text: /*
   *  Copyright (c) 2015 The WebM project authors. All Rights Reserved.
   *
   *  Use of this source code is governed by a BSD-style license
   *  that can be found in the LICENSE file in the root of the source
   *  tree. An additional intellectual property rights grant can be found
   *  in the file PATENTS.  All contributing project authors may
   *  be found in the AUTHORS file in the root of the source tree.
   */
  
  #include <stdlib.h>
  
  #include "./vpx_config.h"
  #include "vpx_dsp/vpx_dsp_common.h"
  #include "vpx_ports/mem.h"
  
  static INLINE int8_t signed_char_clamp(int t) {
    return (int8_t)clamp(t, -128, 127);
  }
  
  #if CONFIG_VP9_HIGHBITDEPTH
  static INLINE int16_t signed_char_clamp_high(int t, int bd) {
    switch (bd) {
      case 10:
        return (int16_t)clamp(t, -128*4, 128*4-1);
      case 12:
        return (int16_t)clamp(t, -128*16, 128*16-1);
      case 8:
      default:
        return (int16_t)clamp(t, -128, 128-1);
    }
  }
  #endif
  
  // should we apply any filter at all: 11111111 yes, 00000000 no
  static INLINE int8_t filter_mask(uint8_t limit, uint8_t blimit,
                                   uint8_t p3, uint8_t p2,
                                   uint8_t p1, uint8_t p0,
                                   uint8_t q0, uint8_t q1,
                                   uint8_t q2, uint8_t q3) {
    int8_t mask = 0;
    mask |= (abs(p3 - p2) > limit) * -1;
    mask |= (abs(p2 - p1) > limit) * -1;
    mask |= (abs(p1 - p0) > limit) * -1;
    mask |= (abs(q1 - q0) > limit) * -1;
    mask |= (abs(q2 - q1) > limit) * -1;
    mask |= (abs(q3 - q2) > limit) * -1;
    mask |= (abs(p0 - q0) * 2 + abs(p1 - q1) / 2  > blimit) * -1;
    return ~mask;
  }
  
  static INLINE int8_t flat_mask4(uint8_t thresh,
                                  uint8_t p3, uint8_t p2,
                                  uint8_t p1, uint8_t p0,
                                  uint8_t q0, uint8_t q1,
                                  uint8_t q2, uint8_t q3) {
    int8_t mask = 0;
    mask |= (abs(p1 - p0) > thresh) * -1;
    mask |= (abs(q1 - q0) > thresh) * -1;
    mask |= (abs(p2 - p0) > thresh) * -1;
    mask |= (abs(q2 - q0) > thresh) * -1;
    mask |= (abs(p3 - p0) > thresh) * -1;
    mask |= (abs(q3 - q0) > thresh) * -1;
    return ~mask;
  }
  
  static INLINE int8_t flat_mask5(uint8_t thresh,
                                  uint8_t p4, uint8_t p3,
                                  uint8_t p2, uint8_t p1,
                                  uint8_t p0, uint8_t q0,
                                  uint8_t q1, uint8_t q2,
                                  uint8_t q3, uint8_t q4) {
    int8_t mask = ~flat_mask4(thresh, p3, p2, p1, p0, q0, q1, q2, q3);
    mask |= (abs(p4 - p0) > thresh) * -1;
    mask |= (abs(q4 - q0) > thresh) * -1;
    return ~mask;
  }
  
  // is there high edge variance internal edge: 11111111 yes, 00000000 no
  static INLINE int8_t hev_mask(uint8_t thresh, uint8_t p1, uint8_t p0,
                                uint8_t q0, uint8_t q1) {
    int8_t hev = 0;
    hev  |= (abs(p1 - p0) > thresh) * -1;
    hev  |= (abs(q1 - q0) > thresh) * -1;
    return hev;
  }
  
  static INLINE void filter4(int8_t mask, uint8_t thresh, uint8_t *op1,
                             uint8_t *op0, uint8_t *oq0, uint8_t *oq1) {
    int8_t filter1, filter2;
  
    const int8_t ps1 = (int8_t) *op1 ^ 0x80;
    const int8_t ps0 = (int8_t) *op0 ^ 0x80;
    const int8_t qs0 = (int8_t) *oq0 ^ 0x80;
    const int8_t qs1 = (int8_t) *oq1 ^ 0x80;
    const uint8_t hev = hev_mask(thresh, *op1, *op0, *oq0, *oq1);
  
    // add outer taps if we have high edge variance
    int8_t filter = signed_char_clamp(ps1 - qs1) & hev;
  
    // inner taps
    filter = signed_char_clamp(filter + 3 * (qs0 - ps0)) & mask;
  
    // save bottom 3 bits so that we round one side +4 and the other +3
    // if it equals 4 we'll set to adjust by -1 to account for the fact
    // we'd round 3 the other way
    filter1 = signed_char_clamp(filter + 4) >> 3;
    filter2 = signed_char_clamp(filter + 3) >> 3;
  
    *oq0 = signed_char_clamp(qs0 - filter1) ^ 0x80;
    *op0 = signed_char_clamp(ps0 + filter2) ^ 0x80;
  
    // outer tap adjustments
    filter = ROUND_POWER_OF_TWO(filter1, 1) & ~hev;
  
