// Copyright 2011 Google Inc. All Rights Reserved.

//

// Use of this source code is governed by a BSD-style license

// that can be found in the COPYING file in the root of the source

// tree. An additional intellectual property rights grant can be found

// in the file PATENTS. All contributing project authors may

// be found in the AUTHORS file in the root of the source tree.

// -----------------------------------------------------------------------------

//

// SSE2 version of speed-critical encoding functions.

//

// Author: Christian Duvivier (cduvivier@google.com)

#include "src/dsp/dsp.h"

#if defined(WEBP_USE_SSE2)

#include <assert.h>

#include <emmintrin.h>

#include <stdlib.h>  // for abs()

#include <string.h>

#include "src/dsp/common_sse2.h"

#include "src/dsp/cpu.h"

#include "src/enc/cost_enc.h"

#include "src/enc/vp8i_enc.h"

#include "src/utils/utils.h"

#include "src/webp/types.h"

//------------------------------------------------------------------------------

// Transforms (Paragraph 14.4)

// Does one inverse transform.

static void ITransform_One_SSE2(const uint8_t* WEBP_RESTRICT ref,

                                const int16_t* WEBP_RESTRICT in,

                                uint8_t* WEBP_RESTRICT dst) {

  // This implementation makes use of 16-bit fixed point versions of two

  // multiply constants:

  //    K1 = sqrt(2) * cos (pi/8) ~= 85627 / 2^16

  //    K2 = sqrt(2) * sin (pi/8) ~= 35468 / 2^16

  //

  // To be able to use signed 16-bit integers, we use the following trick to

  // have constants within range:

  // - Associated constants are obtained by subtracting the 16-bit fixed point

  //   version of one:

  //      k = K - (1 << 16)  =>  K = k + (1 << 16)

  //      K1 = 85267  =>  k1 =  20091

  //      K2 = 35468  =>  k2 = -30068

  // - The multiplication of a variable by a constant become the sum of the

  //   variable and the multiplication of that variable by the associated

  //   constant:

  //      (x * K) >> 16 = (x * (k + (1 << 16))) >> 16 = ((x * k ) >> 16) + x

  const __m128i k1k2 =

      _mm_set_epi16(-30068, -30068, -30068, -30068, 20091, 20091, 20091, 20091);

  const __m128i k2k1 =

      _mm_set_epi16(20091, 20091, 20091, 20091, -30068, -30068, -30068, -30068);

  const __m128i zero = _mm_setzero_si128();

  const __m128i zero_four = _mm_set_epi16(0, 0, 0, 0, 4, 4, 4, 4);

  __m128i T01, T23;

  // Load and concatenate the transform coefficients.

  const __m128i in01 = _mm_loadu_si128((const __m128i*)&in[0]);

  const __m128i in23 = _mm_loadu_si128((const __m128i*)&in[8]);

  // a00 a10 a20 a30   a01 a11 a21 a31

  // a02 a12 a22 a32   a03 a13 a23 a33

  // Vertical pass and subsequent transpose.

  {

    const __m128i in1 = _mm_unpackhi_epi64(in01, in01);

    const __m128i in3 = _mm_unpackhi_epi64(in23, in23);

    // First pass, c and d calculations are longer because of the "trick"

    // multiplications.

    // c = MUL(in1, K2) - MUL(in3, K1) = MUL(in1, k2) - MUL(in3, k1) + in1 - in3

    // d = MUL(in1, K1) + MUL(in3, K2) = MUL(in1, k1) + MUL(in3, k2) + in1 + in3

    const __m128i a_d3 = _mm_add_epi16(in01, in23);

    const __m128i b_c3 = _mm_sub_epi16(in01, in23);

    const __m128i c1d1 = _mm_mulhi_epi16(in1, k2k1);

    const __m128i c2d2 = _mm_mulhi_epi16(in3, k1k2);

    const __m128i c3 = _mm_unpackhi_epi64(b_c3, b_c3);

    const __m128i c4 = _mm_sub_epi16(c1d1, c2d2);

    const __m128i c = _mm_add_epi16(c3, c4);

    const __m128i d4u = _mm_add_epi16(c1d1, c2d2);

    const __m128i du = _mm_add_epi16(a_d3, d4u);

    const __m128i d = _mm_unpackhi_epi64(du, du);

    // Second pass.

    const __m128i comb_ab = _mm_unpacklo_epi64(a_d3, b_c3);

    const __m128i comb_dc = _mm_unpacklo_epi64(d, c);

    const __m128i tmp01 = _mm_add_epi16(comb_ab, comb_dc);

    const __m128i tmp32 = _mm_sub_epi16(comb_ab, comb_dc);

    const __m128i tmp23 = _mm_shuffle_epi32(tmp32, _MM_SHUFFLE(1, 0, 3, 2));

    const __m128i transpose_0 = _mm_unpacklo_epi16(tmp01, tmp23);

    const __m128i transpose_1 = _mm_unpackhi_epi16(tmp01, tmp23);

    // a00 a20 a01 a21   a02 a22 a03 a23

    // a10 a30 a11 a31   a12 a32 a13 a33

    T01 = _mm_unpacklo_epi16(transpose_0, transpose_1);

    T23 = _mm_unpackhi_epi16(transpose_0, transpose_1);

    // a00 a10 a20 a30   a01 a11 a21 a31

    // a02 a12 a22 a32   a03 a13 a23 a33

  }

  // Horizontal pass and subsequent transpose.

  {

    const __m128i T1 = _mm_unpackhi_epi64(T01, T01);

    const __m128i T3 = _mm_unpackhi_epi64(T23, T23);

    // First pass, c and d calculations are longer because of the "trick"

    // multiplications.

    const __m128i dc = _mm_add_epi16(T01, zero_four);

    // c = MUL(T1, K2) - MUL(T3, K1) = MUL(T1, k2) - MUL(T3, k1) + T1 - T3

    // d = MUL(T1, K1) + MUL(T3, K2) = MUL(T1, k1) + MUL(T3, k2) + T1 + T3

    const __m128i a_d3 = _mm_add_epi16(dc, T23);

    const __m128i b_c3 = _mm_sub_epi16(dc, T23);

    const __m128i c1d1 = _mm_mulhi_epi16(T1, k2k1);

    const __m128i c2d2 = _mm_mulhi_epi16(T3, k1k2);

    const __m128i c3 = _mm_unpackhi_epi64(b_c3, b_c3);

    const __m128i c4 = _mm_sub_epi16(c1d1, c2d2);

    const __m128i c = _mm_add_epi16(c3, c4);

    const __m128i d4u = _mm_add_epi16(c1d1, c2d2);

    const __m128i du = _mm_add_epi16(a_d3, d4u);

    const __m128i d = _mm_unpackhi_epi64(du, du);

    // Second pass.

    const __m128i comb_ab = _mm_unpacklo_epi64(a_d3, b_c3);

    const __m128i comb_dc = _mm_unpacklo_epi64(d, c);

    const __m128i tmp01 = _mm_add_epi16(comb_ab, comb_dc);

    const __m128i tmp32 = _mm_sub_epi16(comb_ab, comb_dc);

    const __m128i tmp23 = _mm_shuffle_epi32(tmp32, _MM_SHUFFLE(1, 0, 3, 2));

    const __m128i shifted01 = _mm_srai_epi16(tmp01, 3);

    const __m128i shifted23 = _mm_srai_epi16(tmp23, 3);

    // a00 a01 a02 a03   a10 a11 a12 a13

    // a20 a21 a22 a23   a30 a31 a32 a33

    const __m128i transpose_0 = _mm_unpacklo_epi16(shifted01, shifted23);

    const __m128i transpose_1 = _mm_unpackhi_epi16(shifted01, shifted23);

    // a00 a20 a01 a21   a02 a22 a03 a23

    // a10 a30 a11 a31   a12 a32 a13 a33

    T01 = _mm_unpacklo_epi16(transpose_0, transpose_1);

    T23 = _mm_unpackhi_epi16(transpose_0, transpose_1);

    // a00 a10 a20 a30   a01 a11 a21 a31

    // a02 a12 a22 a32   a03 a13 a23 a33

  }

  // Add inverse transform to 'ref' and store.

