/*

 * 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 <math.h>

#include <stddef.h>

#include "config/aom_config.h"

#include "config/aom_scale_rtcd.h"

#include "aom/internal/aom_codec_internal.h"

#include "aom_mem/aom_mem.h"

#include "aom_dsp/aom_dsp_common.h"

#include "aom_mem/aom_mem.h"

#include "aom_ports/mem.h"

#include "aom_util/aom_pthread.h"

#include "av1/common/av1_common_int.h"

#include "av1/common/convolve.h"

#include "av1/common/enums.h"

#include "av1/common/resize.h"

#include "av1/common/restoration.h"

#include "av1/common/thread_common.h"

// The 's' values are calculated based on original 'r' and 'e' values in the

// spec using GenSgrprojVtable().

// Note: Setting r = 0 skips the filter; with corresponding s = -1 (invalid).

const sgr_params_type av1_sgr_params[SGRPROJ_PARAMS] = {

  { { 2, 1 }, { 140, 3236 } }, { { 2, 1 }, { 112, 2158 } },

  { { 2, 1 }, { 93, 1618 } },  { { 2, 1 }, { 80, 1438 } },

  { { 2, 1 }, { 70, 1295 } },  { { 2, 1 }, { 58, 1177 } },

  { { 2, 1 }, { 47, 1079 } },  { { 2, 1 }, { 37, 996 } },

  { { 2, 1 }, { 30, 925 } },   { { 2, 1 }, { 25, 863 } },

  { { 0, 1 }, { -1, 2589 } },  { { 0, 1 }, { -1, 1618 } },

  { { 0, 1 }, { -1, 1177 } },  { { 0, 1 }, { -1, 925 } },

  { { 2, 0 }, { 56, -1 } },    { { 2, 0 }, { 22, -1 } },

};

void av1_get_upsampled_plane_size(const AV1_COMMON *cm, int is_uv, int *plane_w,

                                  int *plane_h) {

  int ss_x = is_uv && cm->seq_params->subsampling_x;

  int ss_y = is_uv && cm->seq_params->subsampling_y;

  *plane_w = ROUND_POWER_OF_TWO(cm->superres_upscaled_width, ss_x);

  *plane_h = ROUND_POWER_OF_TWO(cm->height, ss_y);

}

// Count horizontal or vertical units in a plane (use a width or height for

// plane_size, respectively). We basically want to divide the plane size by the

// size of a restoration unit. Rather than rounding up unconditionally as you

// might expect, we round to nearest, which models the way a right or bottom

// restoration unit can extend to up to 150% its normal width or height.

//

// The max with 1 is to deal with small frames, which may be smaller than

// half of an LR unit in size.

int av1_lr_count_units(int unit_size, int plane_size) {

  return AOMMAX((plane_size + (unit_size >> 1)) / unit_size, 1);

}

void av1_alloc_restoration_struct(AV1_COMMON *cm, RestorationInfo *rsi,

                                  int is_uv) {

  int plane_w, plane_h;

  av1_get_upsampled_plane_size(cm, is_uv, &plane_w, &plane_h);

  const int unit_size = rsi->restoration_unit_size;

  const int horz_units = av1_lr_count_units(unit_size, plane_w);

  const int vert_units = av1_lr_count_units(unit_size, plane_h);

  rsi->num_rest_units = horz_units * vert_units;

  rsi->horz_units = horz_units;

  rsi->vert_units = vert_units;

  aom_free(rsi->unit_info);

  CHECK_MEM_ERROR(cm, rsi->unit_info,

                  (RestorationUnitInfo *)aom_memalign(

                      16, sizeof(*rsi->unit_info) * rsi->num_rest_units));

}

void av1_free_restoration_struct(RestorationInfo *rst_info) {

  aom_free(rst_info->unit_info);

  rst_info->unit_info = NULL;

}

#if 0

// Pair of values for each sgrproj parameter:

// Index 0 corresponds to r[0], e[0]

// Index 1 corresponds to r[1], e[1]

int sgrproj_mtable[SGRPROJ_PARAMS][2];

static void GenSgrprojVtable(void) {

  for (int i = 0; i < SGRPROJ_PARAMS; ++i) {

    const sgr_params_type *const params = &av1_sgr_params[i];

    for (int j = 0; j < 2; ++j) {

      const int e = params->e[j];

      const int r = params->r[j];

      if (r == 0) {                 // filter is disabled

        sgrproj_mtable[i][j] = -1;  // mark invalid

      } else {                      // filter is enabled

        const int n = (2 * r + 1) * (2 * r + 1);

        const int n2e = n * n * e;

        assert(n2e != 0);

        sgrproj_mtable[i][j] = (((1 << SGRPROJ_MTABLE_BITS) + n2e / 2) / n2e);

      }

    }

  }

}

#endif

void av1_loop_restoration_precal(void) {

#if 0

  GenSgrprojVtable();

#endif

}

static void extend_frame_lowbd(uint8_t *data, int width, int height,

                               ptrdiff_t stride, int border_horz,

                               int border_vert) {

  uint8_t *data_p;

  int i;

  for (i = 0; i < height; ++i) {

    data_p = data + i * stride;

    memset(data_p - border_horz, data_p[0], border_horz);

    memset(data_p + width, data_p[width - 1], border_horz);

