/*
 * Copyright (c) 2020, 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 <assert.h>

#include "config/aom_config.h"
#include "config/av1_rtcd.h"

#include "aom/aom_integer.h"
#include "aom_dsp/arm/mem_neon.h"
#include "aom_dsp/arm/sum_neon.h"

#define MAX_UPSAMPLE_SZ 16
#define FILTER_INTRA_SCALE_BITS 4

// These kernels are a transposed version of those defined in reconintra.c,
// with the absolute value of the negatives taken in the top row.
DECLARE_ALIGNED(16, static const uint8_t,
                av1_filter_intra_taps_neon[FILTER_INTRA_MODES][7][8]) = {
  // clang-format off
  {
      {  6,  5,  3,  3,  4,  3,  3,  3 },
      { 10,  2,  1,  1,  6,  2,  2,  1 },
      {  0, 10,  1,  1,  0,  6,  2,  2 },
      {  0,  0, 10,  2,  0,  0,  6,  2 },
      {  0,  0,  0, 10,  0,  0,  0,  6 },
      { 12,  9,  7,  5,  2,  2,  2,  3 },
      {  0,  0,  0,  0, 12,  9,  7,  5 }
  },
  {
      { 10,  6,  4,  2, 10,  6,  4,  2 },
      { 16,  0,  0,  0, 16,  0,  0,  0 },
      {  0, 16,  0,  0,  0, 16,  0,  0 },
      {  0,  0, 16,  0,  0,  0, 16,  0 },
      {  0,  0,  0, 16,  0,  0,  0, 16 },
      { 10,  6,  4,  2,  0,  0,  0,  0 },
      {  0,  0,  0,  0, 10,  6,  4,  2 }
  },
  {
      {  8,  8,  8,  8,  4,  4,  4,  4 },
      {  8,  0,  0,  0,  4,  0,  0,  0 },
      {  0,  8,  0,  0,  0,  4,  0,  0 },
      {  0,  0,  8,  0,  0,  0,  4,  0 },
      {  0,  0,  0,  8,  0,  0,  0,  4 },
      { 16, 16, 16, 16,  0,  0,  0,  0 },
      {  0,  0,  0,  0, 16, 16, 16, 16 }
  },
  {
      {  2,  1,  1,  0,  1,  1,  1,  1 },
      {  8,  3,  2,  1,  4,  3,  2,  2 },
      {  0,  8,  3,  2,  0,  4,  3,  2 },
      {  0,  0,  8,  3,  0,  0,  4,  3 },
      {  0,  0,  0,  8,  0,  0,  0,  4 },
      { 10,  6,  4,  2,  3,  4,  4,  3 },
      {  0,  0,  0,  0, 10,  6,  4,  3 }
  },
  {
      { 12, 10,  9,  8, 10,  9,  8,  7 },
      { 14,  0,  0,  0, 12,  1,  0,  0 },
      {  0, 14,  0,  0,  0, 12,  0,  0 },
      {  0,  0, 14,  0,  0,  0, 12,  1 },
      {  0,  0,  0, 14,  0,  0,  0, 12 },
      { 14, 12, 11, 10,  0,  0,  1,  1 },
      {  0,  0,  0,  0, 14, 12, 11,  9 }
  }
  // clang-format on
};

static inline uint8x8_t filter_intra_predictor(
    uint8x8_t s0, uint8x8_t s1, uint8x8_t s2, uint8x8_t s3, uint8x8_t s4,
    uint8x8_t s5, uint8x8_t s6, const uint8x8_t f0, const uint8x8_t f1,
    const uint8x8_t f2, const uint8x8_t f3, const uint8x8_t f4,
    const uint8x8_t f5, const uint8x8_t f6) {
  uint16x8_t acc = vmull_u8(s1, f1);
  // First row of each filter has all negative values so subtract.
  acc = vmlsl_u8(acc, s0, f0);
  acc = vmlal_u8(acc, s2, f2);
  acc = vmlal_u8(acc, s3, f3);
  acc = vmlal_u8(acc, s4, f4);
  acc = vmlal_u8(acc, s5, f5);
  acc = vmlal_u8(acc, s6, f6);

