/*
 * Copyright (c) 2016, Alliance for Open Media. All rights reserved
 *
 * This source code is subject to the terms of the BSD 2 Clause License and
 * the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
 * was not distributed with this source code in the LICENSE file, you can
 * obtain it at www.aomedia.org/license/software. If the Alliance for Open
 * Media Patent License 1.0 was not distributed with this source code in the
 * PATENTS file, you can obtain it at www.aomedia.org/license/patent.
 */
#include <immintrin.h>  // AVX2

#include "config/aom_dsp_rtcd.h"

#include "aom/aom_integer.h"

void aom_sadMxNx4d_avx2(int M, int N, const uint8_t *src, int src_stride,
                        const uint8_t *const ref[4], int ref_stride,
                        uint32_t res[4]) {
  __m256i src_reg, ref0_reg, ref1_reg, ref2_reg, ref3_reg;
  __m256i sum_ref0, sum_ref1, sum_ref2, sum_ref3;
  int i, j;
  const uint8_t *ref0, *ref1, *ref2, *ref3;

  ref0 = ref[0];
  ref1 = ref[1];
  ref2 = ref[2];
  ref3 = ref[3];
  sum_ref0 = _mm256_setzero_si256();
  sum_ref2 = _mm256_setzero_si256();
  sum_ref1 = _mm256_setzero_si256();
  sum_ref3 = _mm256_setzero_si256();

  for (i = 0; i < N; i++) {
    for (j = 0; j < M; j += 32) {
      // load src and all refs
      src_reg = _mm256_loadu_si256((const __m256i *)(src + j));
      ref0_reg = _mm256_loadu_si256((const __m256i *)(ref0 + j));
      ref1_reg = _mm256_loadu_si256((const __m256i *)(ref1 + j));
      ref2_reg = _mm256_loadu_si256((const __m256i *)(ref2 + j));
      ref3_reg = _mm256_loadu_si256((const __m256i *)(ref3 + j));

      // sum of the absolute differences between every ref-i to src
      ref0_reg = _mm256_sad_epu8(ref0_reg, src_reg);
      ref1_reg = _mm256_sad_epu8(ref1_reg, src_reg);
      ref2_reg = _mm256_sad_epu8(ref2_reg, src_reg);
      ref3_reg = _mm256_sad_epu8(ref3_reg, src_reg);
      // sum every ref-i
      sum_ref0 = _mm256_add_epi32(sum_ref0, ref0_reg);
      sum_ref1 = _mm256_add_epi32(sum_ref1, ref1_reg);
      sum_ref2 = _mm256_add_epi32(sum_ref2, ref2_reg);
      sum_ref3 = _mm256_add_epi32(sum_ref3, ref3_reg);
    }
    src += src_stride;
    ref0 += ref_stride;
    ref1 += ref_stride;
    ref2 += ref_stride;
    ref3 += ref_stride;
  }
  {
    __m128i sum;
    __m256i sum_mlow, sum_mhigh;
    // in sum_ref-i the result is saved in the first 4 bytes
    // the other 4 bytes are zeroed.
    // sum_ref1 and sum_ref3 are shifted left by 4 bytes
    sum_ref1 = _mm256_slli_si256(sum_ref1, 4);
    sum_ref3 = _mm256_slli_si256(sum_ref3, 4);

    // merge sum_ref0 and sum_ref1 also sum_ref2 and sum_ref3
    sum_ref0 = _mm256_or_si256(sum_ref0, sum_ref1);
    sum_ref2 = _mm256_or_si256(sum_ref2, sum_ref3);

    // merge every 64 bit from each sum_ref-i
    sum_mlow = _mm256_unpacklo_epi64(sum_ref0, sum_ref2);
    sum_mhigh = _mm256_unpackhi_epi64(sum_ref0, sum_ref2);

    // add the low 64 bit to the high 64 bit
    sum_mlow = _mm256_add_epi32(sum_mlow, sum_mhigh);

    // add the low 128 bit to the high 128 bit
    sum = _mm_add_epi32(_mm256_castsi256_si128(sum_mlow),
                        _mm256_extractf128_si256(sum_mlow, 1));

    _mm_storeu_si128((__m128i *)(res), sum);
  }
}

#define sadMxN_avx2(m, n)                                                      \
  void aom_sad##m##x##n##x4d_avx2(const uint8_t *src, int src_stride,          \
                                  const uint8_t *const ref[4], int ref_stride, \
                                  uint32_t res[4]) {                           \
    aom_sadMxNx4d_avx2(m, n, src, src_stride, ref, ref_stride, res);           \
  }

sadMxN_avx2(32, 8);
sadMxN_avx2(32, 16);
sadMxN_avx2(32, 32);
sadMxN_avx2(32, 64);

sadMxN_avx2(64, 16);
sadMxN_avx2(64, 32);
sadMxN_avx2(64, 64);
sadMxN_avx2(64, 128);

sadMxN_avx2(128, 64);
sadMxN_avx2(128, 128);
