/*
 * Copyright (c) 2017, 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>

#include "./av1_rtcd.h"

#include "av1/common/cfl.h"

#include "av1/common/x86/cfl_simd.h"

/**
 * Adds 4 pixels (in a 2x2 grid) and multiplies them by 2. Resulting in a more
 * precise version of a box filter 4:2:0 pixel subsampling in Q3.
 *
 * The CfL prediction buffer is always of size CFL_BUF_SQUARE. However, the
 * active area is specified using width and height.
 *
 * Note: We don't need to worry about going over the active area, as long as we
 * stay inside the CfL prediction buffer.
 *
 * Note: For 4:2:0 luma subsampling, the width will never be greater than 16.
 */
static void cfl_luma_subsampling_420_lbd_avx2(const uint8_t *input,
                                              int input_stride,
                                              int16_t *pred_buf_q3, int width,
                                              int height) {
  (void)width;  // Max chroma width is 16, so all widths fit in one __m256i

  const __m256i twos = _mm256_set1_epi8(2);  // Thirty two twos
  const int luma_stride = input_stride << 1;
  const int16_t *end = pred_buf_q3 + (height >> 1) * CFL_BUF_LINE;
  do {
    // Load 32 values for the top and bottom rows.
    // t_0, t_1, ... t_31
    __m256i top = _mm256_loadu_si256((__m256i *)(input));
    // b_0, b_1, ... b_31
    __m256i bot = _mm256_loadu_si256((__m256i *)(input + input_stride));

    // Horizontal add of the 32 values into 16 values that are multiplied by 2
    // (t_0 + t_1) * 2, (t_2 + t_3) * 2, ... (t_30 + t_31) *2
    top = _mm256_maddubs_epi16(top, twos);
    // (b_0 + b_1) * 2, (b_2 + b_3) * 2, ... (b_30 + b_31) *2
    bot = _mm256_maddubs_epi16(bot, twos);

    // Add the 16 values in top with the 16 values in bottom
    _mm256_storeu_si256((__m256i *)pred_buf_q3, _mm256_add_epi16(top, bot));

    input += luma_stride;
    pred_buf_q3 += CFL_BUF_LINE;
  } while (pred_buf_q3 < end);
}

CFL_GET_SUBSAMPLE_FUNCTION(avx2)

static INLINE __m256i predict_unclipped(const __m256i *input, __m256i alpha_q12,
                                        __m256i alpha_sign, __m256i dc_q0) {
  __m256i ac_q3 = _mm256_loadu_si256(input);
  __m256i ac_sign = _mm256_sign_epi16(alpha_sign, ac_q3);
  __m256i scaled_luma_q0 =
      _mm256_mulhrs_epi16(_mm256_abs_epi16(ac_q3), alpha_q12);
  scaled_luma_q0 = _mm256_sign_epi16(scaled_luma_q0, ac_sign);
  return _mm256_add_epi16(scaled_luma_q0, dc_q0);
}

static INLINE void cfl_predict_lbd_32_avx2(const int16_t *pred_buf_q3,
                                           uint8_t *dst, int dst_stride,
                                           TX_SIZE tx_size, int alpha_q3) {
  const __m256i alpha_sign = _mm256_set1_epi16(alpha_q3);
  const __m256i alpha_q12 = _mm256_slli_epi16(_mm256_abs_epi16(alpha_sign), 9);
  const __m256i dc_q0 = _mm256_set1_epi16(*dst);
  __m256i *row = (__m256i *)pred_buf_q3;
  const __m256i *row_end = row + tx_size_high[tx_size] * CFL_BUF_LINE_I256;

  do {
    __m256i res = predict_unclipped(row, alpha_q12, alpha_sign, dc_q0);
    __m256i next = predict_unclipped(row + 1, alpha_q12, alpha_sign, dc_q0);
    res = _mm256_packus_epi16(res, next);
    res = _mm256_permute4x64_epi64(res, _MM_SHUFFLE(3, 1, 2, 0));
    _mm256_storeu_si256((__m256i *)dst, res);
    dst += dst_stride;
  } while ((row += CFL_BUF_LINE_I256) < row_end);
}

static __m256i highbd_max_epi16(int bd) {
  const __m256i neg_one = _mm256_set1_epi16(-1);
  // (1 << bd) - 1 => -(-1 << bd) -1 => -1 - (-1 << bd) => -1 ^ (-1 << bd)
  return _mm256_xor_si256(_mm256_slli_epi16(neg_one, bd), neg_one);
}

static __m256i highbd_clamp_epi16(__m256i u, __m256i zero, __m256i max) {
  return _mm256_max_epi16(_mm256_min_epi16(u, max), zero);
}

static INLINE void cfl_predict_hbd(__m256i *dst, __m256i *src,
                                   __m256i alpha_q12, __m256i alpha_sign,
                                   __m256i dc_q0, __m256i max) {
  __m256i res = predict_unclipped(src, alpha_q12, alpha_sign, dc_q0);
  _mm256_storeu_si256(dst,
                      highbd_clamp_epi16(res, _mm256_setzero_si256(), max));
}

static INLINE void cfl_predict_hbd_x(const int16_t *pred_buf_q3, uint16_t *dst,
                                     int dst_stride, TX_SIZE tx_size,
                                     int alpha_q3, int bd, int width) {
  // Use SSSE3 version for smaller widths
  assert(width == 16 || width == 32);
  const __m256i alpha_sign = _mm256_set1_epi16(alpha_q3);
  const __m256i alpha_q12 = _mm256_slli_epi16(_mm256_abs_epi16(alpha_sign), 9);
  const __m256i dc_q0 = _mm256_loadu_si256((__m256i *)dst);
  const __m256i max = highbd_max_epi16(bd);

