You are viewing a plain text version of this content. The canonical link for it is here.
Posted to commits@orc.apache.org by om...@apache.org on 2017/07/24 17:49:39 UTC
[37/51] [partial] orc git commit: ORC-204 Update and use CMake
External Project to build C++ compression libraries.
http://git-wip-us.apache.org/repos/asf/orc/blob/590245a0/c++/libs/snappy-1.1.2/snappy-test.h
----------------------------------------------------------------------
diff --git a/c++/libs/snappy-1.1.2/snappy-test.h b/c++/libs/snappy-1.1.2/snappy-test.h
deleted file mode 100644
index 0f18bf1..0000000
--- a/c++/libs/snappy-1.1.2/snappy-test.h
+++ /dev/null
@@ -1,582 +0,0 @@
-// 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 unit tests for the open-source version of Snappy.
-
-#ifndef UTIL_SNAPPY_OPENSOURCE_SNAPPY_TEST_H_
-#define UTIL_SNAPPY_OPENSOURCE_SNAPPY_TEST_H_
-
-#include <iostream>
-#include <string>
-
-#include "snappy-stubs-internal.h"
-
-#include <stdio.h>
-#include <stdarg.h>
-
-#ifdef HAVE_SYS_MMAN_H
-#include <sys/mman.h>
-#endif
-
-#ifdef HAVE_SYS_RESOURCE_H
-#include <sys/resource.h>
-#endif
-
-#ifdef HAVE_SYS_TIME_H
-#include <sys/time.h>
-#endif
-
-#ifdef HAVE_WINDOWS_H
-#define WIN32_LEAN_AND_MEAN
-#include <windows.h>
-#endif
-
-#include <string>
-
-#ifdef HAVE_GTEST
-
-#include <gtest/gtest.h>
-#undef TYPED_TEST
-#define TYPED_TEST TEST
-#define INIT_GTEST(argc, argv) ::testing::InitGoogleTest(argc, *argv)
-
-#else
-
-// Stubs for if the user doesn't have Google Test installed.
-
-#define TEST(test_case, test_subcase) \
- void Test_ ## test_case ## _ ## test_subcase()
-#define INIT_GTEST(argc, argv)
-
-#define TYPED_TEST TEST
-#define EXPECT_EQ CHECK_EQ
-#define EXPECT_NE CHECK_NE
-#define EXPECT_FALSE(cond) CHECK(!(cond))
-
-#endif
-
-#ifdef HAVE_GFLAGS
-
-#include <gflags/gflags.h>
-
-// This is tricky; both gflags and Google Test want to look at the command line
-// arguments. Google Test seems to be the most happy with unknown arguments,
-// though, so we call it first and hope for the best.
-#define InitGoogle(argv0, argc, argv, remove_flags) \
- INIT_GTEST(argc, argv); \
- google::ParseCommandLineFlags(argc, argv, remove_flags);
-
-#else
-
-// If we don't have the gflags package installed, these can only be
-// changed at compile time.
-#define DEFINE_int32(flag_name, default_value, description) \
- static int FLAGS_ ## flag_name = default_value;
-
-#define InitGoogle(argv0, argc, argv, remove_flags) \
- INIT_GTEST(argc, argv)
-
-#endif
-
-#ifdef HAVE_LIBZ
-#include "zlib.h"
-#endif
-
-#ifdef HAVE_LIBLZO2
-#include "lzo/lzo1x.h"
-#endif
-
-#ifdef HAVE_LIBLZF
-extern "C" {
-#include "lzf.h"
-}
-#endif
-
-#ifdef HAVE_LIBFASTLZ
-#include "fastlz.h"
-#endif
-
-#ifdef HAVE_LIBQUICKLZ
-#include "quicklz.h"
-#endif
-
-namespace {
-
-namespace File {
- void Init() { }
-} // namespace File
-
-namespace file {
- int Defaults() { }
-
- class DummyStatus {
- public:
- void CheckSuccess() { }
- };
-
- DummyStatus GetContents(const string& filename, string* data, int unused) {
- FILE* fp = fopen(filename.c_str(), "rb");
- if (fp == NULL) {
- perror(filename.c_str());
- exit(1);
- }
-
- data->clear();
- while (!feof(fp)) {
- char buf[4096];
- size_t ret = fread(buf, 1, 4096, fp);
- if (ret == 0 && ferror(fp)) {
- perror("fread");
- exit(1);
- }
- data->append(string(buf, ret));
- }
-
- fclose(fp);
- }
-
- DummyStatus SetContents(const string& filename,
- const string& str,
- int unused) {
- FILE* fp = fopen(filename.c_str(), "wb");
- if (fp == NULL) {
- perror(filename.c_str());
- exit(1);
- }
-
- int ret = fwrite(str.data(), str.size(), 1, fp);
- if (ret != 1) {
- perror("fwrite");
- exit(1);
- }
-
- fclose(fp);
- }
-} // namespace file
-
-} // namespace
-
-namespace snappy {
-
-#define FLAGS_test_random_seed 301
-typedef string TypeParam;
-
-void Test_CorruptedTest_VerifyCorrupted();
-void Test_Snappy_SimpleTests();
-void Test_Snappy_MaxBlowup();
-void Test_Snappy_RandomData();
-void Test_Snappy_FourByteOffset();
-void Test_SnappyCorruption_TruncatedVarint();
-void Test_SnappyCorruption_UnterminatedVarint();
-void Test_Snappy_ReadPastEndOfBuffer();
-void Test_Snappy_FindMatchLength();
-void Test_Snappy_FindMatchLengthRandom();
-
-string ReadTestDataFile(const string& base, size_t size_limit);
-
-string ReadTestDataFile(const string& base);
-
-// A sprintf() variant that returns a std::string.
-// Not safe for general use due to truncation issues.
-string StringPrintf(const char* format, ...);
-
-// A simple, non-cryptographically-secure random generator.
-class ACMRandom {
- public:
- explicit ACMRandom(uint32 seed) : seed_(seed) {}
-
- int32 Next();
-
- int32 Uniform(int32 n) {
- return Next() % n;
- }
- uint8 Rand8() {
- return static_cast<uint8>((Next() >> 1) & 0x000000ff);
- }
- bool OneIn(int X) { return Uniform(X) == 0; }
-
- // Skewed: pick "base" uniformly from range [0,max_log] and then
- // return "base" random bits. The effect is to pick a number in the
- // range [0,2^max_log-1] with bias towards smaller numbers.
- int32 Skewed(int max_log);
-
- private:
- static const uint32 M = 2147483647L; // 2^31-1
- uint32 seed_;
-};
-
-inline int32 ACMRandom::Next() {
- static const uint64 A = 16807; // bits 14, 8, 7, 5, 2, 1, 0
- // We are computing
- // seed_ = (seed_ * A) % M, where M = 2^31-1
- //
- // seed_ must not be zero or M, or else all subsequent computed values
- // will be zero or M respectively. For all other values, seed_ will end
- // up cycling through every number in [1,M-1]
- uint64 product = seed_ * A;
-
- // Compute (product % M) using the fact that ((x << 31) % M) == x.
- seed_ = (product >> 31) + (product & M);
- // The first reduction may overflow by 1 bit, so we may need to repeat.
- // mod == M is not possible; using > allows the faster sign-bit-based test.
- if (seed_ > M) {
- seed_ -= M;
- }
- return seed_;
-}
-
-inline int32 ACMRandom::Skewed(int max_log) {
- const int32 base = (Next() - 1) % (max_log+1);
- return (Next() - 1) & ((1u << base)-1);
-}
-
-// A wall-time clock. This stub is not super-accurate, nor resistant to the
-// system time changing.
