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added constant ZSTD_MAGIC_SKIPPABLE_MASK

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and updated several API comments
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Yann Collet
2018-11-13 17:36:35 -08:00
parent b83d1e7714
commit 2c8fde538f
4 changed files with 106 additions and 63 deletions
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doc/zstd_manual.html
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@@ -20,16 +20,17 @@
<li><a href="#Chapter10">Streaming decompression - HowTo</a></li>
<li><a href="#Chapter11">ADVANCED AND EXPERIMENTAL FUNCTIONS</a></li>
<li><a href="#Chapter12">Candidate API for promotion into stable</a></li>
<li><a href="#Chapter13">Frame size functions</a></li>
<li><a href="#Chapter14">Memory management</a></li>
<li><a href="#Chapter15">Advanced compression functions</a></li>
<li><a href="#Chapter16">Advanced decompression functions</a></li>
<li><a href="#Chapter17">Advanced streaming functions</a></li>
<li><a href="#Chapter18">Buffer-less and synchronous inner streaming functions</a></li>
<li><a href="#Chapter19">Buffer-less streaming compression (synchronous mode)</a></li>
<li><a href="#Chapter20">Buffer-less streaming decompression (synchronous mode)</a></li>
<li><a href="#Chapter21">New advanced API (experimental)</a></li>
<li><a href="#Chapter22">Block level API</a></li>
<li><a href="#Chapter13">Purely experimental API</a></li>
<li><a href="#Chapter14">Frame size functions</a></li>
<li><a href="#Chapter15">Memory management</a></li>
<li><a href="#Chapter16">Advanced compression functions</a></li>
<li><a href="#Chapter17">Advanced decompression functions</a></li>
<li><a href="#Chapter18">Advanced streaming functions</a></li>
<li><a href="#Chapter19">Buffer-less and synchronous inner streaming functions</a></li>
<li><a href="#Chapter20">Buffer-less streaming compression (synchronous mode)</a></li>
<li><a href="#Chapter21">Buffer-less streaming decompression (synchronous mode)</a></li>
<li><a href="#Chapter22">New advanced API (experimental)</a></li>
<li><a href="#Chapter23">Block level API</a></li>
</ol>
<hr>
<a name="Chapter1"></a><h2>Introduction</h2><pre>
@@ -356,23 +357,38 @@ size_t ZSTD_decompressStream(ZSTD_DStream* zds, ZSTD_outBuffer* output, ZSTD_inB
<pre><b>int ZSTD_minCLevel(void); </b>/*!< minimum negative compression level allowed */<b>
</b></pre><BR>
<pre><b>typedef enum { ZSTD_fast=1, ZSTD_dfast, ZSTD_greedy, ZSTD_lazy, ZSTD_lazy2,
ZSTD_btlazy2, ZSTD_btopt, ZSTD_btultra } ZSTD_strategy; </b>/* from faster to stronger */<b>
<a name="Chapter13"></a><h2>Purely experimental API</h2><pre>
The following symbols and constants are not planned
to join "stable API" status anytime soon.
Some of them might even be removed in the future.
<BR></pre>
<pre><b>typedef enum { ZSTD_fast=1,
ZSTD_dfast=2,
ZSTD_greedy=3,
ZSTD_lazy=4,
ZSTD_lazy2=5,
ZSTD_btlazy2=6,
ZSTD_btopt=7,
ZSTD_btultra=8
</b>/* note : new strategies might be added in the future */<b>
} ZSTD_strategy;
</b></pre><BR>
<pre><b>typedef struct {
unsigned windowLog; </b>/**< largest match distance : larger == more compression, more memory needed during decompression */<b>
unsigned chainLog; </b>/**< fully searched segment : larger == more compression, slower, more memory (useless for fast) */<b>
unsigned hashLog; </b>/**< dispatch table : larger == faster, more memory */<b>
unsigned searchLog; </b>/**< nb of searches : larger == more compression, slower */<b>
unsigned searchLength; </b>/**< match length searched : larger == faster decompression, sometimes less compression */<b>
unsigned targetLength; </b>/**< acceptable match size for optimal parser (only) : larger == more compression, slower */<b>
ZSTD_strategy strategy;
unsigned windowLog; </b>/**< largest match distance : larger == more compression, more memory needed during decompression */<b>
unsigned chainLog; </b>/**< fully searched segment : larger == more compression, slower, more memory (useless for fast) */<b>
unsigned hashLog; </b>/**< dispatch table : larger == faster, more memory */<b>
unsigned searchLog; </b>/**< nb of searches : larger == more compression, slower */<b>
