Added snappy-1.1.3 compression library

This commit is contained in:
Jordan Cristiano 2016-03-12 17:08:51 -05:00
parent 7c9fc12b63
commit 27319d4532
15 changed files with 3756 additions and 0 deletions

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opensource@google.com

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Copyright 2011, Google Inc.
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the following disclaimer
in the documentation and/or other materials provided with the
distribution.
* Neither the name of Google Inc. nor the names of its
contributors may be used to endorse or promote products derived from
this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
===
Some of the benchmark data in testdata/ is licensed differently:
- fireworks.jpeg is Copyright 2013 Steinar H. Gunderson, and
is licensed under the Creative Commons Attribution 3.0 license
(CC-BY-3.0). See https://creativecommons.org/licenses/by/3.0/
for more information.
- kppkn.gtb is taken from the Gaviota chess tablebase set, and
is licensed under the MIT License. See
https://sites.google.com/site/gaviotachessengine/Home/endgame-tablebases-1
for more information.
- paper-100k.pdf is an excerpt (bytes 92160 to 194560) from the paper
“Combinatorial Modeling of Chromatin Features Quantitatively Predicts DNA
Replication Timing in _Drosophila_” by Federico Comoglio and Renato Paro,
which is licensed under the CC-BY license. See
http://www.ploscompbiol.org/static/license for more ifnormation.
- alice29.txt, asyoulik.txt, plrabn12.txt and lcet10.txt are from Project
Gutenberg. The first three have expired copyrights and are in the public
domain; the latter does not have expired copyright, but is still in the
public domain according to the license information
(http://www.gutenberg.org/ebooks/53).

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Installation Instructions
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Snappy v1.1.3, July 6th 2015:
This is the first release to be done from GitHub, which means that
some minor things like the ChangeLog format has changed (git log
format instead of svn log).
* Add support for Uncompress() from a Source to a Sink.
* Various minor changes to improve MSVC support; in particular,
the unit tests now compile and run under MSVC.
Snappy v1.1.2, February 28th 2014:
This is a maintenance release with no changes to the actual library
source code.
* Stop distributing benchmark data files that have unclear
or unsuitable licensing.
* Add support for padding chunks in the framing format.
Snappy v1.1.1, October 15th 2013:
* Add support for uncompressing to iovecs (scatter I/O).
The bulk of this patch was contributed by Mohit Aron.
* Speed up decompression by ~2%; much more so (~13-20%) on
a few benchmarks on given compilers and CPUs.
* Fix a few issues with MSVC compilation.
* Support truncated test data in the benchmark.
Snappy v1.1.0, January 18th 2013:
* Snappy now uses 64 kB block size instead of 32 kB. On average,
this means it compresses about 3% denser (more so for some
inputs), at the same or better speeds.
* libsnappy no longer depends on iostream.
* Some small performance improvements in compression on x86
(0.51%).
* Various portability fixes for ARM-based platforms, for MSVC,
and for GNU/Hurd.
Snappy v1.0.5, February 24th 2012:
* More speed improvements. Exactly how big will depend on
the architecture:
- 310% faster decompression for the base case (x86-64).
- ARMv7 and higher can now use unaligned accesses,
and will see about 30% faster decompression and
2040% faster compression.
- 32-bit platforms (ARM and 32-bit x86) will see 25%
faster compression.
These are all cumulative (e.g., ARM gets all three speedups).
* Fixed an issue where the unit test would crash on system
with less than 256 MB address space available,
e.g. some embedded platforms.
* Added a framing format description, for use over e.g. HTTP,
or for a command-line compressor. We do not have any
implementations of this at the current point, but there seems
to be enough of a general interest in the topic.
Also make the format description slightly clearer.
* Remove some compile-time warnings in -Wall
(mostly signed/unsigned comparisons), for easier embedding
into projects that use -Wall -Werror.
Snappy v1.0.4, September 15th 2011:
* Speeded up the decompressor somewhat; typically about 28%
for Core i7, in 64-bit mode (comparable for Opteron).
Somewhat more for some tests, almost no gain for others.
* Make Snappy compile on certain platforms it didn't before
(Solaris with SunPro C++, HP-UX, AIX).
* Correct some minor errors in the format description.
Snappy v1.0.3, June 2nd 2011:
* Speeded up the decompressor somewhat; about 3-6% for Core 2,
6-13% for Core i7, and 5-12% for Opteron (all in 64-bit mode).
* Added compressed format documentation. This text is new,
but an earlier version from Zeev Tarantov was used as reference.
* Only link snappy_unittest against -lz and other autodetected
libraries, not libsnappy.so (which doesn't need any such dependency).
* Fixed some display issues in the microbenchmarks, one of which would
frequently make the test crash on GNU/Hurd.
Snappy v1.0.2, April 29th 2011:
* Relicense to a BSD-type license.
* Added C bindings, contributed by Martin Gieseking.
* More Win32 fixes, in particular for MSVC.
* Replace geo.protodata with a newer version.
* Fix timing inaccuracies in the unit test when comparing Snappy
to other algorithms.
Snappy v1.0.1, March 25th 2011:
This is a maintenance release, mostly containing minor fixes.
There is no new functionality. The most important fixes include:
* The COPYING file and all licensing headers now correctly state that
Snappy is licensed under the Apache 2.0 license.
* snappy_unittest should now compile natively under Windows,
as well as on embedded systems with no mmap().
* Various autotools nits have been fixed.
Snappy v1.0, March 17th 2011:
* Initial version.

