/*
  * lzf decompression algorithm
  * Copyright (c) 2015 Luca Barbato
  *

  * 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
  */
 
 /**
  * @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;

                 p = *buf + len;

             }
 
             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;

                 p = *buf + len;

             }
 
             av_memcpy_backptr(p, off, l);
 
             p   += l;
             len += l;
         }
     }
 
     *size = len;
 
     return 0;
 }