  return vqrshrun_n_s16(vreinterpretq_s16_u16(acc), FILTER_INTRA_SCALE_BITS);
}

void av1_filter_intra_predictor_neon(uint8_t *dst, ptrdiff_t stride,
                                     TX_SIZE tx_size, const uint8_t *above,
                                     const uint8_t *left, int mode) {
  const int width = tx_size_wide[tx_size];
  const int height = tx_size_high[tx_size];
  assert(width <= 32 && height <= 32);

  const uint8x8_t f0 = vld1_u8(av1_filter_intra_taps_neon[mode][0]);
  const uint8x8_t f1 = vld1_u8(av1_filter_intra_taps_neon[mode][1]);
  const uint8x8_t f2 = vld1_u8(av1_filter_intra_taps_neon[mode][2]);
  const uint8x8_t f3 = vld1_u8(av1_filter_intra_taps_neon[mode][3]);
  const uint8x8_t f4 = vld1_u8(av1_filter_intra_taps_neon[mode][4]);
  const uint8x8_t f5 = vld1_u8(av1_filter_intra_taps_neon[mode][5]);
  const uint8x8_t f6 = vld1_u8(av1_filter_intra_taps_neon[mode][6]);

  // Computing 4 cols per iteration (instead of 8) for 8x<h> blocks is faster.
  if (width <= 8) {
    uint8x8_t s0 = vdup_n_u8(above[-1]);
    uint8x8_t s5 = vdup_n_u8(left[0]);
    uint8x8_t s6 = vdup_n_u8(left[1]);

    int c = 0;
    do {
      uint8x8_t s1234 = load_u8_4x1(above + c);
      uint8x8_t s1 = vdup_lane_u8(s1234, 0);
      uint8x8_t s2 = vdup_lane_u8(s1234, 1);
      uint8x8_t s3 = vdup_lane_u8(s1234, 2);
      uint8x8_t s4 = vdup_lane_u8(s1234, 3);

      uint8x8_t res = filter_intra_predictor(s0, s1, s2, s3, s4, s5, s6, f0, f1,
                                             f2, f3, f4, f5, f6);

      store_u8x4_strided_x2(dst + c, stride, res);

      s0 = s4;
      s5 = vdup_lane_u8(res, 3);
      s6 = vdup_lane_u8(res, 7);

      c += 4;
    } while (c < width);

    int r = 2;
    do {
      s0 = vdup_n_u8(left[r - 1]);
      s5 = vdup_n_u8(left[r + 0]);
      s6 = vdup_n_u8(left[r + 1]);

      c = 0;
      do {
        uint8x8_t s1234 = load_u8_4x1(dst + (r - 1) * stride + c);
        uint8x8_t s1 = vdup_lane_u8(s1234, 0);
        uint8x8_t s2 = vdup_lane_u8(s1234, 1);
        uint8x8_t s3 = vdup_lane_u8(s1234, 2);
        uint8x8_t s4 = vdup_lane_u8(s1234, 3);

        uint8x8_t res = filter_intra_predictor(s0, s1, s2, s3, s4, s5, s6, f0,
                                               f1, f2, f3, f4, f5, f6);

        store_u8x4_strided_x2(dst + r * stride + c, stride, res);

        s0 = s4;
        s5 = vdup_lane_u8(res, 3);
        s6 = vdup_lane_u8(res, 7);

        c += 4;
      } while (c < width);

      r += 2;
    } while (r < height);
  } else {
    uint8x8_t s0_lo = vdup_n_u8(above[-1]);
    uint8x8_t s5_lo = vdup_n_u8(left[0]);
    uint8x8_t s6_lo = vdup_n_u8(left[1]);