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Snappy, a fast compressor/decompressor.
Introduction
============
Snappy is a compression/decompression library. It does not aim for maximum
compression, or compatibility with any other compression library; instead,
it aims for very high speeds and reasonable compression. For instance,
compared to the fastest mode of zlib, Snappy is an order of magnitude faster
for most inputs, but the resulting compressed files are anywhere from 20% to
100% bigger. (For more information, see "Performance", below.)
Snappy has the following properties:
* Fast: Compression speeds at 250 MB/sec and beyond, with no assembler code.
See "Performance" below.
* Stable: Over the last few years, Snappy has compressed and decompressed
petabytes of data in Google's production environment. The Snappy bitstream
format is stable and will not change between versions.
* Robust: The Snappy decompressor is designed not to crash in the face of
corrupted or malicious input.
* Free and open source software: Snappy is licensed under a BSD-type license.
For more information, see the included COPYING file.
Snappy has previously been called "Zippy" in some Google presentations
and the like.
Performance
===========
Snappy is intended to be fast. On a single core of a Core i7 processor
in 64-bit mode, it compresses at about 250 MB/sec or more and decompresses at
about 500 MB/sec or more. (These numbers are for the slowest inputs in our
benchmark suite; others are much faster.) In our tests, Snappy usually
is faster than algorithms in the same class (e.g. LZO, LZF, FastLZ, QuickLZ,
etc.) while achieving comparable compression ratios.
Typical compression ratios (based on the benchmark suite) are about 1.5-1.7x
for plain text, about 2-4x for HTML, and of course 1.0x for JPEGs, PNGs and
other already-compressed data. Similar numbers for zlib in its fastest mode
are 2.6-2.8x, 3-7x and 1.0x, respectively. More sophisticated algorithms are
capable of achieving yet higher compression rates, although usually at the
expense of speed. Of course, compression ratio will vary significantly with
the input.
Although Snappy should be fairly portable, it is primarily optimized
for 64-bit x86-compatible processors, and may run slower in other environments.
In particular:
- Snappy uses 64-bit operations in several places to process more data at
once than would otherwise be possible.
- Snappy assumes unaligned 32- and 64-bit loads and stores are cheap.
On some platforms, these must be emulated with single-byte loads
and stores, which is much slower.
- Snappy assumes little-endian throughout, and needs to byte-swap data in
several places if running on a big-endian platform.
Experience has shown that even heavily tuned code can be improved.
Performance optimizations, whether for 64-bit x86 or other platforms,
are of course most welcome; see "Contact", below.
Usage
=====
Note that Snappy, both the implementation and the main interface,
is written in C++. However, several third-party bindings to other languages
are available; see the Google Code page at http://code.google.com/p/snappy/
for more information. Also, if you want to use Snappy from C code, you can
use the included C bindings in snappy-c.h.
To use Snappy from your own C++ program, include the file "snappy.h" from
your calling file, and link against the compiled library.
There are many ways to call Snappy, but the simplest possible is
snappy::Compress(input.data(), input.size(), &output);
and similarly
snappy::Uncompress(input.data(), input.size(), &output);
where "input" and "output" are both instances of std::string.
There are other interfaces that are more flexible in various ways, including
support for custom (non-array) input sources. See the header file for more
information.
Tests and benchmarks
====================
When you compile Snappy, snappy_unittest is compiled in addition to the
library itself. You do not need it to use the compressor from your own library,
but it contains several useful components for Snappy development.
First of all, it contains unit tests, verifying correctness on your machine in
various scenarios. If you want to change or optimize Snappy, please run the
tests to verify you have not broken anything. Note that if you have the
Google Test library installed, unit test behavior (especially failures) will be
significantly more user-friendly. You can find Google Test at
http://code.google.com/p/googletest/
You probably also want the gflags library for handling of command-line flags;
you can find it at
http://code.google.com/p/google-gflags/
In addition to the unit tests, snappy contains microbenchmarks used to
tune compression and decompression performance. These are automatically run
before the unit tests, but you can disable them using the flag
--run_microbenchmarks=false if you have gflags installed (otherwise you will
need to edit the source).
Finally, snappy can benchmark Snappy against a few other compression libraries
(zlib, LZO, LZF, FastLZ and QuickLZ), if they were detected at configure time.
To benchmark using a given file, give the compression algorithm you want to test
Snappy against (e.g. --zlib) and then a list of one or more file names on the
command line. The testdata/ directory contains the files used by the
microbenchmark, which should provide a reasonably balanced starting point for
benchmarking. (Note that baddata[1-3].snappy are not intended as benchmarks; they
are used to verify correctness in the presence of corrupted data in the unit
test.)
Contact
=======
Snappy is distributed through Google Code. For the latest version, a bug tracker,
and other information, see
http://code.google.com/p/snappy/

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/*
* Copyright 2011 Martin Gieseking <martin.gieseking@uos.de>.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* Plain C interface (a wrapper around the C++ implementation).
*/
#ifndef THIRD_PARTY_SNAPPY_OPENSOURCE_SNAPPY_C_H_
#define THIRD_PARTY_SNAPPY_OPENSOURCE_SNAPPY_C_H_
#ifdef __cplusplus
extern "C" {
#endif
#include <stddef.h>
/*
* Return values; see the documentation for each function to know
* what each can return.
*/
typedef enum {
SNAPPY_OK = 0,
SNAPPY_INVALID_INPUT = 1,
SNAPPY_BUFFER_TOO_SMALL = 2
} snappy_status;
/*
* Takes the data stored in "input[0..input_length-1]" and stores
* it in the array pointed to by "compressed".
*
* <compressed_length> signals the space available in "compressed".
* If it is not at least equal to "snappy_max_compressed_length(input_length)",
* SNAPPY_BUFFER_TOO_SMALL is returned. After successful compression,
* <compressed_length> contains the true length of the compressed output,
* and SNAPPY_OK is returned.
*
* Example:
* size_t output_length = snappy_max_compressed_length(input_length);
* char* output = (char*)malloc(output_length);
* if (snappy_compress(input, input_length, output, &output_length)
* == SNAPPY_OK) {
* ... Process(output, output_length) ...
* }
* free(output);
*/
snappy_status snappy_compress(const char* input,
size_t input_length,
char* compressed,
size_t* compressed_length);
/*
* Given data in "compressed[0..compressed_length-1]" generated by
* calling the snappy_compress routine, this routine stores
* the uncompressed data to
* uncompressed[0..uncompressed_length-1].
* Returns failure (a value not equal to SNAPPY_OK) if the message
* is corrupted and could not be decrypted.
*
* <uncompressed_length> signals the space available in "uncompressed".
* If it is not at least equal to the value returned by
* snappy_uncompressed_length for this stream, SNAPPY_BUFFER_TOO_SMALL
* is returned. After successful decompression, <uncompressed_length>
* contains the true length of the decompressed output.
*
* Example:
* size_t output_length;
* if (snappy_uncompressed_length(input, input_length, &output_length)
* != SNAPPY_OK) {
* ... fail ...
* }
* char* output = (char*)malloc(output_length);
* if (snappy_uncompress(input, input_length, output, &output_length)
* == SNAPPY_OK) {
* ... Process(output, output_length) ...
* }
* free(output);
*/
snappy_status snappy_uncompress(const char* compressed,
size_t compressed_length,
char* uncompressed,
size_t* uncompressed_length);
/*
* Returns the maximal size of the compressed representation of
* input data that is "source_length" bytes in length.
*/
size_t snappy_max_compressed_length(size_t source_length);
/*
* REQUIRES: "compressed[]" was produced by snappy_compress()
* Returns SNAPPY_OK and stores the length of the uncompressed data in
* *result normally. Returns SNAPPY_INVALID_INPUT on parsing error.
* This operation takes O(1) time.
*/
snappy_status snappy_uncompressed_length(const char* compressed,
size_t compressed_length,
size_t* result);
/*
* Check if the contents of "compressed[]" can be uncompressed successfully.
* Does not return the uncompressed data; if so, returns SNAPPY_OK,
* or if not, returns SNAPPY_INVALID_INPUT.
* Takes time proportional to compressed_length, but is usually at least a
* factor of four faster than actual decompression.
*/
snappy_status snappy_validate_compressed_buffer(const char* compressed,
size_t compressed_length);
#ifdef __cplusplus
} // extern "C"
#endif
#endif /* THIRD_PARTY_SNAPPY_OPENSOURCE_SNAPPY_C_H_ */

