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Diffstat (limited to 'ACE/ace/Compression/rle/RLECompressor.h')
| -rw-r--r-- | ACE/ace/Compression/rle/RLECompressor.h | 111 |
1 files changed, 111 insertions, 0 deletions
diff --git a/ACE/ace/Compression/rle/RLECompressor.h b/ACE/ace/Compression/rle/RLECompressor.h new file mode 100644 index 00000000000..db00eb12ee1 --- /dev/null +++ b/ACE/ace/Compression/rle/RLECompressor.h @@ -0,0 +1,111 @@ +// -*- C++ -*- +//============================================================================= +/** + * @file RLECompressor.h + * + * $Id: RLECompressor.h + * + * @author TAO version by + * @author Derek Dominish <derek.dominish@dsto.defence.gov.au> + * @author ACE version by + * @author Derek Dominish <derek.dominish@dsto.defence.gov.au> + * + * Run-length encoding (RLE) is a very simple form of data compression + * in which runs of data (that is, sequences in which the same data value + * occurs in many consecutive data elements) are stored as a single data + * value and count, rather than as the original run. This is most useful + * on data that contains many such runs: for example, simple graphic + * images such as icons, line drawings, and animations. It is not useful + * with files that don't have many runs as it could slightly increase the + * output size. + * ALGORITHM: This algorithm is an optimised version of the traditional + * RLE algorithm in that it behaves better with very few runs. + * + * With a run of a character where that run is >= 3 this is + * replaced with the repeat indicator 0X80 and then the repeat count OR'd + * over this ident. This repeat count is therefore has a maximum value + * of 127 (0x7F) which is to be interpreted as the next charater repeated + * another 'repeat count' times (i.e. a maximum of 128 characters can be + * represented in any single dupal). if the repeat ident is not present + * then the count is to be interpreted as a copy of the next repeat count + * charaters + 1. + * + * EXAMPLE: the following arbitary string of 67 bytes:- + * WWWWWWWWWWWWBWWWWWWWWWWWWBBBWWWWWWWWWWWWWWWWWWWWWWWWBWWWWWWWWWWWWWW + * will produce (as a HEXDUMP) of 14 bytes + * 8B 57 00 42 8B 57 82 42 97 57 00 42 8D 57 .W.B.W.B.W.B.W + */ +//============================================================================= + +#ifndef ACE_RLECOMPRESSOR_H +#define ACE_RLECOMPRESSOR_H + +#include /**/ "ace/pre.h" + +#include "ACE_RLECompression_export.h" + +#if !defined (ACE_LACKS_PRAGMA_ONCE) +# pragma once +#endif /* ACE_LACKS_PRAGMA_ONCE */ + +#include "ace/Compression/Compressor.h" +#include "ace/Singleton.h" + +ACE_BEGIN_VERSIONED_NAMESPACE_DECL + +class ACE_RLECompression_Export ACE_RLECompressor : public ACE_Compressor +{ +public: + /** + * Default constructor. Should use instance() to get global instance. + */ + ACE_RLECompressor(void); + + /** + * Compress the @a in_ptr buffer for @a in_len into the + * @a dest_ptr buffer with a maximum @a max_out_len using + * the Run Length Ecoding (RLE) algorithm. If the + * @a max_out_len is exhausted through the compress process + * then a value of -1 will be returned from the function, + * otherwise the return value will indicate the resultant + * @a out_ptr compressed buffer length. + * + * @note It is advisable that the @max_out_len be slightly + * larger of the input @a in_len (i.e. x 1.1F) to cater + * for the possibility that a reduced compressed length + * is not possible. + */ + virtual ACE_UINT64 compress( const void *in_ptr, + ACE_UINT64 in_len, + void *out_ptr, + ACE_UINT64 max_out_len ); + + /** + * DeCompress the @a in_ptr buffer for @a in_len into the + * @a out_ptr buffer with a maximum @a max_out_len using + * the Run Length Ecoding (RLE) algorithm. If the + * @a max_out_len is exhausted during decompression + * then a value of -1 will be returned from the function, + * otherwise the return value will indicate the resultant + * @a out_ptr decompressed buffer length. + */ + virtual ACE_UINT64 decompress( const void *in_ptr, + ACE_UINT64 in_len, + void *out_ptr, + ACE_UINT64 max_out_len ); +}; + +typedef class ACE_Singleton<ACE_RLECompressor, ACE_SYNCH_MUTEX> ACE_RLECompression; + +// This is needed to get only one of these defined across a set of DLLs and EXE +#if defined(ACE_RLECOMPRESSION_BUILD_DLL) + ACE_EXPORT_SINGLETON_DECLARE(ACE_Singleton, ACE_RLECompressor, ACE_SYNCH_MUTEX); +#else + ACE_IMPORT_SINGLETON_DECLARE(ACE_Singleton, ACE_RLECompressor, ACE_SYNCH_MUTEX); +#endif + +ACE_END_VERSIONED_NAMESPACE_DECL + +#include /**/ "ace/post.h" + +#endif // ACE_RLECOMPRESSOR_H
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