xref: /freebsd/contrib/xz/src/liblzma/common/block_encoder.h (revision 53f2fbcab4ca497c4bed5e5728534468e2b9e992)
1 ///////////////////////////////////////////////////////////////////////////////
2 //
3 /// \file       block_encoder.h
4 /// \brief      Encodes .xz Blocks
5 //
6 //  Author:     Lasse Collin
7 //
8 //  This file has been put into the public domain.
9 //  You can do whatever you want with this file.
10 //
11 ///////////////////////////////////////////////////////////////////////////////
12 
13 #ifndef LZMA_BLOCK_ENCODER_H
14 #define LZMA_BLOCK_ENCODER_H
15 
16 #include "common.h"
17 
18 
19 /// \brief      Biggest Compressed Size value that the Block encoder supports
20 ///
21 /// The maximum size of a single Block is limited by the maximum size of
22 /// a Stream, which in theory is 2^63 - 3 bytes (i.e. LZMA_VLI_MAX - 3).
23 /// While the size is really big and no one should hit it in practice, we
24 /// take it into account in some places anyway to catch some errors e.g. if
25 /// application passes insanely big value to some function.
26 ///
27 /// We could take into account the headers etc. to determine the exact
28 /// maximum size of the Compressed Data field, but the complexity would give
29 /// us nothing useful. Instead, limit the size of Compressed Data so that
30 /// even with biggest possible Block Header and Check fields the total
31 /// encoded size of the Block stays as a valid VLI. This doesn't guarantee
32 /// that the size of the Stream doesn't grow too big, but that problem is
33 /// taken care outside the Block handling code.
34 ///
35 /// ~LZMA_VLI_C(3) is to guarantee that if we need padding at the end of
36 /// the Compressed Data field, it will still stay in the proper limit.
37 ///
38 /// This constant is in this file because it is needed in both
39 /// block_encoder.c and block_buffer_encoder.c.
40 #define COMPRESSED_SIZE_MAX ((LZMA_VLI_MAX - LZMA_BLOCK_HEADER_SIZE_MAX \
41 		- LZMA_CHECK_SIZE_MAX) & ~LZMA_VLI_C(3))
42 
43 
44 extern lzma_ret lzma_block_encoder_init(lzma_next_coder *next,
45 		const lzma_allocator *allocator, lzma_block *block);
46 
47 #endif
48