  {

    // Load the reference(s).

    __m128i ref01, ref23, ref0123;

    int32_t buf[4];

    // Load four bytes/pixels per line.

    const __m128i ref0 = _mm_cvtsi32_si128(WebPMemToInt32(&ref[0 * BPS]));

    const __m128i ref1 = _mm_cvtsi32_si128(WebPMemToInt32(&ref[1 * BPS]));

    const __m128i ref2 = _mm_cvtsi32_si128(WebPMemToInt32(&ref[2 * BPS]));

    const __m128i ref3 = _mm_cvtsi32_si128(WebPMemToInt32(&ref[3 * BPS]));

    ref01 = _mm_unpacklo_epi32(ref0, ref1);

    ref23 = _mm_unpacklo_epi32(ref2, ref3);

    // Convert to 16b.

    ref01 = _mm_unpacklo_epi8(ref01, zero);

    ref23 = _mm_unpacklo_epi8(ref23, zero);

    // Add the inverse transform(s).

    ref01 = _mm_add_epi16(ref01, T01);

    ref23 = _mm_add_epi16(ref23, T23);

    // Unsigned saturate to 8b.

    ref0123 = _mm_packus_epi16(ref01, ref23);

    _mm_storeu_si128((__m128i*)buf, ref0123);

    // Store four bytes/pixels per line.

    WebPInt32ToMem(&dst[0 * BPS], buf[0]);

    WebPInt32ToMem(&dst[1 * BPS], buf[1]);

    WebPInt32ToMem(&dst[2 * BPS], buf[2]);

    WebPInt32ToMem(&dst[3 * BPS], buf[3]);

  }

}

// Does two inverse transforms.

static void ITransform_Two_SSE2(const uint8_t* WEBP_RESTRICT ref,

                                const int16_t* WEBP_RESTRICT in,

                                uint8_t* WEBP_RESTRICT dst) {

  // This implementation makes use of 16-bit fixed point versions of two

  // multiply constants:

  //    K1 = sqrt(2) * cos (pi/8) ~= 85627 / 2^16

  //    K2 = sqrt(2) * sin (pi/8) ~= 35468 / 2^16

  //

  // To be able to use signed 16-bit integers, we use the following trick to

  // have constants within range:

  // - Associated constants are obtained by subtracting the 16-bit fixed point

  //   version of one:

  //      k = K - (1 << 16)  =>  K = k + (1 << 16)

  //      K1 = 85267  =>  k1 =  20091

  //      K2 = 35468  =>  k2 = -30068

  // - The multiplication of a variable by a constant become the sum of the

  //   variable and the multiplication of that variable by the associated

  //   constant:

  //      (x * K) >> 16 = (x * (k + (1 << 16))) >> 16 = ((x * k ) >> 16) + x

  const __m128i k1 = _mm_set1_epi16(20091);

  const __m128i k2 = _mm_set1_epi16(-30068);

  __m128i T0, T1, T2, T3;

  // Load and concatenate the transform coefficients (we'll do two inverse

  // transforms in parallel).

  __m128i in0, in1, in2, in3;

  {

    const __m128i tmp0 = _mm_loadu_si128((const __m128i*)&in[0]);

    const __m128i tmp1 = _mm_loadu_si128((const __m128i*)&in[8]);

    const __m128i tmp2 = _mm_loadu_si128((const __m128i*)&in[16]);

    const __m128i tmp3 = _mm_loadu_si128((const __m128i*)&in[24]);

    in0 = _mm_unpacklo_epi64(tmp0, tmp2);

    in1 = _mm_unpackhi_epi64(tmp0, tmp2);

    in2 = _mm_unpacklo_epi64(tmp1, tmp3);

    in3 = _mm_unpackhi_epi64(tmp1, tmp3);

    // a00 a10 a20 a30   b00 b10 b20 b30

    // a01 a11 a21 a31   b01 b11 b21 b31

    // a02 a12 a22 a32   b02 b12 b22 b32

    // a03 a13 a23 a33   b03 b13 b23 b33

  }

  // Vertical pass and subsequent transpose.

  {

    // First pass, c and d calculations are longer because of the "trick"

    // multiplications.

    const __m128i a = _mm_add_epi16(in0, in2);

    const __m128i b = _mm_sub_epi16(in0, in2);

    // c = MUL(in1, K2) - MUL(in3, K1) = MUL(in1, k2) - MUL(in3, k1) + in1 - in3

    const __m128i c1 = _mm_mulhi_epi16(in1, k2);

    const __m128i c2 = _mm_mulhi_epi16(in3, k1);

    const __m128i c3 = _mm_sub_epi16(in1, in3);

    const __m128i c4 = _mm_sub_epi16(c1, c2);

    const __m128i c = _mm_add_epi16(c3, c4);

    // d = MUL(in1, K1) + MUL(in3, K2) = MUL(in1, k1) + MUL(in3, k2) + in1 + in3

    const __m128i d1 = _mm_mulhi_epi16(in1, k1);

    const __m128i d2 = _mm_mulhi_epi16(in3, k2);

    const __m128i d3 = _mm_add_epi16(in1, in3);

    const __m128i d4 = _mm_add_epi16(d1, d2);

    const __m128i d = _mm_add_epi16(d3, d4);

    // Second pass.

    const __m128i tmp0 = _mm_add_epi16(a, d);

    const __m128i tmp1 = _mm_add_epi16(b, c);

    const __m128i tmp2 = _mm_sub_epi16(b, c);

    const __m128i tmp3 = _mm_sub_epi16(a, d);

    // Transpose the two 4x4.

    VP8Transpose_2_4x4_16b(&tmp0, &tmp1, &tmp2, &tmp3, &T0, &T1, &T2, &T3);

  }

  // Horizontal pass and subsequent transpose.

