text: /*
   * lzf decompression algorithm
   * Copyright (c) 2015 Luca Barbato
   *
   * This file is part of Libav.
   *
   * Libav 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.
   *
   * Libav 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 Libav; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
   */
  
  /**
   * @file
   * lzf decompression
   *
   * LZF is a fast compression/decompression algorithm that takes very little
   * code space and working memory, ideal for real-time and block compression.
   *
   * https://en.wikibooks.org/wiki/Data_Compression/Dictionary_compression#LZF
   */
  
  #include "libavutil/mem.h"
  
  #include "bytestream.h"
  #include "lzf.h"
  
  #define LZF_LITERAL_MAX (1 << 5)
  #define LZF_LONG_BACKREF 7 + 2
  
  int ff_lzf_uncompress(GetByteContext *gb, uint8_t **buf, int64_t *size)
  {
      int ret     = 0;
      uint8_t *p  = *buf;
      int64_t len = 0;
  
      while (bytestream2_get_bytes_left(gb) > 2) {
          uint8_t s = bytestream2_get_byte(gb);
  
          if (s < LZF_LITERAL_MAX) {
              s++;
              if (s > *size - len) {
                  *size += *size /2;
                  ret = av_reallocp(buf, *size);
                  if (ret < 0)
                      return ret;
              }
  
              bytestream2_get_buffer(gb, p, s);
              p   += s;
              len += s;
          } else {
              int l   = 2 + (s >> 5);
              int off = ((s & 0x1f) << 8) + 1;
  
              if (l == LZF_LONG_BACKREF)
                  l += bytestream2_get_byte(gb);
  
              off += bytestream2_get_byte(gb);
  
              if (off > len)
                  return AVERROR_INVALIDDATA;
  
              if (l > *size - len) {
                  *size += *size / 2;
                  ret = av_reallocp(buf, *size);
                  if (ret < 0)
                      return ret;
              }
  
              av_memcpy_backptr(p, off, l);
  
              p   += l;
              len += l;
          }
      }
  
      *size = len;
  
      return 0;
  }
  