/*

  * This file is part of FFmpeg.

  *

  * FFmpeg is free software; you can redistribute it and/or

  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *

  * FFmpeg is distributed in the hope that it will be useful,

  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public

  * License along with FFmpeg; if not, write to the Free Software

  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #include <stdint.h>
 
 #include "libavutil/attributes.h"
 #include "libavutil/common.h"
 #include "config.h"
 #include "h263dsp.h"
 

 const uint8_t ff_h263_loop_filter_strength[32] = {
     0, 1, 1, 2, 2, 3, 3,  4,  4,  4,  5,  5,  6,  6,  7, 7,
     7, 8, 8, 8, 9, 9, 9, 10, 10, 10, 11, 11, 11, 12, 12, 12

 };
 

 static void h263_h_loop_filter_c(uint8_t *src, int stride, int qscale)
 {

     int y;

     const int strength = ff_h263_loop_filter_strength[qscale];

     for (y = 0; y < 8; y++) {

         int d1, d2, ad1;

         int p0 = src[y * stride - 2];
         int p1 = src[y * stride - 1];
         int p2 = src[y * stride + 0];
         int p3 = src[y * stride + 1];
         int d  = (p0 - p3 + 4 * (p2 - p1)) / 8;
 
         if (d < -2 * strength)
             d1 = 0;
         else if (d < -strength)
             d1 = -2 * strength - d;
         else if (d < strength)
             d1 = d;
         else if (d < 2 * strength)
             d1 = 2 * strength - d;
         else
             d1 = 0;

 
         p1 += d1;
         p2 -= d1;

         if (p1 & 256)
             p1 = ~(p1 >> 31);
         if (p2 & 256)
             p2 = ~(p2 >> 31);

         src[y * stride - 1] = p1;
         src[y * stride + 0] = p2;

         ad1 = FFABS(d1) >> 1;

         d2 = av_clip((p0 - p3) / 4, -ad1, ad1);

         src[y * stride - 2] = p0 - d2;
         src[y * stride + 1] = p3 + d2;

     }
 }
 

 static void h263_v_loop_filter_c(uint8_t *src, int stride, int qscale)
 {

     int x;

     const int strength = ff_h263_loop_filter_strength[qscale];

     for (x = 0; x < 8; x++) {

         int d1, d2, ad1;

         int p0 = src[x - 2 * stride];
         int p1 = src[x - 1 * stride];
         int p2 = src[x + 0 * stride];
         int p3 = src[x + 1 * stride];
         int d  = (p0 - p3 + 4 * (p2 - p1)) / 8;
 
         if (d < -2 * strength)
             d1 = 0;
         else if (d < -strength)
             d1 = -2 * strength - d;
         else if (d < strength)
             d1 = d;
         else if (d < 2 * strength)
             d1 = 2 * strength - d;
         else
             d1 = 0;

 
         p1 += d1;
         p2 -= d1;

         if (p1 & 256)
             p1 = ~(p1 >> 31);
         if (p2 & 256)
             p2 = ~(p2 >> 31);

         src[x - 1 * stride] = p1;
         src[x + 0 * stride] = p2;

         ad1 = FFABS(d1) >> 1;

         d2 = av_clip((p0 - p3) / 4, -ad1, ad1);

         src[x - 2 * stride] = p0 - d2;
         src[x + stride]     = p3 + d2;

     }
 }
 
 av_cold void ff_h263dsp_init(H263DSPContext *ctx)
 {
     ctx->h263_h_loop_filter = h263_h_loop_filter_c;
     ctx->h263_v_loop_filter = h263_v_loop_filter_c;
 
     if (ARCH_X86)
         ff_h263dsp_init_x86(ctx);
 }