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// Copyright 2011 Google Inc. All Rights Reserved.
// Author: sesse@google.com (Steinar H. Gunderson)
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// Various type stubs for the open-source version of Snappy.
//
// This file cannot include config.h, as it is included from snappy.h,
// which is a public header. Instead, snappy-stubs-public.h is generated by
// from snappy-stubs-public.h.in at configure time.
#ifndef THIRD_PARTY_SNAPPY_OPENSOURCE_SNAPPY_STUBS_PUBLIC_H_
#define THIRD_PARTY_SNAPPY_OPENSOURCE_SNAPPY_STUBS_PUBLIC_H_
#if 1
#include <stdint.h>
#endif
#if 1
#include <stddef.h>
#endif
#if defined(_MSC_VER) && (_MSC_VER <= 1900)
#include <basetsd.h>
typedef SSIZE_T ssize_t;
#endif
#if 0
#include <sys/uio.h>
#endif
#define SNAPPY_MAJOR 1
#define SNAPPY_MINOR 1
#define SNAPPY_PATCHLEVEL 3
#define SNAPPY_VERSION \
((SNAPPY_MAJOR << 16) | (SNAPPY_MINOR << 8) | SNAPPY_PATCHLEVEL)
#include <string>
namespace snappy {
#if 1
typedef int8_t int8;
typedef uint8_t uint8;
typedef int16_t int16;
typedef uint16_t uint16;
typedef int32_t int32;
typedef uint32_t uint32;
typedef int64_t int64;
typedef uint64_t uint64;
#else
typedef signed char int8;
typedef unsigned char uint8;
typedef short int16;
typedef unsigned short uint16;
typedef int int32;
typedef unsigned int uint32;
typedef long long int64;
typedef unsigned long long uint64;
#endif
typedef std::string string;
#define DISALLOW_COPY_AND_ASSIGN(TypeName) \
TypeName(const TypeName&); \
void operator=(const TypeName&)
#if !0
// Windows does not have an iovec type, yet the concept is universally useful.
// It is simple to define it ourselves, so we put it inside our own namespace.
struct iovec {
void* iov_base;
size_t iov_len;
};
#endif
} // namespace snappy
#endif // THIRD_PARTY_SNAPPY_OPENSOURCE_SNAPPY_STUBS_PUBLIC_H_

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// Copyright 2005 and onwards Google Inc.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// A light-weight compression algorithm. It is designed for speed of
// compression and decompression, rather than for the utmost in space
// savings.
//
// For getting better compression ratios when you are compressing data
// with long repeated sequences or compressing data that is similar to
// other data, while still compressing fast, you might look at first
// using BMDiff and then compressing the output of BMDiff with
// Snappy.
#ifndef THIRD_PARTY_SNAPPY_SNAPPY_H__
#define THIRD_PARTY_SNAPPY_SNAPPY_H__
#include <stddef.h>
#include <string>
#include "snappy/snappy-stubs-public.h"
namespace snappy {
class Source;
class Sink;
// ------------------------------------------------------------------------
// Generic compression/decompression routines.
// ------------------------------------------------------------------------
// Compress the bytes read from "*source" and append to "*sink". Return the
// number of bytes written.
size_t Compress(Source* source, Sink* sink);
// Find the uncompressed length of the given stream, as given by the header.
// Note that the true length could deviate from this; the stream could e.g.
// be truncated.
//
// Also note that this leaves "*source" in a state that is unsuitable for
// further operations, such as RawUncompress(). You will need to rewind
// or recreate the source yourself before attempting any further calls.
bool GetUncompressedLength(Source* source, uint32* result);
// ------------------------------------------------------------------------
// Higher-level string based routines (should be sufficient for most users)
// ------------------------------------------------------------------------
// Sets "*output" to the compressed version of "input[0,input_length-1]".
// Original contents of *output are lost.
//
// REQUIRES: "input[]" is not an alias of "*output".
size_t Compress(const char* input, size_t input_length, string* output);
// Decompresses "compressed[0,compressed_length-1]" to "*uncompressed".
// Original contents of "*uncompressed" are lost.
//
// REQUIRES: "compressed[]" is not an alias of "*uncompressed".
//
// returns false if the message is corrupted and could not be decompressed
bool Uncompress(const char* compressed, size_t compressed_length,
string* uncompressed);
// Decompresses "compressed" to "*uncompressed".
//
// returns false if the message is corrupted and could not be decompressed
bool Uncompress(Source* compressed, Sink* uncompressed);
// This routine uncompresses as much of the "compressed" as possible
// into sink. It returns the number of valid bytes added to sink
// (extra invalid bytes may have been added due to errors; the caller
// should ignore those). The emitted data typically has length
// GetUncompressedLength(), but may be shorter if an error is
// encountered.
size_t UncompressAsMuchAsPossible(Source* compressed, Sink* uncompressed);
// ------------------------------------------------------------------------
// Lower-level character array based routines. May be useful for
// efficiency reasons in certain circumstances.
// ------------------------------------------------------------------------
// REQUIRES: "compressed" must point to an area of memory that is at
// least "MaxCompressedLength(input_length)" bytes in length.
//
// Takes the data stored in "input[0..input_length]" and stores
// it in the array pointed to by "compressed".
//
// "*compressed_length" is set to the length of the compressed output.
//
// Example:
// char* output = new char[snappy::MaxCompressedLength(input_length)];
// size_t output_length;
// RawCompress(input, input_length, output, &output_length);
// ... Process(output, output_length) ...
// delete [] output;
void RawCompress(const char* input,
size_t input_length,
char* compressed,
size_t* compressed_length);
// Given data in "compressed[0..compressed_length-1]" generated by
// calling the Snappy::Compress routine, this routine
// stores the uncompressed data to
// uncompressed[0..GetUncompressedLength(compressed)-1]
// returns false if the message is corrupted and could not be decrypted
bool RawUncompress(const char* compressed, size_t compressed_length,
char* uncompressed);
// Given data from the byte source 'compressed' generated by calling
// the Snappy::Compress routine, this routine stores the uncompressed
// data to
// uncompressed[0..GetUncompressedLength(compressed,compressed_length)-1]
// returns false if the message is corrupted and could not be decrypted
bool RawUncompress(Source* compressed, char* uncompressed);
// Given data in "compressed[0..compressed_length-1]" generated by
// calling the Snappy::Compress routine, this routine
// stores the uncompressed data to the iovec "iov". The number of physical
// buffers in "iov" is given by iov_cnt and their cumulative size
// must be at least GetUncompressedLength(compressed). The individual buffers
// in "iov" must not overlap with each other.
//
// returns false if the message is corrupted and could not be decrypted
bool RawUncompressToIOVec(const char* compressed, size_t compressed_length,
const struct iovec* iov, size_t iov_cnt);
// Given data from the byte source 'compressed' generated by calling
// the Snappy::Compress routine, this routine stores the uncompressed
// data to the iovec "iov". The number of physical
// buffers in "iov" is given by iov_cnt and their cumulative size
// must be at least GetUncompressedLength(compressed). The individual buffers
// in "iov" must not overlap with each other.
//
// returns false if the message is corrupted and could not be decrypted
bool RawUncompressToIOVec(Source* compressed, const struct iovec* iov,
size_t iov_cnt);
// Returns the maximal size of the compressed representation of
// input data that is "source_bytes" bytes in length;
size_t MaxCompressedLength(size_t source_bytes);
// REQUIRES: "compressed[]" was produced by RawCompress() or Compress()
// Returns true and stores the length of the uncompressed data in
// *result normally. Returns false on parsing error.
// This operation takes O(1) time.
bool GetUncompressedLength(const char* compressed, size_t compressed_length,
size_t* result);
// Returns true iff the contents of "compressed[]" can be uncompressed
// successfully. Does not return the uncompressed data. Takes
// time proportional to compressed_length, but is usually at least
// a factor of four faster than actual decompression.
bool IsValidCompressedBuffer(const char* compressed,
size_t compressed_length);
// Returns true iff the contents of "compressed" can be uncompressed
// successfully. Does not return the uncompressed data. Takes
// time proportional to *compressed length, but is usually at least
// a factor of four faster than actual decompression.
// On success, consumes all of *compressed. On failure, consumes an
// unspecified prefix of *compressed.
bool IsValidCompressed(Source* compressed);
// The size of a compression block. Note that many parts of the compression
// code assumes that kBlockSize <= 65536; in particular, the hash table
// can only store 16-bit offsets, and EmitCopy() also assumes the offset
// is 65535 bytes or less. Note also that if you change this, it will
// affect the framing format (see framing_format.txt).
//
// Note that there might be older data around that is compressed with larger
// block sizes, so the decompression code should not rely on the
// non-existence of long backreferences.
static const int kBlockLog = 16;
static const size_t kBlockSize = 1 << kBlockLog;
static const int kMaxHashTableBits = 14;
static const size_t kMaxHashTableSize = 1 << kMaxHashTableBits;
} // end namespace snappy
#endif // THIRD_PARTY_SNAPPY_SNAPPY_H__