-class CycleTimer {
- public:
- CycleTimer() : real_time_us_(0) {}
-
- void Start() {
-#ifdef WIN32
- QueryPerformanceCounter(&start_);
-#else
- gettimeofday(&start_, NULL);
-#endif
- }
-
- void Stop() {
-#ifdef WIN32
- LARGE_INTEGER stop;
- LARGE_INTEGER frequency;
- QueryPerformanceCounter(&stop);
- QueryPerformanceFrequency(&frequency);
-
- double elapsed = static_cast<double>(stop.QuadPart - start_.QuadPart) /
- frequency.QuadPart;
- real_time_us_ += elapsed * 1e6 + 0.5;
-#else
- struct timeval stop;
- gettimeofday(&stop, NULL);
-
- real_time_us_ += 1000000 * (stop.tv_sec - start_.tv_sec);
- real_time_us_ += (stop.tv_usec - start_.tv_usec);
-#endif
- }
-
- double Get() {
- return real_time_us_ * 1e-6;
- }
-
- private:
- int64 real_time_us_;
-#ifdef WIN32
- LARGE_INTEGER start_;
-#else
- struct timeval start_;
-#endif
-};
-
-// Minimalistic microbenchmark framework.
-
-typedef void (*BenchmarkFunction)(int, int);
-
-class Benchmark {
- public:
- Benchmark(const string& name, BenchmarkFunction function) :
- name_(name), function_(function) {}
-
- Benchmark* DenseRange(int start, int stop) {
- start_ = start;
- stop_ = stop;
- return this;
- }
-
- void Run();
-
- private:
- const string name_;
- const BenchmarkFunction function_;
- int start_, stop_;
-};
-#define BENCHMARK(benchmark_name) \
- Benchmark* Benchmark_ ## benchmark_name = \
- (new Benchmark(#benchmark_name, benchmark_name))
-
-extern Benchmark* Benchmark_BM_UFlat;
-extern Benchmark* Benchmark_BM_UIOVec;
-extern Benchmark* Benchmark_BM_UValidate;
-extern Benchmark* Benchmark_BM_ZFlat;
-
-void ResetBenchmarkTiming();
-void StartBenchmarkTiming();
-void StopBenchmarkTiming();
-void SetBenchmarkLabel(const string& str);
-void SetBenchmarkBytesProcessed(int64 bytes);
-
-#ifdef HAVE_LIBZ
-
-// Object-oriented wrapper around zlib.
-class ZLib {
- public:
- ZLib();
- ~ZLib();
-
- // Wipe a ZLib object to a virgin state. This differs from Reset()
- // in that it also breaks any state.
- void Reinit();
-
- // Call this to make a zlib buffer as good as new. Here's the only
- // case where they differ:
- // CompressChunk(a); CompressChunk(b); CompressChunkDone(); vs
- // CompressChunk(a); Reset(); CompressChunk(b); CompressChunkDone();
- // You'll want to use Reset(), then, when you interrupt a compress
- // (or uncompress) in the middle of a chunk and want to start over.
- void Reset();
-
- // According to the zlib manual, when you Compress, the destination
- // buffer must have size at least src + .1%*src + 12. This function
- // helps you calculate that. Augment this to account for a potential
- // gzip header and footer, plus a few bytes of slack.
- static int MinCompressbufSize(int uncompress_size) {
- return uncompress_size + uncompress_size/1000 + 40;
- }
-
- // Compresses the source buffer into the destination buffer.
- // sourceLen is the byte length of the source buffer.
- // Upon entry, destLen is the total size of the destination buffer,
- // which must be of size at least MinCompressbufSize(sourceLen).
- // Upon exit, destLen is the actual size of the compressed buffer.
- //
- // This function can be used to compress a whole file at once if the
- // input file is mmap'ed.
- //
- // Returns Z_OK if success, Z_MEM_ERROR if there was not
- // enough memory, Z_BUF_ERROR if there was not enough room in the
- // output buffer. Note that if the output buffer is exactly the same
- // size as the compressed result, we still return Z_BUF_ERROR.
- // (check CL#1936076)
- int Compress(Bytef *dest, uLongf *destLen,
- const Bytef *source, uLong sourceLen);
-
- // Uncompresses the source buffer into the destination buffer.
- // The destination buffer must be long enough to hold the entire
- // decompressed contents.
- //
- // Returns Z_OK on success, otherwise, it returns a zlib error code.
- int Uncompress(Bytef *dest, uLongf *destLen,
- const Bytef *source, uLong sourceLen);
-
- // Uncompress data one chunk at a time -- ie you can call this
- // more than once. To get this to work you need to call per-chunk
- // and "done" routines.
- //
- // Returns Z_OK if success, Z_MEM_ERROR if there was not
- // enough memory, Z_BUF_ERROR if there was not enough room in the
- // output buffer.
-
- int UncompressAtMost(Bytef *dest, uLongf *destLen,
- const Bytef *source, uLong *sourceLen);
-
- // Checks gzip footer information, as needed. Mostly this just
- // makes sure the checksums match. Whenever you call this, it
- // will assume the last 8 bytes from the previous UncompressChunk
- // call are the footer. Returns true iff everything looks ok.
- bool UncompressChunkDone();
-
- private:
- int InflateInit(); // sets up the zlib inflate structure
- int DeflateInit(); // sets up the zlib deflate structure
-
- // These init the zlib data structures for compressing/uncompressing
- int CompressInit(Bytef *dest, uLongf *destLen,
- const Bytef *source, uLong *sourceLen);
- int UncompressInit(Bytef *dest, uLongf *destLen,
- const Bytef *source, uLong *sourceLen);
- // Initialization method to be called if we hit an error while
- // uncompressing. On hitting an error, call this method before
- // returning the error.
- void UncompressErrorInit();
-
- // Helper function for Compress
- int CompressChunkOrAll(Bytef *dest, uLongf *destLen,
- const Bytef *source, uLong sourceLen,
- int flush_mode);
- int CompressAtMostOrAll(Bytef *dest, uLongf *destLen,
- const Bytef *source, uLong *sourceLen,
- int flush_mode);
-
- // Likewise for UncompressAndUncompressChunk
- int UncompressChunkOrAll(Bytef *dest, uLongf *destLen,
- const Bytef *source, uLong sourceLen,
- int flush_mode);
-
- int UncompressAtMostOrAll(Bytef *dest, uLongf *destLen,
- const Bytef *source, uLong *sourceLen,
- int flush_mode);
-
- // Initialization method to be called if we hit an error while
- // compressing. On hitting an error, call this method before
- // returning the error.
- void CompressErrorInit();
-
- int compression_level_; // compression level
- int window_bits_; // log base 2 of the window size used in compression
- int mem_level_; // specifies the amount of memory to be used by
- // compressor (1-9)
- z_stream comp_stream_; // Zlib stream data structure
- bool comp_init_; // True if we have initialized comp_stream_
- z_stream uncomp_stream_; // Zlib stream data structure
- bool uncomp_init_; // True if we have initialized uncomp_stream_
-
- // These are used only with chunked compression.