    int c = 0;
    do {
      uint8x8_t s1234 = vld1_u8(above + c);
      uint8x8_t s1_lo = vdup_lane_u8(s1234, 0);
      uint8x8_t s2_lo = vdup_lane_u8(s1234, 1);
      uint8x8_t s3_lo = vdup_lane_u8(s1234, 2);
      uint8x8_t s4_lo = vdup_lane_u8(s1234, 3);

      uint8x8_t res_lo =
          filter_intra_predictor(s0_lo, s1_lo, s2_lo, s3_lo, s4_lo, s5_lo,
                                 s6_lo, f0, f1, f2, f3, f4, f5, f6);

      uint8x8_t s0_hi = s4_lo;
      uint8x8_t s1_hi = vdup_lane_u8(s1234, 4);
      uint8x8_t s2_hi = vdup_lane_u8(s1234, 5);
      uint8x8_t s3_hi = vdup_lane_u8(s1234, 6);
      uint8x8_t s4_hi = vdup_lane_u8(s1234, 7);
      uint8x8_t s5_hi = vdup_lane_u8(res_lo, 3);
      uint8x8_t s6_hi = vdup_lane_u8(res_lo, 7);

      uint8x8_t res_hi =
          filter_intra_predictor(s0_hi, s1_hi, s2_hi, s3_hi, s4_hi, s5_hi,
                                 s6_hi, f0, f1, f2, f3, f4, f5, f6);

      uint32x2x2_t res =
          vzip_u32(vreinterpret_u32_u8(res_lo), vreinterpret_u32_u8(res_hi));

      vst1_u8(dst + 0 * stride + c, vreinterpret_u8_u32(res.val[0]));
      vst1_u8(dst + 1 * stride + c, vreinterpret_u8_u32(res.val[1]));

      s0_lo = s4_hi;
      s5_lo = vdup_lane_u8(res_hi, 3);
      s6_lo = vdup_lane_u8(res_hi, 7);
      c += 8;
    } while (c < width);

    int r = 2;
    do {
      s0_lo = vdup_n_u8(left[r - 1]);
      s5_lo = vdup_n_u8(left[r + 0]);
      s6_lo = vdup_n_u8(left[r + 1]);

      c = 0;
      do {
        uint8x8_t s1234 = vld1_u8(dst + (r - 1) * stride + c);
        uint8x8_t s1_lo = vdup_lane_u8(s1234, 0);
        uint8x8_t s2_lo = vdup_lane_u8(s1234, 1);
        uint8x8_t s3_lo = vdup_lane_u8(s1234, 2);
        uint8x8_t s4_lo = vdup_lane_u8(s1234, 3);

        uint8x8_t res_lo =
            filter_intra_predictor(s0_lo, s1_lo, s2_lo, s3_lo, s4_lo, s5_lo,
                                   s6_lo, f0, f1, f2, f3, f4, f5, f6);

        uint8x8_t s0_hi = s4_lo;
        uint8x8_t s1_hi = vdup_lane_u8(s1234, 4);
        uint8x8_t s2_hi = vdup_lane_u8(s1234, 5);
        uint8x8_t s3_hi = vdup_lane_u8(s1234, 6);
        uint8x8_t s4_hi = vdup_lane_u8(s1234, 7);
        uint8x8_t s5_hi = vdup_lane_u8(res_lo, 3);
        uint8x8_t s6_hi = vdup_lane_u8(res_lo, 7);

        uint8x8_t res_hi =
            filter_intra_predictor(s0_hi, s1_hi, s2_hi, s3_hi, s4_hi, s5_hi,
                                   s6_hi, f0, f1, f2, f3, f4, f5, f6);

        uint32x2x2_t res =
            vzip_u32(vreinterpret_u32_u8(res_lo), vreinterpret_u32_u8(res_hi));

        vst1_u8(dst + (r + 0) * stride + c, vreinterpret_u8_u32(res.val[0]));
        vst1_u8(dst + (r + 1) * stride + c, vreinterpret_u8_u32(res.val[1]));