  }

  data_p = data - border_horz;

  for (i = -border_vert; i < 0; ++i) {

    memcpy(data_p + i * stride, data_p, width + 2 * border_horz);

  }

  for (i = height; i < height + border_vert; ++i) {

    memcpy(data_p + i * stride, data_p + (height - 1) * stride,

           width + 2 * border_horz);

  }

}

#if CONFIG_AV1_HIGHBITDEPTH

static void extend_frame_highbd(uint16_t *data, int width, int height,

                                ptrdiff_t stride, int border_horz,

                                int border_vert) {

  uint16_t *data_p;

  int i, j;

  for (i = 0; i < height; ++i) {

    data_p = data + i * stride;

    for (j = -border_horz; j < 0; ++j) data_p[j] = data_p[0];

    for (j = width; j < width + border_horz; ++j) data_p[j] = data_p[width - 1];

  }

  data_p = data - border_horz;

  for (i = -border_vert; i < 0; ++i) {

    memcpy(data_p + i * stride, data_p,

           (width + 2 * border_horz) * sizeof(uint16_t));

  }

  for (i = height; i < height + border_vert; ++i) {

    memcpy(data_p + i * stride, data_p + (height - 1) * stride,

           (width + 2 * border_horz) * sizeof(uint16_t));

  }

}

static void copy_rest_unit_highbd(int width, int height, const uint16_t *src,

                                  int src_stride, uint16_t *dst,

                                  int dst_stride) {

  for (int i = 0; i < height; ++i)

    memcpy(dst + i * dst_stride, src + i * src_stride, width * sizeof(*dst));

}

#endif

void av1_extend_frame(uint8_t *data, int width, int height, int stride,

                      int border_horz, int border_vert, int highbd) {

#if CONFIG_AV1_HIGHBITDEPTH

  if (highbd) {

    extend_frame_highbd(CONVERT_TO_SHORTPTR(data), width, height, stride,

                        border_horz, border_vert);

    return;

  }

#endif

  (void)highbd;

  extend_frame_lowbd(data, width, height, stride, border_horz, border_vert);

}

static void copy_rest_unit_lowbd(int width, int height, const uint8_t *src,

                                 int src_stride, uint8_t *dst, int dst_stride) {

  for (int i = 0; i < height; ++i)

    memcpy(dst + i * dst_stride, src + i * src_stride, width);

}

static void copy_rest_unit(int width, int height, const uint8_t *src,

                           int src_stride, uint8_t *dst, int dst_stride,

                           int highbd) {

#if CONFIG_AV1_HIGHBITDEPTH

  if (highbd) {

    copy_rest_unit_highbd(width, height, CONVERT_TO_SHORTPTR(src), src_stride,

                          CONVERT_TO_SHORTPTR(dst), dst_stride);

    return;

  }

#endif

  (void)highbd;

  copy_rest_unit_lowbd(width, height, src, src_stride, dst, dst_stride);

}

#define REAL_PTR(hbd, d) ((hbd) ? (uint8_t *)CONVERT_TO_SHORTPTR(d) : (d))

// With striped loop restoration, the filtering for each 64-pixel stripe gets

// most of its input from the output of CDEF (stored in data8), but we need to

// fill out a border of 3 pixels above/below the stripe according to the

// following rules:

//

// * At the top and bottom of the frame, we copy the outermost row of CDEF

//   pixels three times. This extension is done by a call to av1_extend_frame()

//   at the start of the loop restoration process, so the value of

//   copy_above/copy_below doesn't strictly matter.

//

// * All other boundaries are stripe boundaries within the frame. In that case,

//   we take 2 rows of deblocked pixels and extend them to 3 rows of context.

static void get_stripe_boundary_info(const RestorationTileLimits *limits,

                                     int plane_w, int plane_h, int ss_y,

                                     int *copy_above, int *copy_below) {

  (void)plane_w;

  *copy_above = 1;

  *copy_below = 1;

  const int full_stripe_height = RESTORATION_PROC_UNIT_SIZE >> ss_y;

  const int runit_offset = RESTORATION_UNIT_OFFSET >> ss_y;

  const int first_stripe_in_plane = (limits->v_start == 0);

  const int this_stripe_height =

      full_stripe_height - (first_stripe_in_plane ? runit_offset : 0);

  const int last_stripe_in_plane =

      (limits->v_start + this_stripe_height >= plane_h);

  if (first_stripe_in_plane) *copy_above = 0;

  if (last_stripe_in_plane) *copy_below = 0;

}

// Overwrite the border pixels around a processing stripe so that the conditions

// listed above get_stripe_boundary_info() are preserved.

// We save the pixels which get overwritten into a temporary buffer, so that

// they can be restored by restore_processing_stripe_boundary() after we've

// processed the stripe.