- bool first_chunk_; // true if we need to emit headers with this chunk
-};
-
-#endif // HAVE_LIBZ
-
-} // namespace snappy
-
-DECLARE_bool(run_microbenchmarks);
-
-static void RunSpecifiedBenchmarks() {
- if (!FLAGS_run_microbenchmarks) {
- return;
- }
-
- fprintf(stderr, "Running microbenchmarks.\n");
-#ifndef NDEBUG
- fprintf(stderr, "WARNING: Compiled with assertions enabled, will be slow.\n");
-#endif
-#ifndef __OPTIMIZE__
- fprintf(stderr, "WARNING: Compiled without optimization, will be slow.\n");
-#endif
- fprintf(stderr, "Benchmark Time(ns) CPU(ns) Iterations\n");
- fprintf(stderr, "---------------------------------------------------\n");
-
- snappy::Benchmark_BM_UFlat->Run();
- snappy::Benchmark_BM_UIOVec->Run();
- snappy::Benchmark_BM_UValidate->Run();
- snappy::Benchmark_BM_ZFlat->Run();
-
- fprintf(stderr, "\n");
-}
-
-#ifndef HAVE_GTEST
-
-static inline int RUN_ALL_TESTS() {
- fprintf(stderr, "Running correctness tests.\n");
- snappy::Test_CorruptedTest_VerifyCorrupted();
- snappy::Test_Snappy_SimpleTests();
- snappy::Test_Snappy_MaxBlowup();
- snappy::Test_Snappy_RandomData();
- snappy::Test_Snappy_FourByteOffset();
- snappy::Test_SnappyCorruption_TruncatedVarint();
- snappy::Test_SnappyCorruption_UnterminatedVarint();
- snappy::Test_Snappy_ReadPastEndOfBuffer();
- snappy::Test_Snappy_FindMatchLength();
- snappy::Test_Snappy_FindMatchLengthRandom();
- fprintf(stderr, "All tests passed.\n");
-
- return 0;
-}
-
-#endif // HAVE_GTEST
-
-// For main().
-namespace snappy {
-
-static void CompressFile(const char* fname);
-static void UncompressFile(const char* fname);
-static void MeasureFile(const char* fname);
-
-// Logging.
-
-#define LOG(level) LogMessage()
-#define VLOG(level) true ? (void)0 : \
- snappy::LogMessageVoidify() & snappy::LogMessage()
-
-class LogMessage {
- public:
- LogMessage() { }
- ~LogMessage() {
- cerr << endl;
- }
-
- LogMessage& operator<<(const std::string& msg) {
- cerr << msg;
- return *this;
- }
- LogMessage& operator<<(int x) {
- cerr << x;
- return *this;
- }
-};
-
-// Asserts, both versions activated in debug mode only,
-// and ones that are always active.
-
-#define CRASH_UNLESS(condition) \
- PREDICT_TRUE(condition) ? (void)0 : \
- snappy::LogMessageVoidify() & snappy::LogMessageCrash()
-
-class LogMessageCrash : public LogMessage {
- public:
- LogMessageCrash() { }
- ~LogMessageCrash() {
- cerr << endl;
- abort();
- }
-};
-
-// This class is used to explicitly ignore values in the conditional
-// logging macros. This avoids compiler warnings like "value computed
-// is not used" and "statement has no effect".
-
-class LogMessageVoidify {
- public:
- LogMessageVoidify() { }
- // This has to be an operator with a precedence lower than << but
- // higher than ?:
- void operator&(const LogMessage&) { }
-};
-
-#define CHECK(cond) CRASH_UNLESS(cond)
-#define CHECK_LE(a, b) CRASH_UNLESS((a) <= (b))
-#define CHECK_GE(a, b) CRASH_UNLESS((a) >= (b))
-#define CHECK_EQ(a, b) CRASH_UNLESS((a) == (b))
-#define CHECK_NE(a, b) CRASH_UNLESS((a) != (b))
-#define CHECK_LT(a, b) CRASH_UNLESS((a) < (b))
-#define CHECK_GT(a, b) CRASH_UNLESS((a) > (b))
-
-} // namespace
-
-using snappy::CompressFile;
-using snappy::UncompressFile;
-using snappy::MeasureFile;
-
-#endif // UTIL_SNAPPY_OPENSOURCE_SNAPPY_TEST_H_
http://git-wip-us.apache.org/repos/asf/orc/blob/590245a0/c++/libs/snappy-1.1.2/snappy.cc
----------------------------------------------------------------------
diff --git a/c++/libs/snappy-1.1.2/snappy.cc b/c++/libs/snappy-1.1.2/snappy.cc
deleted file mode 100644
index f8d0d23..0000000
--- a/c++/libs/snappy-1.1.2/snappy.cc
+++ /dev/null
@@ -1,1306 +0,0 @@
-// Copyright 2005 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 "snappy.h"
-#include "snappy-internal.h"
-#include "snappy-sinksource.h"
-
-#include <stdio.h>
-
-#include <algorithm>
-#include <string>
-#include <vector>
-
-
-namespace snappy {
-
-// Any hash function will produce a valid compressed bitstream, but a good
-// hash function reduces the number of collisions and thus yields better
-// compression for compressible input, and more speed for incompressible
-// input. Of course, it doesn't hurt if the hash function is reasonably fast
-// either, as it gets called a lot.
-static inline uint32 HashBytes(uint32 bytes, int shift) {
- uint32 kMul = 0x1e35a7bd;
- return (bytes * kMul) >> shift;
-}
-static inline uint32 Hash(const char* p, int shift) {
- return HashBytes(UNALIGNED_LOAD32(p), shift);
-}
-
-size_t MaxCompressedLength(size_t source_len) {
- // Compressed data can be defined as:
- // compressed := item* literal*
- // item := literal* copy
- //
- // The trailing literal sequence has a space blowup of at most 62/60
- // since a literal of length 60 needs one tag byte + one extra byte
- // for length information.
- //
- // Item blowup is trickier to measure. Suppose the "copy" op copies
- // 4 bytes of data. Because of a special check in the encoding code,
- // we produce a 4-byte copy only if the offset is < 65536. Therefore
- // the copy op takes 3 bytes to encode, and this type of item leads
- // to at most the 62/60 blowup for representing literals.
- //
- // Suppose the "copy" op copies 5 bytes of data. If the offset is big
- // enough, it will take 5 bytes to encode the copy op. Therefore the
- // worst case here is a one-byte literal followed by a five-byte copy.
- // I.e., 6 bytes of input turn into 7 bytes of "compressed" data.
- //
- // This last factor dominates the blowup, so the final estimate is:
- return 32 + source_len + source_len/6;
-}
-
-enum {
- LITERAL = 0,
- COPY_1_BYTE_OFFSET = 1, // 3 bit length + 3 bits of offset in opcode
- COPY_2_BYTE_OFFSET = 2,
- COPY_4_BYTE_OFFSET = 3
-};
-static const int kMaximumTagLength = 5; // COPY_4_BYTE_OFFSET plus the actual offset.
-
-// Copy "len" bytes from "src" to "op", one byte at a time. Used for
-// handling COPY operations where the input and output regions may
-// overlap. For example, suppose:
-// src == "ab"
-// op == src + 2
-// len == 20
-// After IncrementalCopy(src, op, len), the result will have
-// eleven copies of "ab"
-// ababababababababababab
-// Note that this does not match the semantics of either memcpy()
-// or memmove().
-static inline void IncrementalCopy(const char* src, char* op, ssize_t len) {
- assert(len > 0);
- do {
- *op++ = *src++;
- } while (--len > 0);
-}
-
-// Equivalent to IncrementalCopy except that it can write up to ten extra
-// bytes after the end of the copy, and that it is faster.
