| Index: xz/src/liblzma/api/lzma/lzma.h
|
| ===================================================================
|
| --- xz/src/liblzma/api/lzma/lzma.h (revision 0)
|
| +++ xz/src/liblzma/api/lzma/lzma.h (revision 0)
|
| @@ -0,0 +1,397 @@
|
| +/**
|
| + * \file lzma/lzma.h
|
| + * \brief LZMA1 and LZMA2 filters
|
| + */
|
| +
|
| +/*
|
| + * Author: Lasse Collin
|
| + *
|
| + * This file has been put into the public domain.
|
| + * You can do whatever you want with this file.
|
| + *
|
| + * See ../lzma.h for information about liblzma as a whole.
|
| + */
|
| +
|
| +#ifndef LZMA_H_INTERNAL
|
| +# error Never include this file directly. Use <lzma.h> instead.
|
| +#endif
|
| +
|
| +
|
| +/**
|
| + * \brief LZMA1 Filter ID
|
| + *
|
| + * LZMA1 is the very same thing as what was called just LZMA in LZMA Utils,
|
| + * 7-Zip, and LZMA SDK. It's called LZMA1 here to prevent developers from
|
| + * accidentally using LZMA when they actually want LZMA2.
|
| + *
|
| + * LZMA1 shouldn't be used for new applications unless you _really_ know
|
| + * what you are doing. LZMA2 is almost always a better choice.
|
| + */
|
| +#define LZMA_FILTER_LZMA1 LZMA_VLI_C(0x4000000000000001)
|
| +
|
| +/**
|
| + * \brief LZMA2 Filter ID
|
| + *
|
| + * Usually you want this instead of LZMA1. Compared to LZMA1, LZMA2 adds
|
| + * support for LZMA_SYNC_FLUSH, uncompressed chunks (smaller expansion
|
| + * when trying to compress uncompressible data), possibility to change
|
| + * lc/lp/pb in the middle of encoding, and some other internal improvements.
|
| + */
|
| +#define LZMA_FILTER_LZMA2 LZMA_VLI_C(0x21)
|
| +
|
| +
|
| +/**
|
| + * \brief Match finders
|
| + *
|
| + * Match finder has major effect on both speed and compression ratio.
|
| + * Usually hash chains are faster than binary trees.
|
| + *
|
| + * The memory usage formulas are only rough estimates, which are closest to
|
| + * reality when dict_size is a power of two. The formulas are more complex
|
| + * in reality, and can also change a little between liblzma versions. Use
|
| + * lzma_memusage_encoder() to get more accurate estimate of memory usage.
|
| + */
|
| +typedef enum {
|
| + LZMA_MF_HC3 = 0x03,
|
| + /**<
|
| + * \brief Hash Chain with 2- and 3-byte hashing
|
| + *
|
| + * Minimum nice_len: 3
|
| + *
|
| + * Memory usage:
|
| + * - dict_size <= 16 MiB: dict_size * 7.5
|
| + * - dict_size > 16 MiB: dict_size * 5.5 + 64 MiB
|
| + */
|
| +
|
| + LZMA_MF_HC4 = 0x04,
|
| + /**<
|
| + * \brief Hash Chain with 2-, 3-, and 4-byte hashing
|
| + *
|
| + * Minimum nice_len: 4
|
| + *
|
| + * Memory usage: dict_size * 7.5
|
| + */
|
| +
|
| + LZMA_MF_BT2 = 0x12,
|
| + /**<
|
| + * \brief Binary Tree with 2-byte hashing
|
| + *
|
| + * Minimum nice_len: 2
|
| + *
|
| + * Memory usage: dict_size * 9.5
|
| + */
|
| +
|
| + LZMA_MF_BT3 = 0x13,
|
| + /**<
|
| + * \brief Binary Tree with 2- and 3-byte hashing
|
| + *
|
| + * Minimum nice_len: 3
|
| + *
|
| + * Memory usage:
|
| + * - dict_size <= 16 MiB: dict_size * 11.5
|
| + * - dict_size > 16 MiB: dict_size * 9.5 + 64 MiB
|
| + */
|
| +
|
| + LZMA_MF_BT4 = 0x14
|
| + /**<
|
| + * \brief Binary Tree with 2-, 3-, and 4-byte hashing
|
| + *
|
| + * Minimum nice_len: 4
|
| + *
|
| + * Memory usage: dict_size * 11.5
|
| + */
|
| +} lzma_match_finder;
|
| +
|
| +
|
| +/**
|
| + * \brief Test if given match finder is supported
|
| + *
|
| + * Return true if the given match finder is supported by this liblzma build.