//

// limits gives the rectangular limits of the remaining stripes for the current

// restoration unit. rsb is the stored stripe boundaries (taken from either

// deblock or CDEF output as necessary).

static void setup_processing_stripe_boundary(

    const RestorationTileLimits *limits, const RestorationStripeBoundaries *rsb,

    int rsb_row, int use_highbd, int h, uint8_t *data8, int data_stride,

    RestorationLineBuffers *rlbs, int copy_above, int copy_below, int opt) {

  // Offsets within the line buffers. The buffer logically starts at column

  // -RESTORATION_EXTRA_HORZ so the 1st column (at x0 - RESTORATION_EXTRA_HORZ)

  // has column x0 in the buffer.

  const int buf_stride = rsb->stripe_boundary_stride;

  const int buf_x0_off = limits->h_start;

  const int line_width =

      (limits->h_end - limits->h_start) + 2 * RESTORATION_EXTRA_HORZ;

  const int line_size = line_width << use_highbd;

  const int data_x0 = limits->h_start - RESTORATION_EXTRA_HORZ;

  // Replace RESTORATION_BORDER pixels above the top of the stripe

  // We expand RESTORATION_CTX_VERT=2 lines from rsb->stripe_boundary_above

  // to fill RESTORATION_BORDER=3 lines of above pixels. This is done by

  // duplicating the topmost of the 2 lines (see the AOMMAX call when

  // calculating src_row, which gets the values 0, 0, 1 for i = -3, -2, -1).

  if (!opt) {

    if (copy_above) {

      uint8_t *data8_tl = data8 + data_x0 + limits->v_start * data_stride;

      for (int i = -RESTORATION_BORDER; i < 0; ++i) {

        const int buf_row = rsb_row + AOMMAX(i + RESTORATION_CTX_VERT, 0);

        const int buf_off = buf_x0_off + buf_row * buf_stride;

        const uint8_t *buf =

            rsb->stripe_boundary_above + (buf_off << use_highbd);

        uint8_t *dst8 = data8_tl + i * data_stride;

        // Save old pixels, then replace with data from stripe_boundary_above

        memcpy(rlbs->tmp_save_above[i + RESTORATION_BORDER],

               REAL_PTR(use_highbd, dst8), line_size);

        memcpy(REAL_PTR(use_highbd, dst8), buf, line_size);

      }

    }

    // Replace RESTORATION_BORDER pixels below the bottom of the stripe.

    // The second buffer row is repeated, so src_row gets the values 0, 1, 1

    // for i = 0, 1, 2.

    if (copy_below) {

      const int stripe_end = limits->v_start + h;

      uint8_t *data8_bl = data8 + data_x0 + stripe_end * data_stride;

      for (int i = 0; i < RESTORATION_BORDER; ++i) {

        const int buf_row = rsb_row + AOMMIN(i, RESTORATION_CTX_VERT - 1);

        const int buf_off = buf_x0_off + buf_row * buf_stride;

        const uint8_t *src =

            rsb->stripe_boundary_below + (buf_off << use_highbd);

        uint8_t *dst8 = data8_bl + i * data_stride;

        // Save old pixels, then replace with data from stripe_boundary_below

        memcpy(rlbs->tmp_save_below[i], REAL_PTR(use_highbd, dst8), line_size);

        memcpy(REAL_PTR(use_highbd, dst8), src, line_size);

      }

    }

  } else {

    if (copy_above) {

      uint8_t *data8_tl = data8 + data_x0 + limits->v_start * data_stride;

      // Only save and overwrite i=-RESTORATION_BORDER line.

      uint8_t *dst8 = data8_tl + (-RESTORATION_BORDER) * data_stride;

      // Save old pixels, then replace with data from stripe_boundary_above

      memcpy(rlbs->tmp_save_above[0], REAL_PTR(use_highbd, dst8), line_size);

      memcpy(REAL_PTR(use_highbd, dst8),

             REAL_PTR(use_highbd,

                      data8_tl + (-RESTORATION_BORDER + 1) * data_stride),

             line_size);

    }

    if (copy_below) {

      const int stripe_end = limits->v_start + h;

      uint8_t *data8_bl = data8 + data_x0 + stripe_end * data_stride;

      // Only save and overwrite i=2 line.

      uint8_t *dst8 = data8_bl + 2 * data_stride;

      // Save old pixels, then replace with data from stripe_boundary_below

      memcpy(rlbs->tmp_save_below[2], REAL_PTR(use_highbd, dst8), line_size);

      memcpy(REAL_PTR(use_highbd, dst8),

             REAL_PTR(use_highbd, data8_bl + (2 - 1) * data_stride), line_size);

    }

  }

}

// Once a processing stripe is finished, this function sets the boundary

// pixels which were overwritten by setup_processing_stripe_boundary()

// back to their original values

static void restore_processing_stripe_boundary(

    const RestorationTileLimits *limits, const RestorationLineBuffers *rlbs,

    int use_highbd, int h, uint8_t *data8, int data_stride, int copy_above,

    int copy_below, int opt) {

  const int line_width =

      (limits->h_end - limits->h_start) + 2 * RESTORATION_EXTRA_HORZ;

  const int line_size = line_width << use_highbd;

  const int data_x0 = limits->h_start - RESTORATION_EXTRA_HORZ;

  if (!opt) {

    if (copy_above) {

      uint8_t *data8_tl = data8 + data_x0 + limits->v_start * data_stride;

      for (int i = -RESTORATION_BORDER; i < 0; ++i) {

        uint8_t *dst8 = data8_tl + i * data_stride;

        memcpy(REAL_PTR(use_highbd, dst8),

               rlbs->tmp_save_above[i + RESTORATION_BORDER], line_size);

