/*
  * 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 "avcodec.h"
 #include "rle.h"

 #include "libavutil/common.h"

 
 /**
  * Count up to 127 consecutive pixels which are either all the same or
  * all differ from the previous and next pixels.
  * @param start Pointer to the first pixel
  * @param len Maximum number of pixels
  * @param bpp Bytes per pixel
  * @param same 1 if searching for identical pixel values.  0 for differing
  * @return Number of matching consecutive pixels found
  */
 static int 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 = 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 = 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;
 }