|
| + * Otherwise false is returned. It is safe to call this with a value that
|
| + * isn't listed in lzma_match_finder enumeration; the return value will be
|
| + * false.
|
| + *
|
| + * There is no way to list which match finders are available in this
|
| + * particular liblzma version and build. It would be useless, because
|
| + * a new match finder, which the application developer wasn't aware,
|
| + * could require giving additional options to the encoder that the older
|
| + * match finders don't need.
|
| + */
|
| +extern LZMA_API(lzma_bool) lzma_mf_is_supported(lzma_match_finder match_finder)
|
| + lzma_nothrow lzma_attr_const;
|
| +
|
| +
|
| +/**
|
| + * \brief Compression modes
|
| + *
|
| + * This selects the function used to analyze the data produced by the match
|
| + * finder.
|
| + */
|
| +typedef enum {
|
| + LZMA_MODE_FAST = 1,
|
| + /**<
|
| + * \brief Fast compression
|
| + *
|
| + * Fast mode is usually at its best when combined with
|
| + * a hash chain match finder.
|
| + */
|
| +
|
| + LZMA_MODE_NORMAL = 2
|
| + /**<
|
| + * \brief Normal compression
|
| + *
|
| + * This is usually notably slower than fast mode. Use this
|
| + * together with binary tree match finders to expose the
|
| + * full potential of the LZMA1 or LZMA2 encoder.
|
| + */
|
| +} lzma_mode;
|
| +
|
| +
|
| +/**
|
| + * \brief Test if given compression mode is supported
|
| + *
|
| + * Return true if the given compression mode is supported by this liblzma
|
| + * build. Otherwise false is returned. It is safe to call this with a value
|
| + * that isn't listed in lzma_mode enumeration; the return value will be false.
|
| + *
|
| + * There is no way to list which modes are available in this particular
|
| + * liblzma version and build. It would be useless, because a new compression
|
| + * mode, which the application developer wasn't aware, could require giving
|
| + * additional options to the encoder that the older modes don't need.
|
| + */
|
| +extern LZMA_API(lzma_bool) lzma_mode_is_supported(lzma_mode mode)
|
| + lzma_nothrow lzma_attr_const;
|
| +
|
| +
|
| +/**
|
| + * \brief Options specific to the LZMA1 and LZMA2 filters
|
| + *
|
| + * Since LZMA1 and LZMA2 share most of the code, it's simplest to share
|
| + * the options structure too. For encoding, all but the reserved variables
|
| + * need to be initialized unless specifically mentioned otherwise.
|
| + *
|
| + * For raw decoding, both LZMA1 and LZMA2 need dict_size, preset_dict, and
|
| + * preset_dict_size (if preset_dict != NULL). LZMA1 needs also lc, lp, and pb.
|
| + */
|
| +typedef struct {
|
| + /**
|
| + * \brief Dictionary size in bytes
|
| + *
|
| + * Dictionary size indicates how many bytes of the recently processed
|
| + * uncompressed data is kept in memory. One method to reduce size of
|
| + * the uncompressed data is to store distance-length pairs, which
|
| + * indicate what data to repeat from the dictionary buffer. Thus,
|
| + * the bigger the dictionary, the better the compression ratio
|
| + * usually is.
|
| + *
|
| + * Maximum size of the dictionary depends on multiple things:
|
| + * - Memory usage limit
|
| + * - Available address space (not a problem on 64-bit systems)
|
| + * - Selected match finder (encoder only)
|
| + *
|
| + * Currently the maximum dictionary size for encoding is 1.5 GiB
|
| + * (i.e. (UINT32_C(1) << 30) + (UINT32_C(1) << 29)) even on 64-bit
|
| + * systems for certain match finder implementation reasons. In the
|
| + * future, there may be match finders that support bigger
|
| + * dictionaries.
|
| + *
|
| + * Decoder already supports dictionaries up to 4 GiB - 1 B (i.e.
|
| + * UINT32_MAX), so increasing the maximum dictionary size of the
|
| + * encoder won't cause problems for old decoders.
