argminmax 0.6.3

/// Implementation of the argminmax operations for u16.
/// As there are no SIMD instructions for uints (on x86 & x86_64) we transform the u16
/// values to i16 ordinal values:
///     ord_i16 = v ^ -0x8000
///
/// This transformation is a bijection, i.e. it is reversible:
///     v = ord_i16 ^ -0x8000
///
/// Through this transformation we can perform the argminmax operations using SIMD on
/// the ordinal integer values and then transform the result back to the original u16
/// values.
///
#[cfg(any(
    target_arch = "x86",
    target_arch = "x86_64",
    all(target_arch = "arm", feature = "nightly_simd"),
    target_arch = "aarch64",
))]
use super::config::SIMDInstructionSet;
#[cfg(any(
    target_arch = "x86",
    target_arch = "x86_64",
    all(target_arch = "arm", feature = "nightly_simd"),
    target_arch = "aarch64",
))]
use super::generic::{impl_SIMDArgMinMax, impl_SIMDInit_Int, SIMDArgMinMax, SIMDInit, SIMDOps};
#[cfg(any(
    target_arch = "x86",
    target_arch = "x86_64",
    all(target_arch = "arm", feature = "nightly_simd"),
    target_arch = "aarch64",
))]
use crate::SCALAR;
#[cfg(target_arch = "aarch64")]
use std::arch::aarch64::*;
#[cfg(all(target_arch = "arm", feature = "nightly_simd"))]
use std::arch::arm::*;
#[cfg(target_arch = "x86")]
use std::arch::x86::*;
#[cfg(target_arch = "x86_64")]
use std::arch::x86_64::*;

/// The dtype-strategy for performing operations on u16 data: (default) Int
#[cfg(any(
    target_arch = "x86",
    target_arch = "x86_64",
    all(target_arch = "arm", feature = "nightly_simd"),
    target_arch = "aarch64",
))]
use super::super::dtype_strategy::Int;

#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
const XOR_VALUE: i16 = -0x8000; // i16::MIN

#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
#[inline(always)]
#[allow(unnecessary_transmutes)]
fn _i16ord_to_u16(ord_i16: i16) -> u16 {
    // let v = ord_i16 ^ -0x8000;
    unsafe { std::mem::transmute::<i16, u16>(ord_i16 ^ XOR_VALUE) }
}

#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
const MAX_INDEX: usize = i16::MAX as usize; // SIMD operations on signed ints
#[cfg(any(
    all(target_arch = "arm", feature = "nightly_simd"),
    target_arch = "aarch64"
))]
const MAX_INDEX: usize = u8::MAX as usize; // SIMD operations on unsigned ints

// --------------------------------------- AVX2 ----------------------------------------

#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
mod avx2 {
    use super::super::config::AVX2;
    use super::*;

    const LANE_SIZE: usize = AVX2::<Int>::LANE_SIZE_16;
    const XOR_MASK: __m256i = unsafe { std::mem::transmute([XOR_VALUE; LANE_SIZE]) };

    #[inline(always)]
    unsafe fn _u16_as_m256i_to_i16ord(u16_as_m256i: __m256i) -> __m256i {
        // on a scalar: v ^ -0x8000
        // transforms to monotonically increasing order
        _mm256_xor_si256(u16_as_m256i, XOR_MASK)
    }

    #[inline(always)]
    unsafe fn _reg_to_i16_arr(reg: __m256i) -> [i16; LANE_SIZE] {
        std::mem::transmute::<__m256i, [i16; LANE_SIZE]>(reg)
    }

    impl SIMDOps<u16, __m256i, __m256i, LANE_SIZE> for AVX2<Int> {
        const INITIAL_INDEX: __m256i = unsafe {
            std::mem::transmute([
                0i16, 1i16, 2i16, 3i16, 4i16, 5i16, 6i16, 7i16, 8i16, 9i16, 10i16, 11i16, 12i16,
                13i16, 14i16, 15i16,
            ])
        };
        const INDEX_INCREMENT: __m256i =
            unsafe { std::mem::transmute([LANE_SIZE as i16; LANE_SIZE]) };
        const MAX_INDEX: usize = MAX_INDEX;