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// Copyright 2011 Martin Gieseking <martin.gieseking@uos.de>.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include "snappy/snappy.h"
#include "snappy/snappy-c.h"
extern "C" {
snappy_status snappy_compress(const char* input,
size_t input_length,
char* compressed,
size_t *compressed_length) {
if (*compressed_length < snappy_max_compressed_length(input_length)) {
return SNAPPY_BUFFER_TOO_SMALL;
}
snappy::RawCompress(input, input_length, compressed, compressed_length);
return SNAPPY_OK;
}
snappy_status snappy_uncompress(const char* compressed,
size_t compressed_length,
char* uncompressed,
size_t* uncompressed_length) {
size_t real_uncompressed_length;
if (!snappy::GetUncompressedLength(compressed,
compressed_length,
&real_uncompressed_length)) {
return SNAPPY_INVALID_INPUT;
}
if (*uncompressed_length < real_uncompressed_length) {
return SNAPPY_BUFFER_TOO_SMALL;
}
if (!snappy::RawUncompress(compressed, compressed_length, uncompressed)) {
return SNAPPY_INVALID_INPUT;
}
*uncompressed_length = real_uncompressed_length;
return SNAPPY_OK;
}
size_t snappy_max_compressed_length(size_t source_length) {
return snappy::MaxCompressedLength(source_length);
}
snappy_status snappy_uncompressed_length(const char *compressed,
size_t compressed_length,
size_t *result) {
if (snappy::GetUncompressedLength(compressed,
compressed_length,
result)) {
return SNAPPY_OK;
} else {
return SNAPPY_INVALID_INPUT;
}
}
snappy_status snappy_validate_compressed_buffer(const char *compressed,
size_t compressed_length) {
if (snappy::IsValidCompressedBuffer(compressed, compressed_length)) {
return SNAPPY_OK;
} else {
return SNAPPY_INVALID_INPUT;
}
}
} // extern "C"