  {

    // First pass, c and d calculations are longer because of the "trick"

    // multiplications.

    const __m128i four = _mm_set1_epi16(4);

    const __m128i dc = _mm_add_epi16(T0, four);

    const __m128i a = _mm_add_epi16(dc, T2);

    const __m128i b = _mm_sub_epi16(dc, T2);

    // c = MUL(T1, K2) - MUL(T3, K1) = MUL(T1, k2) - MUL(T3, k1) + T1 - T3

    const __m128i c1 = _mm_mulhi_epi16(T1, k2);

    const __m128i c2 = _mm_mulhi_epi16(T3, k1);

    const __m128i c3 = _mm_sub_epi16(T1, T3);

    const __m128i c4 = _mm_sub_epi16(c1, c2);

    const __m128i c = _mm_add_epi16(c3, c4);

    // d = MUL(T1, K1) + MUL(T3, K2) = MUL(T1, k1) + MUL(T3, k2) + T1 + T3

    const __m128i d1 = _mm_mulhi_epi16(T1, k1);

    const __m128i d2 = _mm_mulhi_epi16(T3, k2);

    const __m128i d3 = _mm_add_epi16(T1, T3);

    const __m128i d4 = _mm_add_epi16(d1, d2);

    const __m128i d = _mm_add_epi16(d3, d4);

    // Second pass.

    const __m128i tmp0 = _mm_add_epi16(a, d);

    const __m128i tmp1 = _mm_add_epi16(b, c);

    const __m128i tmp2 = _mm_sub_epi16(b, c);

    const __m128i tmp3 = _mm_sub_epi16(a, d);

    const __m128i shifted0 = _mm_srai_epi16(tmp0, 3);

    const __m128i shifted1 = _mm_srai_epi16(tmp1, 3);

    const __m128i shifted2 = _mm_srai_epi16(tmp2, 3);

    const __m128i shifted3 = _mm_srai_epi16(tmp3, 3);

    // Transpose the two 4x4.

    VP8Transpose_2_4x4_16b(&shifted0, &shifted1, &shifted2, &shifted3, &T0, &T1,

                           &T2, &T3);

  }

  // Add inverse transform to 'ref' and store.

  {

    const __m128i zero = _mm_setzero_si128();

    // Load the reference(s).

    __m128i ref0, ref1, ref2, ref3;

    // Load eight bytes/pixels per line.

    ref0 = _mm_loadl_epi64((const __m128i*)&ref[0 * BPS]);

    ref1 = _mm_loadl_epi64((const __m128i*)&ref[1 * BPS]);

    ref2 = _mm_loadl_epi64((const __m128i*)&ref[2 * BPS]);

    ref3 = _mm_loadl_epi64((const __m128i*)&ref[3 * BPS]);

    // Convert to 16b.

    ref0 = _mm_unpacklo_epi8(ref0, zero);

    ref1 = _mm_unpacklo_epi8(ref1, zero);

    ref2 = _mm_unpacklo_epi8(ref2, zero);

    ref3 = _mm_unpacklo_epi8(ref3, zero);

    // Add the inverse transform(s).

    ref0 = _mm_add_epi16(ref0, T0);

    ref1 = _mm_add_epi16(ref1, T1);

    ref2 = _mm_add_epi16(ref2, T2);

    ref3 = _mm_add_epi16(ref3, T3);

    // Unsigned saturate to 8b.

    ref0 = _mm_packus_epi16(ref0, ref0);

    ref1 = _mm_packus_epi16(ref1, ref1);

    ref2 = _mm_packus_epi16(ref2, ref2);

    ref3 = _mm_packus_epi16(ref3, ref3);

    // Store eight bytes/pixels per line.

    _mm_storel_epi64((__m128i*)&dst[0 * BPS], ref0);

    _mm_storel_epi64((__m128i*)&dst[1 * BPS], ref1);

    _mm_storel_epi64((__m128i*)&dst[2 * BPS], ref2);

    _mm_storel_epi64((__m128i*)&dst[3 * BPS], ref3);

  }

}

// Does one or two inverse transforms.

static void ITransform_SSE2(const uint8_t* WEBP_RESTRICT ref,

                            const int16_t* WEBP_RESTRICT in,

                            uint8_t* WEBP_RESTRICT dst, int do_two) {

  if (do_two) {

    ITransform_Two_SSE2(ref, in, dst);

  } else {

    ITransform_One_SSE2(ref, in, dst);

  }

}

static void FTransformPass1_SSE2(const __m128i* const in01,

                                 const __m128i* const in23,

                                 __m128i* const out01, __m128i* const out32) {

  const __m128i k937 = _mm_set1_epi32(937);

  const __m128i k1812 = _mm_set1_epi32(1812);

  const __m128i k88p = _mm_set_epi16(8, 8, 8, 8, 8, 8, 8, 8);

  const __m128i k88m = _mm_set_epi16(-8, 8, -8, 8, -8, 8, -8, 8);

  const __m128i k5352_2217p =

      _mm_set_epi16(2217, 5352, 2217, 5352, 2217, 5352, 2217, 5352);

  const __m128i k5352_2217m =

      _mm_set_epi16(-5352, 2217, -5352, 2217, -5352, 2217, -5352, 2217);

  // *in01 = 00 01 10 11 02 03 12 13

  // *in23 = 20 21 30 31 22 23 32 33

  const __m128i shuf01_p = _mm_shufflehi_epi16(*in01, _MM_SHUFFLE(2, 3, 0, 1));

  const __m128i shuf23_p = _mm_shufflehi_epi16(*in23, _MM_SHUFFLE(2, 3, 0, 1));

  // 00 01 10 11 03 02 13 12

  // 20 21 30 31 23 22 33 32

  const __m128i s01 = _mm_unpacklo_epi64(shuf01_p, shuf23_p);

  const __m128i s32 = _mm_unpackhi_epi64(shuf01_p, shuf23_p);

  // 00 01 10 11 20 21 30 31

  // 03 02 13 12 23 22 33 32

  const __m128i a01 = _mm_add_epi16(s01, s32);

  const __m128i a32 = _mm_sub_epi16(s01, s32);

  // [d0 + d3 | d1 + d2 | ...] = [a0 a1 | a0' a1' | ... ]

  // [d0 - d3 | d1 - d2 | ...] = [a3 a2 | a3' a2' | ... ]

  const __m128i tmp0 = _mm_madd_epi16(a01, k88p);  // [ (a0 + a1) << 3, ... ]

  const __m128i tmp2 = _mm_madd_epi16(a01, k88m);  // [ (a0 - a1) << 3, ... ]

  const __m128i tmp1_1 = _mm_madd_epi16(a32, k5352_2217p);

  const __m128i tmp3_1 = _mm_madd_epi16(a32, k5352_2217m);

  const __m128i tmp1_2 = _mm_add_epi32(tmp1_1, k1812);

  const __m128i tmp3_2 = _mm_add_epi32(tmp3_1, k937);

  const __m128i tmp1 = _mm_srai_epi32(tmp1_2, 9);

  const __m128i tmp3 = _mm_srai_epi32(tmp3_2, 9);

  const __m128i s03 = _mm_packs_epi32(tmp0, tmp2);

  const __m128i s12 = _mm_packs_epi32(tmp1, tmp3);

  const __m128i s_lo = _mm_unpacklo_epi16(s03, s12);  // 0 1 0 1 0 1...

  const __m128i s_hi = _mm_unpackhi_epi16(s03, s12);  // 2 3 2 3 2 3

  const __m128i v23 = _mm_unpackhi_epi32(s_lo, s_hi);

  *out01 = _mm_unpacklo_epi32(s_lo, s_hi);

  *out32 = _mm_shuffle_epi32(v23, _MM_SHUFFLE(1, 0, 3, 2));  // 3 2 3 2 3 2..