      }

    }

    if (copy_below) {

      const int stripe_bottom = limits->v_start + h;

      uint8_t *data8_bl = data8 + data_x0 + stripe_bottom * data_stride;

      for (int i = 0; i < RESTORATION_BORDER; ++i) {

        if (stripe_bottom + i >= limits->v_end + RESTORATION_BORDER) break;

        uint8_t *dst8 = data8_bl + i * data_stride;

        memcpy(REAL_PTR(use_highbd, dst8), rlbs->tmp_save_below[i], line_size);

      }

    }

  } else {

    if (copy_above) {

      uint8_t *data8_tl = data8 + data_x0 + limits->v_start * data_stride;

      // Only restore i=-RESTORATION_BORDER line.

      uint8_t *dst8 = data8_tl + (-RESTORATION_BORDER) * data_stride;

      memcpy(REAL_PTR(use_highbd, dst8), rlbs->tmp_save_above[0], line_size);

    }

    if (copy_below) {

      const int stripe_bottom = limits->v_start + h;

      uint8_t *data8_bl = data8 + data_x0 + stripe_bottom * data_stride;

      // Only restore i=2 line.

      if (stripe_bottom + 2 < limits->v_end + RESTORATION_BORDER) {

        uint8_t *dst8 = data8_bl + 2 * data_stride;

        memcpy(REAL_PTR(use_highbd, dst8), rlbs->tmp_save_below[2], line_size);

      }

    }

  }

}

static void wiener_filter_stripe(const RestorationUnitInfo *rui,

                                 int stripe_width, int stripe_height,

                                 int procunit_width, const uint8_t *src,

                                 int src_stride, uint8_t *dst, int dst_stride,

                                 int32_t *tmpbuf, int bit_depth,

                                 struct aom_internal_error_info *error_info) {

  (void)tmpbuf;

  (void)bit_depth;

  (void)error_info;

  assert(bit_depth == 8);

  const WienerConvolveParams conv_params = get_conv_params_wiener(8);

  for (int j = 0; j < stripe_width; j += procunit_width) {

    int w = AOMMIN(procunit_width, (stripe_width - j + 15) & ~15);

    const uint8_t *src_p = src + j;

    uint8_t *dst_p = dst + j;

    av1_wiener_convolve_add_src(

        src_p, src_stride, dst_p, dst_stride, rui->wiener_info.hfilter, 16,

        rui->wiener_info.vfilter, 16, w, stripe_height, &conv_params);

  }

}

/* Calculate windowed sums (if sqr=0) or sums of squares (if sqr=1)

   over the input. The window is of size (2r + 1)x(2r + 1), and we

   specialize to r = 1, 2, 3. A default function is used for r > 3.

   Each loop follows the same format: We keep a window's worth of input

   in individual variables and select data out of that as appropriate.

*/

static void boxsum1(int32_t *src, int width, int height, int src_stride,

                    int sqr, int32_t *dst, int dst_stride) {

  int i, j, a, b, c;

  assert(width > 2 * SGRPROJ_BORDER_HORZ);

  assert(height > 2 * SGRPROJ_BORDER_VERT);

  // Vertical sum over 3-pixel regions, from src into dst.

  if (!sqr) {

    for (j = 0; j < width; ++j) {

      a = src[j];

      b = src[src_stride + j];

      c = src[2 * src_stride + j];

      dst[j] = a + b;

      for (i = 1; i < height - 2; ++i) {

        // Loop invariant: At the start of each iteration,

        // a = src[(i - 1) * src_stride + j]

        // b = src[(i    ) * src_stride + j]

        // c = src[(i + 1) * src_stride + j]

        dst[i * dst_stride + j] = a + b + c;

        a = b;

        b = c;

        c = src[(i + 2) * src_stride + j];

      }

      dst[i * dst_stride + j] = a + b + c;

      dst[(i + 1) * dst_stride + j] = b + c;

    }

  } else {

    for (j = 0; j < width; ++j) {

      a = src[j] * src[j];

      b = src[src_stride + j] * src[src_stride + j];

      c = src[2 * src_stride + j] * src[2 * src_stride + j];

      dst[j] = a + b;

      for (i = 1; i < height - 2; ++i) {

        dst[i * dst_stride + j] = a + b + c;

        a = b;

        b = c;

        c = src[(i + 2) * src_stride + j] * src[(i + 2) * src_stride + j];

      }

      dst[i * dst_stride + j] = a + b + c;

      dst[(i + 1) * dst_stride + j] = b + c;

    }

  }

  // Horizontal sum over 3-pixel regions of dst

  for (i = 0; i < height; ++i) {

    a = dst[i * dst_stride];

    b = dst[i * dst_stride + 1];

    c = dst[i * dst_stride + 2];

    dst[i * dst_stride] = a + b;

    for (j = 1; j < width - 2; ++j) {

      // Loop invariant: At the start of each iteration,

      // a = src[i * src_stride + (j - 1)]

      // b = src[i * src_stride + (j    )]

      // c = src[i * src_stride + (j + 1)]

      dst[i * dst_stride + j] = a + b + c;

      a = b;

      b = c;

      c = dst[i * dst_stride + (j + 2)];

    }

    dst[i * dst_stride + j] = a + b + c;

    dst[i * dst_stride + (j + 1)] = b + c;