        #[inline(always)]
        unsafe fn _reg_to_arr(_: __m256i) -> [u16; LANE_SIZE] {
            // Not implemented because we will perform the horizontal operations on the
            // signed integer values instead of trying to retransform **only** the values
            // (and thus not the indices) to signed integers.
            unimplemented!()
        }

        #[inline(always)]
        unsafe fn _mm_loadu(data: *const u16) -> __m256i {
            _u16_as_m256i_to_i16ord(_mm256_loadu_si256(data as *const __m256i))
        }

        #[inline(always)]
        unsafe fn _mm_add(a: __m256i, b: __m256i) -> __m256i {
            _mm256_add_epi16(a, b)
        }

        #[inline(always)]
        unsafe fn _mm_cmpgt(a: __m256i, b: __m256i) -> __m256i {
            _mm256_cmpgt_epi16(a, b)
        }

        #[inline(always)]
        unsafe fn _mm_cmplt(a: __m256i, b: __m256i) -> __m256i {
            _mm256_cmpgt_epi16(b, a)
        }

        #[inline(always)]
        unsafe fn _mm_blendv(a: __m256i, b: __m256i, mask: __m256i) -> __m256i {
            _mm256_blendv_epi8(a, b, mask)
        }

        #[inline(always)]
        unsafe fn _horiz_min(index: __m256i, value: __m256i) -> (usize, u16) {
            // 0. Find the minimum value
            let mut vmin: __m256i = value;
            vmin = _mm256_min_epi16(vmin, _mm256_permute2x128_si256(vmin, vmin, 1));
            vmin = _mm256_min_epi16(vmin, _mm256_alignr_epi8(vmin, vmin, 8));
            vmin = _mm256_min_epi16(vmin, _mm256_alignr_epi8(vmin, vmin, 4));
            vmin = _mm256_min_epi16(vmin, _mm256_alignr_epi8(vmin, vmin, 2));
            let min_value: i16 = _mm256_extract_epi16(vmin, 0) as i16;

            // Extract the index of the minimum value
            // 1. Create a mask with the index of the minimum value
            let mask = _mm256_cmpeq_epi16(value, vmin);
            // 2. Blend the mask with the index
            let search_index = _mm256_blendv_epi8(
                _mm256_set1_epi16(i16::MAX), // if mask is 0, use i16::MAX
                index,                       // if mask is 1, use index
                mask,
            );
            // 3. Find the minimum index
            let mut imin: __m256i = search_index;
            imin = _mm256_min_epi16(imin, _mm256_permute2x128_si256(imin, imin, 1));
            imin = _mm256_min_epi16(imin, _mm256_alignr_epi8(imin, imin, 8));
            imin = _mm256_min_epi16(imin, _mm256_alignr_epi8(imin, imin, 4));
            imin = _mm256_min_epi16(imin, _mm256_alignr_epi8(imin, imin, 2));
            let min_index: usize = _mm256_extract_epi16(imin, 0) as usize;

            (min_index, _i16ord_to_u16(min_value))
        }

        #[inline(always)]
        unsafe fn _horiz_max(index: __m256i, value: __m256i) -> (usize, u16) {
            // 0. Find the maximum value
            let mut vmax: __m256i = value;
            vmax = _mm256_max_epi16(vmax, _mm256_permute2x128_si256(vmax, vmax, 1));
            vmax = _mm256_max_epi16(vmax, _mm256_alignr_epi8(vmax, vmax, 8));
            vmax = _mm256_max_epi16(vmax, _mm256_alignr_epi8(vmax, vmax, 4));
            vmax = _mm256_max_epi16(vmax, _mm256_alignr_epi8(vmax, vmax, 2));
            let max_value: i16 = _mm256_extract_epi16(vmax, 0) as i16;