}

static void FTransformPass2_SSE2(const __m128i* const v01,

                                 const __m128i* const v32,

                                 int16_t* WEBP_RESTRICT out) {

  const __m128i zero = _mm_setzero_si128();

  const __m128i seven = _mm_set1_epi16(7);

  const __m128i k5352_2217 =

      _mm_set_epi16(5352, 2217, 5352, 2217, 5352, 2217, 5352, 2217);

  const __m128i k2217_5352 =

      _mm_set_epi16(2217, -5352, 2217, -5352, 2217, -5352, 2217, -5352);

  const __m128i k12000_plus_one = _mm_set1_epi32(12000 + (1 << 16));

  const __m128i k51000 = _mm_set1_epi32(51000);

  // Same operations are done on the (0,3) and (1,2) pairs.

  // a3 = v0 - v3

  // a2 = v1 - v2

  const __m128i a32 = _mm_sub_epi16(*v01, *v32);

  const __m128i a22 = _mm_unpackhi_epi64(a32, a32);

  const __m128i b23 = _mm_unpacklo_epi16(a22, a32);

  const __m128i c1 = _mm_madd_epi16(b23, k5352_2217);

  const __m128i c3 = _mm_madd_epi16(b23, k2217_5352);

  const __m128i d1 = _mm_add_epi32(c1, k12000_plus_one);

  const __m128i d3 = _mm_add_epi32(c3, k51000);

  const __m128i e1 = _mm_srai_epi32(d1, 16);

  const __m128i e3 = _mm_srai_epi32(d3, 16);

  // f1 = ((b3 * 5352 + b2 * 2217 + 12000) >> 16)

  // f3 = ((b3 * 2217 - b2 * 5352 + 51000) >> 16)

  const __m128i f1 = _mm_packs_epi32(e1, e1);

  const __m128i f3 = _mm_packs_epi32(e3, e3);

  // g1 = f1 + (a3 != 0);

  // The compare will return (0xffff, 0) for (==0, !=0). To turn that into the

  // desired (0, 1), we add one earlier through k12000_plus_one.

  // -> g1 = f1 + 1 - (a3 == 0)

  const __m128i g1 = _mm_add_epi16(f1, _mm_cmpeq_epi16(a32, zero));

  // a0 = v0 + v3

  // a1 = v1 + v2

  const __m128i a01 = _mm_add_epi16(*v01, *v32);

  const __m128i a01_plus_7 = _mm_add_epi16(a01, seven);

  const __m128i a11 = _mm_unpackhi_epi64(a01, a01);

  const __m128i c0 = _mm_add_epi16(a01_plus_7, a11);

  const __m128i c2 = _mm_sub_epi16(a01_plus_7, a11);

  // d0 = (a0 + a1 + 7) >> 4;

  // d2 = (a0 - a1 + 7) >> 4;

  const __m128i d0 = _mm_srai_epi16(c0, 4);

  const __m128i d2 = _mm_srai_epi16(c2, 4);

  const __m128i d0_g1 = _mm_unpacklo_epi64(d0, g1);

  const __m128i d2_f3 = _mm_unpacklo_epi64(d2, f3);

  _mm_storeu_si128((__m128i*)&out[0], d0_g1);

  _mm_storeu_si128((__m128i*)&out[8], d2_f3);

}

static void FTransform_SSE2(const uint8_t* WEBP_RESTRICT src,

                            const uint8_t* WEBP_RESTRICT ref,

                            int16_t* WEBP_RESTRICT out) {

  const __m128i zero = _mm_setzero_si128();

  // Load src.

  const __m128i src0 = _mm_loadl_epi64((const __m128i*)&src[0 * BPS]);

  const __m128i src1 = _mm_loadl_epi64((const __m128i*)&src[1 * BPS]);

  const __m128i src2 = _mm_loadl_epi64((const __m128i*)&src[2 * BPS]);

  const __m128i src3 = _mm_loadl_epi64((const __m128i*)&src[3 * BPS]);

  // 00 01 02 03 *

  // 10 11 12 13 *

  // 20 21 22 23 *

  // 30 31 32 33 *

  // Shuffle.

  const __m128i src_0 = _mm_unpacklo_epi16(src0, src1);

  const __m128i src_1 = _mm_unpacklo_epi16(src2, src3);

  // 00 01 10 11 02 03 12 13 * * ...

  // 20 21 30 31 22 22 32 33 * * ...

  // Load ref.

  const __m128i ref0 = _mm_loadl_epi64((const __m128i*)&ref[0 * BPS]);

  const __m128i ref1 = _mm_loadl_epi64((const __m128i*)&ref[1 * BPS]);

  const __m128i ref2 = _mm_loadl_epi64((const __m128i*)&ref[2 * BPS]);

  const __m128i ref3 = _mm_loadl_epi64((const __m128i*)&ref[3 * BPS]);

  const __m128i ref_0 = _mm_unpacklo_epi16(ref0, ref1);

  const __m128i ref_1 = _mm_unpacklo_epi16(ref2, ref3);

  // Convert both to 16 bit.

  const __m128i src_0_16b = _mm_unpacklo_epi8(src_0, zero);

  const __m128i src_1_16b = _mm_unpacklo_epi8(src_1, zero);

  const __m128i ref_0_16b = _mm_unpacklo_epi8(ref_0, zero);

  const __m128i ref_1_16b = _mm_unpacklo_epi8(ref_1, zero);

  // Compute the difference.

  const __m128i row01 = _mm_sub_epi16(src_0_16b, ref_0_16b);

  const __m128i row23 = _mm_sub_epi16(src_1_16b, ref_1_16b);

  __m128i v01, v32;

  // First pass

  FTransformPass1_SSE2(&row01, &row23, &v01, &v32);

  // Second pass

  FTransformPass2_SSE2(&v01, &v32, out);

}

static void FTransform2_SSE2(const uint8_t* WEBP_RESTRICT src,

                             const uint8_t* WEBP_RESTRICT ref,

                             int16_t* WEBP_RESTRICT out) {

  const __m128i zero = _mm_setzero_si128();

  // Load src and convert to 16b.

  const __m128i src0 = _mm_loadl_epi64((const __m128i*)&src[0 * BPS]);

  const __m128i src1 = _mm_loadl_epi64((const __m128i*)&src[1 * BPS]);

  const __m128i src2 = _mm_loadl_epi64((const __m128i*)&src[2 * BPS]);

  const __m128i src3 = _mm_loadl_epi64((const __m128i*)&src[3 * BPS]);

  const __m128i src_0 = _mm_unpacklo_epi8(src0, zero);

  const __m128i src_1 = _mm_unpacklo_epi8(src1, zero);

  const __m128i src_2 = _mm_unpacklo_epi8(src2, zero);

  const __m128i src_3 = _mm_unpacklo_epi8(src3, zero);

  // Load ref and convert to 16b.