  }

}

static void boxsum2(int32_t *src, int width, int height, int src_stride,

                    int sqr, int32_t *dst, int dst_stride) {

  int i, j, a, b, c, d, e;

  assert(width > 2 * SGRPROJ_BORDER_HORZ);

  assert(height > 2 * SGRPROJ_BORDER_VERT);

  // Vertical sum over 5-pixel regions, from src into dst.

  if (!sqr) {

    for (j = 0; j < width; ++j) {

      a = src[j];

      b = src[src_stride + j];

      c = src[2 * src_stride + j];

      d = src[3 * src_stride + j];

      e = src[4 * src_stride + j];

      dst[j] = a + b + c;

      dst[dst_stride + j] = a + b + c + d;

      for (i = 2; i < height - 3; ++i) {

        // Loop invariant: At the start of each iteration,

        // a = src[(i - 2) * src_stride + j]

        // b = src[(i - 1) * src_stride + j]

        // c = src[(i    ) * src_stride + j]

        // d = src[(i + 1) * src_stride + j]

        // e = src[(i + 2) * src_stride + j]

        dst[i * dst_stride + j] = a + b + c + d + e;

        a = b;

        b = c;

        c = d;

        d = e;

        e = src[(i + 3) * src_stride + j];

      }

      dst[i * dst_stride + j] = a + b + c + d + e;

      dst[(i + 1) * dst_stride + j] = b + c + d + e;

      dst[(i + 2) * dst_stride + j] = c + d + e;

    }

  } else {

    for (j = 0; j < width; ++j) {

      a = src[j] * src[j];

      b = src[src_stride + j] * src[src_stride + j];

      c = src[2 * src_stride + j] * src[2 * src_stride + j];

      d = src[3 * src_stride + j] * src[3 * src_stride + j];

      e = src[4 * src_stride + j] * src[4 * src_stride + j];

      dst[j] = a + b + c;

      dst[dst_stride + j] = a + b + c + d;

      for (i = 2; i < height - 3; ++i) {

        dst[i * dst_stride + j] = a + b + c + d + e;

        a = b;

        b = c;

        c = d;

        d = e;

        e = src[(i + 3) * src_stride + j] * src[(i + 3) * src_stride + j];

      }

      dst[i * dst_stride + j] = a + b + c + d + e;

      dst[(i + 1) * dst_stride + j] = b + c + d + e;

      dst[(i + 2) * dst_stride + j] = c + d + e;

    }

  }

  // Horizontal sum over 5-pixel regions of dst

  for (i = 0; i < height; ++i) {

    a = dst[i * dst_stride];

    b = dst[i * dst_stride + 1];

    c = dst[i * dst_stride + 2];

    d = dst[i * dst_stride + 3];

    e = dst[i * dst_stride + 4];

    dst[i * dst_stride] = a + b + c;

    dst[i * dst_stride + 1] = a + b + c + d;

    for (j = 2; j < width - 3; ++j) {

      // Loop invariant: At the start of each iteration,

      // a = src[i * src_stride + (j - 2)]

      // b = src[i * src_stride + (j - 1)]

      // c = src[i * src_stride + (j    )]

      // d = src[i * src_stride + (j + 1)]

      // e = src[i * src_stride + (j + 2)]

      dst[i * dst_stride + j] = a + b + c + d + e;

      a = b;

      b = c;

      c = d;

      d = e;

      e = dst[i * dst_stride + (j + 3)];

    }

    dst[i * dst_stride + j] = a + b + c + d + e;

    dst[i * dst_stride + (j + 1)] = b + c + d + e;

    dst[i * dst_stride + (j + 2)] = c + d + e;

  }

}

static void boxsum(int32_t *src, int width, int height, int src_stride, int r,

                   int sqr, int32_t *dst, int dst_stride) {

  if (r == 1)

    boxsum1(src, width, height, src_stride, sqr, dst, dst_stride);

  else if (r == 2)

    boxsum2(src, width, height, src_stride, sqr, dst, dst_stride);

  else

    assert(0 && "Invalid value of r in self-guided filter");

}

void av1_decode_xq(const int *xqd, int *xq, const sgr_params_type *params) {

  if (params->r[0] == 0) {

    xq[0] = 0;

    xq[1] = (1 << SGRPROJ_PRJ_BITS) - xqd[1];

  } else if (params->r[1] == 0) {

    xq[0] = xqd[0];

    xq[1] = 0;

  } else {

    xq[0] = xqd[0];

    xq[1] = (1 << SGRPROJ_PRJ_BITS) - xq[0] - xqd[1];

  }

}

const int32_t av1_x_by_xplus1[256] = {

  // Special case: Map 0 -> 1 (corresponding to a value of 1/256)

