Compress-Zstd
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ext/zstd/contrib/linux-kernel/0002-lib-Add-zstd-modules.patch view on Meta::CPAN
+ DStatePtr->state = DInfo.newState + lowBits;
+ return symbol;
+}
+
+ZSTD_STATIC unsigned FSE_endOfDState(const FSE_DState_t *DStatePtr) { return DStatePtr->state == 0; }
+
+/* **************************************************************
+* Tuning parameters
+****************************************************************/
+/*!MEMORY_USAGE :
+* Memory usage formula : N->2^N Bytes (examples : 10 -> 1KB; 12 -> 4KB ; 16 -> 64KB; 20 -> 1MB; etc.)
+* Increasing memory usage improves compression ratio
+* Reduced memory usage can improve speed, due to cache effect
+* Recommended max value is 14, for 16KB, which nicely fits into Intel x86 L1 cache */
+#ifndef FSE_MAX_MEMORY_USAGE
+#define FSE_MAX_MEMORY_USAGE 14
+#endif
+#ifndef FSE_DEFAULT_MEMORY_USAGE
+#define FSE_DEFAULT_MEMORY_USAGE 13
+#endif
+
ext/zstd/contrib/linux-kernel/lib/zstd/fse.h view on Meta::CPAN
DStatePtr->state = DInfo.newState + lowBits;
return symbol;
}
ZSTD_STATIC unsigned FSE_endOfDState(const FSE_DState_t *DStatePtr) { return DStatePtr->state == 0; }
/* **************************************************************
* Tuning parameters
****************************************************************/
/*!MEMORY_USAGE :
* Memory usage formula : N->2^N Bytes (examples : 10 -> 1KB; 12 -> 4KB ; 16 -> 64KB; 20 -> 1MB; etc.)
* Increasing memory usage improves compression ratio
* Reduced memory usage can improve speed, due to cache effect
* Recommended max value is 14, for 16KB, which nicely fits into Intel x86 L1 cache */
#ifndef FSE_MAX_MEMORY_USAGE
#define FSE_MAX_MEMORY_USAGE 14
#endif
#ifndef FSE_DEFAULT_MEMORY_USAGE
#define FSE_DEFAULT_MEMORY_USAGE 13
#endif
ext/zstd/doc/educational_decoder/zstd_decompress.c view on Meta::CPAN
const u16 lower_mask = ((u16)1 << (bits - 1)) - 1;
const u16 threshold = ((u16)1 << bits) - 1 - (remaining + 1);
if ((val & lower_mask) < threshold) {
IO_rewind_bits(in, 1);
val = val & lower_mask;
} else if (val > lower_mask) {
val = val - threshold;
}
// "Probability is obtained from Value decoded by following formula :
// Proba = value - 1"
const i16 proba = (i16)val - 1;
// "It means value 0 becomes negative probability -1. -1 is a special
// probability, which means "less than 1". Its effect on distribution
// table is described in next paragraph. For the purpose of calculating
// cumulated distribution, it counts as one."
remaining -= proba < 0 ? -proba : proba;
frequencies[symb] = proba;
ext/zstd/doc/zstd_compression_format.md view on Meta::CPAN
The `Window_Descriptor` byte is optional.
When `Single_Segment_flag` is set, `Window_Descriptor` is not present.
In this case, `Window_Size` is `Frame_Content_Size`,
which can be any value from 0 to 2^64-1 bytes (16 ExaBytes).
| Bit numbers | 7-3 | 2-0 |
| ----------- | ---------- | ---------- |
| Field name | `Exponent` | `Mantissa` |
The minimum memory buffer size is called `Window_Size`.
It is described by the following formulas :
```
windowLog = 10 + Exponent;
windowBase = 1 << windowLog;
windowAdd = (windowBase / 8) * Mantissa;
Window_Size = windowBase + windowAdd;
```
The minimum `Window_Size` is 1 KB.