  const __m128i ref0 = _mm_loadl_epi64((const __m128i*)&ref[0 * BPS]);

  const __m128i ref1 = _mm_loadl_epi64((const __m128i*)&ref[1 * BPS]);

  const __m128i ref2 = _mm_loadl_epi64((const __m128i*)&ref[2 * BPS]);

  const __m128i ref3 = _mm_loadl_epi64((const __m128i*)&ref[3 * BPS]);

  const __m128i ref_0 = _mm_unpacklo_epi8(ref0, zero);

  const __m128i ref_1 = _mm_unpacklo_epi8(ref1, zero);

  const __m128i ref_2 = _mm_unpacklo_epi8(ref2, zero);

  const __m128i ref_3 = _mm_unpacklo_epi8(ref3, zero);

  // Compute difference. -> 00 01 02 03  00' 01' 02' 03'

  const __m128i diff0 = _mm_sub_epi16(src_0, ref_0);

  const __m128i diff1 = _mm_sub_epi16(src_1, ref_1);

  const __m128i diff2 = _mm_sub_epi16(src_2, ref_2);

  const __m128i diff3 = _mm_sub_epi16(src_3, ref_3);

  // Unpack and shuffle

  // 00 01 02 03   0 0 0 0

  // 10 11 12 13   0 0 0 0

  // 20 21 22 23   0 0 0 0

  // 30 31 32 33   0 0 0 0

  const __m128i shuf01l = _mm_unpacklo_epi32(diff0, diff1);

  const __m128i shuf23l = _mm_unpacklo_epi32(diff2, diff3);

  const __m128i shuf01h = _mm_unpackhi_epi32(diff0, diff1);

  const __m128i shuf23h = _mm_unpackhi_epi32(diff2, diff3);

  __m128i v01l, v32l;

  __m128i v01h, v32h;

  // First pass

  FTransformPass1_SSE2(&shuf01l, &shuf23l, &v01l, &v32l);

  FTransformPass1_SSE2(&shuf01h, &shuf23h, &v01h, &v32h);

  // Second pass

  FTransformPass2_SSE2(&v01l, &v32l, out + 0);

  FTransformPass2_SSE2(&v01h, &v32h, out + 16);

}

static void FTransformWHTRow_SSE2(const int16_t* WEBP_RESTRICT const in,

                                  __m128i* const out) {

  const __m128i kMult = _mm_set_epi16(-1, 1, -1, 1, 1, 1, 1, 1);

  const __m128i src0 = _mm_loadl_epi64((__m128i*)&in[0 * 16]);

  const __m128i src1 = _mm_loadl_epi64((__m128i*)&in[1 * 16]);

  const __m128i src2 = _mm_loadl_epi64((__m128i*)&in[2 * 16]);

  const __m128i src3 = _mm_loadl_epi64((__m128i*)&in[3 * 16]);

  const __m128i A01 = _mm_unpacklo_epi16(src0, src1);  // A0 A1 | ...

  const __m128i A23 = _mm_unpacklo_epi16(src2, src3);  // A2 A3 | ...

  const __m128i B0 = _mm_adds_epi16(A01, A23);         // a0 | a1 | ...

  const __m128i B1 = _mm_subs_epi16(A01, A23);         // a3 | a2 | ...

  const __m128i C0 = _mm_unpacklo_epi32(B0, B1);  // a0 | a1 | a3 | a2 | ...

  const __m128i C1 = _mm_unpacklo_epi32(B1, B0);  // a3 | a2 | a0 | a1 | ...

  const __m128i D = _mm_unpacklo_epi64(C0, C1);   // a0 a1 a3 a2 a3 a2 a0 a1

  *out = _mm_madd_epi16(D, kMult);

}

static void FTransformWHT_SSE2(const int16_t* WEBP_RESTRICT in,

                               int16_t* WEBP_RESTRICT out) {

  // Input is 12b signed.

  __m128i row0, row1, row2, row3;

  // Rows are 14b signed.

  FTransformWHTRow_SSE2(in + 0 * 64, &row0);

  FTransformWHTRow_SSE2(in + 1 * 64, &row1);

  FTransformWHTRow_SSE2(in + 2 * 64, &row2);

  FTransformWHTRow_SSE2(in + 3 * 64, &row3);

  {

    // The a* are 15b signed.

    const __m128i a0 = _mm_add_epi32(row0, row2);

    const __m128i a1 = _mm_add_epi32(row1, row3);

    const __m128i a2 = _mm_sub_epi32(row1, row3);

    const __m128i a3 = _mm_sub_epi32(row0, row2);

    const __m128i a0a3 = _mm_packs_epi32(a0, a3);

    const __m128i a1a2 = _mm_packs_epi32(a1, a2);

    // The b* are 16b signed.

    const __m128i b0b1 = _mm_add_epi16(a0a3, a1a2);

    const __m128i b3b2 = _mm_sub_epi16(a0a3, a1a2);

    const __m128i tmp_b2b3 = _mm_unpackhi_epi64(b3b2, b3b2);

    const __m128i b2b3 = _mm_unpacklo_epi64(tmp_b2b3, b3b2);

    _mm_storeu_si128((__m128i*)&out[0], _mm_srai_epi16(b0b1, 1));

    _mm_storeu_si128((__m128i*)&out[8], _mm_srai_epi16(b2b3, 1));

  }

}

//------------------------------------------------------------------------------

// Compute susceptibility based on DCT-coeff histograms:

// the higher, the "easier" the macroblock is to compress.

static void CollectHistogram_SSE2(const uint8_t* WEBP_RESTRICT ref,

                                  const uint8_t* WEBP_RESTRICT pred,

                                  int start_block, int end_block,

                                  VP8Histogram* WEBP_RESTRICT const histo) {

  const __m128i zero = _mm_setzero_si128();

  const __m128i max_coeff_thresh = _mm_set1_epi16(MAX_COEFF_THRESH);

  int j;

  int distribution[MAX_COEFF_THRESH + 1] = {0};

  for (j = start_block; j < end_block; ++j) {

    int16_t out[16];

    int k;

    FTransform_SSE2(ref + VP8DspScan[j], pred + VP8DspScan[j], out);

    // Convert coefficients to bin (within out[]).

    {

      // Load.

      const __m128i out0 = _mm_loadu_si128((__m128i*)&out[0]);

      const __m128i out1 = _mm_loadu_si128((__m128i*)&out[8]);

      const __m128i d0 = _mm_sub_epi16(zero, out0);

      const __m128i d1 = _mm_sub_epi16(zero, out1);

      const __m128i abs0 = _mm_max_epi16(out0, d0);  // abs(v), 16b

      const __m128i abs1 = _mm_max_epi16(out1, d1);

      // v = abs(out) >> 3

      const __m128i v0 = _mm_srai_epi16(abs0, 3);

      const __m128i v1 = _mm_srai_epi16(abs1, 3);

      // bin = min(v, MAX_COEFF_THRESH)

      const __m128i bin0 = _mm_min_epi16(v0, max_coeff_thresh);

      const __m128i bin1 = _mm_min_epi16(v1, max_coeff_thresh);

      // Store.

