/*
 * Copyright (c) 2022, 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 <arm_neon.h>

#include "config/aom_config.h"
#include "config/aom_dsp_rtcd.h"

#include "aom_dsp/variance.h"
#include "aom_dsp/aom_filter.h"
#include "aom_dsp/arm/sum_neon.h"

typedef void (*high_variance_fn_t)(const uint16_t *src, int src_stride,
                                   const uint16_t *ref, int ref_stride,
                                   uint32_t *sse, int *sum);

void aom_highbd_calc16x16var_neon(const uint16_t *src, int src_stride,
                                  const uint16_t *ref, int ref_stride,
                                  uint32_t *sse, int *sum) {
  int i, j;
  int16x8_t v_sum = vdupq_n_s16(0);
  int32x4_t v_sse_lo = vdupq_n_s32(0);
  int32x4_t v_sse_hi = vdupq_n_s32(0);

  for (i = 0; i < 16; ++i) {
    for (j = 0; j < 16; j += 8) {
      const uint16x8_t v_a = vld1q_u16(&src[j]);
      const uint16x8_t v_b = vld1q_u16(&ref[j]);
      const int16x8_t sv_diff = vreinterpretq_s16_u16(vsubq_u16(v_a, v_b));
      v_sum = vaddq_s16(v_sum, sv_diff);
      v_sse_lo =
          vmlal_s16(v_sse_lo, vget_low_s16(sv_diff), vget_low_s16(sv_diff));
      v_sse_hi =
          vmlal_s16(v_sse_hi, vget_high_s16(sv_diff), vget_high_s16(sv_diff));
    }
    src += src_stride;
    ref += ref_stride;
  }

  *sum = horizontal_add_s16x8(v_sum);
  *sse = (unsigned int)horizontal_add_s32x4(vaddq_s32(v_sse_lo, v_sse_hi));
}

void aom_highbd_calc8x8var_neon(const uint16_t *src, int src_stride,
                                const uint16_t *ref, int ref_stride,
                                uint32_t *sse, int *sum) {
  int i;
  int16x8_t v_sum = vdupq_n_s16(0);
  int32x4_t v_sse_lo = vdupq_n_s32(0);
  int32x4_t v_sse_hi = vdupq_n_s32(0);

  for (i = 0; i < 8; ++i) {
    const uint16x8_t v_a = vld1q_u16(&src[0]);
    const uint16x8_t v_b = vld1q_u16(&ref[0]);
    const int16x8_t sv_diff = vreinterpretq_s16_u16(vsubq_u16(v_a, v_b));
    v_sum = vaddq_s16(v_sum, sv_diff);
    v_sse_lo =
        vmlal_s16(v_sse_lo, vget_low_s16(sv_diff), vget_low_s16(sv_diff));
    v_sse_hi =
        vmlal_s16(v_sse_hi, vget_high_s16(sv_diff), vget_high_s16(sv_diff));
    src += src_stride;
    ref += ref_stride;
  }

  *sum = horizontal_add_s16x8(v_sum);
  *sse = (unsigned int)horizontal_add_s32x4(vaddq_s32(v_sse_lo, v_sse_hi));
}

void aom_highbd_calc4x4var_neon(const uint16_t *src, int src_stride,
                                const uint16_t *ref, int ref_stride,
                                uint32_t *sse, int *sum) {
  int i;
  int16x8_t v_sum = vdupq_n_s16(0);
  int32x4_t v_sse_lo = vdupq_n_s32(0);
  int32x4_t v_sse_hi = vdupq_n_s32(0);