        s0_lo = s4_hi;
        s5_lo = vdup_lane_u8(res_hi, 3);
        s6_lo = vdup_lane_u8(res_hi, 7);
        c += 8;
      } while (c < width);

      r += 2;
    } while (r < height);
  }
}

void av1_filter_intra_edge_neon(uint8_t *p, int sz, int strength) {
  if (!strength) return;
  assert(sz >= 0 && sz <= 129);

  uint8_t edge[160];  // Max value of sz + enough padding for vector accesses.
  memcpy(edge + 1, p, sz * sizeof(*p));

  // Populate extra space appropriately.
  edge[0] = edge[1];
  edge[sz + 1] = edge[sz];
  edge[sz + 2] = edge[sz];

  // Don't overwrite first pixel.
  uint8_t *dst = p + 1;
  sz--;

  if (strength == 1) {  // Filter: {4, 8, 4}.
    const uint8_t *src = edge + 1;

    while (sz >= 8) {
      uint8x8_t s0 = vld1_u8(src);
      uint8x8_t s1 = vld1_u8(src + 1);
      uint8x8_t s2 = vld1_u8(src + 2);

      // Make use of the identity:
      // (4*a + 8*b + 4*c) >> 4 == (a + (b << 1) + c) >> 2
      uint16x8_t t0 = vaddl_u8(s0, s2);
      uint16x8_t t1 = vaddl_u8(s1, s1);
      uint16x8_t sum = vaddq_u16(t0, t1);
      uint8x8_t res = vrshrn_n_u16(sum, 2);

      vst1_u8(dst, res);

      src += 8;
      dst += 8;
      sz -= 8;
    }

    if (sz > 0) {  // Handle sz < 8 to avoid modifying out-of-bounds values.
      uint8x8_t s0 = vld1_u8(src);
      uint8x8_t s1 = vld1_u8(src + 1);
      uint8x8_t s2 = vld1_u8(src + 2);

      uint16x8_t t0 = vaddl_u8(s0, s2);
      uint16x8_t t1 = vaddl_u8(s1, s1);
      uint16x8_t sum = vaddq_u16(t0, t1);
      uint8x8_t res = vrshrn_n_u16(sum, 2);

      // Mask off out-of-bounds indices.
      uint8x8_t current_dst = vld1_u8(dst);
      uint8x8_t mask = vcgt_u8(vdup_n_u8(sz), vcreate_u8(0x0706050403020100));
      res = vbsl_u8(mask, res, current_dst);

      vst1_u8(dst, res);
    }
  } else if (strength == 2) {  // Filter: {5, 6, 5}.
    const uint8_t *src = edge + 1;

    const uint8x8x3_t filter = { { vdup_n_u8(5), vdup_n_u8(6), vdup_n_u8(5) } };

    while (sz >= 8) {
      uint8x8_t s0 = vld1_u8(src);
      uint8x8_t s1 = vld1_u8(src + 1);
      uint8x8_t s2 = vld1_u8(src + 2);

      uint16x8_t accum = vmull_u8(s0, filter.val[0]);
      accum = vmlal_u8(accum, s1, filter.val[1]);
      accum = vmlal_u8(accum, s2, filter.val[2]);
      uint8x8_t res = vrshrn_n_u16(accum, 4);

      vst1_u8(dst, res);

      src += 8;
      dst += 8;
      sz -= 8;
    }

    if (sz > 0) {  // Handle sz < 8 to avoid modifying out-of-bounds values.
      uint8x8_t s0 = vld1_u8(src);
      uint8x8_t s1 = vld1_u8(src + 1);
      uint8x8_t s2 = vld1_u8(src + 2);

      uint16x8_t accum = vmull_u8(s0, filter.val[0]);
      accum = vmlal_u8(accum, s1, filter.val[1]);
      accum = vmlal_u8(accum, s2, filter.val[2]);
      uint8x8_t res = vrshrn_n_u16(accum, 4);

