/*

  * 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 "config.h"
 #include "libavutil/attributes.h"
 #include "mathops.h"
 #include "huffyuvdsp.h"
 

 // 0x00010001 or 0x0001000100010001 or whatever, depending on the cpu's native arithmetic size
 #define pw_1 (ULONG_MAX / UINT16_MAX)
 

 static void add_int16_c(uint16_t *dst, const uint16_t *src, unsigned mask, int w){
     long i;

     unsigned long pw_lsb = (mask >> 1) * pw_1;
     unsigned long pw_msb = pw_lsb +  pw_1;

     for (i = 0; i <= w - (int)sizeof(long)/2; i += sizeof(long)/2) {
         long a = *(long*)(src+i);
         long b = *(long*)(dst+i);
         *(long*)(dst+i) = ((a&pw_lsb) + (b&pw_lsb)) ^ ((a^b)&pw_msb);
     }
     for(; i<w; i++)
         dst[i] = (dst[i] + src[i]) & mask;
 }
 
 static void add_hfyu_median_pred_int16_c(uint16_t *dst, const uint16_t *src, const uint16_t *diff, unsigned mask, int w, int *left, int *left_top){
     int i;
     uint16_t l, lt;
 
     l  = *left;
     lt = *left_top;
 
     for(i=0; i<w; i++){
         l  = (mid_pred(l, src[i], (l + src[i] - lt) & mask) + diff[i]) & mask;
         lt = src[i];
         dst[i] = l;
     }
 
     *left     = l;
     *left_top = lt;
 }
 

 static void add_hfyu_left_pred_bgr32_c(uint8_t *dst, const uint8_t *src,

                                        intptr_t w, uint8_t *left)

 {

     int i;
     uint8_t r = left[R], g = left[G], b = left[B], a = left[A];

 
     for (i = 0; i < w; i++) {
         b += src[4 * i + B];
         g += src[4 * i + G];
         r += src[4 * i + R];
         a += src[4 * i + A];
 
         dst[4 * i + B] = b;
         dst[4 * i + G] = g;
         dst[4 * i + R] = r;
         dst[4 * i + A] = a;
     }
 

     left[B] = b;
     left[G] = g;
     left[R] = r;
     left[A] = a;

 }
 

 av_cold void ff_huffyuvdsp_init(HuffYUVDSPContext *c, enum AVPixelFormat pix_fmt)

 {

     c->add_int16 = add_int16_c;
     c->add_hfyu_median_pred_int16 = add_hfyu_median_pred_int16_c;

     c->add_hfyu_left_pred_bgr32 = add_hfyu_left_pred_bgr32_c;
 
     if (ARCH_X86)

         ff_huffyuvdsp_init_x86(c, pix_fmt);

 }