  __m256i *row = (__m256i *)pred_buf_q3;
  const __m256i *row_end = row + tx_size_high[tx_size] * CFL_BUF_LINE_I256;
  do {
    cfl_predict_hbd((__m256i *)dst, row, alpha_q12, alpha_sign, dc_q0, max);
    if (width == 32) {
      cfl_predict_hbd((__m256i *)(dst + 16), row + 1, alpha_q12, alpha_sign,
                      dc_q0, max);
    }
    dst += dst_stride;
  } while ((row += CFL_BUF_LINE_I256) < row_end);
}

CFL_PREDICT_HBD_X(16, avx2)
CFL_PREDICT_HBD_X(32, avx2)

cfl_predict_lbd_fn get_predict_lbd_fn_avx2(TX_SIZE tx_size) {
  // Sizes 4, 8 and 16 reuse the SSSE3 version
  static const cfl_predict_lbd_fn predict_lbd[4] = { cfl_predict_lbd_4_ssse3,
                                                     cfl_predict_lbd_8_ssse3,
                                                     cfl_predict_lbd_16_ssse3,
                                                     cfl_predict_lbd_32_avx2 };
  return predict_lbd[(tx_size_wide_log2[tx_size] - tx_size_wide_log2[0]) & 3];
}

cfl_predict_hbd_fn get_predict_hbd_fn_avx2(TX_SIZE tx_size) {
  static const cfl_predict_hbd_fn predict_hbd[4] = { cfl_predict_hbd_4_ssse3,
                                                     cfl_predict_hbd_8_ssse3,
                                                     cfl_predict_hbd_16_avx2,
                                                     cfl_predict_hbd_32_avx2 };
  return predict_hbd[(tx_size_wide_log2[tx_size] - tx_size_wide_log2[0]) & 3];
}

static INLINE __m256i fill_sum_epi32(__m256i l0) {
  l0 = _mm256_add_epi32(l0, _mm256_shuffle_epi32(l0, _MM_SHUFFLE(1, 0, 3, 2)));
  return _mm256_add_epi32(l0,
                          _mm256_shuffle_epi32(l0, _MM_SHUFFLE(2, 3, 0, 1)));
}

static INLINE void subtract_average_avx2(int16_t *pred_buf, int width,
                                         int height, int round_offset,
                                         int num_pel_log2) {
  const __m256i zeros = _mm256_setzero_si256();
  __m256i *row = (__m256i *)pred_buf;
  const __m256i *const end = row + height * CFL_BUF_LINE_I256;
  const int step = CFL_BUF_LINE_I256 * (1 + (width == 8) + 3 * (width == 4));
  union {
    __m256i v;
    int32_t i32[8];
  } sum;
  sum.v = zeros;
  do {
    if (width == 4) {
      __m256i l0 = _mm256_loadu_si256(row);
      __m256i l1 = _mm256_loadu_si256(row + CFL_BUF_LINE_I256);
      __m256i l2 = _mm256_loadu_si256(row + 2 * CFL_BUF_LINE_I256);
      __m256i l3 = _mm256_loadu_si256(row + 3 * CFL_BUF_LINE_I256);

      __m256i t0 = _mm256_add_epi16(l0, l1);
      __m256i t1 = _mm256_add_epi16(l2, l3);

      sum.v = _mm256_add_epi32(
          sum.v, _mm256_add_epi32(_mm256_unpacklo_epi16(t0, zeros),
                                  _mm256_unpacklo_epi16(t1, zeros)));
    } else {
      __m256i l0;
      if (width == 8) {
        l0 = _mm256_add_epi16(_mm256_loadu_si256(row),
                              _mm256_loadu_si256(row + CFL_BUF_LINE_I256));
      } else {
        l0 = _mm256_loadu_si256(row);
        l0 = _mm256_add_epi16(l0, _mm256_permute2x128_si256(l0, l0, 1));
      }
      sum.v = _mm256_add_epi32(
          sum.v, _mm256_add_epi32(_mm256_unpacklo_epi16(l0, zeros),
                                  _mm256_unpackhi_epi16(l0, zeros)));
      if (width == 32) {
        l0 = _mm256_loadu_si256(row + 1);
        l0 = _mm256_add_epi16(l0, _mm256_permute2x128_si256(l0, l0, 1));
        sum.v = _mm256_add_epi32(
            sum.v, _mm256_add_epi32(_mm256_unpacklo_epi16(l0, zeros),
                                    _mm256_unpackhi_epi16(l0, zeros)));
      }
    }
  } while ((row += step) < end);

  sum.v = fill_sum_epi32(sum.v);

  __m256i avg_epi16 =
      _mm256_set1_epi16((sum.i32[0] + round_offset) >> num_pel_log2);

  row = (__m256i *)pred_buf;
  do {
    _mm256_storeu_si256(row,
                        _mm256_sub_epi16(_mm256_loadu_si256(row), avg_epi16));
    if (width == 32) {
      _mm256_storeu_si256(
          row + 1, _mm256_sub_epi16(_mm256_loadu_si256(row + 1), avg_epi16));
    }
  } while ((row += CFL_BUF_LINE_I256) < end);
}

CFL_SUB_AVG_FN(avx2)