  // instead of 0. See comments in selfguided_restoration_internal() for why

  1,   128, 171, 192, 205, 213, 219, 224, 228, 230, 233, 235, 236, 238, 239,

  240, 241, 242, 243, 243, 244, 244, 245, 245, 246, 246, 247, 247, 247, 247,

  248, 248, 248, 248, 249, 249, 249, 249, 249, 250, 250, 250, 250, 250, 250,

  250, 251, 251, 251, 251, 251, 251, 251, 251, 251, 251, 252, 252, 252, 252,

  252, 252, 252, 252, 252, 252, 252, 252, 252, 252, 252, 252, 252, 253, 253,

  253, 253, 253, 253, 253, 253, 253, 253, 253, 253, 253, 253, 253, 253, 253,

  253, 253, 253, 253, 253, 253, 253, 253, 253, 253, 253, 253, 254, 254, 254,

  254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254,

  254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254,

  254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254,

  254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254, 254,

  254, 254, 254, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,

  255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,

  255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,

  255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,

  255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,

  255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,

  256,

};

const int32_t av1_one_by_x[MAX_NELEM] = {

  4096, 2048, 1365, 1024, 819, 683, 585, 512, 455, 410, 372, 341, 315,

  293,  273,  256,  241,  228, 216, 205, 195, 186, 178, 171, 164,

};

static void calculate_intermediate_result(int32_t *dgd, int width, int height,

                                          int dgd_stride, int bit_depth,

                                          int sgr_params_idx, int radius_idx,

                                          int pass, int32_t *A, int32_t *B) {

  const sgr_params_type *const params = &av1_sgr_params[sgr_params_idx];

  const int r = params->r[radius_idx];

  const int width_ext = width + 2 * SGRPROJ_BORDER_HORZ;

  const int height_ext = height + 2 * SGRPROJ_BORDER_VERT;

  // Adjusting the stride of A and B here appears to avoid bad cache effects,

  // leading to a significant speed improvement.

  // We also align the stride to a multiple of 16 bytes, for consistency

  // with the SIMD version of this function.

  int buf_stride = ((width_ext + 3) & ~3) + 16;

  const int step = pass == 0 ? 1 : 2;

  int i, j;

  assert(r <= MAX_RADIUS && "Need MAX_RADIUS >= r");

  assert(r <= SGRPROJ_BORDER_VERT - 1 && r <= SGRPROJ_BORDER_HORZ - 1 &&

         "Need SGRPROJ_BORDER_* >= r+1");

  boxsum(dgd - dgd_stride * SGRPROJ_BORDER_VERT - SGRPROJ_BORDER_HORZ,

         width_ext, height_ext, dgd_stride, r, 0, B, buf_stride);

  boxsum(dgd - dgd_stride * SGRPROJ_BORDER_VERT - SGRPROJ_BORDER_HORZ,

         width_ext, height_ext, dgd_stride, r, 1, A, buf_stride);

  A += SGRPROJ_BORDER_VERT * buf_stride + SGRPROJ_BORDER_HORZ;

  B += SGRPROJ_BORDER_VERT * buf_stride + SGRPROJ_BORDER_HORZ;

  // Calculate the eventual A[] and B[] arrays. Include a 1-pixel border - ie,

  // for a 64x64 processing unit, we calculate 66x66 pixels of A[] and B[].

  for (i = -1; i < height + 1; i += step) {

    for (j = -1; j < width + 1; ++j) {

      const int k = i * buf_stride + j;

      const int n = (2 * r + 1) * (2 * r + 1);

      // a < 2^16 * n < 2^22 regardless of bit depth

      uint32_t a = ROUND_POWER_OF_TWO(A[k], 2 * (bit_depth - 8));

      // b < 2^8 * n < 2^14 regardless of bit depth

      uint32_t b = ROUND_POWER_OF_TWO(B[k], bit_depth - 8);

      // Each term in calculating p = a * n - b * b is < 2^16 * n^2 < 2^28,

      // and p itself satisfies p < 2^14 * n^2 < 2^26.

      // This bound on p is due to:

      // https://en.wikipedia.org/wiki/Popoviciu's_inequality_on_variances

      //

      // Note: Sometimes, in high bit depth, we can end up with a*n < b*b.

      // This is an artefact of rounding, and can only happen if all pixels

      // are (almost) identical, so in this case we saturate to p=0.

      uint32_t p = (a * n < b * b) ? 0 : a * n - b * b;

      const uint32_t s = params->s[radius_idx];

      // p * s < (2^14 * n^2) * round(2^20 / n^2 eps) < 2^34 / eps < 2^32

      // as long as eps >= 4. So p * s fits into a uint32_t, and z < 2^12

      // (this holds even after accounting for the rounding in s)

      const uint32_t z = ROUND_POWER_OF_TWO(p * s, SGRPROJ_MTABLE_BITS);

      // Note: We have to be quite careful about the value of A[k].

      // This is used as a blend factor between individual pixel values and the

      // local mean. So it logically has a range of [0, 256], including both

      // endpoints.

      //

      // This is a pain for hardware, as we'd like something which can be stored

      // in exactly 8 bits.

      // Further, in the calculation of B[k] below, if z == 0 and r == 2,

      // then A[k] "should be" 0. But then we can end up setting B[k] to a value

      // slightly above 2^(8 + bit depth), due to rounding in the value of

      // av1_one_by_x[25-1].

      //

      // Thus we saturate so that, when z == 0, A[k] is set to 1 instead of 0.

      // This fixes the above issues (256 - A[k] fits in a uint8, and we can't

      // overflow), without significantly affecting the final result: z == 0

      // implies that the image is essentially "flat", so the local mean and

      // individual pixel values are very similar.

      //

      // Note that saturating on the other side, ie. requring A[k] <= 255,

      // would be a bad idea, as that corresponds to the case where the image

      // is very variable, when we want to preserve the local pixel value as

      // much as possible.