            // Extract the index of the maximum value
            // 1. Create a mask with the index of the maximum value
            let mask = _mm256_cmpeq_epi16(value, vmax);
            // 2. Blend the mask with the index
            let search_index = _mm256_blendv_epi8(
                _mm256_set1_epi16(i16::MAX), // if mask is 0, use i16::MAX
                index,                       // if mask is 1, use index
                mask,
            );
            // 3. Find the maximum index
            let mut imin: __m256i = search_index;
            imin = _mm256_min_epi16(imin, _mm256_permute2x128_si256(imin, imin, 1));
            imin = _mm256_min_epi16(imin, _mm256_alignr_epi8(imin, imin, 8));
            imin = _mm256_min_epi16(imin, _mm256_alignr_epi8(imin, imin, 4));
            imin = _mm256_min_epi16(imin, _mm256_alignr_epi8(imin, imin, 2));
            let max_index: usize = _mm256_extract_epi16(imin, 0) as usize;

            (max_index, _i16ord_to_u16(max_value))
        }
    }

    impl_SIMDInit_Int!(u16, __m256i, __m256i, LANE_SIZE, AVX2<Int>);

    impl_SIMDArgMinMax!(
        u16,
        __m256i,
        __m256i,
        LANE_SIZE,
        SCALAR<Int>,
        AVX2<Int>,
        "avx2"
    );
}

// ---------------------------------------- SSE ----------------------------------------

#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
mod sse {
    use super::super::config::SSE;
    use super::*;

    const LANE_SIZE: usize = SSE::<Int>::LANE_SIZE_16;
    const XOR_MASK: __m128i = unsafe { std::mem::transmute([XOR_VALUE; LANE_SIZE]) };

    #[inline(always)]
    unsafe fn _u16_as_m128i_to_i16ord(u16_as_m128i: __m128i) -> __m128i {
        // on a scalar: v ^ -0x8000
        // transforms to monotonically increasing order
        _mm_xor_si128(u16_as_m128i, XOR_MASK)
    }

    #[inline(always)]
    unsafe fn _reg_to_i16_arr(reg: __m128i) -> [i16; LANE_SIZE] {
        std::mem::transmute::<__m128i, [i16; LANE_SIZE]>(reg)
    }

    impl SIMDOps<u16, __m128i, __m128i, LANE_SIZE> for SSE<Int> {
        const INITIAL_INDEX: __m128i =
            unsafe { std::mem::transmute([0i16, 1i16, 2i16, 3i16, 4i16, 5i16, 6i16, 7i16]) };
        const INDEX_INCREMENT: __m128i =
            unsafe { std::mem::transmute([LANE_SIZE as i16; LANE_SIZE]) };
        const MAX_INDEX: usize = MAX_INDEX;

        #[inline(always)]
        unsafe fn _reg_to_arr(_: __m128i) -> [u16; LANE_SIZE] {
            // Not implemented because we will perform the horizontal operations on the
            // signed integer values instead of trying to retransform **only** the values
            // (and thus not the indices) to signed integers.
            unimplemented!()
        }

        #[inline(always)]
        unsafe fn _mm_loadu(data: *const u16) -> __m128i {
            _u16_as_m128i_to_i16ord(_mm_loadu_si128(data as *const __m128i))
        }

        #[inline(always)]
        unsafe fn _mm_add(a: __m128i, b: __m128i) -> __m128i {
            _mm_add_epi16(a, b)
        }

        #[inline(always)]
        unsafe fn _mm_cmpgt(a: __m128i, b: __m128i) -> __m128i {
            _mm_cmpgt_epi16(a, b)
        }

        #[inline(always)]
        unsafe fn _mm_cmplt(a: __m128i, b: __m128i) -> __m128i {
            _mm_cmplt_epi16(a, b)
        }

        #[inline(always)]
        unsafe fn _mm_blendv(a: __m128i, b: __m128i, mask: __m128i) -> __m128i {
            _mm_blendv_epi8(a, b, mask)
        }