    *oq1 = signed_char_clamp(qs1 - filter) ^ 0x80;
    *op1 = signed_char_clamp(ps1 + filter) ^ 0x80;
  }
  
  void vpx_lpf_horizontal_4_c(uint8_t *s, int p /* pitch */,
                              const uint8_t *blimit, const uint8_t *limit,
                              const uint8_t *thresh, int count) {
    int i;
  
    // loop filter designed to work using chars so that we can make maximum use
    // of 8 bit simd instructions.
    for (i = 0; i < 8 * count; ++i) {
      const uint8_t p3 = s[-4 * p], p2 = s[-3 * p], p1 = s[-2 * p], p0 = s[-p];
      const uint8_t q0 = s[0 * p],  q1 = s[1 * p],  q2 = s[2 * p],  q3 = s[3 * p];
      const int8_t mask = filter_mask(*limit, *blimit,
                                      p3, p2, p1, p0, q0, q1, q2, q3);
      filter4(mask, *thresh, s - 2 * p, s - 1 * p, s, s + 1 * p);
      ++s;
    }
  }
  
  void vpx_lpf_horizontal_4_dual_c(uint8_t *s, int p, const uint8_t *blimit0,
                                   const uint8_t *limit0, const uint8_t *thresh0,
                                   const uint8_t *blimit1, const uint8_t *limit1,
                                   const uint8_t *thresh1) {
    vpx_lpf_horizontal_4_c(s, p, blimit0, limit0, thresh0, 1);
    vpx_lpf_horizontal_4_c(s + 8, p, blimit1, limit1, thresh1, 1);
  }
  
  void vpx_lpf_vertical_4_c(uint8_t *s, int pitch, const uint8_t *blimit,
                            const uint8_t *limit, const uint8_t *thresh,
                            int count) {
    int i;
  
    // loop filter designed to work using chars so that we can make maximum use
    // of 8 bit simd instructions.
    for (i = 0; i < 8 * count; ++i) {
      const uint8_t p3 = s[-4], p2 = s[-3], p1 = s[-2], p0 = s[-1];
      const uint8_t q0 = s[0],  q1 = s[1],  q2 = s[2],  q3 = s[3];
      const int8_t mask = filter_mask(*limit, *blimit,
                                      p3, p2, p1, p0, q0, q1, q2, q3);
      filter4(mask, *thresh, s - 2, s - 1, s, s + 1);
      s += pitch;
    }
  }
  
  void vpx_lpf_vertical_4_dual_c(uint8_t *s, int pitch, const uint8_t *blimit0,
                                 const uint8_t *limit0, const uint8_t *thresh0,
                                 const uint8_t *blimit1, const uint8_t *limit1,
                                 const uint8_t *thresh1) {
    vpx_lpf_vertical_4_c(s, pitch, blimit0, limit0, thresh0, 1);
    vpx_lpf_vertical_4_c(s + 8 * pitch, pitch, blimit1, limit1,
                                    thresh1, 1);
  }
  
  static INLINE void filter8(int8_t mask, uint8_t thresh, uint8_t flat,
                             uint8_t *op3, uint8_t *op2,
                             uint8_t *op1, uint8_t *op0,
                             uint8_t *oq0, uint8_t *oq1,
                             uint8_t *oq2, uint8_t *oq3) {
    if (flat && mask) {
      const uint8_t p3 = *op3, p2 = *op2, p1 = *op1, p0 = *op0;
      const uint8_t q0 = *oq0, q1 = *oq1, q2 = *oq2, q3 = *oq3;
  
      // 7-tap filter [1, 1, 1, 2, 1, 1, 1]
      *op2 = ROUND_POWER_OF_TWO(p3 + p3 + p3 + 2 * p2 + p1 + p0 + q0, 3);
      *op1 = ROUND_POWER_OF_TWO(p3 + p3 + p2 + 2 * p1 + p0 + q0 + q1, 3);
      *op0 = ROUND_POWER_OF_TWO(p3 + p2 + p1 + 2 * p0 + q0 + q1 + q2, 3);
      *oq0 = ROUND_POWER_OF_TWO(p2 + p1 + p0 + 2 * q0 + q1 + q2 + q3, 3);
      *oq1 = ROUND_POWER_OF_TWO(p1 + p0 + q0 + 2 * q1 + q2 + q3 + q3, 3);
      *oq2 = ROUND_POWER_OF_TWO(p0 + q0 + q1 + 2 * q2 + q3 + q3 + q3, 3);
    } else {
      filter4(mask, thresh, op1,  op0, oq0, oq1);
    }
  }
  
  void vpx_lpf_horizontal_8_c(uint8_t *s, int p, const uint8_t *blimit,
                              const uint8_t *limit, const uint8_t *thresh,
                              int count) {
    int i;
  