|
| + *
|
| + * Because extremely small dictionaries sizes would have unneeded
|
| + * overhead in the decoder, the minimum dictionary size is 4096 bytes.
|
| + *
|
| + * \note When decoding, too big dictionary does no other harm
|
| + * than wasting memory.
|
| + */
|
| + uint32_t dict_size;
|
| +# define LZMA_DICT_SIZE_MIN UINT32_C(4096)
|
| +# define LZMA_DICT_SIZE_DEFAULT (UINT32_C(1) << 23)
|
| +
|
| + /**
|
| + * \brief Pointer to an initial dictionary
|
| + *
|
| + * It is possible to initialize the LZ77 history window using
|
| + * a preset dictionary. It is useful when compressing many
|
| + * similar, relatively small chunks of data independently from
|
| + * each other. The preset dictionary should contain typical
|
| + * strings that occur in the files being compressed. The most
|
| + * probable strings should be near the end of the preset dictionary.
|
| + *
|
| + * This feature should be used only in special situations. For
|
| + * now, it works correctly only with raw encoding and decoding.
|
| + * Currently none of the container formats supported by
|
| + * liblzma allow preset dictionary when decoding, thus if
|
| + * you create a .xz or .lzma file with preset dictionary, it
|
| + * cannot be decoded with the regular decoder functions. In the
|
| + * future, the .xz format will likely get support for preset
|
| + * dictionary though.
|
| + */
|
| + const uint8_t *preset_dict;
|
| +
|
| + /**
|
| + * \brief Size of the preset dictionary
|
| + *
|
| + * Specifies the size of the preset dictionary. If the size is
|
| + * bigger than dict_size, only the last dict_size bytes are
|
| + * processed.
|
| + *
|
| + * This variable is read only when preset_dict is not NULL.
|
| + * If preset_dict is not NULL but preset_dict_size is zero,
|
| + * no preset dictionary is used (identical to only setting
|
| + * preset_dict to NULL).
|
| + */
|
| + uint32_t preset_dict_size;
|
| +
|
| + /**
|
| + * \brief Number of literal context bits
|
| + *
|
| + * How many of the highest bits of the previous uncompressed
|
| + * eight-bit byte (also known as `literal') are taken into
|
| + * account when predicting the bits of the next literal.
|
| + *
|
| + * \todo Example
|
| + *
|
| + * There is a limit that applies to literal context bits and literal
|
| + * position bits together: lc + lp <= 4. Without this limit the
|
| + * decoding could become very slow, which could have security related
|
| + * results in some cases like email servers doing virus scanning.
|
| + * This limit also simplifies the internal implementation in liblzma.
|
| + *
|
| + * There may be LZMA1 streams that have lc + lp > 4 (maximum possible
|
| + * lc would be 8). It is not possible to decode such streams with
|
| + * liblzma.
|
| + */
|
| + uint32_t lc;
|
| +# define LZMA_LCLP_MIN 0
|
| +# define LZMA_LCLP_MAX 4
|
| +# define LZMA_LC_DEFAULT 3
|
| +
|
| + /**
|
| + * \brief Number of literal position bits
|
| + *
|
| + * How many of the lowest bits of the current position (number
|
| + * of bytes from the beginning of the uncompressed data) in the
|
| + * uncompressed data is taken into account when predicting the
|
| + * bits of the next literal (a single eight-bit byte).
|
| + *
|
| + * \todo Example
|
| + */
|
| + uint32_t lp;
|
| +# define LZMA_LP_DEFAULT 0
|
| +
|
| + /**
|
| + * \brief Number of position bits
|
| + *
|
| + * How many of the lowest bits of the current position in the
|
| + * uncompressed data is taken into account when estimating
|
| + * probabilities of matches. A match is a sequence of bytes for
|
| + * which a matching sequence is found from the dictionary and
|
| + * thus can be stored as distance-length pair.
|
| + *
|
| + * Example: If most of the matches occur at byte positions of
|
| + * 8 * n + 3, that is, 3, 11, 19, ... set pb to 3, because 2**3 == 8.