unsigned searchLength; </b>/**< match length searched : larger == faster decompression, sometimes less compression */<b>
unsigned targetLength; </b>/**< acceptable match size for optimal parser (only) : larger == more compression, slower */<b>
ZSTD_strategy strategy; </b>/**< see ZSTD_strategy definition above */<b>
} ZSTD_compressionParameters;
</b></pre><BR>
<pre><b>typedef struct {
unsigned contentSizeFlag; </b>/**< 1: content size will be in frame header (when known) */<b>
unsigned checksumFlag; </b>/**< 1: generate a 32-bits checksum at end of frame, for error detection */<b>
unsigned noDictIDFlag; </b>/**< 1: no dictID will be saved into frame header (if dictionary compression) */<b>
unsigned checksumFlag; </b>/**< 1: generate a 32-bits checksum using XXH64 algorithm at end of frame, for error detection */<b>
unsigned noDictIDFlag; </b>/**< 1: no dictID will be saved into frame header (dictID is only useful for dictionary compression) */<b>
} ZSTD_frameParameters;
</b></pre><BR>
<pre><b>typedef struct {
@@ -381,17 +397,17 @@ size_t ZSTD_decompressStream(ZSTD_DStream* zds, ZSTD_outBuffer* output, ZSTD_inB
} ZSTD_parameters;
</b></pre><BR>
<pre><b>typedef enum {
ZSTD_dct_auto = 0, </b>/* dictionary is "full" when starting with ZSTD_MAGIC_DICTIONARY, otherwise it is "rawContent" */<b>
ZSTD_dct_rawContent, </b>/* ensures dictionary is always loaded as rawContent, even if it starts with ZSTD_MAGIC_DICTIONARY */<b>
ZSTD_dct_fullDict </b>/* refuses to load a dictionary if it does not respect Zstandard's specification */<b>
ZSTD_dct_auto = 0, </b>/* dictionary is "full" when starting with ZSTD_MAGIC_DICTIONARY, otherwise it is "rawContent" */<b>
ZSTD_dct_rawContent = 1, </b>/* ensures dictionary is always loaded as rawContent, even if it starts with ZSTD_MAGIC_DICTIONARY */<b>
ZSTD_dct_fullDict = 2 </b>/* refuses to load a dictionary if it does not respect Zstandard's specification, starting with ZSTD_MAGIC_DICTIONARY */<b>
} ZSTD_dictContentType_e;
</b></pre><BR>
<pre><b>typedef enum {
ZSTD_dlm_byCopy = 0, </b>/**< Copy dictionary content internally */<b>
ZSTD_dlm_byRef, </b>/**< Reference dictionary content -- the dictionary buffer must outlive its users. */<b>
ZSTD_dlm_byCopy = 0, </b>/**< Copy dictionary content internally */<b>
ZSTD_dlm_byRef = 1, </b>/**< Reference dictionary content -- the dictionary buffer must outlive its users. */<b>
} ZSTD_dictLoadMethod_e;
</b></pre><BR>
<a name="Chapter13"></a><h2>Frame size functions</h2><pre></pre>
<a name="Chapter14"></a><h2>Frame size functions</h2><pre></pre>
<pre><b>size_t ZSTD_findFrameCompressedSize(const void* src, size_t srcSize);
</b><p> `src` should point to the start of a ZSTD encoded frame or skippable frame
@@ -430,7 +446,7 @@ size_t ZSTD_decompressStream(ZSTD_DStream* zds, ZSTD_outBuffer* output, ZSTD_inB
or an error code (if srcSize is too small)
</p></pre><BR>
<a name="Chapter14"></a><h2>Memory management</h2><pre></pre>
<a name="Chapter15"></a><h2>Memory management</h2><pre></pre>
<pre><b>size_t ZSTD_sizeof_CCtx(const ZSTD_CCtx* cctx);
size_t ZSTD_sizeof_DCtx(const ZSTD_DCtx* dctx);
@@ -520,7 +536,7 @@ static ZSTD_customMem const ZSTD_defaultCMem = { NULL, NULL, NULL }; </b>/**< t
</p></pre><BR>
<a name="Chapter15"></a><h2>Advanced compression functions</h2><pre></pre>
<a name="Chapter16"></a><h2>Advanced compression functions</h2><pre></pre>
<pre><b>ZSTD_CDict* ZSTD_createCDict_byReference(const void* dictBuffer, size_t dictSize, int compressionLevel);
</b><p> Create a digested dictionary for compression
@@ -562,7 +578,7 @@ static ZSTD_customMem const ZSTD_defaultCMem = { NULL, NULL, NULL }; </b>/**< t
</b><p> Same as ZSTD_compress_usingCDict(), with fine-tune control over frame parameters
</p></pre><BR>
<a name="Chapter16"></a><h2>Advanced decompression functions</h2><pre></pre>
<a name="Chapter17"></a><h2>Advanced decompression functions</h2><pre></pre>
<pre><b>unsigned ZSTD_isFrame(const void* buffer, size_t size);
</b><p> Tells if the content of `buffer` starts with a valid Frame Identifier.
@@ -602,7 +618,7 @@ static ZSTD_customMem const ZSTD_defaultCMem = { NULL, NULL, NULL }; </b>/**< t
When identifying the exact failure cause, it's possible to use ZSTD_getFrameHeader(), which will provide a more precise error code.