    // loop filter designed to work using chars so that we can make maximum use
    // of 8 bit simd instructions.
    for (i = 0; i < 8 * count; ++i) {
      const uint8_t p3 = s[-4 * p], p2 = s[-3 * p], p1 = s[-2 * p], p0 = s[-p];
      const uint8_t q0 = s[0 * p], q1 = s[1 * p], q2 = s[2 * p], q3 = s[3 * p];
  
      const int8_t mask = filter_mask(*limit, *blimit,
                                      p3, p2, p1, p0, q0, q1, q2, q3);
      const int8_t flat = flat_mask4(1, p3, p2, p1, p0, q0, q1, q2, q3);
      filter8(mask, *thresh, flat, s - 4 * p, s - 3 * p, s - 2 * p, s - 1 * p,
                                   s,         s + 1 * p, s + 2 * p, s + 3 * p);
      ++s;
    }
  }
  
  void vpx_lpf_horizontal_8_dual_c(uint8_t *s, int p, const uint8_t *blimit0,
                                   const uint8_t *limit0, const uint8_t *thresh0,
                                   const uint8_t *blimit1, const uint8_t *limit1,
                                   const uint8_t *thresh1) {
    vpx_lpf_horizontal_8_c(s, p, blimit0, limit0, thresh0, 1);
    vpx_lpf_horizontal_8_c(s + 8, p, blimit1, limit1, thresh1, 1);
  }
  
  void vpx_lpf_vertical_8_c(uint8_t *s, int pitch, const uint8_t *blimit,
                            const uint8_t *limit, const uint8_t *thresh,
                            int count) {
    int i;
  
    for (i = 0; i < 8 * count; ++i) {
      const uint8_t p3 = s[-4], p2 = s[-3], p1 = s[-2], p0 = s[-1];
      const uint8_t q0 = s[0], q1 = s[1], q2 = s[2], q3 = s[3];
      const int8_t mask = filter_mask(*limit, *blimit,
                                      p3, p2, p1, p0, q0, q1, q2, q3);
      const int8_t flat = flat_mask4(1, p3, p2, p1, p0, q0, q1, q2, q3);
      filter8(mask, *thresh, flat, s - 4, s - 3, s - 2, s - 1,
                                   s,     s + 1, s + 2, s + 3);
      s += pitch;
    }
  }
  
  void vpx_lpf_vertical_8_dual_c(uint8_t *s, int pitch, const uint8_t *blimit0,
                                 const uint8_t *limit0, const uint8_t *thresh0,
                                 const uint8_t *blimit1, const uint8_t *limit1,
                                 const uint8_t *thresh1) {
    vpx_lpf_vertical_8_c(s, pitch, blimit0, limit0, thresh0, 1);
    vpx_lpf_vertical_8_c(s + 8 * pitch, pitch, blimit1, limit1,
                                      thresh1, 1);
  }
  
  static INLINE void filter16(int8_t mask, uint8_t thresh,
                              uint8_t flat, uint8_t flat2,
                              uint8_t *op7, uint8_t *op6,
                              uint8_t *op5, uint8_t *op4,
                              uint8_t *op3, uint8_t *op2,
                              uint8_t *op1, uint8_t *op0,
                              uint8_t *oq0, uint8_t *oq1,
                              uint8_t *oq2, uint8_t *oq3,
                              uint8_t *oq4, uint8_t *oq5,
                              uint8_t *oq6, uint8_t *oq7) {
    if (flat2 && flat && mask) {
      const uint8_t p7 = *op7, p6 = *op6, p5 = *op5, p4 = *op4,
                    p3 = *op3, p2 = *op2, p1 = *op1, p0 = *op0;
  
      const uint8_t q0 = *oq0, q1 = *oq1, q2 = *oq2, q3 = *oq3,
                    q4 = *oq4, q5 = *oq5, q6 = *oq6, q7 = *oq7;
  
      // 15-tap filter [1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1]
      *op6 = ROUND_POWER_OF_TWO(p7 * 7 + p6 * 2 + p5 + p4 + p3 + p2 + p1 + p0 +
                                q0, 4);
      *op5 = ROUND_POWER_OF_TWO(p7 * 6 + p6 + p5 * 2 + p4 + p3 + p2 + p1 + p0 +
                                q0 + q1, 4);
      *op4 = ROUND_POWER_OF_TWO(p7 * 5 + p6 + p5 + p4 * 2 + p3 + p2 + p1 + p0 +
                                q0 + q1 + q2, 4);
      *op3 = ROUND_POWER_OF_TWO(p7 * 4 + p6 + p5 + p4 + p3 * 2 + p2 + p1 + p0 +
                                q0 + q1 + q2 + q3, 4);
      *op2 = ROUND_POWER_OF_TWO(p7 * 3 + p6 + p5 + p4 + p3 + p2 * 2 + p1 + p0 +
                                q0 + q1 + q2 + q3 + q4, 4);
      *op1 = ROUND_POWER_OF_TWO(p7 * 2 + p6 + p5 + p4 + p3 + p2 + p1 * 2 + p0 +
                                q0 + q1 + q2 + q3 + q4 + q5, 4);
      *op0 = ROUND_POWER_OF_TWO(p7 + p6 + p5 + p4 + p3 + p2 + p1 + p0 * 2 +
                                q0 + q1 + q2 + q3 + q4 + q5 + q6, 4);
      *oq0 = ROUND_POWER_OF_TWO(p6 + p5 + p4 + p3 + p2 + p1 + p0 +
                                q0 * 2 + q1 + q2 + q3 + q4 + q5 + q6 + q7, 4);
      *oq1 = ROUND_POWER_OF_TWO(p5 + p4 + p3 + p2 + p1 + p0 +
                                q0 + q1 * 2 + q2 + q3 + q4 + q5 + q6 + q7 * 2, 4);
      *oq2 = ROUND_POWER_OF_TWO(p4 + p3 + p2 + p1 + p0 +
                                q0 + q1 + q2 * 2 + q3 + q4 + q5 + q6 + q7 * 3, 4);
      *oq3 = ROUND_POWER_OF_TWO(p3 + p2 + p1 + p0 +
                                q0 + q1 + q2 + q3 * 2 + q4 + q5 + q6 + q7 * 4, 4);
      *oq4 = ROUND_POWER_OF_TWO(p2 + p1 + p0 +
                                q0 + q1 + q2 + q3 + q4 * 2 + q5 + q6 + q7 * 5, 4);
      *oq5 = ROUND_POWER_OF_TWO(p1 + p0 +
                                q0 + q1 + q2 + q3 + q4 + q5 * 2 + q6 + q7 * 6, 4);
      *oq6 = ROUND_POWER_OF_TWO(p0 +
                                q0 + q1 + q2 + q3 + q4 + q5 + q6 * 2 + q7 * 7, 4);
    } else {
      filter8(mask, thresh, flat, op3, op2, op1, op0, oq0, oq1, oq2, oq3);
    }
  }
  