The maximum `Window_Size` is `(1<<41) + 7*(1<<38)` bytes, which is 3.75 TB.
In general, larger `Window_Size` tend to improve compression ratio,
ext/zstd/doc/zstd_compression_format.md view on Meta::CPAN
##### Offset codes
Offset codes are values ranging from `0` to `N`.
A decoder is free to limit its maximum `N` supported.
Recommendation is to support at least up to `22`.
For information, at the time of this writing.
the reference decoder supports a maximum `N` value of `31`.
An offset code is also the number of additional bits to read in __little-endian__ fashion,
and can be translated into an `Offset_Value` using the following formulas :
```
Offset_Value = (1 << offsetCode) + readNBits(offsetCode);
if (Offset_Value > 3) offset = Offset_Value - 3;
```
It means that maximum `Offset_Value` is `(2^(N+1))-1`
supporting back-reference distances up to `(2^(N+1))-4`,
but is limited by [maximum back-reference distance](#window_descriptor).
`Offset_Value` from 1 to 3 are special : they define "repeat codes".
ext/zstd/doc/zstd_compression_format.md view on Meta::CPAN
| Value read | Value decoded | Number of bits used |
| ---------- | ------------- | ------------------- |
| 0 - 97 | 0 - 97 | 7 |
| 98 - 127 | 98 - 127 | 8 |
| 128 - 225 | 0 - 97 | 7 |
| 226 - 255 | 128 - 157 | 8 |
Symbols probabilities are read one by one, in order.
Probability is obtained from Value decoded by following formula :
`Proba = value - 1`
It means value `0` becomes negative probability `-1`.
`-1` is a special probability, which means "less than 1".
Its effect on distribution table is described in the [next section].
For the purpose of calculating total allocated probability points, it counts as one.
[next section]:#from-normalized-distribution-to-decoding-tables
When a symbol has a __probability__ of `zero`,
ext/zstd/doc/zstd_compression_format.md view on Meta::CPAN
Prefix code must not exceed a maximum code length.
More bits improve accuracy but cost more header size,
and require more memory or more complex decoding operations.
This specification limits maximum code length to 11 bits.
#### Representation
All literal values from zero (included) to last present one (excluded)
are represented by `Weight` with values from `0` to `Max_Number_of_Bits`.
Transformation from `Weight` to `Number_of_Bits` follows this formula :
```
Number_of_Bits = Weight ? (Max_Number_of_Bits + 1 - Weight) : 0
```
The last symbol's `Weight` is deduced from previously decoded ones,
by completing to the nearest power of 2.
This power of 2 gives `Max_Number_of_Bits`, the depth of the current tree.
`Max_Number_of_Bits` must be <= 11,
otherwise the representation is considered corrupted.
__Example__ :
ext/zstd/doc/zstd_compression_format.md view on Meta::CPAN
| literal value | 0 | 1 | 2 | 3 | 4 | 5 |
| ---------------- | --- | --- | --- | --- | --- | --- |
| `Number_of_Bits` | 1 | 2 | 3 | 0 | 4 | 4 |
The tree depth is 4, since its longest elements uses 4 bits
(longest elements are the one with smallest frequency).
Value `5` will not be listed, as it can be determined from values for 0-4,
nor will values above `5` as they are all 0.
Values from `0` to `4` will be listed using `Weight` instead of `Number_of_Bits`.
Weight formula is :
```
Weight = Number_of_Bits ? (Max_Number_of_Bits + 1 - Number_of_Bits) : 0
```
It gives the following series of weights :
| literal value | 0 | 1 | 2 | 3 | 4 |
| ------------- | --- | --- | --- | --- | --- |
| `Weight` | 4 | 3 | 2 | 0 | 1 |
The decoder will do the inverse operation :
ext/zstd/doc/zstd_compression_format.md view on Meta::CPAN
The number of symbols to decode is determined
by tracking bitStream overflow condition:
If updating state after decoding a symbol would require more bits than
remain in the stream, it is assumed that extra bits are 0. Then,
symbols for each of the final states are decoded and the process is complete.