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// Copyright 2008 Google Inc. All Rights Reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// Internals shared between the Snappy implementation and its unittest.
#ifndef THIRD_PARTY_SNAPPY_SNAPPY_INTERNAL_H_
#define THIRD_PARTY_SNAPPY_SNAPPY_INTERNAL_H_
#include "snappy-stubs-internal.h"
namespace snappy {
namespace internal {
class WorkingMemory {
public:
WorkingMemory() : large_table_(NULL) { }
~WorkingMemory() { delete[] large_table_; }
// Allocates and clears a hash table using memory in "*this",
// stores the number of buckets in "*table_size" and returns a pointer to
// the base of the hash table.
uint16* GetHashTable(size_t input_size, int* table_size);
private:
uint16 small_table_[1<<10]; // 2KB
uint16* large_table_; // Allocated only when needed
DISALLOW_COPY_AND_ASSIGN(WorkingMemory);
};
// Flat array compression that does not emit the "uncompressed length"
// prefix. Compresses "input" string to the "*op" buffer.
//
// REQUIRES: "input_length <= kBlockSize"
// REQUIRES: "op" points to an array of memory that is at least
// "MaxCompressedLength(input_length)" in size.
// REQUIRES: All elements in "table[0..table_size-1]" are initialized to zero.
// REQUIRES: "table_size" is a power of two
//
// Returns an "end" pointer into "op" buffer.
// "end - op" is the compressed size of "input".
char* CompressFragment(const char* input,
size_t input_length,
char* op,
uint16* table,
const int table_size);
// Return the largest n such that
//
// s1[0,n-1] == s2[0,n-1]
// and n <= (s2_limit - s2).
//
// Does not read *s2_limit or beyond.
// Does not read *(s1 + (s2_limit - s2)) or beyond.
// Requires that s2_limit >= s2.
//
// Separate implementation for x86_64, for speed. Uses the fact that
// x86_64 is little endian.
#if defined(ARCH_K8)
static inline int FindMatchLength(const char* s1,
const char* s2,
const char* s2_limit) {
assert(s2_limit >= s2);
int matched = 0;
// Find out how long the match is. We loop over the data 64 bits at a
// time until we find a 64-bit block that doesn't match; then we find
// the first non-matching bit and use that to calculate the total
// length of the match.
while (PREDICT_TRUE(s2 <= s2_limit - 8)) {
if (UNALIGNED_LOAD64(s2) == UNALIGNED_LOAD64(s1 + matched)) {
s2 += 8;
matched += 8;
} else {
// On current (mid-2008) Opteron models there is a 3% more
// efficient code sequence to find the first non-matching byte.
// However, what follows is ~10% better on Intel Core 2 and newer,
// and we expect AMD's bsf instruction to improve.
uint64 x = UNALIGNED_LOAD64(s2) ^ UNALIGNED_LOAD64(s1 + matched);
int matching_bits = Bits::FindLSBSetNonZero64(x);
matched += matching_bits >> 3;
return matched;
}
}
while (PREDICT_TRUE(s2 < s2_limit)) {
if (s1[matched] == *s2) {
++s2;
++matched;
} else {
return matched;
}
}
return matched;
}
#else
static inline int FindMatchLength(const char* s1,
const char* s2,
const char* s2_limit) {
// Implementation based on the x86-64 version, above.
assert(s2_limit >= s2);
int matched = 0;
while (s2 <= s2_limit - 4 &&
UNALIGNED_LOAD32(s2) == UNALIGNED_LOAD32(s1 + matched)) {
s2 += 4;
matched += 4;
}
if (LittleEndian::IsLittleEndian() && s2 <= s2_limit - 4) {
uint32 x = UNALIGNED_LOAD32(s2) ^ UNALIGNED_LOAD32(s1 + matched);
int matching_bits = Bits::FindLSBSetNonZero(x);
matched += matching_bits >> 3;
} else {
while ((s2 < s2_limit) && (s1[matched] == *s2)) {
++s2;
++matched;
}
}
return matched;
}
#endif
} // end namespace internal
} // end namespace snappy
#endif // THIRD_PARTY_SNAPPY_SNAPPY_INTERNAL_H_

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// Copyright 2011 Google Inc. All Rights Reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include <string.h>
#include "snappy-sinksource.h"
namespace snappy {
Source::~Source() { }
Sink::~Sink() { }
char* Sink::GetAppendBuffer(size_t length, char* scratch) {
return scratch;
}
char* Sink::GetAppendBufferVariable(
size_t min_size, size_t desired_size_hint, char* scratch,
size_t scratch_size, size_t* allocated_size) {
*allocated_size = scratch_size;
return scratch;
}
void Sink::AppendAndTakeOwnership(
char* bytes, size_t n,
void (*deleter)(void*, const char*, size_t),
void *deleter_arg) {
Append(bytes, n);
(*deleter)(deleter_arg, bytes, n);
}
ByteArraySource::~ByteArraySource() { }
size_t ByteArraySource::Available() const { return left_; }
const char* ByteArraySource::Peek(size_t* len) {
*len = left_;
return ptr_;
}
void ByteArraySource::Skip(size_t n) {
left_ -= n;
ptr_ += n;
}
UncheckedByteArraySink::~UncheckedByteArraySink() { }
void UncheckedByteArraySink::Append(const char* data, size_t n) {
// Do no copying if the caller filled in the result of GetAppendBuffer()
if (data != dest_) {
memcpy(dest_, data, n);
}
dest_ += n;
}
char* UncheckedByteArraySink::GetAppendBuffer(size_t len, char* scratch) {
return dest_;
}
void UncheckedByteArraySink::AppendAndTakeOwnership(
char* data, size_t n,
void (*deleter)(void*, const char*, size_t),
void *deleter_arg) {
if (data != dest_) {
memcpy(dest_, data, n);
(*deleter)(deleter_arg, data, n);
}
dest_ += n;
}
char* UncheckedByteArraySink::GetAppendBufferVariable(
size_t min_size, size_t desired_size_hint, char* scratch,
size_t scratch_size, size_t* allocated_size) {
*allocated_size = desired_size_hint;
return dest_;
}
} // namespace snappy