  void vpx_lpf_horizontal_16_c(uint8_t *s, int p, const uint8_t *blimit,
                               const uint8_t *limit, const uint8_t *thresh,
                               int count) {
    int i;
  
    // loop filter designed to work using chars so that we can make maximum use
    // of 8 bit simd instructions.
    for (i = 0; i < 8 * count; ++i) {
      const uint8_t p3 = s[-4 * p], p2 = s[-3 * p], p1 = s[-2 * p], p0 = s[-p];
      const uint8_t q0 = s[0 * p], q1 = s[1 * p], q2 = s[2 * p], q3 = s[3 * p];
      const int8_t mask = filter_mask(*limit, *blimit,
                                      p3, p2, p1, p0, q0, q1, q2, q3);
      const int8_t flat = flat_mask4(1, p3, p2, p1, p0, q0, q1, q2, q3);
      const int8_t flat2 = flat_mask5(1,
                               s[-8 * p], s[-7 * p], s[-6 * p], s[-5 * p], p0,
                               q0, s[4 * p], s[5 * p], s[6 * p], s[7 * p]);
  
      filter16(mask, *thresh, flat, flat2,
               s - 8 * p, s - 7 * p, s - 6 * p, s - 5 * p,
               s - 4 * p, s - 3 * p, s - 2 * p, s - 1 * p,
               s,         s + 1 * p, s + 2 * p, s + 3 * p,
               s + 4 * p, s + 5 * p, s + 6 * p, s + 7 * p);
      ++s;
    }
  }
  
  static void mb_lpf_vertical_edge_w(uint8_t *s, int p,
                                     const uint8_t *blimit,
                                     const uint8_t *limit,
                                     const uint8_t *thresh,
                                     int count) {
    int i;
  
    for (i = 0; i < count; ++i) {
      const uint8_t p3 = s[-4], p2 = s[-3], p1 = s[-2], p0 = s[-1];
      const uint8_t q0 = s[0], q1 = s[1],  q2 = s[2], q3 = s[3];
      const int8_t mask = filter_mask(*limit, *blimit,
                                      p3, p2, p1, p0, q0, q1, q2, q3);
      const int8_t flat = flat_mask4(1, p3, p2, p1, p0, q0, q1, q2, q3);
      const int8_t flat2 = flat_mask5(1, s[-8], s[-7], s[-6], s[-5], p0,
                                      q0, s[4], s[5], s[6], s[7]);
  
      filter16(mask, *thresh, flat, flat2,
               s - 8, s - 7, s - 6, s - 5, s - 4, s - 3, s - 2, s - 1,
               s,     s + 1, s + 2, s + 3, s + 4, s + 5, s + 6, s + 7);
      s += p;
    }
  }
  
  void vpx_lpf_vertical_16_c(uint8_t *s, int p, const uint8_t *blimit,
                             const uint8_t *limit, const uint8_t *thresh) {
    mb_lpf_vertical_edge_w(s, p, blimit, limit, thresh, 8);
  }
  
  void vpx_lpf_vertical_16_dual_c(uint8_t *s, int p, const uint8_t *blimit,
                                  const uint8_t *limit, const uint8_t *thresh) {
    mb_lpf_vertical_edge_w(s, p, blimit, limit, thresh, 16);
  }
  
  #if CONFIG_VP9_HIGHBITDEPTH
  // Should we apply any filter at all: 11111111 yes, 00000000 no ?
  static INLINE int8_t highbd_filter_mask(uint8_t limit, uint8_t blimit,
                                          uint16_t p3, uint16_t p2,
                                          uint16_t p1, uint16_t p0,
                                          uint16_t q0, uint16_t q1,
                                          uint16_t q2, uint16_t q3, int bd) {
    int8_t mask = 0;
    int16_t limit16 = (uint16_t)limit << (bd - 8);
    int16_t blimit16 = (uint16_t)blimit << (bd - 8);
    mask |= (abs(p3 - p2) > limit16) * -1;
    mask |= (abs(p2 - p1) > limit16) * -1;
    mask |= (abs(p1 - p0) > limit16) * -1;
    mask |= (abs(q1 - q0) > limit16) * -1;
    mask |= (abs(q2 - q1) > limit16) * -1;
    mask |= (abs(q3 - q2) > limit16) * -1;
    mask |= (abs(p0 - q0) * 2 + abs(p1 - q1) / 2  > blimit16) * -1;
    return ~mask;
  }
  