-//
-// The main part of this loop is a simple copy of eight bytes at a time until
-// we've copied (at least) the requested amount of bytes. However, if op and
-// src are less than eight bytes apart (indicating a repeating pattern of
-// length < 8), we first need to expand the pattern in order to get the correct
-// results. For instance, if the buffer looks like this, with the eight-byte
-// <src> and <op> patterns marked as intervals:
-//
-// abxxxxxxxxxxxx
-// [------] src
-// [------] op
-//
-// a single eight-byte copy from <src> to <op> will repeat the pattern once,
-// after which we can move <op> two bytes without moving <src>:
-//
-// ababxxxxxxxxxx
-// [------] src
-// [------] op
-//
-// and repeat the exercise until the two no longer overlap.
-//
-// This allows us to do very well in the special case of one single byte
-// repeated many times, without taking a big hit for more general cases.
-//
-// The worst case of extra writing past the end of the match occurs when
-// op - src == 1 and len == 1; the last copy will read from byte positions
-// [0..7] and write to [4..11], whereas it was only supposed to write to
-// position 1. Thus, ten excess bytes.
-
-namespace {
-
-const int kMaxIncrementCopyOverflow = 10;
-
-inline void IncrementalCopyFastPath(const char* src, char* op, ssize_t len) {
- while (op - src < 8) {
- UnalignedCopy64(src, op);
- len -= op - src;
- op += op - src;
- }
- while (len > 0) {
- UnalignedCopy64(src, op);
- src += 8;
- op += 8;
- len -= 8;
- }
-}
-
-} // namespace
-
-static inline char* EmitLiteral(char* op,
- const char* literal,
- int len,
- bool allow_fast_path) {
- int n = len - 1; // Zero-length literals are disallowed
- if (n < 60) {
- // Fits in tag byte
- *op++ = LITERAL | (n << 2);
-
- // The vast majority of copies are below 16 bytes, for which a
- // call to memcpy is overkill. This fast path can sometimes
- // copy up to 15 bytes too much, but that is okay in the
- // main loop, since we have a bit to go on for both sides:
- //
- // - The input will always have kInputMarginBytes = 15 extra
- // available bytes, as long as we're in the main loop, and
- // if not, allow_fast_path = false.
- // - The output will always have 32 spare bytes (see
- // MaxCompressedLength).
- if (allow_fast_path && len <= 16) {
- UnalignedCopy64(literal, op);
- UnalignedCopy64(literal + 8, op + 8);
- return op + len;
- }
- } else {
- // Encode in upcoming bytes
- char* base = op;
- int count = 0;
- op++;
- while (n > 0) {
- *op++ = n & 0xff;
- n >>= 8;
- count++;
- }
- assert(count >= 1);
- assert(count <= 4);
- *base = LITERAL | ((59+count) << 2);
- }
- memcpy(op, literal, len);
- return op + len;
-}
-
-static inline char* EmitCopyLessThan64(char* op, size_t offset, int len) {
- assert(len <= 64);
- assert(len >= 4);
- assert(offset < 65536);
-
- if ((len < 12) && (offset < 2048)) {
- size_t len_minus_4 = len - 4;
- assert(len_minus_4 < 8); // Must fit in 3 bits
- *op++ = COPY_1_BYTE_OFFSET + ((len_minus_4) << 2) + ((offset >> 8) << 5);
- *op++ = offset & 0xff;
- } else {
- *op++ = COPY_2_BYTE_OFFSET + ((len-1) << 2);
- LittleEndian::Store16(op, offset);
- op += 2;
- }
- return op;
-}
-
-static inline char* EmitCopy(char* op, size_t offset, int len) {
- // Emit 64 byte copies but make sure to keep at least four bytes reserved
- while (len >= 68) {
- op = EmitCopyLessThan64(op, offset, 64);
- len -= 64;
- }
-
- // Emit an extra 60 byte copy if have too much data to fit in one copy
- if (len > 64) {
- op = EmitCopyLessThan64(op, offset, 60);
- len -= 60;
- }
-
- // Emit remainder
- op = EmitCopyLessThan64(op, offset, len);
- return op;
-}
-
-
-bool GetUncompressedLength(const char* start, size_t n, size_t* result) {
- uint32 v = 0;
- const char* limit = start + n;
- if (Varint::Parse32WithLimit(start, limit, &v) != NULL) {
- *result = v;
- return true;
- } else {
- return false;
- }
-}
-
-namespace internal {
-uint16* WorkingMemory::GetHashTable(size_t input_size, int* table_size) {
- // Use smaller hash table when input.size() is smaller, since we
- // fill the table, incurring O(hash table size) overhead for
- // compression, and if the input is short, we won't need that
- // many hash table entries anyway.
- assert(kMaxHashTableSize >= 256);
- size_t htsize = 256;
- while (htsize < kMaxHashTableSize && htsize < input_size) {
- htsize <<= 1;
- }
-
- uint16* table;
- if (htsize <= ARRAYSIZE(small_table_)) {
- table = small_table_;
- } else {
- if (large_table_ == NULL) {
- large_table_ = new uint16[kMaxHashTableSize];
- }
- table = large_table_;
- }
-
- *table_size = htsize;
- memset(table, 0, htsize * sizeof(*table));
- return table;
-}
-} // end namespace internal
-
-// For 0 <= offset <= 4, GetUint32AtOffset(GetEightBytesAt(p), offset) will
-// equal UNALIGNED_LOAD32(p + offset). Motivation: On x86-64 hardware we have
-// empirically found that overlapping loads such as
-// UNALIGNED_LOAD32(p) ... UNALIGNED_LOAD32(p+1) ... UNALIGNED_LOAD32(p+2)
-// are slower than UNALIGNED_LOAD64(p) followed by shifts and casts to uint32.
-//
-// We have different versions for 64- and 32-bit; ideally we would avoid the
-// two functions and just inline the UNALIGNED_LOAD64 call into
-// GetUint32AtOffset, but GCC (at least not as of 4.6) is seemingly not clever
-// enough to avoid loading the value multiple times then. For 64-bit, the load
-// is done when GetEightBytesAt() is called, whereas for 32-bit, the load is
-// done at GetUint32AtOffset() time.
-
-#ifdef ARCH_K8
-
-typedef uint64 EightBytesReference;
-
-static inline EightBytesReference GetEightBytesAt(const char* ptr) {
- return UNALIGNED_LOAD64(ptr);
-}
-
-static inline uint32 GetUint32AtOffset(uint64 v, int offset) {
- assert(offset >= 0);
- assert(offset <= 4);
- return v >> (LittleEndian::IsLittleEndian() ? 8 * offset : 32 - 8 * offset);
-}
-
-#else
-
-typedef const char* EightBytesReference;
-
-static inline EightBytesReference GetEightBytesAt(const char* ptr) {
- return ptr;
-}
-
-static inline uint32 GetUint32AtOffset(const char* v, int offset) {
- assert(offset >= 0);
- assert(offset <= 4);
- return UNALIGNED_LOAD32(v + offset);
-}
-
-#endif
-
-// Flat array compression that does not emit the "uncompressed length"
-// prefix. Compresses "input" string to the "*op" buffer.
-//
-// REQUIRES: "input" is at most "kBlockSize" bytes long.
-// REQUIRES: "op" points to an array of memory that is at least
-// "MaxCompressedLength(input.size())" 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".
-namespace internal {
-char* CompressFragment(const char* input,
- size_t input_size,
- char* op,
- uint16* table,
- const int table_size) {
- // "ip" is the input pointer, and "op" is the output pointer.
- const char* ip = input;
- assert(input_size <= kBlockSize);
- assert((table_size & (table_size - 1)) == 0); // table must be power of two
- const int shift = 32 - Bits::Log2Floor(table_size);
- assert(static_cast<int>(kuint32max >> shift) == table_size - 1);
- const char* ip_end = input + input_size;
- const char* base_ip = ip;
- // Bytes in [next_emit, ip) will be emitted as literal bytes. Or
- // [next_emit, ip_end) after the main loop.