      _mm_storeu_si128((__m128i*)&out[0], bin0);

      _mm_storeu_si128((__m128i*)&out[8], bin1);

    }

    // Convert coefficients to bin.

    for (k = 0; k < 16; ++k) {

      ++distribution[out[k]];

    }

  }

  VP8SetHistogramData(distribution, histo);

}

//------------------------------------------------------------------------------

// Intra predictions

// helper for chroma-DC predictions

static WEBP_INLINE void Put8x8uv_SSE2(uint8_t v, uint8_t* dst) {

  int j;

  const __m128i values = _mm_set1_epi8((char)v);

  for (j = 0; j < 8; ++j) {

    _mm_storel_epi64((__m128i*)(dst + j * BPS), values);

  }

}

static WEBP_INLINE void Put16_SSE2(uint8_t v, uint8_t* dst) {

  int j;

  const __m128i values = _mm_set1_epi8((char)v);

  for (j = 0; j < 16; ++j) {

    _mm_store_si128((__m128i*)(dst + j * BPS), values);

  }

}

static WEBP_INLINE void Fill_SSE2(uint8_t* dst, int value, int size) {

  if (size == 4) {

    int j;

    for (j = 0; j < 4; ++j) {

      memset(dst + j * BPS, value, 4);

    }

  } else if (size == 8) {

    Put8x8uv_SSE2(value, dst);

  } else {

    Put16_SSE2(value, dst);

  }

}

static WEBP_INLINE void VE8uv_SSE2(uint8_t* WEBP_RESTRICT dst,

                                   const uint8_t* WEBP_RESTRICT top) {

  int j;

  const __m128i top_values = _mm_loadl_epi64((const __m128i*)top);

  for (j = 0; j < 8; ++j) {

    _mm_storel_epi64((__m128i*)(dst + j * BPS), top_values);

  }

}

static WEBP_INLINE void VE16_SSE2(uint8_t* WEBP_RESTRICT dst,

                                  const uint8_t* WEBP_RESTRICT top) {

  const __m128i top_values = _mm_load_si128((const __m128i*)top);

  int j;

  for (j = 0; j < 16; ++j) {

    _mm_store_si128((__m128i*)(dst + j * BPS), top_values);

  }

}

static WEBP_INLINE void VerticalPred_SSE2(uint8_t* WEBP_RESTRICT dst,

                                          const uint8_t* WEBP_RESTRICT top,

                                          int size) {

  if (top != NULL) {

    if (size == 8) {

      VE8uv_SSE2(dst, top);

    } else {

      VE16_SSE2(dst, top);

    }

  } else {

    Fill_SSE2(dst, 127, size);

  }

}

static WEBP_INLINE void HE8uv_SSE2(uint8_t* WEBP_RESTRICT dst,

                                   const uint8_t* WEBP_RESTRICT left) {

  int j;

  for (j = 0; j < 8; ++j) {

    const __m128i values = _mm_set1_epi8((char)left[j]);

    _mm_storel_epi64((__m128i*)dst, values);

    dst += BPS;

  }

}

static WEBP_INLINE void HE16_SSE2(uint8_t* WEBP_RESTRICT dst,

                                  const uint8_t* WEBP_RESTRICT left) {

  int j;

  for (j = 0; j < 16; ++j) {

    const __m128i values = _mm_set1_epi8((char)left[j]);

    _mm_store_si128((__m128i*)dst, values);

    dst += BPS;

  }

}

static WEBP_INLINE void HorizontalPred_SSE2(uint8_t* WEBP_RESTRICT dst,

                                            const uint8_t* WEBP_RESTRICT left,

                                            int size) {

  if (left != NULL) {

    if (size == 8) {

      HE8uv_SSE2(dst, left);

    } else {

      HE16_SSE2(dst, left);

    }

  } else {

    Fill_SSE2(dst, 129, size);

  }

}

static WEBP_INLINE void TM_SSE2(uint8_t* WEBP_RESTRICT dst,

                                const uint8_t* WEBP_RESTRICT left,

                                const uint8_t* WEBP_RESTRICT top, int size) {

  const __m128i zero = _mm_setzero_si128();

  int y;

  if (size == 8) {

    const __m128i top_values = _mm_loadl_epi64((const __m128i*)top);

    const __m128i top_base = _mm_unpacklo_epi8(top_values, zero);

    for (y = 0; y < 8; ++y, dst += BPS) {

      const int val = left[y] - left[-1];

      const __m128i base = _mm_set1_epi16(val);

      const __m128i out = _mm_packus_epi16(_mm_add_epi16(base, top_base), zero);

      _mm_storel_epi64((__m128i*)dst, out);

    }

  } else {

    const __m128i top_values = _mm_load_si128((const __m128i*)top);

    const __m128i top_base_0 = _mm_unpacklo_epi8(top_values, zero);

    const __m128i top_base_1 = _mm_unpackhi_epi8(top_values, zero);

    for (y = 0; y < 16; ++y, dst += BPS) {

      const int val = left[y] - left[-1];

      const __m128i base = _mm_set1_epi16(val);

      const __m128i out_0 = _mm_add_epi16(base, top_base_0);

      const __m128i out_1 = _mm_add_epi16(base, top_base_1);

      const __m128i out = _mm_packus_epi16(out_0, out_1);

      _mm_store_si128((__m128i*)dst, out);

    }

  }

}

static WEBP_INLINE void TrueMotion_SSE2(uint8_t* WEBP_RESTRICT dst,

                                        const uint8_t* WEBP_RESTRICT left,

                                        const uint8_t* WEBP_RESTRICT top,

                                        int size) {

  if (left != NULL) {

    if (top != NULL) {

      TM_SSE2(dst, left, top, size);

    } else {

      HorizontalPred_SSE2(dst, left, size);

    }

  } else {

    // true motion without left samples (hence: with default 129 value)

    // is equivalent to VE prediction where you just copy the top samples.

    // Note that if top samples are not available, the default value is

    // then 129, and not 127 as in the VerticalPred case.

    if (top != NULL) {

      VerticalPred_SSE2(dst, top, size);

    } else {

      Fill_SSE2(dst, 129, size);

    }

  }

}

static WEBP_INLINE void DC8uv_SSE2(uint8_t* WEBP_RESTRICT dst,

                                   const uint8_t* WEBP_RESTRICT left,

                                   const uint8_t* WEBP_RESTRICT top) {

  const __m128i top_values = _mm_loadl_epi64((const __m128i*)top);

  const __m128i left_values = _mm_loadl_epi64((const __m128i*)left);

  const __m128i combined = _mm_unpacklo_epi64(top_values, left_values);

  const int DC = VP8HorizontalAdd8b(&combined) + 8;

  Put8x8uv_SSE2(DC >> 4, dst);

}

static WEBP_INLINE void DC8uvNoLeft_SSE2(uint8_t* WEBP_RESTRICT dst,

                                         const uint8_t* WEBP_RESTRICT top) {

  const __m128i zero = _mm_setzero_si128();

  const __m128i top_values = _mm_loadl_epi64((const __m128i*)top);

  const __m128i sum = _mm_sad_epu8(top_values, zero);

  const int DC = _mm_cvtsi128_si32(sum) + 4;

  Put8x8uv_SSE2(DC >> 3, dst);

}

static WEBP_INLINE void DC8uvNoTop_SSE2(uint8_t* WEBP_RESTRICT dst,

                                        const uint8_t* WEBP_RESTRICT left) {

  // 'left' is contiguous so we can reuse the top summation.