        #[inline(always)]
        unsafe fn _horiz_min(index: __m128i, value: __m128i) -> (usize, u16) {
            // 0. Find the minimum value
            let mut vmin: __m128i = value;
            vmin = _mm_min_epi16(vmin, _mm_alignr_epi8(vmin, vmin, 8));
            vmin = _mm_min_epi16(vmin, _mm_alignr_epi8(vmin, vmin, 4));
            vmin = _mm_min_epi16(vmin, _mm_alignr_epi8(vmin, vmin, 2));
            let min_value: i16 = _mm_extract_epi16(vmin, 0) as i16;

            // Extract the index of the minimum value
            // 1. Create a mask with the index of the minimum value
            let mask = _mm_cmpeq_epi16(value, vmin);
            // 2. Blend the mask with the index
            let search_index = _mm_blendv_epi8(
                _mm_set1_epi16(i16::MAX), // if mask is 0, use i16::MAX
                index,                    // if mask is 1, use index
                mask,
            );
            // 3. Find the minimum index
            let mut imin: __m128i = search_index;
            imin = _mm_min_epi16(imin, _mm_alignr_epi8(imin, imin, 8));
            imin = _mm_min_epi16(imin, _mm_alignr_epi8(imin, imin, 4));
            imin = _mm_min_epi16(imin, _mm_alignr_epi8(imin, imin, 2));
            let min_index: usize = _mm_extract_epi16(imin, 0) as usize;

            (min_index, _i16ord_to_u16(min_value))
        }

        #[inline(always)]
        unsafe fn _horiz_max(index: __m128i, value: __m128i) -> (usize, u16) {
            // 0. Find the maximum value
            let mut vmax: __m128i = value;
            vmax = _mm_max_epi16(vmax, _mm_alignr_epi8(vmax, vmax, 8));
            vmax = _mm_max_epi16(vmax, _mm_alignr_epi8(vmax, vmax, 4));
            vmax = _mm_max_epi16(vmax, _mm_alignr_epi8(vmax, vmax, 2));
            let max_value: i16 = _mm_extract_epi16(vmax, 0) as i16;

            // Extract the index of the maximum value
            // 1. Create a mask with the index of the maximum value
            let mask = _mm_cmpeq_epi16(value, vmax);
            // 2. Blend the mask with the index
            let search_index = _mm_blendv_epi8(
                _mm_set1_epi16(i16::MAX), // if mask is 0, use i8::MAX
                index,                    // if mask is 1, use index
                mask,
            );
            // 3. Find the maximum index
            let mut imin: __m128i = search_index;
            imin = _mm_min_epi16(imin, _mm_alignr_epi8(imin, imin, 8));
            imin = _mm_min_epi16(imin, _mm_alignr_epi8(imin, imin, 4));
            imin = _mm_min_epi16(imin, _mm_alignr_epi8(imin, imin, 2));
            let max_index: usize = _mm_extract_epi16(imin, 0) as usize;

            (max_index, _i16ord_to_u16(max_value))
        }
    }

    impl_SIMDInit_Int!(u16, __m128i, __m128i, LANE_SIZE, SSE<Int>);

    impl_SIMDArgMinMax!(
        u16,
        __m128i,
        __m128i,
        LANE_SIZE,
        SCALAR<Int>,
        SSE<Int>,
        "sse4.1"
    );
}

// -------------------------------------- AVX512 ---------------------------------------

#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
#[cfg(feature = "nightly_simd")]
mod avx512 {
    use super::super::config::AVX512;
    use super::*;

    const LANE_SIZE: usize = AVX512::<Int>::LANE_SIZE_16;
    const XOR_MASK: __m512i = unsafe { std::mem::transmute([XOR_VALUE; LANE_SIZE]) };

    #[inline(always)]
    unsafe fn _u16_as_m512i_to_i16ord(u16_as_m512i: __m512i) -> __m512i {
        // on a scalar: v ^ -0x8000
        // transforms to monotonically increasing order
        _mm512_xor_si512(u16_as_m512i, XOR_MASK)
    }

