block_encoder.h revision 292588 
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
44extern lzma_ret lzma_block_encoder_init(lzma_next_coder *next,
45		const lzma_allocator *allocator, lzma_block *block);
46
47#endif
48