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// Copyright 2011 Google Inc. All Rights Reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef THIRD_PARTY_SNAPPY_SNAPPY_SINKSOURCE_H_
#define THIRD_PARTY_SNAPPY_SNAPPY_SINKSOURCE_H_
#include <stddef.h>
namespace snappy {
// A Sink is an interface that consumes a sequence of bytes.
class Sink {
public:
Sink() { }
virtual ~Sink();
// Append "bytes[0,n-1]" to this.
virtual void Append(const char* bytes, size_t n) = 0;
// Returns a writable buffer of the specified length for appending.
// May return a pointer to the caller-owned scratch buffer which
// must have at least the indicated length. The returned buffer is
// only valid until the next operation on this Sink.
//
// After writing at most "length" bytes, call Append() with the
// pointer returned from this function and the number of bytes
// written. Many Append() implementations will avoid copying
// bytes if this function returned an internal buffer.
//
// If a non-scratch buffer is returned, the caller may only pass a
// prefix of it to Append(). That is, it is not correct to pass an
// interior pointer of the returned array to Append().
//
// The default implementation always returns the scratch buffer.
virtual char* GetAppendBuffer(size_t length, char* scratch);
// For higher performance, Sink implementations can provide custom
// AppendAndTakeOwnership() and GetAppendBufferVariable() methods.
// These methods can reduce the number of copies done during
// compression/decompression.
// Append "bytes[0,n-1] to the sink. Takes ownership of "bytes"
// and calls the deleter function as (*deleter)(deleter_arg, bytes, n)
// to free the buffer. deleter function must be non NULL.
//
// The default implementation just calls Append and frees "bytes".
// Other implementations may avoid a copy while appending the buffer.
virtual void AppendAndTakeOwnership(
char* bytes, size_t n, void (*deleter)(void*, const char*, size_t),
void *deleter_arg);
// Returns a writable buffer for appending and writes the buffer's capacity to
// *allocated_size. Guarantees *allocated_size >= min_size.
// May return a pointer to the caller-owned scratch buffer which must have
// scratch_size >= min_size.
//
// The returned buffer is only valid until the next operation
// on this ByteSink.
//
// After writing at most *allocated_size bytes, call Append() with the
// pointer returned from this function and the number of bytes written.
// Many Append() implementations will avoid copying bytes if this function
// returned an internal buffer.
//
// If the sink implementation allocates or reallocates an internal buffer,
// it should use the desired_size_hint if appropriate. If a caller cannot
// provide a reasonable guess at the desired capacity, it should set
// desired_size_hint = 0.
//
// If a non-scratch buffer is returned, the caller may only pass
// a prefix to it to Append(). That is, it is not correct to pass an
// interior pointer to Append().
//
// The default implementation always returns the scratch buffer.
virtual char* GetAppendBufferVariable(
size_t min_size, size_t desired_size_hint, char* scratch,
size_t scratch_size, size_t* allocated_size);
private:
// No copying
Sink(const Sink&);
void operator=(const Sink&);
};
// A Source is an interface that yields a sequence of bytes
class Source {
public:
Source() { }
virtual ~Source();
// Return the number of bytes left to read from the source
virtual size_t Available() const = 0;
// Peek at the next flat region of the source. Does not reposition
// the source. The returned region is empty iff Available()==0.
//
// Returns a pointer to the beginning of the region and store its
// length in *len.
//
// The returned region is valid until the next call to Skip() or
// until this object is destroyed, whichever occurs first.
//
// The returned region may be larger than Available() (for example
// if this ByteSource is a view on a substring of a larger source).
// The caller is responsible for ensuring that it only reads the
// Available() bytes.
virtual const char* Peek(size_t* len) = 0;
// Skip the next n bytes. Invalidates any buffer returned by
// a previous call to Peek().
// REQUIRES: Available() >= n
virtual void Skip(size_t n) = 0;
private:
// No copying
Source(const Source&);
void operator=(const Source&);
};
// A Source implementation that yields the contents of a flat array
class ByteArraySource : public Source {
public:
ByteArraySource(const char* p, size_t n) : ptr_(p), left_(n) { }
virtual ~ByteArraySource();
virtual size_t Available() const;
virtual const char* Peek(size_t* len);
virtual void Skip(size_t n);
private:
const char* ptr_;
size_t left_;
};
// A Sink implementation that writes to a flat array without any bound checks.
class UncheckedByteArraySink : public Sink {
public:
explicit UncheckedByteArraySink(char* dest) : dest_(dest) { }
virtual ~UncheckedByteArraySink();
virtual void Append(const char* data, size_t n);
virtual char* GetAppendBuffer(size_t len, char* scratch);
virtual char* GetAppendBufferVariable(
size_t min_size, size_t desired_size_hint, char* scratch,
size_t scratch_size, size_t* allocated_size);
virtual void AppendAndTakeOwnership(
char* bytes, size_t n, void (*deleter)(void*, const char*, size_t),
void *deleter_arg);
// Return the current output pointer so that a caller can see how
// many bytes were produced.
// Note: this is not a Sink method.
char* CurrentDestination() const { return dest_; }
private:
char* dest_;
};
} // namespace snappy
#endif // THIRD_PARTY_SNAPPY_SNAPPY_SINKSOURCE_H_

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// Copyright 2011 Google Inc. All Rights Reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include <algorithm>
#include <string>
#include "snappy-stubs-internal.h"
namespace snappy {
void Varint::Append32(string* s, uint32 value) {
char buf[Varint::kMax32];
const char* p = Varint::Encode32(buf, value);
s->append(buf, p - buf);
}
} // namespace snappy