  static INLINE int8_t highbd_flat_mask4(uint8_t thresh,
                                         uint16_t p3, uint16_t p2,
                                         uint16_t p1, uint16_t p0,
                                         uint16_t q0, uint16_t q1,
                                         uint16_t q2, uint16_t q3, int bd) {
    int8_t mask = 0;
    int16_t thresh16 = (uint16_t)thresh << (bd - 8);
    mask |= (abs(p1 - p0) > thresh16) * -1;
    mask |= (abs(q1 - q0) > thresh16) * -1;
    mask |= (abs(p2 - p0) > thresh16) * -1;
    mask |= (abs(q2 - q0) > thresh16) * -1;
    mask |= (abs(p3 - p0) > thresh16) * -1;
    mask |= (abs(q3 - q0) > thresh16) * -1;
    return ~mask;
  }
  
  static INLINE int8_t highbd_flat_mask5(uint8_t thresh,
                                         uint16_t p4, uint16_t p3,
                                         uint16_t p2, uint16_t p1,
                                         uint16_t p0, uint16_t q0,
                                         uint16_t q1, uint16_t q2,
                                         uint16_t q3, uint16_t q4, int bd) {
    int8_t mask = ~highbd_flat_mask4(thresh, p3, p2, p1, p0, q0, q1, q2, q3, bd);
    int16_t thresh16 = (uint16_t)thresh << (bd - 8);
    mask |= (abs(p4 - p0) > thresh16) * -1;
    mask |= (abs(q4 - q0) > thresh16) * -1;
    return ~mask;
  }
  
  // Is there high edge variance internal edge:
  // 11111111_11111111 yes, 00000000_00000000 no ?
  static INLINE int16_t highbd_hev_mask(uint8_t thresh, uint16_t p1, uint16_t p0,
                                        uint16_t q0, uint16_t q1, int bd) {
    int16_t hev = 0;
    int16_t thresh16 = (uint16_t)thresh << (bd - 8);
    hev |= (abs(p1 - p0) > thresh16) * -1;
    hev |= (abs(q1 - q0) > thresh16) * -1;
    return hev;
  }
  
  static INLINE void highbd_filter4(int8_t mask, uint8_t thresh, uint16_t *op1,
                                    uint16_t *op0, uint16_t *oq0, uint16_t *oq1,
                                    int bd) {
    int16_t filter1, filter2;
    // ^0x80 equivalent to subtracting 0x80 from the values to turn them
    // into -128 to +127 instead of 0 to 255.
    int shift = bd - 8;
    const int16_t ps1 = (int16_t)*op1 - (0x80 << shift);
    const int16_t ps0 = (int16_t)*op0 - (0x80 << shift);
    const int16_t qs0 = (int16_t)*oq0 - (0x80 << shift);
    const int16_t qs1 = (int16_t)*oq1 - (0x80 << shift);
    const uint16_t hev = highbd_hev_mask(thresh, *op1, *op0, *oq0, *oq1, bd);
  
    // Add outer taps if we have high edge variance.
    int16_t filter = signed_char_clamp_high(ps1 - qs1, bd) & hev;
  
    // Inner taps.
    filter = signed_char_clamp_high(filter + 3 * (qs0 - ps0), bd) & mask;
  
    // Save bottom 3 bits so that we round one side +4 and the other +3
    // if it equals 4 we'll set to adjust by -1 to account for the fact
    // we'd round 3 the other way.
    filter1 = signed_char_clamp_high(filter + 4, bd) >> 3;
    filter2 = signed_char_clamp_high(filter + 3, bd) >> 3;
  
    *oq0 = signed_char_clamp_high(qs0 - filter1, bd) + (0x80 << shift);
    *op0 = signed_char_clamp_high(ps0 + filter2, bd) + (0x80 << shift);
  
    // Outer tap adjustments.
    filter = ROUND_POWER_OF_TWO(filter1, 1) & ~hev;
  
    *oq1 = signed_char_clamp_high(qs1 - filter, bd) + (0x80 << shift);
    *op1 = signed_char_clamp_high(ps1 + filter, bd) + (0x80 << shift);
  }
  
  void vpx_highbd_lpf_horizontal_4_c(uint16_t *s, int p /* pitch */,
                                     const uint8_t *blimit, const uint8_t *limit,
                                     const uint8_t *thresh, int count, int bd) {
    int i;
  