  DC8uvNoLeft_SSE2(dst, left);

}

static WEBP_INLINE void DC8uvNoTopLeft_SSE2(uint8_t* dst) {

  Put8x8uv_SSE2(0x80, dst);

}

static WEBP_INLINE void DC8uvMode_SSE2(uint8_t* WEBP_RESTRICT dst,

                                       const uint8_t* WEBP_RESTRICT left,

                                       const uint8_t* WEBP_RESTRICT top) {

  if (top != NULL) {

    if (left != NULL) {  // top and left present

      DC8uv_SSE2(dst, left, top);

    } else {  // top, but no left

      DC8uvNoLeft_SSE2(dst, top);

    }

  } else if (left != NULL) {  // left but no top

    DC8uvNoTop_SSE2(dst, left);

  } else {  // no top, no left, nothing.

    DC8uvNoTopLeft_SSE2(dst);

  }

}

static WEBP_INLINE void DC16_SSE2(uint8_t* WEBP_RESTRICT dst,

                                  const uint8_t* WEBP_RESTRICT left,

                                  const uint8_t* WEBP_RESTRICT top) {

  const __m128i top_row = _mm_load_si128((const __m128i*)top);

  const __m128i left_row = _mm_load_si128((const __m128i*)left);

  const int DC =

      VP8HorizontalAdd8b(&top_row) + VP8HorizontalAdd8b(&left_row) + 16;

  Put16_SSE2(DC >> 5, dst);

}

static WEBP_INLINE void DC16NoLeft_SSE2(uint8_t* WEBP_RESTRICT dst,

                                        const uint8_t* WEBP_RESTRICT top) {

  const __m128i top_row = _mm_load_si128((const __m128i*)top);

  const int DC = VP8HorizontalAdd8b(&top_row) + 8;

  Put16_SSE2(DC >> 4, dst);

}

static WEBP_INLINE void DC16NoTop_SSE2(uint8_t* WEBP_RESTRICT dst,

                                       const uint8_t* WEBP_RESTRICT left) {

  // 'left' is contiguous so we can reuse the top summation.

  DC16NoLeft_SSE2(dst, left);

}

static WEBP_INLINE void DC16NoTopLeft_SSE2(uint8_t* dst) {

  Put16_SSE2(0x80, dst);

}

static WEBP_INLINE void DC16Mode_SSE2(uint8_t* WEBP_RESTRICT dst,

                                      const uint8_t* WEBP_RESTRICT left,

                                      const uint8_t* WEBP_RESTRICT top) {

  if (top != NULL) {

    if (left != NULL) {  // top and left present

      DC16_SSE2(dst, left, top);

    } else {  // top, but no left

      DC16NoLeft_SSE2(dst, top);

    }

  } else if (left != NULL) {  // left but no top

    DC16NoTop_SSE2(dst, left);

  } else {  // no top, no left, nothing.

    DC16NoTopLeft_SSE2(dst);

  }

}

//------------------------------------------------------------------------------

// 4x4 predictions

#define DST(x, y) dst[(x) + (y) * BPS]

#define AVG3(a, b, c) (((a) + 2 * (b) + (c) + 2) >> 2)

#define AVG2(a, b) (((a) + (b) + 1) >> 1)

// We use the following 8b-arithmetic tricks:

//     (a + 2 * b + c + 2) >> 2 = (AC + b + 1) >> 1

//   where: AC = (a + c) >> 1 = [(a + c + 1) >> 1] - [(a^c) & 1]

// and:

//     (a + 2 * b + c + 2) >> 2 = (AB + BC + 1) >> 1 - (ab|bc)&lsb

//   where: AC = (a + b + 1) >> 1,   BC = (b + c + 1) >> 1

//   and ab = a ^ b, bc = b ^ c, lsb = (AC^BC)&1

// vertical

static WEBP_INLINE void VE4_SSE2(uint8_t* WEBP_RESTRICT dst,

                                 const uint8_t* WEBP_RESTRICT top) {

  const __m128i one = _mm_set1_epi8(1);

  const __m128i ABCDEFGH = _mm_loadl_epi64((__m128i*)(top - 1));

  const __m128i BCDEFGH0 = _mm_srli_si128(ABCDEFGH, 1);

  const __m128i CDEFGH00 = _mm_srli_si128(ABCDEFGH, 2);

  const __m128i a = _mm_avg_epu8(ABCDEFGH, CDEFGH00);

  const __m128i lsb = _mm_and_si128(_mm_xor_si128(ABCDEFGH, CDEFGH00), one);

  const __m128i b = _mm_subs_epu8(a, lsb);

  const __m128i avg = _mm_avg_epu8(b, BCDEFGH0);

  const int vals = _mm_cvtsi128_si32(avg);

  int i;

  for (i = 0; i < 4; ++i) {

    WebPInt32ToMem(dst + i * BPS, vals);

  }

}

// horizontal

static WEBP_INLINE void HE4_SSE2(uint8_t* WEBP_RESTRICT dst,

                                 const uint8_t* WEBP_RESTRICT top) {

  const int X = top[-1];

  const int I = top[-2];

  const int J = top[-3];

  const int K = top[-4];

  const int L = top[-5];

  WebPUint32ToMem(dst + 0 * BPS, 0x01010101U * AVG3(X, I, J));

  WebPUint32ToMem(dst + 1 * BPS, 0x01010101U * AVG3(I, J, K));

  WebPUint32ToMem(dst + 2 * BPS, 0x01010101U * AVG3(J, K, L));

  WebPUint32ToMem(dst + 3 * BPS, 0x01010101U * AVG3(K, L, L));

}

static WEBP_INLINE void DC4_SSE2(uint8_t* WEBP_RESTRICT dst,

                                 const uint8_t* WEBP_RESTRICT top) {

  uint32_t dc = 4;

  int i;

  for (i = 0; i < 4; ++i) dc += top[i] + top[-5 + i];

  Fill_SSE2(dst, dc >> 3, 4);

}

// Down-Left

static WEBP_INLINE void LD4_SSE2(uint8_t* WEBP_RESTRICT dst,

                                 const uint8_t* WEBP_RESTRICT top) {

  const __m128i one = _mm_set1_epi8(1);

  const __m128i ABCDEFGH = _mm_loadl_epi64((const __m128i*)top);

  const __m128i BCDEFGH0 = _mm_srli_si128(ABCDEFGH, 1);

  const __m128i CDEFGH00 = _mm_srli_si128(ABCDEFGH, 2);

  const __m128i CDEFGHH0 = _mm_insert_epi16(CDEFGH00, top[7], 3);

  const __m128i avg1 = _mm_avg_epu8(ABCDEFGH, CDEFGHH0);

  const __m128i lsb = _mm_and_si128(_mm_xor_si128(ABCDEFGH, CDEFGHH0), one);

  const __m128i avg2 = _mm_subs_epu8(avg1, lsb);

  const __m128i abcdefg = _mm_avg_epu8(avg2, BCDEFGH0);

  WebPInt32ToMem(dst + 0 * BPS, _mm_cvtsi128_si32(abcdefg));

  WebPInt32ToMem(dst + 1 * BPS, _mm_cvtsi128_si32(_mm_srli_si128(abcdefg, 1)));