#### Conversion from weights to Huffman prefix codes
All present symbols shall now have a `Weight` value.
It is possible to transform weights into `Number_of_Bits`, using this formula:
```
Number_of_Bits = (Weight>0) ? Max_Number_of_Bits + 1 - Weight : 0
```
Symbols are sorted by `Weight`.
Within same `Weight`, symbols keep natural sequential order.
Symbols with a `Weight` of zero are removed.
Then, starting from lowest `Weight`, prefix codes are distributed in sequential order.
__Example__ :
Let's presume the following list of weights has been decoded :
ext/zstd/doc/zstd_manual.html view on Meta::CPAN
</p></pre><BR>
<pre><b>size_t ZSTD_findFrameCompressedSize(const void* src, size_t srcSize);
</b><p> `src` should point to the start of a ZSTD frame or skippable frame.
`srcSize` must be >= first frame size
@return : the compressed size of the first frame starting at `src`,
suitable to pass as `srcSize` to `ZSTD_decompress` or similar,
or an error code if input is invalid
</p></pre><BR>
<h3>Helper functions</h3><pre></pre><b><pre>#define ZSTD_COMPRESSBOUND(srcSize) ((srcSize) + ((srcSize)>>8) + (((srcSize) < (128<<10)) ? (((128<<10) - (srcSize)) >> 11) </b>/* margin, from 64 to 0 */ : 0)) /* this formula ensures that bound(A) + b...
size_t ZSTD_compressBound(size_t srcSize); </b>/*!< maximum compressed size in worst case single-pass scenario */<b>
unsigned ZSTD_isError(size_t code); </b>/*!< tells if a `size_t` function result is an error code */<b>
const char* ZSTD_getErrorName(size_t code); </b>/*!< provides readable string from an error code */<b>
int ZSTD_minCLevel(void); </b>/*!< minimum negative compression level allowed */<b>
int ZSTD_maxCLevel(void); </b>/*!< maximum compression level available */<b>
</pre></b><BR>
<a name="Chapter4"></a><h2>Explicit context</h2><pre></pre>
<h3>Compression context</h3><pre> When compressing many times,
it is recommended to allocate a context just once,
ext/zstd/lib/common/fse.h view on Meta::CPAN
}
#ifndef FSE_COMMONDEFS_ONLY
/* **************************************************************
* Tuning parameters
****************************************************************/
/*!MEMORY_USAGE :
* Memory usage formula : N->2^N Bytes (examples : 10 -> 1KB; 12 -> 4KB ; 16 -> 64KB; 20 -> 1MB; etc.)
* Increasing memory usage improves compression ratio
* Reduced memory usage can improve speed, due to cache effect
* Recommended max value is 14, for 16KB, which nicely fits into Intel x86 L1 cache */
#ifndef FSE_MAX_MEMORY_USAGE
# define FSE_MAX_MEMORY_USAGE 14
#endif
#ifndef FSE_DEFAULT_MEMORY_USAGE
# define FSE_DEFAULT_MEMORY_USAGE 13
#endif
ext/zstd/lib/compress/zstd_compress_internal.h view on Meta::CPAN
ZSTD_bounds const bounds = ZSTD_cParam_getBounds(cParam);
if (ZSTD_isError(bounds.error)) return 0;
if (value < bounds.lowerBound) return 0;
if (value > bounds.upperBound) return 0;
return 1;
}
/* ZSTD_minGain() :
* minimum compression required
* to generate a compress block or a compressed literals section.