    // loop filter designed to work using chars so that we can make maximum use
    // of 8 bit simd instructions.
    for (i = 0; i < 8 * count; ++i) {
      const uint16_t p3 = s[-4 * p];
      const uint16_t p2 = s[-3 * p];
      const uint16_t p1 = s[-2 * p];
      const uint16_t p0 = s[-p];
      const uint16_t q0 = s[0 * p];
      const uint16_t q1 = s[1 * p];
      const uint16_t q2 = s[2 * p];
      const uint16_t q3 = s[3 * p];
      const int8_t mask = highbd_filter_mask(*limit, *blimit,
                                             p3, p2, p1, p0, q0, q1, q2, q3, bd);
      highbd_filter4(mask, *thresh, s - 2 * p, s - 1 * p, s, s + 1 * p, bd);
      ++s;
    }
  }
  
  void vpx_highbd_lpf_horizontal_4_dual_c(uint16_t *s, int p,
                                          const uint8_t *blimit0,
                                          const uint8_t *limit0,
                                          const uint8_t *thresh0,
                                          const uint8_t *blimit1,
                                          const uint8_t *limit1,
                                          const uint8_t *thresh1,
                                          int bd) {
    vpx_highbd_lpf_horizontal_4_c(s, p, blimit0, limit0, thresh0, 1, bd);
    vpx_highbd_lpf_horizontal_4_c(s + 8, p, blimit1, limit1, thresh1, 1, bd);
  }
  
  void vpx_highbd_lpf_vertical_4_c(uint16_t *s, int pitch, const uint8_t *blimit,
                                   const uint8_t *limit, const uint8_t *thresh,
                                   int count, int bd) {
    int i;
  
    // loop filter designed to work using chars so that we can make maximum use
    // of 8 bit simd instructions.
    for (i = 0; i < 8 * count; ++i) {
      const uint16_t p3 = s[-4], p2 = s[-3], p1 = s[-2], p0 = s[-1];
      const uint16_t q0 = s[0],  q1 = s[1],  q2 = s[2],  q3 = s[3];
      const int8_t mask = highbd_filter_mask(*limit, *blimit,
                                             p3, p2, p1, p0, q0, q1, q2, q3, bd);
      highbd_filter4(mask, *thresh, s - 2, s - 1, s, s + 1, bd);
      s += pitch;
    }
  }
  
  void vpx_highbd_lpf_vertical_4_dual_c(uint16_t *s, int pitch,
                                        const uint8_t *blimit0,
                                        const uint8_t *limit0,
                                        const uint8_t *thresh0,
                                        const uint8_t *blimit1,
                                        const uint8_t *limit1,
                                        const uint8_t *thresh1,
                                        int bd) {
    vpx_highbd_lpf_vertical_4_c(s, pitch, blimit0, limit0, thresh0, 1, bd);
    vpx_highbd_lpf_vertical_4_c(s + 8 * pitch, pitch, blimit1, limit1,
                                thresh1, 1, bd);
  }
  
  static INLINE void highbd_filter8(int8_t mask, uint8_t thresh, uint8_t flat,
                                    uint16_t *op3, uint16_t *op2,
                                    uint16_t *op1, uint16_t *op0,
                                    uint16_t *oq0, uint16_t *oq1,
                                    uint16_t *oq2, uint16_t *oq3, int bd) {
    if (flat && mask) {
      const uint16_t p3 = *op3, p2 = *op2, p1 = *op1, p0 = *op0;
      const uint16_t q0 = *oq0, q1 = *oq1, q2 = *oq2, q3 = *oq3;
  
      // 7-tap filter [1, 1, 1, 2, 1, 1, 1]
      *op2 = ROUND_POWER_OF_TWO(p3 + p3 + p3 + 2 * p2 + p1 + p0 + q0, 3);
      *op1 = ROUND_POWER_OF_TWO(p3 + p3 + p2 + 2 * p1 + p0 + q0 + q1, 3);
      *op0 = ROUND_POWER_OF_TWO(p3 + p2 + p1 + 2 * p0 + q0 + q1 + q2, 3);
      *oq0 = ROUND_POWER_OF_TWO(p2 + p1 + p0 + 2 * q0 + q1 + q2 + q3, 3);
      *oq1 = ROUND_POWER_OF_TWO(p1 + p0 + q0 + 2 * q1 + q2 + q3 + q3, 3);
      *oq2 = ROUND_POWER_OF_TWO(p0 + q0 + q1 + 2 * q2 + q3 + q3 + q3, 3);
    } else {
      highbd_filter4(mask, thresh, op1,  op0, oq0, oq1, bd);
    }
  }
  
  void vpx_highbd_lpf_horizontal_8_c(uint16_t *s, int p, const uint8_t *blimit,
                                     const uint8_t *limit, const uint8_t *thresh,
                                     int count, int bd) {
    int i;
  
    // loop filter designed to work using chars so that we can make maximum use
    // of 8 bit simd instructions.
    for (i = 0; i < 8 * count; ++i) {
      const uint16_t p3 = s[-4 * p], p2 = s[-3 * p], p1 = s[-2 * p], p0 = s[-p];
      const uint16_t q0 = s[0 * p], q1 = s[1 * p], q2 = s[2 * p], q3 = s[3 * p];
  
      const int8_t mask = highbd_filter_mask(*limit, *blimit,
                                           p3, p2, p1, p0, q0, q1, q2, q3, bd);
      const int8_t flat = highbd_flat_mask4(1, p3, p2, p1, p0, q0, q1, q2, q3,
                                            bd);
      highbd_filter8(mask, *thresh, flat,
                   s - 4 * p, s - 3 * p, s - 2 * p, s - 1 * p,
                   s, s + 1 * p, s + 2 * p, s + 3 * p, bd);
      ++s;
    }
  }
  