- const char* next_emit = ip;
-
- const size_t kInputMarginBytes = 15;
- if (PREDICT_TRUE(input_size >= kInputMarginBytes)) {
- const char* ip_limit = input + input_size - kInputMarginBytes;
-
- for (uint32 next_hash = Hash(++ip, shift); ; ) {
- assert(next_emit < ip);
- // The body of this loop calls EmitLiteral once and then EmitCopy one or
- // more times. (The exception is that when we're close to exhausting
- // the input we goto emit_remainder.)
- //
- // In the first iteration of this loop we're just starting, so
- // there's nothing to copy, so calling EmitLiteral once is
- // necessary. And we only start a new iteration when the
- // current iteration has determined that a call to EmitLiteral will
- // precede the next call to EmitCopy (if any).
- //
- // Step 1: Scan forward in the input looking for a 4-byte-long match.
- // If we get close to exhausting the input then goto emit_remainder.
- //
- // Heuristic match skipping: If 32 bytes are scanned with no matches
- // found, start looking only at every other byte. If 32 more bytes are
- // scanned, look at every third byte, etc.. When a match is found,
- // immediately go back to looking at every byte. This is a small loss
- // (~5% performance, ~0.1% density) for compressible data due to more
- // bookkeeping, but for non-compressible data (such as JPEG) it's a huge
- // win since the compressor quickly "realizes" the data is incompressible
- // and doesn't bother looking for matches everywhere.
- //
- // The "skip" variable keeps track of how many bytes there are since the
- // last match; dividing it by 32 (ie. right-shifting by five) gives the
- // number of bytes to move ahead for each iteration.
- uint32 skip = 32;
-
- const char* next_ip = ip;
- const char* candidate;
- do {
- ip = next_ip;
- uint32 hash = next_hash;
- assert(hash == Hash(ip, shift));
- uint32 bytes_between_hash_lookups = skip++ >> 5;
- next_ip = ip + bytes_between_hash_lookups;
- if (PREDICT_FALSE(next_ip > ip_limit)) {
- goto emit_remainder;
- }
- next_hash = Hash(next_ip, shift);
- candidate = base_ip + table[hash];
- assert(candidate >= base_ip);
- assert(candidate < ip);
-
- table[hash] = ip - base_ip;
- } while (PREDICT_TRUE(UNALIGNED_LOAD32(ip) !=
- UNALIGNED_LOAD32(candidate)));
-
- // Step 2: A 4-byte match has been found. We'll later see if more
- // than 4 bytes match. But, prior to the match, input
- // bytes [next_emit, ip) are unmatched. Emit them as "literal bytes."
- assert(next_emit + 16 <= ip_end);
- op = EmitLiteral(op, next_emit, ip - next_emit, true);
-
- // Step 3: Call EmitCopy, and then see if another EmitCopy could
- // be our next move. Repeat until we find no match for the
- // input immediately after what was consumed by the last EmitCopy call.
- //
- // If we exit this loop normally then we need to call EmitLiteral next,
- // though we don't yet know how big the literal will be. We handle that
- // by proceeding to the next iteration of the main loop. We also can exit
- // this loop via goto if we get close to exhausting the input.
- EightBytesReference input_bytes;
- uint32 candidate_bytes = 0;
-
- do {
- // We have a 4-byte match at ip, and no need to emit any
- // "literal bytes" prior to ip.
- const char* base = ip;
- int matched = 4 + FindMatchLength(candidate + 4, ip + 4, ip_end);
- ip += matched;
- size_t offset = base - candidate;
- assert(0 == memcmp(base, candidate, matched));
- op = EmitCopy(op, offset, matched);
- // We could immediately start working at ip now, but to improve
- // compression we first update table[Hash(ip - 1, ...)].
- const char* insert_tail = ip - 1;
- next_emit = ip;
- if (PREDICT_FALSE(ip >= ip_limit)) {
- goto emit_remainder;
- }
- input_bytes = GetEightBytesAt(insert_tail);
- uint32 prev_hash = HashBytes(GetUint32AtOffset(input_bytes, 0), shift);
- table[prev_hash] = ip - base_ip - 1;
- uint32 cur_hash = HashBytes(GetUint32AtOffset(input_bytes, 1), shift);
- candidate = base_ip + table[cur_hash];
- candidate_bytes = UNALIGNED_LOAD32(candidate);
- table[cur_hash] = ip - base_ip;
- } while (GetUint32AtOffset(input_bytes, 1) == candidate_bytes);
-
- next_hash = HashBytes(GetUint32AtOffset(input_bytes, 2), shift);
- ++ip;
- }
- }
-
- emit_remainder:
- // Emit the remaining bytes as a literal
- if (next_emit < ip_end) {
- op = EmitLiteral(op, next_emit, ip_end - next_emit, false);
- }
-
- return op;
-}
-} // end namespace internal
-
-// Signature of output types needed by decompression code.
-// The decompression code is templatized on a type that obeys this
-// signature so that we do not pay virtual function call overhead in
-// the middle of a tight decompression loop.
-//
-// class DecompressionWriter {
-// public:
-// // Called before decompression
-// void SetExpectedLength(size_t length);
-//
-// // Called after decompression
-// bool CheckLength() const;
-//
-// // Called repeatedly during decompression
-// bool Append(const char* ip, size_t length);
-// bool AppendFromSelf(uint32 offset, size_t length);
-//
-// // The rules for how TryFastAppend differs from Append are somewhat
-// // convoluted:
-// //
-// // - TryFastAppend is allowed to decline (return false) at any
-// // time, for any reason -- just "return false" would be
-// // a perfectly legal implementation of TryFastAppend.
-// // The intention is for TryFastAppend to allow a fast path
-// // in the common case of a small append.
-// // - TryFastAppend is allowed to read up to <available> bytes
-// // from the input buffer, whereas Append is allowed to read
-// // <length>. However, if it returns true, it must leave
-// // at least five (kMaximumTagLength) bytes in the input buffer
-// // afterwards, so that there is always enough space to read the
-// // next tag without checking for a refill.
-// // - TryFastAppend must always return decline (return false)
-// // if <length> is 61 or more, as in this case the literal length is not
-// // decoded fully. In practice, this should not be a big problem,
-// // as it is unlikely that one would implement a fast path accepting
-// // this much data.
-// //
-// bool TryFastAppend(const char* ip, size_t available, size_t length);
-// };
-
-// -----------------------------------------------------------------------
-// Lookup table for decompression code. Generated by ComputeTable() below.