    #[inline(always)]
    unsafe fn _reg_to_i16_arr(reg: __m512i) -> [i16; LANE_SIZE] {
        std::mem::transmute::<__m512i, [i16; LANE_SIZE]>(reg)
    }

    impl SIMDOps<u16, __m512i, u32, LANE_SIZE> for AVX512<Int> {
        const INITIAL_INDEX: __m512i = unsafe {
            std::mem::transmute([
                0i16, 1i16, 2i16, 3i16, 4i16, 5i16, 6i16, 7i16, 8i16, 9i16, 10i16, 11i16, 12i16,
                13i16, 14i16, 15i16, 16i16, 17i16, 18i16, 19i16, 20i16, 21i16, 22i16, 23i16, 24i16,
                25i16, 26i16, 27i16, 28i16, 29i16, 30i16, 31i16,
            ])
        };
        const INDEX_INCREMENT: __m512i =
            unsafe { std::mem::transmute([LANE_SIZE as i16; LANE_SIZE]) };
        const MAX_INDEX: usize = MAX_INDEX;

        #[inline(always)]
        unsafe fn _reg_to_arr(_: __m512i) -> [u16; LANE_SIZE] {
            // Not implemented because we will perform the horizontal operations on the
            // signed integer values instead of trying to retransform **only** the values
            // (and thus not the indices) to signed integers.
            unimplemented!()
        }

        #[inline(always)]
        unsafe fn _mm_loadu(data: *const u16) -> __m512i {
            _u16_as_m512i_to_i16ord(_mm512_loadu_epi16(data as *const i16))
        }

        #[inline(always)]
        unsafe fn _mm_add(a: __m512i, b: __m512i) -> __m512i {
            _mm512_add_epi16(a, b)
        }

        #[inline(always)]
        unsafe fn _mm_cmpgt(a: __m512i, b: __m512i) -> u32 {
            _mm512_cmpgt_epi16_mask(a, b)
        }

        #[inline(always)]
        unsafe fn _mm_cmplt(a: __m512i, b: __m512i) -> u32 {
            _mm512_cmplt_epi16_mask(a, b)
        }

        #[inline(always)]
        unsafe fn _mm_blendv(a: __m512i, b: __m512i, mask: u32) -> __m512i {
            _mm512_mask_blend_epi16(mask, a, b)
        }

        #[inline(always)]
        unsafe fn _horiz_min(index: __m512i, value: __m512i) -> (usize, u16) {
            // 0. Find the minimum value
            let mut vmin: __m512i = value;
            vmin = _mm512_min_epi16(vmin, _mm512_alignr_epi32(vmin, vmin, 8));
            vmin = _mm512_min_epi16(vmin, _mm512_alignr_epi32(vmin, vmin, 4));
            vmin = _mm512_min_epi16(vmin, _mm512_alignr_epi8(vmin, vmin, 8));
            vmin = _mm512_min_epi16(vmin, _mm512_alignr_epi8(vmin, vmin, 4));
            vmin = _mm512_min_epi16(vmin, _mm512_alignr_epi8(vmin, vmin, 2));
            let min_value: i16 = _mm_extract_epi16(_mm512_castsi512_si128(vmin), 0) as i16;

            // Extract the index of the minimum value
            // 1. Create a mask with the index of the minimum value
            let mask = _mm512_cmpeq_epi16_mask(value, vmin);
            // 2. Blend the mask with the index
            let search_index = _mm512_mask_blend_epi16(
                mask,
                _mm512_set1_epi16(i16::MAX), // if mask is 0, use i16::MAX
                index,                       // if mask is 1, use index
            );
            // 3. Find the minimum index
            let mut imin: __m512i = search_index;
            imin = _mm512_min_epi16(imin, _mm512_alignr_epi32(imin, imin, 8));
            imin = _mm512_min_epi16(imin, _mm512_alignr_epi32(imin, imin, 4));
            imin = _mm512_min_epi16(imin, _mm512_alignr_epi8(imin, imin, 8));
            imin = _mm512_min_epi16(imin, _mm512_alignr_epi8(imin, imin, 4));
            imin = _mm512_min_epi16(imin, _mm512_alignr_epi8(imin, imin, 2));
            let min_index: usize = _mm_extract_epi16(_mm512_castsi512_si128(imin), 0) as usize;