  void vpx_highbd_lpf_horizontal_8_dual_c(uint16_t *s, int p,
                                          const uint8_t *blimit0,
                                          const uint8_t *limit0,
                                          const uint8_t *thresh0,
                                          const uint8_t *blimit1,
                                          const uint8_t *limit1,
                                          const uint8_t *thresh1,
                                          int bd) {
    vpx_highbd_lpf_horizontal_8_c(s, p, blimit0, limit0, thresh0, 1, bd);
    vpx_highbd_lpf_horizontal_8_c(s + 8, p, blimit1, limit1, thresh1, 1, bd);
  }
  
  void vpx_highbd_lpf_vertical_8_c(uint16_t *s, int pitch, const uint8_t *blimit,
                                   const uint8_t *limit, const uint8_t *thresh,
                                   int count, int bd) {
    int i;
  
    for (i = 0; i < 8 * count; ++i) {
      const uint16_t p3 = s[-4], p2 = s[-3], p1 = s[-2], p0 = s[-1];
      const uint16_t q0 = s[0], q1 = s[1], q2 = s[2], q3 = s[3];
      const int8_t mask = highbd_filter_mask(*limit, *blimit,
                                             p3, p2, p1, p0, q0, q1, q2, q3, bd);
      const int8_t flat = highbd_flat_mask4(1, p3, p2, p1, p0, q0, q1, q2, q3,
                                            bd);
      highbd_filter8(mask, *thresh, flat,
                   s - 4, s - 3, s - 2, s - 1,
                   s, s + 1, s + 2, s + 3,
                   bd);
      s += pitch;
    }
  }
  
  void vpx_highbd_lpf_vertical_8_dual_c(uint16_t *s, int pitch,
                                        const uint8_t *blimit0,
                                        const uint8_t *limit0,
                                        const uint8_t *thresh0,
                                        const uint8_t *blimit1,
                                        const uint8_t *limit1,
                                        const uint8_t *thresh1,
                                        int bd) {
    vpx_highbd_lpf_vertical_8_c(s, pitch, blimit0, limit0, thresh0, 1, bd);
    vpx_highbd_lpf_vertical_8_c(s + 8 * pitch, pitch, blimit1, limit1,
                                thresh1, 1, bd);
  }
  
  static INLINE void highbd_filter16(int8_t mask, uint8_t thresh,
                                     uint8_t flat, uint8_t flat2,
                                     uint16_t *op7, uint16_t *op6,
                                     uint16_t *op5, uint16_t *op4,
                                     uint16_t *op3, uint16_t *op2,
                                     uint16_t *op1, uint16_t *op0,
                                     uint16_t *oq0, uint16_t *oq1,
                                     uint16_t *oq2, uint16_t *oq3,
                                     uint16_t *oq4, uint16_t *oq5,
                                     uint16_t *oq6, uint16_t *oq7, int bd) {
    if (flat2 && flat && mask) {
      const uint16_t p7 = *op7;
      const uint16_t p6 = *op6;
      const uint16_t p5 = *op5;
      const uint16_t p4 = *op4;
      const uint16_t p3 = *op3;
      const uint16_t p2 = *op2;
      const uint16_t p1 = *op1;
      const uint16_t p0 = *op0;
      const uint16_t q0 = *oq0;
      const uint16_t q1 = *oq1;
      const uint16_t q2 = *oq2;
      const uint16_t q3 = *oq3;
      const uint16_t q4 = *oq4;
      const uint16_t q5 = *oq5;
      const uint16_t q6 = *oq6;
      const uint16_t q7 = *oq7;
  
      // 15-tap filter [1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1]
      *op6 = ROUND_POWER_OF_TWO(p7 * 7 + p6 * 2 + p5 + p4 + p3 + p2 + p1 + p0 +
                                q0, 4);
      *op5 = ROUND_POWER_OF_TWO(p7 * 6 + p6 + p5 * 2 + p4 + p3 + p2 + p1 + p0 +
                                q0 + q1, 4);
      *op4 = ROUND_POWER_OF_TWO(p7 * 5 + p6 + p5 + p4 * 2 + p3 + p2 + p1 + p0 +
                                q0 + q1 + q2, 4);
      *op3 = ROUND_POWER_OF_TWO(p7 * 4 + p6 + p5 + p4 + p3 * 2 + p2 + p1 + p0 +
                                q0 + q1 + q2 + q3, 4);
      *op2 = ROUND_POWER_OF_TWO(p7 * 3 + p6 + p5 + p4 + p3 + p2 * 2 + p1 + p0 +
                                q0 + q1 + q2 + q3 + q4, 4);
      *op1 = ROUND_POWER_OF_TWO(p7 * 2 + p6 + p5 + p4 + p3 + p2 + p1 * 2 + p0 +
                                q0 + q1 + q2 + q3 + q4 + q5, 4);
      *op0 = ROUND_POWER_OF_TWO(p7 + p6 + p5 + p4 + p3 + p2 + p1 + p0 * 2 +
                                q0 + q1 + q2 + q3 + q4 + q5 + q6, 4);
      *oq0 = ROUND_POWER_OF_TWO(p6 + p5 + p4 + p3 + p2 + p1 + p0 +
                                q0 * 2 + q1 + q2 + q3 + q4 + q5 + q6 + q7, 4);
      *oq1 = ROUND_POWER_OF_TWO(p5 + p4 + p3 + p2 + p1 + p0 +
                                q0 + q1 * 2 + q2 + q3 + q4 + q5 + q6 + q7 * 2, 4);
      *oq2 = ROUND_POWER_OF_TWO(p4 + p3 + p2 + p1 + p0 +
                                q0 + q1 + q2 * 2 + q3 + q4 + q5 + q6 + q7 * 3, 4);
      *oq3 = ROUND_POWER_OF_TWO(p3 + p2 + p1 + p0 +
                                q0 + q1 + q2 + q3 * 2 + q4 + q5 + q6 + q7 * 4, 4);
      *oq4 = ROUND_POWER_OF_TWO(p2 + p1 + p0 +
                                q0 + q1 + q2 + q3 + q4 * 2 + q5 + q6 + q7 * 5, 4);
      *oq5 = ROUND_POWER_OF_TWO(p1 + p0 +
                                q0 + q1 + q2 + q3 + q4 + q5 * 2 + q6 + q7 * 6, 4);
      *oq6 = ROUND_POWER_OF_TWO(p0 +
                                q0 + q1 + q2 + q3 + q4 + q5 + q6 * 2 + q7 * 7, 4);
    } else {
      highbd_filter8(mask, thresh, flat, op3, op2, op1, op0, oq0, oq1, oq2, oq3,
                     bd);
    }
  }
  