      A[k] = av1_x_by_xplus1[AOMMIN(z, 255)];  // in range [1, 256]

      // SGRPROJ_SGR - A[k] < 2^8 (from above), B[k] < 2^(bit_depth) * n,

      // av1_one_by_x[n - 1] = round(2^12 / n)

      // => the product here is < 2^(20 + bit_depth) <= 2^32,

      // and B[k] is set to a value < 2^(8 + bit depth)

      // This holds even with the rounding in av1_one_by_x and in the overall

      // result, as long as SGRPROJ_SGR - A[k] is strictly less than 2^8.

      B[k] = (int32_t)ROUND_POWER_OF_TWO((uint32_t)(SGRPROJ_SGR - A[k]) *

                                             (uint32_t)B[k] *

                                             (uint32_t)av1_one_by_x[n - 1],

                                         SGRPROJ_RECIP_BITS);

    }

  }

}

static void selfguided_restoration_fast_internal(

    int32_t *dgd, int width, int height, int dgd_stride, int32_t *dst,

    int dst_stride, int bit_depth, int sgr_params_idx, int radius_idx) {

  const sgr_params_type *const params = &av1_sgr_params[sgr_params_idx];

  const int r = params->r[radius_idx];

  const int width_ext = width + 2 * SGRPROJ_BORDER_HORZ;

  // Adjusting the stride of A and B here appears to avoid bad cache effects,

  // leading to a significant speed improvement.

  // We also align the stride to a multiple of 16 bytes, for consistency

  // with the SIMD version of this function.

  int buf_stride = ((width_ext + 3) & ~3) + 16;

  int32_t A_[RESTORATION_PROC_UNIT_PELS];

  int32_t B_[RESTORATION_PROC_UNIT_PELS];

  int32_t *A = A_;

  int32_t *B = B_;

  int i, j;

  calculate_intermediate_result(dgd, width, height, dgd_stride, bit_depth,

                                sgr_params_idx, radius_idx, 1, A, B);

  A += SGRPROJ_BORDER_VERT * buf_stride + SGRPROJ_BORDER_HORZ;

  B += SGRPROJ_BORDER_VERT * buf_stride + SGRPROJ_BORDER_HORZ;

  // Use the A[] and B[] arrays to calculate the filtered image

  (void)r;

  assert(r == 2);

  for (i = 0; i < height; ++i) {

    if (!(i & 1)) {  // even row

      for (j = 0; j < width; ++j) {

        const int k = i * buf_stride + j;

        const int l = i * dgd_stride + j;

        const int m = i * dst_stride + j;

        const int nb = 5;

        const int32_t a = (A[k - buf_stride] + A[k + buf_stride]) * 6 +

                          (A[k - 1 - buf_stride] + A[k - 1 + buf_stride] +

                           A[k + 1 - buf_stride] + A[k + 1 + buf_stride]) *

                              5;

        const int32_t b = (B[k - buf_stride] + B[k + buf_stride]) * 6 +

                          (B[k - 1 - buf_stride] + B[k - 1 + buf_stride] +

                           B[k + 1 - buf_stride] + B[k + 1 + buf_stride]) *

                              5;

        const int32_t v = a * dgd[l] + b;

        dst[m] =

            ROUND_POWER_OF_TWO(v, SGRPROJ_SGR_BITS + nb - SGRPROJ_RST_BITS);

      }

    } else {  // odd row

      for (j = 0; j < width; ++j) {

        const int k = i * buf_stride + j;

        const int l = i * dgd_stride + j;

        const int m = i * dst_stride + j;

        const int nb = 4;

        const int32_t a = A[k] * 6 + (A[k - 1] + A[k + 1]) * 5;

        const int32_t b = B[k] * 6 + (B[k - 1] + B[k + 1]) * 5;

        const int32_t v = a * dgd[l] + b;

        dst[m] =

            ROUND_POWER_OF_TWO(v, SGRPROJ_SGR_BITS + nb - SGRPROJ_RST_BITS);

      }

    }

  }

}

static void selfguided_restoration_internal(int32_t *dgd, int width, int height,

                                            int dgd_stride, int32_t *dst,

                                            int dst_stride, int bit_depth,

                                            int sgr_params_idx,

                                            int radius_idx) {

  const int width_ext = width + 2 * SGRPROJ_BORDER_HORZ;

  // Adjusting the stride of A and B here appears to avoid bad cache effects,

  // leading to a significant speed improvement.

  // We also align the stride to a multiple of 16 bytes, for consistency

  // with the SIMD version of this function.

  int buf_stride = ((width_ext + 3) & ~3) + 16;

  int32_t A_[RESTORATION_PROC_UNIT_PELS];

  int32_t B_[RESTORATION_PROC_UNIT_PELS];

  int32_t *A = A_;

  int32_t *B = B_;

  int i, j;

  calculate_intermediate_result(dgd, width, height, dgd_stride, bit_depth,

                                sgr_params_idx, radius_idx, 0, A, B);

  A += SGRPROJ_BORDER_VERT * buf_stride + SGRPROJ_BORDER_HORZ;

  B += SGRPROJ_BORDER_VERT * buf_stride + SGRPROJ_BORDER_HORZ;