            (min_index, _i16ord_to_u16(min_value))
        }

        #[inline(always)]
        unsafe fn _horiz_max(index: __m512i, value: __m512i) -> (usize, u16) {
            // 0. Find the maximum value
            let mut vmax: __m512i = value;
            vmax = _mm512_max_epi16(vmax, _mm512_alignr_epi32(vmax, vmax, 8));
            vmax = _mm512_max_epi16(vmax, _mm512_alignr_epi32(vmax, vmax, 4));
            vmax = _mm512_max_epi16(vmax, _mm512_alignr_epi8(vmax, vmax, 8));
            vmax = _mm512_max_epi16(vmax, _mm512_alignr_epi8(vmax, vmax, 4));
            vmax = _mm512_max_epi16(vmax, _mm512_alignr_epi8(vmax, vmax, 2));
            let max_value: i16 = _mm_extract_epi16(_mm512_castsi512_si128(vmax), 0) as i16;

            // Extract the index of the maximum value
            // 1. Create a mask with the index of the maximum value
            let mask = _mm512_cmpeq_epi16_mask(value, vmax);
            // 2. Blend the mask with the index
            let search_index = _mm512_mask_blend_epi16(
                mask,
                _mm512_set1_epi16(i16::MAX), // if mask is 0, use i16::MAX
                index,                       // if mask is 1, use index
            );
            // 3. Find the maximum index
            let mut imin: __m512i = search_index;
            imin = _mm512_min_epi16(imin, _mm512_alignr_epi32(imin, imin, 8));
            imin = _mm512_min_epi16(imin, _mm512_alignr_epi32(imin, imin, 4));
            imin = _mm512_min_epi16(imin, _mm512_alignr_epi8(imin, imin, 8));
            imin = _mm512_min_epi16(imin, _mm512_alignr_epi8(imin, imin, 4));
            imin = _mm512_min_epi16(imin, _mm512_alignr_epi8(imin, imin, 2));
            let max_index: usize = _mm_extract_epi16(_mm512_castsi512_si128(imin), 0) as usize;

            (max_index, _i16ord_to_u16(max_value))
        }
    }

    impl_SIMDInit_Int!(u16, __m512i, u32, LANE_SIZE, AVX512<Int>);

    impl_SIMDArgMinMax!(
        u16,
        __m512i,
        u32,
        LANE_SIZE,
        SCALAR<Int>,
        AVX512<Int>,
        "avx512bw"
    );
}

// --------------------------------------- NEON ----------------------------------------

#[cfg(any(
    all(target_arch = "arm", feature = "nightly_simd"),
    target_arch = "aarch64" // stable for AArch64
))]
mod neon {
    use super::super::config::NEON;
    use super::*;

    const LANE_SIZE: usize = NEON::<Int>::LANE_SIZE_16;

    impl SIMDOps<u16, uint16x8_t, uint16x8_t, LANE_SIZE> for NEON<Int> {
        const INITIAL_INDEX: uint16x8_t =
            unsafe { std::mem::transmute([0i16, 1i16, 2i16, 3i16, 4i16, 5i16, 6i16, 7i16]) };
        const INDEX_INCREMENT: uint16x8_t =
            unsafe { std::mem::transmute([LANE_SIZE as i16; LANE_SIZE]) };
        const MAX_INDEX: usize = MAX_INDEX;

        #[inline(always)]
        unsafe fn _reg_to_arr(reg: uint16x8_t) -> [u16; LANE_SIZE] {
            std::mem::transmute::<uint16x8_t, [u16; LANE_SIZE]>(reg)
        }

        #[inline(always)]
        unsafe fn _mm_loadu(data: *const u16) -> uint16x8_t {
            vld1q_u16(data as *const u16)
        }

