/*
  * RLE encoder
  * Copyright (c) 2007 Bobby Bingham
  *
  * 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 "libavutil/common.h"
 

 #include "avcodec.h"
 #include "rle.h"
 

 int ff_rle_count_pixels(const uint8_t *start, int len, int bpp, int same)

 {
     const uint8_t *pos;
     int count = 1;
 

     for (pos = start + bpp; count < FFMIN(127, len); pos += bpp, count++) {
         if (same != !memcmp(pos - bpp, pos, bpp)) {
             if (!same) {
                 /* if bpp == 1, then 0 1 1 0 is more efficiently encoded as a
                  * single raw block of pixels. For larger bpp, RLE is as good
                  * or better */
                 if (bpp == 1 && count + 1 < FFMIN(127, len) && *pos != *(pos + 1))

                     continue;
 
                 /* if RLE can encode the next block better than as a raw block,
                  * back up and leave _all_ the identical pixels for RLE */

                 count--;

             }
             break;
         }
     }
 
     return count;
 }
 

 int ff_rle_encode(uint8_t *outbuf, int out_size, const uint8_t *ptr, int bpp,
                   int w, int add_rep, int xor_rep, int add_raw, int xor_raw)

 {
     int count, x;

     uint8_t *out = outbuf;

     for (x = 0; x < w; x += count) {

         /* see if we can encode the next set of pixels with RLE */

         if ((count = ff_rle_count_pixels(ptr, w - x, bpp, 1)) > 1) {

             if (out + bpp + 1 > outbuf + out_size)
                 return -1;
 

             *out++ = (count ^ xor_rep) + add_rep;

             memcpy(out, ptr, bpp);
             out += bpp;
         } else {
             /* fall back on uncompressed */

             count = ff_rle_count_pixels(ptr, w - x, bpp, 0);

             if (out + bpp * count >= outbuf + out_size)
                 return -1;

             *out++ = (count ^ xor_raw) + add_raw;

             memcpy(out, ptr, bpp * count);
             out += bpp * count;

         }
 
         ptr += count * bpp;
     }
 
     return out - outbuf;
 }