/*
  * 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 "config.h"
 #include "libavutil/attributes.h"
 #include "lossless_videoencdsp.h"
 #include "mathops.h"
 
 // 0x7f7f7f7f or 0x7f7f7f7f7f7f7f7f or whatever, depending on the cpu's native arithmetic size
 #define pb_7f (~0UL / 255 * 0x7f)
 #define pb_80 (~0UL / 255 * 0x80)
 
 static void diff_bytes_c(uint8_t *dst, const uint8_t *src1, const uint8_t *src2, intptr_t w)
 {
     long i;
 
 #if !HAVE_FAST_UNALIGNED
     if (((long)src1 | (long)src2) & (sizeof(long) - 1)) {
         for (i = 0; i + 7 < w; i += 8) {
             dst[i + 0] = src1[i + 0] - src2[i + 0];
             dst[i + 1] = src1[i + 1] - src2[i + 1];
             dst[i + 2] = src1[i + 2] - src2[i + 2];
             dst[i + 3] = src1[i + 3] - src2[i + 3];
             dst[i + 4] = src1[i + 4] - src2[i + 4];
             dst[i + 5] = src1[i + 5] - src2[i + 5];
             dst[i + 6] = src1[i + 6] - src2[i + 6];
             dst[i + 7] = src1[i + 7] - src2[i + 7];
         }
     } else
 #endif
     for (i = 0; i <= w - (int) sizeof(long); i += sizeof(long)) {
         long a = *(long *) (src1 + i);
         long b = *(long *) (src2 + i);
         *(long *) (dst + i) = ((a | pb_80) - (b & pb_7f)) ^
                               ((a ^ b ^ pb_80) & pb_80);
     }
     for (; i < w; i++)
         dst[i + 0] = src1[i + 0] - src2[i + 0];
 }
 
 static void sub_median_pred_c(uint8_t *dst, const uint8_t *src1,
                               const uint8_t *src2, intptr_t w,
                               int *left, int *left_top)
 {
     int i;
     uint8_t l, lt;
 
     l  = *left;
     lt = *left_top;
 
     for (i = 0; i < w; i++) {
         const int pred = mid_pred(l, src1[i], (l + src1[i] - lt) & 0xFF);
         lt     = src1[i];
         l      = src2[i];
         dst[i] = l - pred;
     }
 
     *left     = l;
     *left_top = lt;
 }
 
 av_cold void ff_llvidencdsp_init(LLVidEncDSPContext *c)
 {
     c->diff_bytes      = diff_bytes_c;
     c->sub_median_pred = sub_median_pred_c;
 
     if (ARCH_X86)
         ff_llvidencdsp_init_x86(c);
 }