* note : use same formula for both situations */
MEM_STATIC size_t ZSTD_minGain(size_t srcSize, ZSTD_strategy strat)
{
U32 const minlog = (strat>=ZSTD_btultra) ? (U32)(strat) - 1 : 6;
ZSTD_STATIC_ASSERT(ZSTD_btultra == 8);
assert(ZSTD_cParam_withinBounds(ZSTD_c_strategy, strat));
return (srcSize >> minlog) + 2;
}
/*! ZSTD_storeSeq() :
* Store a sequence (literal length, literals, offset code and match length code) into seqStore_t.
ext/zstd/lib/legacy/zstd_v01.c view on Meta::CPAN
FSE_DStream_endOfBuffer = 1,
FSE_DStream_completed = 2,
FSE_DStream_tooFar = 3 } FSE_DStream_status; /* result of FSE_reloadDStream() */
/* 1,2,4,8 would be better for bitmap combinations, but slows down performance a bit ... ?! */
/****************************************************************
* Tuning parameters
****************************************************************/
/* MEMORY_USAGE :
* Memory usage formula : N->2^N Bytes (examples : 10 -> 1KB; 12 -> 4KB ; 16 -> 64KB; 20 -> 1MB; etc.)
* Increasing memory usage improves compression ratio
* Reduced memory usage can improve speed, due to cache effect
* Recommended max value is 14, for 16KB, which nicely fits into Intel x86 L1 cache */
#define FSE_MAX_MEMORY_USAGE 14
#define FSE_DEFAULT_MEMORY_USAGE 13
/* FSE_MAX_SYMBOL_VALUE :
* Maximum symbol value authorized.
* Required for proper stack allocation */
#define FSE_MAX_SYMBOL_VALUE 255
ext/zstd/lib/legacy/zstd_v01.c view on Meta::CPAN
You can contact the author at :
- zstd source repository : https://github.com/Cyan4973/zstd
- ztsd public forum : https://groups.google.com/forum/#!forum/lz4c
*/
/****************************************************************
* Tuning parameters
*****************************************************************/
/* MEMORY_USAGE :
* Memory usage formula : N->2^N Bytes (examples : 10 -> 1KB; 12 -> 4KB ; 16 -> 64KB; 20 -> 1MB; etc.)
* Increasing memory usage improves compression ratio
* Reduced memory usage can improve speed, due to cache effect */
#define ZSTD_MEMORY_USAGE 17
/**************************************
CPU Feature Detection
**************************************/
/*
* Automated efficient unaligned memory access detection
ext/zstd/lib/legacy/zstd_v02.c view on Meta::CPAN
- FSE source repository : https://github.com/Cyan4973/FiniteStateEntropy
- Public forum : https://groups.google.com/forum/#!forum/lz4c
****************************************************************** */
#ifndef FSE_COMMONDEFS_ONLY
/****************************************************************
* Tuning parameters
****************************************************************/
/* MEMORY_USAGE :
* Memory usage formula : N->2^N Bytes (examples : 10 -> 1KB; 12 -> 4KB ; 16 -> 64KB; 20 -> 1MB; etc.)
* Increasing memory usage improves compression ratio
* Reduced memory usage can improve speed, due to cache effect
* Recommended max value is 14, for 16KB, which nicely fits into Intel x86 L1 cache */
#define FSE_MAX_MEMORY_USAGE 14
#define FSE_DEFAULT_MEMORY_USAGE 13
/* FSE_MAX_SYMBOL_VALUE :
* Maximum symbol value authorized.
* Required for proper stack allocation */
#define FSE_MAX_SYMBOL_VALUE 255
ext/zstd/lib/legacy/zstd_v02.c view on Meta::CPAN
You can contact the author at :
- zstd source repository : https://github.com/Cyan4973/zstd
- ztsd public forum : https://groups.google.com/forum/#!forum/lz4c
*/
/* ***************************************************************
* Tuning parameters
*****************************************************************/
/*!
* MEMORY_USAGE :
* Memory usage formula : N->2^N Bytes (examples : 10 -> 1KB; 12 -> 4KB ; 16 -> 64KB; 20 -> 1MB; etc.)
* Increasing memory usage improves compression ratio
* Reduced memory usage can improve speed, due to cache effect
*/
#define ZSTD_MEMORY_USAGE 17
/*!