        #[inline(always)]
        unsafe fn _mm_add(a: uint16x8_t, b: uint16x8_t) -> uint16x8_t {
            vaddq_u16(a, b)
        }

        #[inline(always)]
        unsafe fn _mm_cmpgt(a: uint16x8_t, b: uint16x8_t) -> uint16x8_t {
            vcgtq_u16(a, b)
        }

        #[inline(always)]
        unsafe fn _mm_cmplt(a: uint16x8_t, b: uint16x8_t) -> uint16x8_t {
            vcltq_u16(a, b)
        }

        #[inline(always)]
        unsafe fn _mm_blendv(a: uint16x8_t, b: uint16x8_t, mask: uint16x8_t) -> uint16x8_t {
            vbslq_u16(mask, b, a)
        }

        #[inline(always)]
        unsafe fn _horiz_min(index: uint16x8_t, value: uint16x8_t) -> (usize, u16) {
            // 0. Find the minimum value
            let mut vmin: uint16x8_t = value;
            vmin = vminq_u16(vmin, vextq_u16(vmin, vmin, 4));
            vmin = vminq_u16(vmin, vextq_u16(vmin, vmin, 2));
            vmin = vminq_u16(vmin, vextq_u16(vmin, vmin, 1));
            let min_value: u16 = vgetq_lane_u16(vmin, 0);

            // Extract the index of the minimum value
            // 1. Create a mask with the index of the minimum value
            let mask = vceqq_u16(value, vmin);
            // 2. Blend the mask with the index
            let search_index = vbslq_u16(
                mask,
                index,                 // if mask is 1, use index
                vdupq_n_u16(u16::MAX), // if mask is 0, use u16::MAX
            );
            // 3. Find the minimum index
            let mut imin: uint16x8_t = search_index;
            imin = vminq_u16(imin, vextq_u16(imin, imin, 4));
            imin = vminq_u16(imin, vextq_u16(imin, imin, 2));
            imin = vminq_u16(imin, vextq_u16(imin, imin, 1));
            let min_index: usize = vgetq_lane_u16(imin, 0) as usize;

            (min_index, min_value)
        }

        #[inline(always)]
        unsafe fn _horiz_max(index: uint16x8_t, value: uint16x8_t) -> (usize, u16) {
            // 0. Find the maximum value
            let mut vmax: uint16x8_t = value;
            vmax = vmaxq_u16(vmax, vextq_u16(vmax, vmax, 4));
            vmax = vmaxq_u16(vmax, vextq_u16(vmax, vmax, 2));
            vmax = vmaxq_u16(vmax, vextq_u16(vmax, vmax, 1));
            let max_value: u16 = vgetq_lane_u16(vmax, 0);

            // Extract the index of the maximum value
            // 1. Create a mask with the index of the maximum value
            let mask = vceqq_u16(value, vmax);
            // 2. Blend the mask with the index
            let search_index = vbslq_u16(
                mask,
                index,                 // if mask is 1, use index
                vdupq_n_u16(u16::MAX), // if mask is 0, use u16::MAX
            );
            // 3. Find the maximum index
            let mut imin: uint16x8_t = search_index;
            imin = vminq_u16(imin, vextq_u16(imin, imin, 4));
            imin = vminq_u16(imin, vextq_u16(imin, imin, 2));
            imin = vminq_u16(imin, vextq_u16(imin, imin, 1));
            let max_index: usize = vgetq_lane_u16(imin, 0) as usize;

            (max_index, max_value)
        }
    }

    impl_SIMDInit_Int!(u16, uint16x8_t, uint16x8_t, LANE_SIZE, NEON<Int>);

    impl_SIMDArgMinMax!(
        u16,
        uint16x8_t,
        uint16x8_t,
        LANE_SIZE,
        SCALAR<Int>,
        NEON<Int>,
        "neon"
    );
}