-// -----------------------------------------------------------------------
-
-// Mapping from i in range [0,4] to a mask to extract the bottom 8*i bits
-static const uint32 wordmask[] = {
- 0u, 0xffu, 0xffffu, 0xffffffu, 0xffffffffu
-};
-
-// Data stored per entry in lookup table:
-// Range Bits-used Description
-// ------------------------------------
-// 1..64 0..7 Literal/copy length encoded in opcode byte
-// 0..7 8..10 Copy offset encoded in opcode byte / 256
-// 0..4 11..13 Extra bytes after opcode
-//
-// We use eight bits for the length even though 7 would have sufficed
-// because of efficiency reasons:
-// (1) Extracting a byte is faster than a bit-field
-// (2) It properly aligns copy offset so we do not need a <<8
-static const uint16 char_table[256] = {
- 0x0001, 0x0804, 0x1001, 0x2001, 0x0002, 0x0805, 0x1002, 0x2002,
- 0x0003, 0x0806, 0x1003, 0x2003, 0x0004, 0x0807, 0x1004, 0x2004,
- 0x0005, 0x0808, 0x1005, 0x2005, 0x0006, 0x0809, 0x1006, 0x2006,
- 0x0007, 0x080a, 0x1007, 0x2007, 0x0008, 0x080b, 0x1008, 0x2008,
- 0x0009, 0x0904, 0x1009, 0x2009, 0x000a, 0x0905, 0x100a, 0x200a,
- 0x000b, 0x0906, 0x100b, 0x200b, 0x000c, 0x0907, 0x100c, 0x200c,
- 0x000d, 0x0908, 0x100d, 0x200d, 0x000e, 0x0909, 0x100e, 0x200e,
- 0x000f, 0x090a, 0x100f, 0x200f, 0x0010, 0x090b, 0x1010, 0x2010,
- 0x0011, 0x0a04, 0x1011, 0x2011, 0x0012, 0x0a05, 0x1012, 0x2012,
- 0x0013, 0x0a06, 0x1013, 0x2013, 0x0014, 0x0a07, 0x1014, 0x2014,
- 0x0015, 0x0a08, 0x1015, 0x2015, 0x0016, 0x0a09, 0x1016, 0x2016,
- 0x0017, 0x0a0a, 0x1017, 0x2017, 0x0018, 0x0a0b, 0x1018, 0x2018,
- 0x0019, 0x0b04, 0x1019, 0x2019, 0x001a, 0x0b05, 0x101a, 0x201a,
- 0x001b, 0x0b06, 0x101b, 0x201b, 0x001c, 0x0b07, 0x101c, 0x201c,
- 0x001d, 0x0b08, 0x101d, 0x201d, 0x001e, 0x0b09, 0x101e, 0x201e,
- 0x001f, 0x0b0a, 0x101f, 0x201f, 0x0020, 0x0b0b, 0x1020, 0x2020,
- 0x0021, 0x0c04, 0x1021, 0x2021, 0x0022, 0x0c05, 0x1022, 0x2022,
- 0x0023, 0x0c06, 0x1023, 0x2023, 0x0024, 0x0c07, 0x1024, 0x2024,
- 0x0025, 0x0c08, 0x1025, 0x2025, 0x0026, 0x0c09, 0x1026, 0x2026,
- 0x0027, 0x0c0a, 0x1027, 0x2027, 0x0028, 0x0c0b, 0x1028, 0x2028,
- 0x0029, 0x0d04, 0x1029, 0x2029, 0x002a, 0x0d05, 0x102a, 0x202a,
- 0x002b, 0x0d06, 0x102b, 0x202b, 0x002c, 0x0d07, 0x102c, 0x202c,
- 0x002d, 0x0d08, 0x102d, 0x202d, 0x002e, 0x0d09, 0x102e, 0x202e,
- 0x002f, 0x0d0a, 0x102f, 0x202f, 0x0030, 0x0d0b, 0x1030, 0x2030,
- 0x0031, 0x0e04, 0x1031, 0x2031, 0x0032, 0x0e05, 0x1032, 0x2032,
- 0x0033, 0x0e06, 0x1033, 0x2033, 0x0034, 0x0e07, 0x1034, 0x2034,
- 0x0035, 0x0e08, 0x1035, 0x2035, 0x0036, 0x0e09, 0x1036, 0x2036,
- 0x0037, 0x0e0a, 0x1037, 0x2037, 0x0038, 0x0e0b, 0x1038, 0x2038,
- 0x0039, 0x0f04, 0x1039, 0x2039, 0x003a, 0x0f05, 0x103a, 0x203a,
- 0x003b, 0x0f06, 0x103b, 0x203b, 0x003c, 0x0f07, 0x103c, 0x203c,
- 0x0801, 0x0f08, 0x103d, 0x203d, 0x1001, 0x0f09, 0x103e, 0x203e,
- 0x1801, 0x0f0a, 0x103f, 0x203f, 0x2001, 0x0f0b, 0x1040, 0x2040
-};
-
-// In debug mode, allow optional computation of the table at startup.
-// Also, check that the decompression table is correct.
-#ifndef NDEBUG
-DEFINE_bool(snappy_dump_decompression_table, false,
- "If true, we print the decompression table at startup.");
-
-static uint16 MakeEntry(unsigned int extra,
- unsigned int len,
- unsigned int copy_offset) {
- // Check that all of the fields fit within the allocated space
- assert(extra == (extra & 0x7)); // At most 3 bits
- assert(copy_offset == (copy_offset & 0x7)); // At most 3 bits
- assert(len == (len & 0x7f)); // At most 7 bits
- return len | (copy_offset << 8) | (extra << 11);
-}
-
-static void ComputeTable() {
- uint16 dst[256];
-
- // Place invalid entries in all places to detect missing initialization
- int assigned = 0;
- for (int i = 0; i < 256; i++) {
- dst[i] = 0xffff;
- }
-
- // Small LITERAL entries. We store (len-1) in the top 6 bits.
- for (unsigned int len = 1; len <= 60; len++) {
- dst[LITERAL | ((len-1) << 2)] = MakeEntry(0, len, 0);
- assigned++;
- }
-
- // Large LITERAL entries. We use 60..63 in the high 6 bits to
- // encode the number of bytes of length info that follow the opcode.
- for (unsigned int extra_bytes = 1; extra_bytes <= 4; extra_bytes++) {
- // We set the length field in the lookup table to 1 because extra
- // bytes encode len-1.
- dst[LITERAL | ((extra_bytes+59) << 2)] = MakeEntry(extra_bytes, 1, 0);
- assigned++;
- }
-
- // COPY_1_BYTE_OFFSET.
- //
- // The tag byte in the compressed data stores len-4 in 3 bits, and
- // offset/256 in 5 bits. offset%256 is stored in the next byte.
- //
- // This format is used for length in range [4..11] and offset in
- // range [0..2047]
- for (unsigned int len = 4; len < 12; len++) {
- for (unsigned int offset = 0; offset < 2048; offset += 256) {
- dst[COPY_1_BYTE_OFFSET | ((len-4)<<2) | ((offset>>8)<<5)] =
- MakeEntry(1, len, offset>>8);
- assigned++;
- }
- }
-
- // COPY_2_BYTE_OFFSET.
- // Tag contains len-1 in top 6 bits, and offset in next two bytes.
- for (unsigned int len = 1; len <= 64; len++) {
- dst[COPY_2_BYTE_OFFSET | ((len-1)<<2)] = MakeEntry(2, len, 0);
- assigned++;
- }
-
- // COPY_4_BYTE_OFFSET.
- // Tag contents len-1 in top 6 bits, and offset in next four bytes.
- for (unsigned int len = 1; len <= 64; len++) {
- dst[COPY_4_BYTE_OFFSET | ((len-1)<<2)] = MakeEntry(4, len, 0);
- assigned++;
- }
-
- // Check that each entry was initialized exactly once.