  void vpx_highbd_lpf_horizontal_16_c(uint16_t *s, int p, const uint8_t *blimit,
                                      const uint8_t *limit, const uint8_t *thresh,
                                      int count, int bd) {
    int i;
  
    // loop filter designed to work using chars so that we can make maximum use
    // of 8 bit simd instructions.
    for (i = 0; i < 8 * count; ++i) {
      const uint16_t p3 = s[-4 * p];
      const uint16_t p2 = s[-3 * p];
      const uint16_t p1 = s[-2 * p];
      const uint16_t p0 = s[-p];
      const uint16_t q0 = s[0 * p];
      const uint16_t q1 = s[1 * p];
      const uint16_t q2 = s[2 * p];
      const uint16_t q3 = s[3 * p];
      const int8_t mask = highbd_filter_mask(*limit, *blimit,
                                             p3, p2, p1, p0, q0, q1, q2, q3, bd);
      const int8_t flat = highbd_flat_mask4(1, p3, p2, p1, p0, q0, q1, q2, q3,
                                            bd);
      const int8_t flat2 = highbd_flat_mask5(
          1, s[-8 * p], s[-7 * p], s[-6 * p], s[-5 * p], p0,
          q0, s[4 * p], s[5 * p], s[6 * p], s[7 * p], bd);
  
      highbd_filter16(mask, *thresh, flat, flat2,
                      s - 8 * p, s - 7 * p, s - 6 * p, s - 5 * p,
                      s - 4 * p, s - 3 * p, s - 2 * p, s - 1 * p,
                      s, s + 1 * p, s + 2 * p, s + 3 * p,
                      s + 4 * p, s + 5 * p, s + 6 * p, s + 7 * p,
                      bd);
      ++s;
    }
  }
  
  static void highbd_mb_lpf_vertical_edge_w(uint16_t *s, int p,
                                            const uint8_t *blimit,
                                            const uint8_t *limit,
                                            const uint8_t *thresh,
                                            int count, int bd) {
    int i;
  
    for (i = 0; i < count; ++i) {
      const uint16_t p3 = s[-4];
      const uint16_t p2 = s[-3];
      const uint16_t p1 = s[-2];
      const uint16_t p0 = s[-1];
      const uint16_t q0 = s[0];
      const uint16_t q1 = s[1];
      const uint16_t q2 = s[2];
      const uint16_t q3 = s[3];
      const int8_t mask = highbd_filter_mask(*limit, *blimit,
                                             p3, p2, p1, p0, q0, q1, q2, q3, bd);
      const int8_t flat = highbd_flat_mask4(1, p3, p2, p1, p0, q0, q1, q2, q3,
                                            bd);
      const int8_t flat2 = highbd_flat_mask5(1, s[-8], s[-7], s[-6], s[-5], p0,
                                             q0, s[4], s[5], s[6], s[7], bd);
  
      highbd_filter16(mask, *thresh, flat, flat2,
                      s - 8, s - 7, s - 6, s - 5, s - 4, s - 3, s - 2, s - 1,
                      s, s + 1, s + 2, s + 3, s + 4, s + 5, s + 6, s + 7,
                      bd);
      s += p;
    }
  }
  
  void vpx_highbd_lpf_vertical_16_c(uint16_t *s, int p, const uint8_t *blimit,
                                    const uint8_t *limit, const uint8_t *thresh,
                                    int bd) {
    highbd_mb_lpf_vertical_edge_w(s, p, blimit, limit, thresh, 8, bd);
  }
  
  void vpx_highbd_lpf_vertical_16_dual_c(uint16_t *s, int p,
                                         const uint8_t *blimit,
                                         const uint8_t *limit,
                                         const uint8_t *thresh,
                                         int bd) {
    highbd_mb_lpf_vertical_edge_w(s, p, blimit, limit, thresh, 16, bd);
  }
  #endif  // CONFIG_VP9_HIGHBITDEPTH
  