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// Copyright 2011 Google Inc. All Rights Reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// Various stubs for the open-source version of Snappy.
#ifndef THIRD_PARTY_SNAPPY_OPENSOURCE_SNAPPY_STUBS_INTERNAL_H_
#define THIRD_PARTY_SNAPPY_OPENSOURCE_SNAPPY_STUBS_INTERNAL_H_
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <string>
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#ifdef HAVE_SYS_MMAN_H
#include <sys/mman.h>
#endif
#include "snappy/snappy-stubs-public.h"
#if defined(__x86_64__)
// Enable 64-bit optimized versions of some routines.
#define ARCH_K8 1
#endif
// Needed by OS X, among others.
#ifndef MAP_ANONYMOUS
#define MAP_ANONYMOUS MAP_ANON
#endif
// Pull in std::min, std::ostream, and the likes. This is safe because this
// header file is never used from any public header files.
using namespace std;
// The size of an array, if known at compile-time.
// Will give unexpected results if used on a pointer.
// We undefine it first, since some compilers already have a definition.
#ifdef ARRAYSIZE
#undef ARRAYSIZE
#endif
#define ARRAYSIZE(a) (sizeof(a) / sizeof(*(a)))
// Static prediction hints.
#ifdef HAVE_BUILTIN_EXPECT
#define PREDICT_FALSE(x) (__builtin_expect(x, 0))
#define PREDICT_TRUE(x) (__builtin_expect(!!(x), 1))
#else
#define PREDICT_FALSE(x) x
#define PREDICT_TRUE(x) x
#endif
// This is only used for recomputing the tag byte table used during
// decompression; for simplicity we just remove it from the open-source
// version (anyone who wants to regenerate it can just do the call
// themselves within main()).
#define DEFINE_bool(flag_name, default_value, description) \
bool FLAGS_ ## flag_name = default_value
#define DECLARE_bool(flag_name) \
extern bool FLAGS_ ## flag_name
namespace snappy {
static const uint32 kuint32max = static_cast<uint32>(0xFFFFFFFF);
static const int64 kint64max = static_cast<int64>(0x7FFFFFFFFFFFFFFFLL);
// Potentially unaligned loads and stores.
// x86 and PowerPC can simply do these loads and stores native.
#if defined(__i386__) || defined(__x86_64__) || defined(__powerpc__)
#define UNALIGNED_LOAD16(_p) (*reinterpret_cast<const uint16 *>(_p))
#define UNALIGNED_LOAD32(_p) (*reinterpret_cast<const uint32 *>(_p))
#define UNALIGNED_LOAD64(_p) (*reinterpret_cast<const uint64 *>(_p))
#define UNALIGNED_STORE16(_p, _val) (*reinterpret_cast<uint16 *>(_p) = (_val))
#define UNALIGNED_STORE32(_p, _val) (*reinterpret_cast<uint32 *>(_p) = (_val))
#define UNALIGNED_STORE64(_p, _val) (*reinterpret_cast<uint64 *>(_p) = (_val))
// ARMv7 and newer support native unaligned accesses, but only of 16-bit
// and 32-bit values (not 64-bit); older versions either raise a fatal signal,
// do an unaligned read and rotate the words around a bit, or do the reads very
// slowly (trip through kernel mode). There's no simple #define that says just
// “ARMv7 or higher”, so we have to filter away all ARMv5 and ARMv6
// sub-architectures.
//
// This is a mess, but there's not much we can do about it.
#elif defined(__arm__) && \
!defined(__ARM_ARCH_4__) && \
!defined(__ARM_ARCH_4T__) && \
!defined(__ARM_ARCH_5__) && \
!defined(__ARM_ARCH_5T__) && \
!defined(__ARM_ARCH_5TE__) && \
!defined(__ARM_ARCH_5TEJ__) && \
!defined(__ARM_ARCH_6__) && \
!defined(__ARM_ARCH_6J__) && \
!defined(__ARM_ARCH_6K__) && \
!defined(__ARM_ARCH_6Z__) && \
!defined(__ARM_ARCH_6ZK__) && \
!defined(__ARM_ARCH_6T2__)
#define UNALIGNED_LOAD16(_p) (*reinterpret_cast<const uint16 *>(_p))
#define UNALIGNED_LOAD32(_p) (*reinterpret_cast<const uint32 *>(_p))
#define UNALIGNED_STORE16(_p, _val) (*reinterpret_cast<uint16 *>(_p) = (_val))
#define UNALIGNED_STORE32(_p, _val) (*reinterpret_cast<uint32 *>(_p) = (_val))
// TODO(user): NEON supports unaligned 64-bit loads and stores.
// See if that would be more efficient on platforms supporting it,
// at least for copies.
inline uint64 UNALIGNED_LOAD64(const void *p) {
uint64 t;
memcpy(&t, p, sizeof t);
return t;
}
inline void UNALIGNED_STORE64(void *p, uint64 v) {
memcpy(p, &v, sizeof v);
}
#else
// These functions are provided for architectures that don't support
// unaligned loads and stores.
inline uint16 UNALIGNED_LOAD16(const void *p) {
uint16 t;
memcpy(&t, p, sizeof t);
return t;
}
inline uint32 UNALIGNED_LOAD32(const void *p) {
uint32 t;
memcpy(&t, p, sizeof t);
return t;
}
inline uint64 UNALIGNED_LOAD64(const void *p) {
uint64 t;
memcpy(&t, p, sizeof t);
return t;
}
inline void UNALIGNED_STORE16(void *p, uint16 v) {
memcpy(p, &v, sizeof v);
}
inline void UNALIGNED_STORE32(void *p, uint32 v) {
memcpy(p, &v, sizeof v);
}
inline void UNALIGNED_STORE64(void *p, uint64 v) {
memcpy(p, &v, sizeof v);
}
#endif
// This can be more efficient than UNALIGNED_LOAD64 + UNALIGNED_STORE64
// on some platforms, in particular ARM.
inline void UnalignedCopy64(const void *src, void *dst) {
if (sizeof(void *) == 8) {
UNALIGNED_STORE64(dst, UNALIGNED_LOAD64(src));
} else {
const char *src_char = reinterpret_cast<const char *>(src);
char *dst_char = reinterpret_cast<char *>(dst);
UNALIGNED_STORE32(dst_char, UNALIGNED_LOAD32(src_char));
UNALIGNED_STORE32(dst_char + 4, UNALIGNED_LOAD32(src_char + 4));
}
}
// The following guarantees declaration of the byte swap functions.
#ifdef WORDS_BIGENDIAN
#ifdef HAVE_SYS_BYTEORDER_H
#include <sys/byteorder.h>
#endif
#ifdef HAVE_SYS_ENDIAN_H
#include <sys/endian.h>
#endif
#ifdef _MSC_VER
#include <stdlib.h>
#define bswap_16(x) _byteswap_ushort(x)
#define bswap_32(x) _byteswap_ulong(x)
#define bswap_64(x) _byteswap_uint64(x)
#elif defined(__APPLE__)
// Mac OS X / Darwin features
#include <libkern/OSByteOrder.h>
#define bswap_16(x) OSSwapInt16(x)
#define bswap_32(x) OSSwapInt32(x)
#define bswap_64(x) OSSwapInt64(x)
#elif defined(HAVE_BYTESWAP_H)
#include <byteswap.h>
#elif defined(bswap32)
// FreeBSD defines bswap{16,32,64} in <sys/endian.h> (already #included).
#define bswap_16(x) bswap16(x)
#define bswap_32(x) bswap32(x)
#define bswap_64(x) bswap64(x)
#elif defined(BSWAP_64)
// Solaris 10 defines BSWAP_{16,32,64} in <sys/byteorder.h> (already #included).
#define bswap_16(x) BSWAP_16(x)
#define bswap_32(x) BSWAP_32(x)
#define bswap_64(x) BSWAP_64(x)
#else
inline uint16 bswap_16(uint16 x) {
return (x << 8) | (x >> 8);
}
inline uint32 bswap_32(uint32 x) {
x = ((x & 0xff00ff00UL) >> 8) | ((x & 0x00ff00ffUL) << 8);
return (x >> 16) | (x << 16);
}
inline uint64 bswap_64(uint64 x) {
x = ((x & 0xff00ff00ff00ff00ULL) >> 8) | ((x & 0x00ff00ff00ff00ffULL) << 8);
x = ((x & 0xffff0000ffff0000ULL) >> 16) | ((x & 0x0000ffff0000ffffULL) << 16);
return (x >> 32) | (x << 32);
}
#endif
#endif // WORDS_BIGENDIAN