- if (assigned != 256) {
- fprintf(stderr, "ComputeTable: assigned only %d of 256\n", assigned);
- abort();
- }
- for (int i = 0; i < 256; i++) {
- if (dst[i] == 0xffff) {
- fprintf(stderr, "ComputeTable: did not assign byte %d\n", i);
- abort();
- }
- }
-
- if (FLAGS_snappy_dump_decompression_table) {
- printf("static const uint16 char_table[256] = {\n ");
- for (int i = 0; i < 256; i++) {
- printf("0x%04x%s",
- dst[i],
- ((i == 255) ? "\n" : (((i%8) == 7) ? ",\n " : ", ")));
- }
- printf("};\n");
- }
-
- // Check that computed table matched recorded table
- for (int i = 0; i < 256; i++) {
- if (dst[i] != char_table[i]) {
- fprintf(stderr, "ComputeTable: byte %d: computed (%x), expect (%x)\n",
- i, static_cast<int>(dst[i]), static_cast<int>(char_table[i]));
- abort();
- }
- }
-}
-#endif /* !NDEBUG */
-
-// Helper class for decompression
-class SnappyDecompressor {
- private:
- Source* reader_; // Underlying source of bytes to decompress
- const char* ip_; // Points to next buffered byte
- const char* ip_limit_; // Points just past buffered bytes
- uint32 peeked_; // Bytes peeked from reader (need to skip)
- bool eof_; // Hit end of input without an error?
- char scratch_[kMaximumTagLength]; // See RefillTag().
-
- // Ensure that all of the tag metadata for the next tag is available
- // in [ip_..ip_limit_-1]. Also ensures that [ip,ip+4] is readable even
- // if (ip_limit_ - ip_ < 5).
- //
- // Returns true on success, false on error or end of input.
- bool RefillTag();
-
- public:
- explicit SnappyDecompressor(Source* reader)
- : reader_(reader),
- ip_(NULL),
- ip_limit_(NULL),
- peeked_(0),
- eof_(false) {
- }
-
- ~SnappyDecompressor() {
- // Advance past any bytes we peeked at from the reader
- reader_->Skip(peeked_);
- }
-
- // Returns true iff we have hit the end of the input without an error.
- bool eof() const {
- return eof_;
- }
-
- // Read the uncompressed length stored at the start of the compressed data.
- // On succcess, stores the length in *result and returns true.
- // On failure, returns false.
- bool ReadUncompressedLength(uint32* result) {
- assert(ip_ == NULL); // Must not have read anything yet
- // Length is encoded in 1..5 bytes
- *result = 0;
- uint32 shift = 0;
- while (true) {
- if (shift >= 32) return false;
- size_t n;
- const char* ip = reader_->Peek(&n);
- if (n == 0) return false;
- const unsigned char c = *(reinterpret_cast<const unsigned char*>(ip));
- reader_->Skip(1);
- *result |= static_cast<uint32>(c & 0x7f) << shift;
- if (c < 128) {
- break;
- }
- shift += 7;
- }
- return true;
- }
-
- // Process the next item found in the input.
- // Returns true if successful, false on error or end of input.
- template <class Writer>
- void DecompressAllTags(Writer* writer) {
- const char* ip = ip_;
-
- // We could have put this refill fragment only at the beginning of the loop.
- // However, duplicating it at the end of each branch gives the compiler more
- // scope to optimize the <ip_limit_ - ip> expression based on the local
- // context, which overall increases speed.
- #define MAYBE_REFILL() \
- if (ip_limit_ - ip < kMaximumTagLength) { \
- ip_ = ip; \
- if (!RefillTag()) return; \
- ip = ip_; \
- }
-
- MAYBE_REFILL();
- for ( ;; ) {
- const unsigned char c = *(reinterpret_cast<const unsigned char*>(ip++));
-
- if ((c & 0x3) == LITERAL) {
- size_t literal_length = (c >> 2) + 1u;
- if (writer->TryFastAppend(ip, ip_limit_ - ip, literal_length)) {
- assert(literal_length < 61);
- ip += literal_length;
- // NOTE(user): There is no MAYBE_REFILL() here, as TryFastAppend()
- // will not return true unless there's already at least five spare
- // bytes in addition to the literal.
- continue;
- }
- if (PREDICT_FALSE(literal_length >= 61)) {
- // Long literal.
- const size_t literal_length_length = literal_length - 60;
- literal_length =
- (LittleEndian::Load32(ip) & wordmask[literal_length_length]) + 1;
- ip += literal_length_length;
- }
-
- size_t avail = ip_limit_ - ip;
- while (avail < literal_length) {
- if (!writer->Append(ip, avail)) return;
- literal_length -= avail;
- reader_->Skip(peeked_);
- size_t n;
- ip = reader_->Peek(&n);
- avail = n;
- peeked_ = avail;
- if (avail == 0) return; // Premature end of input
- ip_limit_ = ip + avail;
- }
- if (!writer->Append(ip, literal_length)) {
- return;
- }
- ip += literal_length;
- MAYBE_REFILL();
- } else {
- const uint32 entry = char_table[c];
- const uint32 trailer = LittleEndian::Load32(ip) & wordmask[entry >> 11];
- const uint32 length = entry & 0xff;
- ip += entry >> 11;
-
- // copy_offset/256 is encoded in bits 8..10. By just fetching
- // those bits, we get copy_offset (since the bit-field starts at
- // bit 8).
- const uint32 copy_offset = entry & 0x700;
- if (!writer->AppendFromSelf(copy_offset + trailer, length)) {
- return;
- }
- MAYBE_REFILL();
- }
- }
-
-#undef MAYBE_REFILL
- }
-};
-
-bool SnappyDecompressor::RefillTag() {
- const char* ip = ip_;
- if (ip == ip_limit_) {
- // Fetch a new fragment from the reader
- reader_->Skip(peeked_); // All peeked bytes are used up
- size_t n;
- ip = reader_->Peek(&n);
- peeked_ = n;
- if (n == 0) {
- eof_ = true;
- return false;
- }
- ip_limit_ = ip + n;
- }
-
- // Read the tag character
- assert(ip < ip_limit_);
- const unsigned char c = *(reinterpret_cast<const unsigned char*>(ip));
- const uint32 entry = char_table[c];
- const uint32 needed = (entry >> 11) + 1; // +1 byte for 'c'
- assert(needed <= sizeof(scratch_));
-
- // Read more bytes from reader if needed
- uint32 nbuf = ip_limit_ - ip;
- if (nbuf < needed) {
- // Stitch together bytes from ip and reader to form the word
- // contents. We store the needed bytes in "scratch_". They
- // will be consumed immediately by the caller since we do not
- // read more than we need.
- memmove(scratch_, ip, nbuf);
- reader_->Skip(peeked_); // All peeked bytes are used up
- peeked_ = 0;
- while (nbuf < needed) {
- size_t length;
- const char* src = reader_->Peek(&length);
- if (length == 0) return false;
- uint32 to_add = min<uint32>(needed - nbuf, length);
- memcpy(scratch_ + nbuf, src, to_add);
- nbuf += to_add;
- reader_->Skip(to_add);
- }
- assert(nbuf == needed);
- ip_ = scratch_;
- ip_limit_ = scratch_ + needed;
- } else if (nbuf < kMaximumTagLength) {
- // Have enough bytes, but move into scratch_ so that we do not
- // read past end of input
- memmove(scratch_, ip, nbuf);
- reader_->Skip(peeked_); // All peeked bytes are used up
- peeked_ = 0;
- ip_ = scratch_;
- ip_limit_ = scratch_ + nbuf;
- } else {
- // Pass pointer to buffer returned by reader_.
