// Copyright 2017 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 distortion calculation

//

// Author: Skal (pascal.massimino@gmail.com)

#include "src/dsp/dsp.h"

#if defined(WEBP_USE_SSE2)

#include <assert.h>

#include <emmintrin.h>

#include "src/dsp/common_sse2.h"

#if !defined(WEBP_DISABLE_STATS)

// Helper function

static WEBP_INLINE void SubtractAndSquare_SSE2(const __m128i a, const __m128i b,

                                               __m128i* const sum) {

  // take abs(a-b) in 8b

  const __m128i a_b = _mm_subs_epu8(a, b);

  const __m128i b_a = _mm_subs_epu8(b, a);

  const __m128i abs_a_b = _mm_or_si128(a_b, b_a);

  // zero-extend to 16b

  const __m128i zero = _mm_setzero_si128();

  const __m128i C0 = _mm_unpacklo_epi8(abs_a_b, zero);

  const __m128i C1 = _mm_unpackhi_epi8(abs_a_b, zero);

  // multiply with self

  const __m128i sum1 = _mm_madd_epi16(C0, C0);

  const __m128i sum2 = _mm_madd_epi16(C1, C1);

  *sum = _mm_add_epi32(sum1, sum2);

}

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

// SSIM / PSNR entry point

static uint32_t AccumulateSSE_SSE2(const uint8_t* src1,

                                   const uint8_t* src2, int len) {

  int i = 0;

  uint32_t sse2 = 0;

  if (len >= 16) {

    const int limit = len - 32;

    int32_t tmp[4];

    __m128i sum1;

    __m128i sum = _mm_setzero_si128();

    __m128i a0 = _mm_loadu_si128((const __m128i*)&src1[i]);

    __m128i b0 = _mm_loadu_si128((const __m128i*)&src2[i]);

    i += 16;

    while (i <= limit) {

      const __m128i a1 = _mm_loadu_si128((const __m128i*)&src1[i]);

      const __m128i b1 = _mm_loadu_si128((const __m128i*)&src2[i]);

      __m128i sum2;

      i += 16;

      SubtractAndSquare_SSE2(a0, b0, &sum1;;

      sum = _mm_add_epi32(sum, sum1);

      a0 = _mm_loadu_si128((const __m128i*)&src1[i]);

      b0 = _mm_loadu_si128((const __m128i*)&src2[i]);

      i += 16;

      SubtractAndSquare_SSE2(a1, b1, &sum2;;

      sum = _mm_add_epi32(sum, sum2);

    }

    SubtractAndSquare_SSE2(a0, b0, &sum1;;

    sum = _mm_add_epi32(sum, sum1);

    _mm_storeu_si128((__m128i*)tmp, sum);

    sse2 += (tmp[3] + tmp[2] + tmp[1] + tmp[0]);

  }

  for (; i < len; ++i) {

    const int32_t diff = src1[i] - src2[i];

    sse2 += diff * diff;

  }

  return sse2;

}

#endif  // !defined(WEBP_DISABLE_STATS)

#if !defined(WEBP_REDUCE_SIZE)

static uint32_t HorizontalAdd16b_SSE2(const __m128i* const m) {

  uint16_t tmp[8];

  const __m128i a = _mm_srli_si128(*m, 8);

  const __m128i b = _mm_add_epi16(*m, a);

  _mm_storeu_si128((__m128i*)tmp, b);

  return (uint32_t)tmp[3] + tmp[2] + tmp[1] + tmp[0];

}

static uint32_t HorizontalAdd32b_SSE2(const __m128i* const m) {

  const __m128i a = _mm_srli_si128(*m, 8);

  const __m128i b = _mm_add_epi32(*m, a);

  const __m128i c = _mm_add_epi32(b, _mm_srli_si128(b, 4));

  return (uint32_t)_mm_cvtsi128_si32(c);

}

static const uint16_t kWeight[] = { 1, 2, 3, 4, 3, 2, 1, 0 };

#define ACCUMULATE_ROW(WEIGHT) do {                         \

  /* compute row weight (Wx * Wy) */                        \

  const __m128i Wy = _mm_set1_epi16((WEIGHT));              \

  const __m128i W = _mm_mullo_epi16(Wx, Wy);                \

  /* process 8 bytes at a time (7 bytes, actually) */       \

  const __m128i a0 = _mm_loadl_epi64((const __m128i*)src1); \

  const __m128i b0 = _mm_loadl_epi64((const __m128i*)src2); \

  /* convert to 16b and multiply by weight */               \

  const __m128i a1 = _mm_unpacklo_epi8(a0, zero);           \

  const __m128i b1 = _mm_unpacklo_epi8(b0, zero);           \

  const __m128i wa1 = _mm_mullo_epi16(a1, W);               \

  const __m128i wb1 = _mm_mullo_epi16(b1, W);               \

  /* accumulate */                                          \

  xm  = _mm_add_epi16(xm, wa1);                             \

  ym  = _mm_add_epi16(ym, wb1);                             \

  xxm = _mm_add_epi32(xxm, _mm_madd_epi16(a1, wa1));        \

  xym = _mm_add_epi32(xym, _mm_madd_epi16(a1, wb1));        \

  yym = _mm_add_epi32(yym, _mm_madd_epi16(b1, wb1));        \

  src1 += stride1;                                          \

  src2 += stride2;                                          \

} while (0)

static double SSIMGet_SSE2(const uint8_t* src1, int stride1,

                           const uint8_t* src2, int stride2) {

  VP8DistoStats stats;

  const __m128i zero = _mm_setzero_si128();

  __m128i xm = zero, ym = zero;                // 16b accums

  __m128i xxm = zero, yym = zero, xym = zero;  // 32b accum

  const __m128i Wx = _mm_loadu_si128((const __m128i*)kWeight);

  assert(2 * VP8_SSIM_KERNEL + 1 == 7);

  ACCUMULATE_ROW(1);

  ACCUMULATE_ROW(2);

  ACCUMULATE_ROW(3);

  ACCUMULATE_ROW(4);

  ACCUMULATE_ROW(3);

  ACCUMULATE_ROW(2);

  ACCUMULATE_ROW(1);

  stats.xm  = HorizontalAdd16b_SSE2(&xm);

  stats.ym  = HorizontalAdd16b_SSE2(&ym;;

  stats.xxm = HorizontalAdd32b_SSE2(&xxm);

  stats.xym = HorizontalAdd32b_SSE2(&xym);

  stats.yym = HorizontalAdd32b_SSE2(&yym);

  return VP8SSIMFromStats(&stats);

}

#endif  // !defined(WEBP_REDUCE_SIZE)

extern void VP8SSIMDspInitSSE2(void);

WEBP_TSAN_IGNORE_FUNCTION void VP8SSIMDspInitSSE2(void) {

#if !defined(WEBP_DISABLE_STATS)

  VP8AccumulateSSE = AccumulateSSE_SSE2;

#endif

#if !defined(WEBP_REDUCE_SIZE)

  VP8SSIMGet = SSIMGet_SSE2;

#endif

}

#else  // !WEBP_USE_SSE2

WEBP_DSP_INIT_STUB(VP8SSIMDspInitSSE2)

#endif  // WEBP_USE_SSE2