* HEAPMODE :
* Select how default compression functions will allocate memory for their hash table,
* in memory stack (0, fastest), or in memory heap (1, requires malloc())
* Note that compression context is fairly large, as a consequence heap memory is recommended.
ext/zstd/lib/legacy/zstd_v03.c view on Meta::CPAN
- FSE source repository : https://github.com/Cyan4973/FiniteStateEntropy
- Public forum : https://groups.google.com/forum/#!forum/lz4c
****************************************************************** */
#ifndef FSE_COMMONDEFS_ONLY
/****************************************************************
* Tuning parameters
****************************************************************/
/* MEMORY_USAGE :
* Memory usage formula : N->2^N Bytes (examples : 10 -> 1KB; 12 -> 4KB ; 16 -> 64KB; 20 -> 1MB; etc.)
* Increasing memory usage improves compression ratio
* Reduced memory usage can improve speed, due to cache effect
* Recommended max value is 14, for 16KB, which nicely fits into Intel x86 L1 cache */
#define FSE_MAX_MEMORY_USAGE 14
#define FSE_DEFAULT_MEMORY_USAGE 13
/* FSE_MAX_SYMBOL_VALUE :
* Maximum symbol value authorized.
* Required for proper stack allocation */
#define FSE_MAX_SYMBOL_VALUE 255
ext/zstd/lib/legacy/zstd_v03.c view on Meta::CPAN
You can contact the author at :
- zstd source repository : https://github.com/Cyan4973/zstd
- ztsd public forum : https://groups.google.com/forum/#!forum/lz4c
*/
/* ***************************************************************
* Tuning parameters
*****************************************************************/
/*!
* MEMORY_USAGE :
* Memory usage formula : N->2^N Bytes (examples : 10 -> 1KB; 12 -> 4KB ; 16 -> 64KB; 20 -> 1MB; etc.)
* Increasing memory usage improves compression ratio
* Reduced memory usage can improve speed, due to cache effect
*/
#define ZSTD_MEMORY_USAGE 17
/*!
* HEAPMODE :
* Select how default compression functions will allocate memory for their hash table,
* in memory stack (0, fastest), or in memory heap (1, requires malloc())
* Note that compression context is fairly large, as a consequence heap memory is recommended.
ext/zstd/lib/legacy/zstd_v04.c view on Meta::CPAN
- FSE source repository : https://github.com/Cyan4973/FiniteStateEntropy
- Public forum : https://groups.google.com/forum/#!forum/lz4c
****************************************************************** */
#ifndef FSE_COMMONDEFS_ONLY
/* **************************************************************
* Tuning parameters
****************************************************************/
/*!MEMORY_USAGE :
* Memory usage formula : N->2^N Bytes (examples : 10 -> 1KB; 12 -> 4KB ; 16 -> 64KB; 20 -> 1MB; etc.)
* Increasing memory usage improves compression ratio
* Reduced memory usage can improve speed, due to cache effect
* Recommended max value is 14, for 16KB, which nicely fits into Intel x86 L1 cache */
#define FSE_MAX_MEMORY_USAGE 14
#define FSE_DEFAULT_MEMORY_USAGE 13
/*!FSE_MAX_SYMBOL_VALUE :
* Maximum symbol value authorized.
* Required for proper stack allocation */
#define FSE_MAX_SYMBOL_VALUE 255
ext/zstd/lib/legacy/zstd_v05.c view on Meta::CPAN
- FSEv05 source repository : https://github.com/Cyan4973/FiniteStateEntropy
- Public forum : https://groups.google.com/forum/#!forum/lz4c
****************************************************************** */
#ifndef FSEv05_COMMONDEFS_ONLY
/* **************************************************************
* Tuning parameters
****************************************************************/
/*!MEMORY_USAGE :
* Memory usage formula : N->2^N Bytes (examples : 10 -> 1KB; 12 -> 4KB ; 16 -> 64KB; 20 -> 1MB; etc.)
