src/liblzma/common/block_encoder.h

   1 ///////////////////////////////////////////////////////////////////////////////
   2 //
   3 /// \file       block_encoder.h
   4 /// \brief      Encodes .xz Blocks
   5 //
   6 //  Copyright (C) 2007 Lasse Collin
   7 //
   8 //  This library is free software; you can redistribute it and/or
   9 //  modify it under the terms of the GNU Lesser General Public
  10 //  License as published by the Free Software Foundation; either
  11 //  version 2.1 of the License, or (at your option) any later version.
  12 //
  13 //  This library is distributed in the hope that it will be useful,
  14 //  but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 //  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16 //  Lesser General Public License for more details.
  17 //
  18 ///////////////////////////////////////////////////////////////////////////////
  19
  20 #ifndef LZMA_BLOCK_ENCODER_H
  21 #define LZMA_BLOCK_ENCODER_H
  22
  23 #include "common.h"
  24
  25
  26 /// \brief      Biggest Compressed Size value that the Block encoder supports
  27 ///
  28 /// The maximum size of a single Block is limited by the maximum size of
  29 /// a Stream, which in theory is 2^63 - 3 bytes (i.e. LZMA_VLI_MAX - 3).
  30 /// While the size is really big and no one should hit it in practice, we
  31 /// take it into account in some places anyway to catch some errors e.g. if
  32 /// application passes insanely big value to some function.
  33 ///
  34 /// We could take into account the headers etc. to determine the exact
  35 /// maximum size of the Compressed Data field, but the complexity would give
  36 /// us nothing useful. Instead, limit the size of Compressed Data so that
  37 /// even with biggest possible Block Header and Check fields the total
  38 /// encoded size of the Block stays as a valid VLI. This doesn't guarantee
  39 /// that the size of the Stream doesn't grow too big, but that problem is
  40 /// taken care outside the Block handling code.
  41 ///
  42 /// ~LZMA_VLI_C(3) is to guarantee that if we need padding at the end of
  43 /// the Compressed Data field, it will still stay in the proper limit.
  44 ///
  45 /// This constant is in this file because it is needed in both
  46 /// block_encoder.c and block_buffer_encoder.c.
  47 #define COMPRESSED_SIZE_MAX ((LZMA_VLI_MAX - LZMA_BLOCK_HEADER_SIZE_MAX \
  48                 - LZMA_CHECK_SIZE_MAX) & ~LZMA_VLI_C(3))
  49
  50
  51 extern lzma_ret lzma_block_encoder_init(lzma_next_coder *next,
  52                 lzma_allocator *allocator, lzma_block *block);
  53
  54 #endif