  WebPInt32ToMem(dst + 2 * BPS, _mm_cvtsi128_si32(_mm_srli_si128(abcdefg, 2)));

  WebPInt32ToMem(dst + 3 * BPS, _mm_cvtsi128_si32(_mm_srli_si128(abcdefg, 3)));

}

// Vertical-Right

static WEBP_INLINE void VR4_SSE2(uint8_t* WEBP_RESTRICT dst,

                                 const uint8_t* WEBP_RESTRICT top) {

  const __m128i one = _mm_set1_epi8(1);

  const int I = top[-2];

  const int J = top[-3];

  const int K = top[-4];

  const int X = top[-1];

  const __m128i XABCD = _mm_loadl_epi64((const __m128i*)(top - 1));

  const __m128i ABCD0 = _mm_srli_si128(XABCD, 1);

  const __m128i abcd = _mm_avg_epu8(XABCD, ABCD0);

  const __m128i _XABCD = _mm_slli_si128(XABCD, 1);

  const __m128i IXABCD = _mm_insert_epi16(_XABCD, (short)(I | (X << 8)), 0);

  const __m128i avg1 = _mm_avg_epu8(IXABCD, ABCD0);

  const __m128i lsb = _mm_and_si128(_mm_xor_si128(IXABCD, ABCD0), one);

  const __m128i avg2 = _mm_subs_epu8(avg1, lsb);

  const __m128i efgh = _mm_avg_epu8(avg2, XABCD);

  WebPInt32ToMem(dst + 0 * BPS, _mm_cvtsi128_si32(abcd));

  WebPInt32ToMem(dst + 1 * BPS, _mm_cvtsi128_si32(efgh));

  WebPInt32ToMem(dst + 2 * BPS, _mm_cvtsi128_si32(_mm_slli_si128(abcd, 1)));

  WebPInt32ToMem(dst + 3 * BPS, _mm_cvtsi128_si32(_mm_slli_si128(efgh, 1)));

  // these two are hard to implement in SSE2, so we keep the C-version:

  DST(0, 2) = AVG3(J, I, X);

  DST(0, 3) = AVG3(K, J, I);

}

// Vertical-Left

static WEBP_INLINE void VL4_SSE2(uint8_t* WEBP_RESTRICT dst,

                                 const uint8_t* WEBP_RESTRICT top) {

  const __m128i one = _mm_set1_epi8(1);

  const __m128i ABCDEFGH = _mm_loadl_epi64((const __m128i*)top);

  const __m128i BCDEFGH_ = _mm_srli_si128(ABCDEFGH, 1);

  const __m128i CDEFGH__ = _mm_srli_si128(ABCDEFGH, 2);

  const __m128i avg1 = _mm_avg_epu8(ABCDEFGH, BCDEFGH_);

  const __m128i avg2 = _mm_avg_epu8(CDEFGH__, BCDEFGH_);

  const __m128i avg3 = _mm_avg_epu8(avg1, avg2);

  const __m128i lsb1 = _mm_and_si128(_mm_xor_si128(avg1, avg2), one);

  const __m128i ab = _mm_xor_si128(ABCDEFGH, BCDEFGH_);

  const __m128i bc = _mm_xor_si128(CDEFGH__, BCDEFGH_);

  const __m128i abbc = _mm_or_si128(ab, bc);

  const __m128i lsb2 = _mm_and_si128(abbc, lsb1);

  const __m128i avg4 = _mm_subs_epu8(avg3, lsb2);

  const uint32_t extra_out =

      (uint32_t)_mm_cvtsi128_si32(_mm_srli_si128(avg4, 4));

  WebPInt32ToMem(dst + 0 * BPS, _mm_cvtsi128_si32(avg1));

  WebPInt32ToMem(dst + 1 * BPS, _mm_cvtsi128_si32(avg4));

  WebPInt32ToMem(dst + 2 * BPS, _mm_cvtsi128_si32(_mm_srli_si128(avg1, 1)));

  WebPInt32ToMem(dst + 3 * BPS, _mm_cvtsi128_si32(_mm_srli_si128(avg4, 1)));

  // these two are hard to get and irregular

  DST(3, 2) = (extra_out >> 0) & 0xff;

  DST(3, 3) = (extra_out >> 8) & 0xff;

}

// Down-right

static WEBP_INLINE void RD4_SSE2(uint8_t* WEBP_RESTRICT dst,

                                 const uint8_t* WEBP_RESTRICT top) {

  const __m128i one = _mm_set1_epi8(1);

  const __m128i LKJIXABC = _mm_loadl_epi64((const __m128i*)(top - 5));

  const __m128i LKJIXABCD = _mm_insert_epi16(LKJIXABC, top[3], 4);

  const __m128i KJIXABCD_ = _mm_srli_si128(LKJIXABCD, 1);

  const __m128i JIXABCD__ = _mm_srli_si128(LKJIXABCD, 2);

  const __m128i avg1 = _mm_avg_epu8(JIXABCD__, LKJIXABCD);

  const __m128i lsb = _mm_and_si128(_mm_xor_si128(JIXABCD__, LKJIXABCD), one);

  const __m128i avg2 = _mm_subs_epu8(avg1, lsb);

  const __m128i abcdefg = _mm_avg_epu8(avg2, KJIXABCD_);

  WebPInt32ToMem(dst + 3 * BPS, _mm_cvtsi128_si32(abcdefg));

  WebPInt32ToMem(dst + 2 * BPS, _mm_cvtsi128_si32(_mm_srli_si128(abcdefg, 1)));

  WebPInt32ToMem(dst + 1 * BPS, _mm_cvtsi128_si32(_mm_srli_si128(abcdefg, 2)));

  WebPInt32ToMem(dst + 0 * BPS, _mm_cvtsi128_si32(_mm_srli_si128(abcdefg, 3)));

}

static WEBP_INLINE void HU4_SSE2(uint8_t* WEBP_RESTRICT dst,

                                 const uint8_t* WEBP_RESTRICT top) {

  const int I = top[-2];

  const int J = top[-3];

  const int K = top[-4];

  const int L = top[-5];

  DST(0, 0) = AVG2(I, J);

  DST(2, 0) = DST(0, 1) = AVG2(J, K);

  DST(2, 1) = DST(0, 2) = AVG2(K, L);

  DST(1, 0) = AVG3(I, J, K);

  DST(3, 0) = DST(1, 1) = AVG3(J, K, L);

  DST(3, 1) = DST(1, 2) = AVG3(K, L, L);

  DST(3, 2) = DST(2, 2) = DST(0, 3) = DST(1, 3) = DST(2, 3) = DST(3, 3) = L;

}

static WEBP_INLINE void HD4_SSE2(uint8_t* WEBP_RESTRICT dst,

                                 const uint8_t* WEBP_RESTRICT top) {

  const int X = top[-1];

  const int I = top[-2];

  const int J = top[-3];

  const int K = top[-4];

  const int L = top[-5];

  const int A = top[0];

  const int B = top[1];

  const int C = top[2];

  DST(0, 0) = DST(2, 1) = AVG2(I, X);

  DST(0, 1) = DST(2, 2) = AVG2(J, I);

  DST(0, 2) = DST(2, 3) = AVG2(K, J);

  DST(0, 3) = AVG2(L, K);