buffer.to_le_bytes().as_chunks().0[0]
}

pub fn convert_via_std_simd_swizzle(bgra: &[u8; 16]) -> [u8; 12] {
    use std::simd::{Simd, simd_swizzle};
    let bgra = Simd::from_array(*bgra);
    const IDXS: [usize; 16] = [
        2, 1, 0,
        6, 5, 4,
        10, 9, 8,
        14, 13, 12,
        3, 7, 11, 15,
    ];
    let rgb = simd_swizzle!(bgra, IDXS);
    rgb.to_array().as_chunks().0[0]
}

pub fn convert_via_std_simd_scatter(bgra: &[u8; 16]) -> [u8; 12] {
    use std::simd::Simd;//u8x16;
    let vector = Simd::from_array(*bgra);
    let mut rgb = [0; 12];
    let idxs = [
        2, 1, 0, !0,
        5, 4, 3, !0,
        8, 7, 6, !0,
        11, 10, 9, !0,
    ];
    vector.scatter(&mut rgb, Simd::from_array(idxs));
    rgb
}

pub fn convert_raw(bgra: &[u8; 16]) -> [u8; 12] {
    let [
        b0, g0, r0, _a0,
        b1, g1, r1, _a1,
        b2, g2, r2, _a2,
        b3, g3, r3, _a3,
    ] = *bgra;
    [
        r0, g0, b0,
        r1, g1, b1,
        r2, g2, b2,
        r3, g3, b3,
    ]
}

pub fn convert_quinedot(bgr_arr: &[u8; 16]) -> [u8; 12] {
    let mut rgb: [u8; 12] = [0; 12];
    for (src, dst) in bgr_arr.chunks_exact(4).zip(rgb.chunks_exact_mut(3)) {
        dst[0] = src[2];
        dst[1] = src[1];
        dst[2] = src[0];
    }
    rgb
}