      // Mask off out-of-bounds indices.
      uint8x8_t current_dst = vld1_u8(dst);
      uint8x8_t mask = vcgt_u8(vdup_n_u8(sz), vcreate_u8(0x0706050403020100));
      res = vbsl_u8(mask, res, current_dst);

      vst1_u8(dst, res);
    }
  } else {  // Filter {2, 4, 4, 4, 2}.
    const uint8_t *src = edge;

    while (sz >= 8) {
      uint8x8_t s0 = vld1_u8(src);
      uint8x8_t s1 = vld1_u8(src + 1);
      uint8x8_t s2 = vld1_u8(src + 2);
      uint8x8_t s3 = vld1_u8(src + 3);
      uint8x8_t s4 = vld1_u8(src + 4);

      // Make use of the identity:
      // (2*a + 4*b + 4*c + 4*d + 2*e) >> 4 == (a + ((b + c + d) << 1) + e) >> 3
      uint16x8_t t0 = vaddl_u8(s0, s4);
      uint16x8_t t1 = vaddl_u8(s1, s2);
      t1 = vaddw_u8(t1, s3);
      t1 = vaddq_u16(t1, t1);
      uint16x8_t sum = vaddq_u16(t0, t1);
      uint8x8_t res = vrshrn_n_u16(sum, 3);

      vst1_u8(dst, res);

      src += 8;
      dst += 8;
      sz -= 8;
    }

    if (sz > 0) {  // Handle sz < 8 to avoid modifying out-of-bounds values.
      uint8x8_t s0 = vld1_u8(src);
      uint8x8_t s1 = vld1_u8(src + 1);
      uint8x8_t s2 = vld1_u8(src + 2);
      uint8x8_t s3 = vld1_u8(src + 3);
      uint8x8_t s4 = vld1_u8(src + 4);

      uint16x8_t t0 = vaddl_u8(s0, s4);
      uint16x8_t t1 = vaddl_u8(s1, s2);
      t1 = vaddw_u8(t1, s3);
      t1 = vaddq_u16(t1, t1);
      uint16x8_t sum = vaddq_u16(t0, t1);
      uint8x8_t res = vrshrn_n_u16(sum, 3);

      // Mask off out-of-bounds indices.
      uint8x8_t current_dst = vld1_u8(dst);
      uint8x8_t mask = vcgt_u8(vdup_n_u8(sz), vcreate_u8(0x0706050403020100));
      res = vbsl_u8(mask, res, current_dst);

      vst1_u8(dst, res);
    }
  }
}

void av1_upsample_intra_edge_neon(uint8_t *p, int sz) {
  if (!sz) return;

  assert(sz <= MAX_UPSAMPLE_SZ);

  uint8_t edge[MAX_UPSAMPLE_SZ + 3];
  const uint8_t *src = edge;

  // Copy p[-1..(sz-1)] and pad out both ends.
  edge[0] = p[-1];
  edge[1] = p[-1];
  memcpy(edge + 2, p, sz);
  edge[sz + 2] = p[sz - 1];
  p[-2] = p[-1];

  uint8_t *dst = p - 1;

  do {
    uint8x8_t s0 = vld1_u8(src);
    uint8x8_t s1 = vld1_u8(src + 1);
    uint8x8_t s2 = vld1_u8(src + 2);
    uint8x8_t s3 = vld1_u8(src + 3);

    int16x8_t t0 = vreinterpretq_s16_u16(vaddl_u8(s0, s3));
    int16x8_t t1 = vreinterpretq_s16_u16(vaddl_u8(s1, s2));
    t1 = vmulq_n_s16(t1, 9);
    t1 = vsubq_s16(t1, t0);

    uint8x8x2_t res = { { vqrshrun_n_s16(t1, 4), s2 } };

    vst2_u8(dst, res);

    src += 8;
    dst += 16;
    sz -= 8;
  } while (sz > 0);
}