// ======================================= TESTS =======================================

#[cfg(any(
    target_arch = "x86",
    target_arch = "x86_64",
    all(target_arch = "arm", feature = "nightly_simd"),
    target_arch = "aarch64",
))]
#[cfg(test)]
mod tests {
    use rstest::rstest;
    use rstest_reuse::{self, *};
    use std::marker::PhantomData;

    #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
    #[cfg(feature = "nightly_simd")]
    use crate::simd::config::AVX512;
    #[cfg(any(target_arch = "arm", target_arch = "aarch64"))]
    use crate::simd::config::NEON;
    #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
    use crate::simd::config::{AVX2, SSE};
    use crate::{Int, SIMDArgMinMax, SCALAR};

    use super::super::test_utils::{
        test_first_index_identical_values_argminmax, test_no_overflow_argminmax,
        test_return_same_result_argminmax,
    };

    use dev_utils::utils;

    fn get_array_u16(n: usize) -> Vec<u16> {
        utils::SampleUniformFullRange::get_random_array(n)
    }

    // The scalar implementation
    const SCALAR_STRATEGY: SCALAR<Int> = SCALAR {
        _dtype_strategy: PhantomData::<Int>,
    };

    // ------------ Template for x86 / x86_64 -------------

    #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
    #[template]
    #[rstest]
    #[case::sse(SSE {_dtype_strategy: PhantomData::<Int>}, is_x86_feature_detected!("sse4.1"))]
    #[case::avx2(AVX2 {_dtype_strategy: PhantomData::<Int>}, is_x86_feature_detected!("avx2"))]
    #[cfg_attr(feature = "nightly_simd", case::avx512(AVX512 {_dtype_strategy: PhantomData::<Int>}, is_x86_feature_detected!("avx512bw")))]
    fn simd_implementations<T, SIMDV, SIMDM, const LANE_SIZE: usize>(
        #[case] simd: T,
        #[case] simd_available: bool,
    ) {
    }

    // ------------ Template for ARM / AArch64 ------------

    #[cfg(any(target_arch = "arm", target_arch = "aarch64"))]
    #[template]
    #[rstest]
    #[case::neon(NEON {_dtype_strategy: PhantomData::<Int>}, true)]
    fn simd_implementations<T, SIMDV, SIMDM, const LANE_SIZE: usize>(
        #[case] simd: T,
        #[case] simd_available: bool,
    ) {
    }

    // ----------------- The actual tests -----------------

    #[apply(simd_implementations)]
    fn test_first_index_is_returned_when_identical_values_found<
        T,
        SIMDV,
        SIMDM,
        const LANE_SIZE: usize,
    >(
        #[case] simd: T,
        #[case] simd_available: bool,
    ) where
        T: SIMDArgMinMax<u16, SIMDV, SIMDM, LANE_SIZE, SCALAR<Int>>,
        SIMDV: Copy,
        SIMDM: Copy,
    {
        if !simd_available {
            return;
        }
        test_first_index_identical_values_argminmax(SCALAR_STRATEGY, simd);
    }

    #[apply(simd_implementations)]
    fn test_return_same_result<T, SIMDV, SIMDM, const LANE_SIZE: usize>(
        #[case] simd: T,
        #[case] simd_available: bool,
    ) where
        T: SIMDArgMinMax<u16, SIMDV, SIMDM, LANE_SIZE, SCALAR<Int>>,
        SIMDV: Copy,
        SIMDM: Copy,
    {
        if !simd_available {
            return;
        }
        test_return_same_result_argminmax(get_array_u16, SCALAR_STRATEGY, simd);
    }

    #[apply(simd_implementations)]
    fn test_no_overflow<T, SIMDV, SIMDM, const LANE_SIZE: usize>(
        #[case] simd: T,
        #[case] simd_available: bool,
    ) where
        T: SIMDArgMinMax<u16, SIMDV, SIMDM, LANE_SIZE, SCALAR<Int>>,
        SIMDV: Copy,
        SIMDM: Copy,
    {
        if !simd_available {
            return;
        }
        test_no_overflow_argminmax(get_array_u16, SCALAR_STRATEGY, simd, None);
    }
}