</p></pre><BR>
<a name="Chapter17"></a><h2>Advanced streaming functions</h2><pre></pre>
<a name="Chapter18"></a><h2>Advanced streaming functions</h2><pre></pre>
<h3>Advanced Streaming compression functions</h3><pre></pre><b><pre>size_t ZSTD_initCStream_srcSize(ZSTD_CStream* zcs, int compressionLevel, unsigned long long pledgedSrcSize); </b>/**< pledgedSrcSize must be correct. If it is not known at init time, use ZSTD_CONTENTSIZE_UNKNOWN. Note that, for compatibility with older programs, "0" also disables frame content size field. It may be enabled in the future. */<b>
size_t ZSTD_initCStream_usingDict(ZSTD_CStream* zcs, const void* dict, size_t dictSize, int compressionLevel); </b>/**< creates of an internal CDict (incompatible with static CCtx), except if dict == NULL or dictSize < 8, in which case no dict is used. Note: dict is loaded with ZSTD_dm_auto (treated as a full zstd dictionary if it begins with ZSTD_MAGIC_DICTIONARY, else as raw content) and ZSTD_dlm_byCopy.*/<b>
@@ -653,14 +669,14 @@ size_t ZSTD_initDStream_usingDict(ZSTD_DStream* zds, const void* dict, size_t di
size_t ZSTD_initDStream_usingDDict(ZSTD_DStream* zds, const ZSTD_DDict* ddict); </b>/**< note : ddict is referenced, it must outlive decompression session */<b>
size_t ZSTD_resetDStream(ZSTD_DStream* zds); </b>/**< re-use decompression parameters from previous init; saves dictionary loading */<b>
</pre></b><BR>
<a name="Chapter18"></a><h2>Buffer-less and synchronous inner streaming functions</h2><pre>
<a name="Chapter19"></a><h2>Buffer-less and synchronous inner streaming functions</h2><pre>
This is an advanced API, giving full control over buffer management, for users which need direct control over memory.
But it's also a complex one, with several restrictions, documented below.
Prefer normal streaming API for an easier experience.
<BR></pre>
<a name="Chapter19"></a><h2>Buffer-less streaming compression (synchronous mode)</h2><pre>
<a name="Chapter20"></a><h2>Buffer-less streaming compression (synchronous mode)</h2><pre>
A ZSTD_CCtx object is required to track streaming operations.
Use ZSTD_createCCtx() / ZSTD_freeCCtx() to manage resource.
ZSTD_CCtx object can be re-used multiple times within successive compression operations.
@@ -696,7 +712,7 @@ size_t ZSTD_compressBegin_usingCDict(ZSTD_CCtx* cctx, const ZSTD_CDict* cdict);
size_t ZSTD_compressBegin_usingCDict_advanced(ZSTD_CCtx* const cctx, const ZSTD_CDict* const cdict, ZSTD_frameParameters const fParams, unsigned long long const pledgedSrcSize); </b>/* compression parameters are already set within cdict. pledgedSrcSize must be correct. If srcSize is not known, use macro ZSTD_CONTENTSIZE_UNKNOWN */<b>
size_t ZSTD_copyCCtx(ZSTD_CCtx* cctx, const ZSTD_CCtx* preparedCCtx, unsigned long long pledgedSrcSize); </b>/**< note: if pledgedSrcSize is not known, use ZSTD_CONTENTSIZE_UNKNOWN */<b>
</pre></b><BR>
<a name="Chapter20"></a><h2>Buffer-less streaming decompression (synchronous mode)</h2><pre>
<a name="Chapter21"></a><h2>Buffer-less streaming decompression (synchronous mode)</h2><pre>
A ZSTD_DCtx object is required to track streaming operations.
Use ZSTD_createDCtx() / ZSTD_freeDCtx() to manage it.
A ZSTD_DCtx object can be re-used multiple times.
@@ -787,7 +803,7 @@ size_t ZSTD_decodingBufferSize_min(unsigned long long windowSize, unsigned long
</pre></b><BR>
<pre><b>typedef enum { ZSTDnit_frameHeader, ZSTDnit_blockHeader, ZSTDnit_block, ZSTDnit_lastBlock, ZSTDnit_checksum, ZSTDnit_skippableFrame } ZSTD_nextInputType_e;
</b></pre><BR>
<a name="Chapter21"></a><h2>New advanced API (experimental)</h2><pre></pre>
<a name="Chapter22"></a><h2>New advanced API (experimental)</h2><pre></pre>
<pre><b>typedef enum {
</b>/* Opened question : should we have a format ZSTD_f_auto ?<b>
@@ -1283,7 +1299,7 @@ size_t ZSTD_DCtx_refPrefix_advanced(ZSTD_DCtx* dctx,
</p></pre><BR>
<a name="Chapter22"></a><h2>Block level API</h2><pre></pre>
<a name="Chapter23"></a><h2>Block level API</h2><pre></pre>
<pre><b></b><p> Frame metadata cost is typically ~18 bytes, which can be non-negligible for very small blocks (< 100 bytes).
User will have to take in charge required information to regenerate data, such as compressed and content sizes.