* Increasing memory usage improves compression ratio
* Reduced memory usage can improve speed, due to cache effect
* Recommended max value is 14, for 16KB, which nicely fits into Intel x86 L1 cache */
#define FSEv05_MAX_MEMORY_USAGE 14
#define FSEv05_DEFAULT_MEMORY_USAGE 13
/*!FSEv05_MAX_SYMBOL_VALUE :
* Maximum symbol value authorized.
* Required for proper stack allocation */
#define FSEv05_MAX_SYMBOL_VALUE 255
ext/zstd/lib/legacy/zstd_v06.c view on Meta::CPAN
}
#ifndef FSEv06_COMMONDEFS_ONLY
/* **************************************************************
* Tuning parameters
****************************************************************/
/*!MEMORY_USAGE :
* Memory usage formula : N->2^N Bytes (examples : 10 -> 1KB; 12 -> 4KB ; 16 -> 64KB; 20 -> 1MB; etc.)
* Increasing memory usage improves compression ratio
* Reduced memory usage can improve speed, due to cache effect
* Recommended max value is 14, for 16KB, which nicely fits into Intel x86 L1 cache */
#define FSEv06_MAX_MEMORY_USAGE 14
#define FSEv06_DEFAULT_MEMORY_USAGE 13
/*!FSEv06_MAX_SYMBOL_VALUE :
* Maximum symbol value authorized.
* Required for proper stack allocation */
#define FSEv06_MAX_SYMBOL_VALUE 255
ext/zstd/lib/legacy/zstd_v07.c view on Meta::CPAN
}
#ifndef FSEv07_COMMONDEFS_ONLY
/* **************************************************************
* Tuning parameters
****************************************************************/
/*!MEMORY_USAGE :
* Memory usage formula : N->2^N Bytes (examples : 10 -> 1KB; 12 -> 4KB ; 16 -> 64KB; 20 -> 1MB; etc.)
* Increasing memory usage improves compression ratio
* Reduced memory usage can improve speed, due to cache effect
* Recommended max value is 14, for 16KB, which nicely fits into Intel x86 L1 cache */
#define FSEv07_MAX_MEMORY_USAGE 14
#define FSEv07_DEFAULT_MEMORY_USAGE 13
/*!FSEv07_MAX_SYMBOL_VALUE :
* Maximum symbol value authorized.
* Required for proper stack allocation */
#define FSEv07_MAX_SYMBOL_VALUE 255
ext/zstd/lib/zstd.h view on Meta::CPAN
/*! ZSTD_findFrameCompressedSize() :
* `src` should point to the start of a ZSTD frame or skippable frame.
* `srcSize` must be >= first frame size
* @return : the compressed size of the first frame starting at `src`,
* suitable to pass as `srcSize` to `ZSTD_decompress` or similar,
* or an error code if input is invalid */
ZSTDLIB_API size_t ZSTD_findFrameCompressedSize(const void* src, size_t srcSize);
/*====== Helper functions ======*/
#define ZSTD_COMPRESSBOUND(srcSize) ((srcSize) + ((srcSize)>>8) + (((srcSize) < (128<<10)) ? (((128<<10) - (srcSize)) >> 11) /* margin, from 64 to 0 */ : 0)) /* this formula ensures that bound(A) + bound(B) <= bound(A+B) as long as A and B >= 128 ...
ZSTDLIB_API size_t ZSTD_compressBound(size_t srcSize); /*!< maximum compressed size in worst case single-pass scenario */
ZSTDLIB_API unsigned ZSTD_isError(size_t code); /*!< tells if a `size_t` function result is an error code */
ZSTDLIB_API const char* ZSTD_getErrorName(size_t code); /*!< provides readable string from an error code */
ZSTDLIB_API int ZSTD_minCLevel(void); /*!< minimum negative compression level allowed */
ZSTDLIB_API int ZSTD_maxCLevel(void); /*!< maximum compression level available */
/***************************************
* Explicit context
***************************************/
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