  for (i = 0; i < 4; i += 2) {
    const uint16x4_t v_a_r0 = vld1_u16(&src[0]);
    const uint16x4_t v_b_r0 = vld1_u16(&ref[0]);
    const uint16x4_t v_a_r1 = vld1_u16(&src[src_stride]);
    const uint16x4_t v_b_r1 = vld1_u16(&ref[ref_stride]);
    const uint16x8_t v_a = vcombine_u16(v_a_r0, v_a_r1);
    const uint16x8_t v_b = vcombine_u16(v_b_r0, v_b_r1);
    const int16x8_t sv_diff = vreinterpretq_s16_u16(vsubq_u16(v_a, v_b));
    v_sum = vaddq_s16(v_sum, sv_diff);
    v_sse_lo =
        vmlal_s16(v_sse_lo, vget_low_s16(sv_diff), vget_low_s16(sv_diff));
    v_sse_hi =
        vmlal_s16(v_sse_hi, vget_high_s16(sv_diff), vget_high_s16(sv_diff));
    src += src_stride << 1;
    ref += ref_stride << 1;
  }

  *sum = horizontal_add_s16x8(v_sum);
  *sse = (unsigned int)horizontal_add_s32x4(vaddq_s32(v_sse_lo, v_sse_hi));
}

static void highbd_10_variance_neon(const uint16_t *src, int src_stride,
                                    const uint16_t *ref, int ref_stride, int w,
                                    int h, uint32_t *sse, int *sum,
                                    high_variance_fn_t var_fn, int block_size) {
  int i, j;
  uint64_t sse_long = 0;
  int32_t sum_long = 0;

  for (i = 0; i < h; i += block_size) {
    for (j = 0; j < w; j += block_size) {
      unsigned int sse0;
      int sum0;
      var_fn(src + src_stride * i + j, src_stride, ref + ref_stride * i + j,
             ref_stride, &sse0, &sum0);
      sse_long += sse0;
      sum_long += sum0;
    }
  }
  *sum = ROUND_POWER_OF_TWO(sum_long, 2);
  *sse = (uint32_t)ROUND_POWER_OF_TWO(sse_long, 4);
}

#define VAR_FN(w, h, block_size, shift)                                    \
  uint32_t aom_highbd_10_variance##w##x##h##_neon(                         \
      const uint8_t *src8, int src_stride, const uint8_t *ref8,            \
      int ref_stride, uint32_t *sse) {                                     \
    int sum;                                                               \
    int64_t var;                                                           \
    uint16_t *src = CONVERT_TO_SHORTPTR(src8);                             \
    uint16_t *ref = CONVERT_TO_SHORTPTR(ref8);                             \
    highbd_10_variance_neon(                                               \
        src, src_stride, ref, ref_stride, w, h, sse, &sum,                 \
        aom_highbd_calc##block_size##x##block_size##var_neon, block_size); \
    var = (int64_t)(*sse) - (((int64_t)sum * sum) >> shift);               \
    return (var >= 0) ? (uint32_t)var : 0;                                 \
  }

VAR_FN(128, 128, 16, 14)
VAR_FN(128, 64, 16, 13)
VAR_FN(64, 128, 16, 13)
VAR_FN(64, 64, 16, 12)
VAR_FN(64, 32, 16, 11)
VAR_FN(32, 64, 16, 11)
VAR_FN(32, 32, 16, 10)
VAR_FN(32, 16, 16, 9)
VAR_FN(16, 32, 16, 9)
VAR_FN(16, 16, 16, 8)
VAR_FN(16, 8, 8, 7)
VAR_FN(8, 16, 8, 7)
VAR_FN(8, 8, 8, 6)

VAR_FN(16, 4, 4, 6)
VAR_FN(4, 16, 4, 6)

VAR_FN(8, 4, 4, 5)
VAR_FN(4, 8, 4, 5)
VAR_FN(4, 4, 4, 4)

#if !CONFIG_REALTIME_ONLY
VAR_FN(64, 16, 16, 10)
VAR_FN(16, 64, 16, 10)
VAR_FN(8, 32, 8, 8)
VAR_FN(32, 8, 8, 8)
#endif  // !CONFIG_REALTIME_ONLY

#undef VAR_FN