// Convert to little-endian storage, opposite of network format.
// Convert x from host to little endian: x = LittleEndian.FromHost(x);
// convert x from little endian to host: x = LittleEndian.ToHost(x);
//
// Store values into unaligned memory converting to little endian order:
// LittleEndian.Store16(p, x);
//
// Load unaligned values stored in little endian converting to host order:
// x = LittleEndian.Load16(p);
class LittleEndian {
public:
// Conversion functions.
#ifdef WORDS_BIGENDIAN
static uint16 FromHost16(uint16 x) { return bswap_16(x); }
static uint16 ToHost16(uint16 x) { return bswap_16(x); }
static uint32 FromHost32(uint32 x) { return bswap_32(x); }
static uint32 ToHost32(uint32 x) { return bswap_32(x); }
static bool IsLittleEndian() { return false; }
#else // !defined(WORDS_BIGENDIAN)
static uint16 FromHost16(uint16 x) { return x; }
static uint16 ToHost16(uint16 x) { return x; }
static uint32 FromHost32(uint32 x) { return x; }
static uint32 ToHost32(uint32 x) { return x; }
static bool IsLittleEndian() { return true; }
#endif // !defined(WORDS_BIGENDIAN)
// Functions to do unaligned loads and stores in little-endian order.
static uint16 Load16(const void *p) {
return ToHost16(UNALIGNED_LOAD16(p));
}
static void Store16(void *p, uint16 v) {
UNALIGNED_STORE16(p, FromHost16(v));
}
static uint32 Load32(const void *p) {
return ToHost32(UNALIGNED_LOAD32(p));
}
static void Store32(void *p, uint32 v) {
UNALIGNED_STORE32(p, FromHost32(v));
}
};
// Some bit-manipulation functions.
class Bits {
public:
// Return floor(log2(n)) for positive integer n. Returns -1 iff n == 0.
static int Log2Floor(uint32 n);
// Return the first set least / most significant bit, 0-indexed. Returns an
// undefined value if n == 0. FindLSBSetNonZero() is similar to ffs() except
// that it's 0-indexed.
static int FindLSBSetNonZero(uint32 n);
static int FindLSBSetNonZero64(uint64 n);
private:
DISALLOW_COPY_AND_ASSIGN(Bits);
};
#ifdef HAVE_BUILTIN_CTZ
inline int Bits::Log2Floor(uint32 n) {
return n == 0 ? -1 : 31 ^ __builtin_clz(n);
}
inline int Bits::FindLSBSetNonZero(uint32 n) {
return __builtin_ctz(n);
}
inline int Bits::FindLSBSetNonZero64(uint64 n) {
return __builtin_ctzll(n);
}
#else // Portable versions.
inline int Bits::Log2Floor(uint32 n) {
if (n == 0)
return -1;
int log = 0;
uint32 value = n;
for (int i = 4; i >= 0; --i) {
int shift = (1 << i);
uint32 x = value >> shift;
if (x != 0) {
value = x;
log += shift;
}
}
assert(value == 1);
return log;
}
inline int Bits::FindLSBSetNonZero(uint32 n) {
int rc = 31;
for (int i = 4, shift = 1 << 4; i >= 0; --i) {
const uint32 x = n << shift;
if (x != 0) {
n = x;
rc -= shift;
}
shift >>= 1;
}
return rc;
}
// FindLSBSetNonZero64() is defined in terms of FindLSBSetNonZero().
inline int Bits::FindLSBSetNonZero64(uint64 n) {
const uint32 bottombits = static_cast<uint32>(n);
if (bottombits == 0) {
// Bottom bits are zero, so scan in top bits
return 32 + FindLSBSetNonZero(static_cast<uint32>(n >> 32));
} else {
return FindLSBSetNonZero(bottombits);
}
}
#endif // End portable versions.
// Variable-length integer encoding.
class Varint {
public:
// Maximum lengths of varint encoding of uint32.
static const int kMax32 = 5;
// Attempts to parse a varint32 from a prefix of the bytes in [ptr,limit-1].
// Never reads a character at or beyond limit. If a valid/terminated varint32
// was found in the range, stores it in *OUTPUT and returns a pointer just
// past the last byte of the varint32. Else returns NULL. On success,
// "result <= limit".
static const char* Parse32WithLimit(const char* ptr, const char* limit,
uint32* OUTPUT);
// REQUIRES "ptr" points to a buffer of length sufficient to hold "v".
// EFFECTS Encodes "v" into "ptr" and returns a pointer to the
// byte just past the last encoded byte.
static char* Encode32(char* ptr, uint32 v);
// EFFECTS Appends the varint representation of "value" to "*s".
static void Append32(string* s, uint32 value);
};
inline const char* Varint::Parse32WithLimit(const char* p,
const char* l,
uint32* OUTPUT) {
const unsigned char* ptr = reinterpret_cast<const unsigned char*>(p);
const unsigned char* limit = reinterpret_cast<const unsigned char*>(l);
uint32 b, result;
if (ptr >= limit) return NULL;
b = *(ptr++); result = b & 127; if (b < 128) goto done;
if (ptr >= limit) return NULL;
b = *(ptr++); result |= (b & 127) << 7; if (b < 128) goto done;
if (ptr >= limit) return NULL;
b = *(ptr++); result |= (b & 127) << 14; if (b < 128) goto done;
if (ptr >= limit) return NULL;
b = *(ptr++); result |= (b & 127) << 21; if (b < 128) goto done;
if (ptr >= limit) return NULL;
b = *(ptr++); result |= (b & 127) << 28; if (b < 16) goto done;
return NULL; // Value is too long to be a varint32
done:
*OUTPUT = result;
return reinterpret_cast<const char*>(ptr);
}
inline char* Varint::Encode32(char* sptr, uint32 v) {
// Operate on characters as unsigneds
unsigned char* ptr = reinterpret_cast<unsigned char*>(sptr);
static const int B = 128;
if (v < (1<<7)) {
*(ptr++) = v;
} else if (v < (1<<14)) {
*(ptr++) = v | B;
*(ptr++) = v>>7;
} else if (v < (1<<21)) {
*(ptr++) = v | B;
*(ptr++) = (v>>7) | B;
*(ptr++) = v>>14;
} else if (v < (1<<28)) {
*(ptr++) = v | B;
*(ptr++) = (v>>7) | B;
*(ptr++) = (v>>14) | B;
*(ptr++) = v>>21;
} else {
*(ptr++) = v | B;
*(ptr++) = (v>>7) | B;
*(ptr++) = (v>>14) | B;
*(ptr++) = (v>>21) | B;
*(ptr++) = v>>28;
}
return reinterpret_cast<char*>(ptr);
}
// If you know the internal layout of the std::string in use, you can
// replace this function with one that resizes the string without
// filling the new space with zeros (if applicable) --
// it will be non-portable but faster.
inline void STLStringResizeUninitialized(string* s, size_t new_size) {
s->resize(new_size);
}
// Return a mutable char* pointing to a string's internal buffer,
// which may not be null-terminated. Writing through this pointer will
// modify the string.
//
// string_as_array(&str)[i] is valid for 0 <= i < str.size() until the
// next call to a string method that invalidates iterators.
//
// As of 2006-04, there is no standard-blessed way of getting a
// mutable reference to a string's internal buffer. However, issue 530
// (http://www.open-std.org/JTC1/SC22/WG21/docs/lwg-defects.html#530)
// proposes this as the method. It will officially be part of the standard
// for C++0x. This should already work on all current implementations.
inline char* string_as_array(string* str) {
return str->empty() ? NULL : &*str->begin();
}
} // namespace snappy
#endif // THIRD_PARTY_SNAPPY_OPENSOURCE_SNAPPY_STUBS_INTERNAL_H_

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