  // Use the A[] and B[] arrays to calculate the filtered image

  for (i = 0; i < height; ++i) {

    for (j = 0; j < width; ++j) {

      const int k = i * buf_stride + j;

      const int l = i * dgd_stride + j;

      const int m = i * dst_stride + j;

      const int nb = 5;

      const int32_t a =

          (A[k] + A[k - 1] + A[k + 1] + A[k - buf_stride] + A[k + buf_stride]) *

              4 +

          (A[k - 1 - buf_stride] + A[k - 1 + buf_stride] +

           A[k + 1 - buf_stride] + A[k + 1 + buf_stride]) *

              3;

      const int32_t b =

          (B[k] + B[k - 1] + B[k + 1] + B[k - buf_stride] + B[k + buf_stride]) *

              4 +

          (B[k - 1 - buf_stride] + B[k - 1 + buf_stride] +

           B[k + 1 - buf_stride] + B[k + 1 + buf_stride]) *

              3;

      const int32_t v = a * dgd[l] + b;

      dst[m] = ROUND_POWER_OF_TWO(v, SGRPROJ_SGR_BITS + nb - SGRPROJ_RST_BITS);

    }

  }

}

int av1_selfguided_restoration_c(const uint8_t *dgd8, int width, int height,

                                 int dgd_stride, int32_t *flt0, int32_t *flt1,

                                 int flt_stride, int sgr_params_idx,

                                 int bit_depth, int highbd) {

  int32_t dgd32_[RESTORATION_PROC_UNIT_PELS];

  const int dgd32_stride = width + 2 * SGRPROJ_BORDER_HORZ;

  int32_t *dgd32 =

      dgd32_ + dgd32_stride * SGRPROJ_BORDER_VERT + SGRPROJ_BORDER_HORZ;

  if (highbd) {

    const uint16_t *dgd16 = CONVERT_TO_SHORTPTR(dgd8);

    for (int i = -SGRPROJ_BORDER_VERT; i < height + SGRPROJ_BORDER_VERT; ++i) {

      for (int j = -SGRPROJ_BORDER_HORZ; j < width + SGRPROJ_BORDER_HORZ; ++j) {

        dgd32[i * dgd32_stride + j] = dgd16[i * dgd_stride + j];

      }

    }

  } else {

    for (int i = -SGRPROJ_BORDER_VERT; i < height + SGRPROJ_BORDER_VERT; ++i) {

      for (int j = -SGRPROJ_BORDER_HORZ; j < width + SGRPROJ_BORDER_HORZ; ++j) {

        dgd32[i * dgd32_stride + j] = dgd8[i * dgd_stride + j];

      }

    }

  }

  const sgr_params_type *const params = &av1_sgr_params[sgr_params_idx];

  // If params->r == 0 we skip the corresponding filter. We only allow one of

  // the radii to be 0, as having both equal to 0 would be equivalent to

  // skipping SGR entirely.

  assert(!(params->r[0] == 0 && params->r[1] == 0));

  if (params->r[0] > 0)

    selfguided_restoration_fast_internal(dgd32, width, height, dgd32_stride,

                                         flt0, flt_stride, bit_depth,

                                         sgr_params_idx, 0);

  if (params->r[1] > 0)

    selfguided_restoration_internal(dgd32, width, height, dgd32_stride, flt1,

                                    flt_stride, bit_depth, sgr_params_idx, 1);

  return 0;

}

int av1_apply_selfguided_restoration_c(const uint8_t *dat8, int width,

                                       int height, int stride, int eps,

                                       const int *xqd, uint8_t *dst8,

                                       int dst_stride, int32_t *tmpbuf,

                                       int bit_depth, int highbd) {

  int32_t *flt0 = tmpbuf;

  int32_t *flt1 = flt0 + RESTORATION_UNITPELS_MAX;

  assert(width * height <= RESTORATION_UNITPELS_MAX);

  const int ret = av1_selfguided_restoration_c(

      dat8, width, height, stride, flt0, flt1, width, eps, bit_depth, highbd);

  if (ret != 0) return ret;

  const sgr_params_type *const params = &av1_sgr_params[eps];

  int xq[2];

  av1_decode_xq(xqd, xq, params);

  for (int i = 0; i < height; ++i) {

    for (int j = 0; j < width; ++j) {

      const int k = i * width + j;

      uint8_t *dst8ij = dst8 + i * dst_stride + j;

      const uint8_t *dat8ij = dat8 + i * stride + j;

      const uint16_t pre_u = highbd ? *CONVERT_TO_SHORTPTR(dat8ij) : *dat8ij;

      const int32_t u = (int32_t)pre_u << SGRPROJ_RST_BITS;

      int32_t v = u << SGRPROJ_PRJ_BITS;

      // If params->r == 0 then we skipped the filtering in

      // av1_selfguided_restoration_c, i.e. flt[k] == u

      if (params->r[0] > 0) v += xq[0] * (flt0[k] - u);

      if (params->r[1] > 0) v += xq[1] * (flt1[k] - u);

      const int16_t w =

          (int16_t)ROUND_POWER_OF_TWO(v, SGRPROJ_PRJ_BITS + SGRPROJ_RST_BITS);

      const uint16_t out = clip_pixel_highbd(w, bit_depth);

      if (highbd)

        *CONVERT_TO_SHORTPTR(dst8ij) = out;

      else

        *dst8ij = (uint8_t)out;

    }