|
| + */
|
| + uint32_t pb;
|
| +# define LZMA_PB_MIN 0
|
| +# define LZMA_PB_MAX 4
|
| +# define LZMA_PB_DEFAULT 2
|
| +
|
| + /** Compression mode */
|
| + lzma_mode mode;
|
| +
|
| + /**
|
| + * \brief Nice length of a match
|
| + *
|
| + * This determines how many bytes the encoder compares from the match
|
| + * candidates when looking for the best match. Once a match of at
|
| + * least nice_len bytes long is found, the encoder stops looking for
|
| + * better candidates and encodes the match. (Naturally, if the found
|
| + * match is actually longer than nice_len, the actual length is
|
| + * encoded; it's not truncated to nice_len.)
|
| + *
|
| + * Bigger values usually increase the compression ratio and
|
| + * compression time. For most files, 32 to 128 is a good value,
|
| + * which gives very good compression ratio at good speed.
|
| + *
|
| + * The exact minimum value depends on the match finder. The maximum
|
| + * is 273, which is the maximum length of a match that LZMA1 and
|
| + * LZMA2 can encode.
|
| + */
|
| + uint32_t nice_len;
|
| +
|
| + /** Match finder ID */
|
| + lzma_match_finder mf;
|
| +
|
| + /**
|
| + * \brief Maximum search depth in the match finder
|
| + *
|
| + * For every input byte, match finder searches through the hash chain
|
| + * or binary tree in a loop, each iteration going one step deeper in
|
| + * the chain or tree. The searching stops if
|
| + * - a match of at least nice_len bytes long is found;
|
| + * - all match candidates from the hash chain or binary tree have
|
| + * been checked; or
|
| + * - maximum search depth is reached.
|
| + *
|
| + * Maximum search depth is needed to prevent the match finder from
|
| + * wasting too much time in case there are lots of short match
|
| + * candidates. On the other hand, stopping the search before all
|
| + * candidates have been checked can reduce compression ratio.
|
| + *
|
| + * Setting depth to zero tells liblzma to use an automatic default
|
| + * value, that depends on the selected match finder and nice_len.
|
| + * The default is in the range [10, 200] or so (it may vary between
|
| + * liblzma versions).
|
| + *
|
| + * Using a bigger depth value than the default can increase
|
| + * compression ratio in some cases. There is no strict maximum value,
|
| + * but high values (thousands or millions) should be used with care:
|
| + * the encoder could remain fast enough with typical input, but
|
| + * malicious input could cause the match finder to slow down
|
| + * dramatically, possibly creating a denial of service attack.
|
| + */
|
| + uint32_t depth;
|
| +
|
| + /*
|
| + * Reserved space to allow possible future extensions without
|
| + * breaking the ABI. You should not touch these, because the names
|
| + * of these variables may change. These are and will never be used
|
| + * with the currently supported options, so it is safe to leave these
|
| + * uninitialized.
|
| + */
|
| + void *reserved_ptr1;
|
| + void *reserved_ptr2;
|
| + uint32_t reserved_int1;
|
| + uint32_t reserved_int2;
|
| + uint32_t reserved_int3;
|
| + uint32_t reserved_int4;
|
| + uint32_t reserved_int5;
|
| + uint32_t reserved_int6;
|
| + uint32_t reserved_int7;
|
| + uint32_t reserved_int8;
|
| + lzma_reserved_enum reserved_enum1;
|
| + lzma_reserved_enum reserved_enum2;
|
| + lzma_reserved_enum reserved_enum3;
|
| + lzma_reserved_enum reserved_enum4;
|
| +
|
| +} lzma_options_lzma;
|
| +
|
| +
|
| +/**
|
| + * \brief Set a compression preset to lzma_options_lzma structure
|
| + *
|
| + * 0 is the fastest and 9 is the slowest. These match the switches -0 .. -9
|
| + * of the xz command line tool. In addition, it is possible to bitwise-or
|
| + * flags to the preset. Currently only LZMA_PRESET_EXTREME is supported.
|
| + * The flags are defined in container.h, because the flags are used also
|
| + * with lzma_easy_encoder().
|
| + *
|
| + * The preset values are subject to changes between liblzma versions.
|
| + *
|
| + * This function is available only if LZMA1 or LZMA2 encoder has been enabled
|
| + * when building liblzma.
|
| + */
|
| +extern LZMA_API(lzma_bool) lzma_lzma_preset(
|
| + lzma_options_lzma *options, uint32_t preset) lzma_nothrow;
|
|
|
| Property changes on: xz/src/liblzma/api/lzma/lzma.h
|
| ___________________________________________________________________
|
| Added: svn:eol-style
|
| + LF
|
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|
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