- ip_ = ip;
- }
- return true;
-}
-
-template <typename Writer>
-static bool InternalUncompress(Source* r, Writer* writer) {
- // Read the uncompressed length from the front of the compressed input
- SnappyDecompressor decompressor(r);
- uint32 uncompressed_len = 0;
- if (!decompressor.ReadUncompressedLength(&uncompressed_len)) return false;
- return InternalUncompressAllTags(&decompressor, writer, uncompressed_len);
-}
-
-template <typename Writer>
-static bool InternalUncompressAllTags(SnappyDecompressor* decompressor,
- Writer* writer,
- uint32 uncompressed_len) {
- writer->SetExpectedLength(uncompressed_len);
-
- // Process the entire input
- decompressor->DecompressAllTags(writer);
- return (decompressor->eof() && writer->CheckLength());
-}
-
-bool GetUncompressedLength(Source* source, uint32* result) {
- SnappyDecompressor decompressor(source);
- return decompressor.ReadUncompressedLength(result);
-}
-
-size_t Compress(Source* reader, Sink* writer) {
- size_t written = 0;
- size_t N = reader->Available();
- char ulength[Varint::kMax32];
- char* p = Varint::Encode32(ulength, N);
- writer->Append(ulength, p-ulength);
- written += (p - ulength);
-
- internal::WorkingMemory wmem;
- char* scratch = NULL;
- char* scratch_output = NULL;
-
- while (N > 0) {
- // Get next block to compress (without copying if possible)
- size_t fragment_size;
- const char* fragment = reader->Peek(&fragment_size);
- assert(fragment_size != 0); // premature end of input
- const size_t num_to_read = min(N, kBlockSize);
- size_t bytes_read = fragment_size;
-
- size_t pending_advance = 0;
- if (bytes_read >= num_to_read) {
- // Buffer returned by reader is large enough
- pending_advance = num_to_read;
- fragment_size = num_to_read;
- } else {
- // Read into scratch buffer
- if (scratch == NULL) {
- // If this is the last iteration, we want to allocate N bytes
- // of space, otherwise the max possible kBlockSize space.
- // num_to_read contains exactly the correct value
- scratch = new char[num_to_read];
- }
- memcpy(scratch, fragment, bytes_read);
- reader->Skip(bytes_read);
-
- while (bytes_read < num_to_read) {
- fragment = reader->Peek(&fragment_size);
- size_t n = min<size_t>(fragment_size, num_to_read - bytes_read);
- memcpy(scratch + bytes_read, fragment, n);
- bytes_read += n;
- reader->Skip(n);
- }
- assert(bytes_read == num_to_read);
- fragment = scratch;
- fragment_size = num_to_read;
- }
- assert(fragment_size == num_to_read);
-
- // Get encoding table for compression
- int table_size;
- uint16* table = wmem.GetHashTable(num_to_read, &table_size);
-
- // Compress input_fragment and append to dest
- const int max_output = MaxCompressedLength(num_to_read);
-
- // Need a scratch buffer for the output, in case the byte sink doesn't
- // have room for us directly.
- if (scratch_output == NULL) {
- scratch_output = new char[max_output];
- } else {
- // Since we encode kBlockSize regions followed by a region
- // which is <= kBlockSize in length, a previously allocated
- // scratch_output[] region is big enough for this iteration.
- }
- char* dest = writer->GetAppendBuffer(max_output, scratch_output);
- char* end = internal::CompressFragment(fragment, fragment_size,
- dest, table, table_size);
- writer->Append(dest, end - dest);
- written += (end - dest);
-
- N -= num_to_read;
- reader->Skip(pending_advance);
- }
-
- delete[] scratch;
- delete[] scratch_output;
-
- return written;
-}
-
-// -----------------------------------------------------------------------
-// IOVec interfaces
-// -----------------------------------------------------------------------
-
-// A type that writes to an iovec.
-// Note that this is not a "ByteSink", but a type that matches the
-// Writer template argument to SnappyDecompressor::DecompressAllTags().
-class SnappyIOVecWriter {
- private:
- const struct iovec* output_iov_;
- const size_t output_iov_count_;
-
- // We are currently writing into output_iov_[curr_iov_index_].
- int curr_iov_index_;
-
- // Bytes written to output_iov_[curr_iov_index_] so far.
- size_t curr_iov_written_;
-
- // Total bytes decompressed into output_iov_ so far.
- size_t total_written_;
-
- // Maximum number of bytes that will be decompressed into output_iov_.
- size_t output_limit_;
-
- inline char* GetIOVecPointer(int index, size_t offset) {
- return reinterpret_cast<char*>(output_iov_[index].iov_base) +
- offset;
- }
-
- public:
- // Does not take ownership of iov. iov must be valid during the
- // entire lifetime of the SnappyIOVecWriter.
- inline SnappyIOVecWriter(const struct iovec* iov, size_t iov_count)
- : output_iov_(iov),
- output_iov_count_(iov_count),
- curr_iov_index_(0),
- curr_iov_written_(0),
- total_written_(0),
- output_limit_(-1) {
- }
-
- inline void SetExpectedLength(size_t len) {
- output_limit_ = len;
- }
-
- inline bool CheckLength() const {
- return total_written_ == output_limit_;
- }
-
- inline bool Append(const char* ip, size_t len) {
- if (total_written_ + len > output_limit_) {
- return false;
- }
-
- while (len > 0) {
- assert(curr_iov_written_ <= output_iov_[curr_iov_index_].iov_len);
- if (curr_iov_written_ >= output_iov_[curr_iov_index_].iov_len) {
- // This iovec is full. Go to the next one.
- if (curr_iov_index_ + 1 >= output_iov_count_) {
- return false;
- }
- curr_iov_written_ = 0;
- ++curr_iov_index_;
- }
-
- const size_t to_write = std::min(
- len, output_iov_[curr_iov_index_].iov_len - curr_iov_written_);
- memcpy(GetIOVecPointer(curr_iov_index_, curr_iov_written_),
- ip,
- to_write);
- curr_iov_written_ += to_write;
- total_written_ += to_write;
- ip += to_write;
- len -= to_write;
- }
-
- return true;
- }
-
- inline bool TryFastAppend(const char* ip, size_t available, size_t len) {
- const size_t space_left = output_limit_ - total_written_;
- if (len <= 16 && available >= 16 + kMaximumTagLength && space_left >= 16 &&
- output_iov_[curr_iov_index_].iov_len - curr_iov_written_ >= 16) {
- // Fast path, used for the majority (about 95%) of invocations.
- char* ptr = GetIOVecPointer(curr_iov_index_, curr_iov_written_);
- UnalignedCopy64(ip, ptr);
- UnalignedCopy64(ip + 8, ptr + 8);
- curr_iov_written_ += len;
- total_written_ += len;
- return true;
- }
-
- return false;
- }
-
- inline bool AppendFromSelf(size_t offset, size_t len) {
- if (offset > total_written_ || offset == 0) {
- return false;
- }
- const size_t space_left = output_limit_ - total_written_;
- if (len > space_left) {
- return false;
- }
-
- // Locate the iovec from which we need to start the copy.
- int from_iov_index = curr_iov_index_;
- size_t from_iov_offset = curr_iov_written_;
- while (offset > 0) {
- if (from_iov_offset >= offset) {
- from_iov_offset -= offset;
- break;
- }
-
- offset -= from_iov_offset;
- --from_iov_index;
- assert(from_iov_index >= 0);
- from_iov_offset = output_iov_[from_iov_index].iov_len;
- }
-
- // Copy <len> bytes starting from the iovec pointed to by from_iov_index to
- // the current iovec.
- while (len > 0) {
- assert(from_iov_index <= curr_iov_index_);
- if (from_iov_index != curr_iov_index_) {
- const size_t to_copy = std::min(
- output_iov_[from_iov_index].iov_len - from_iov_offset,
- len);
- Append(GetIOVecPointer(from_iov_index, from_iov_offset), to_copy);
- len -= to_copy;
- if (len > 0) {
- ++from_iov_index;
- from_iov_offset = 0;
- }
- } else {
- assert(curr_iov_written_ <= output_iov_[curr_iov_index_].iov_len);
- size_t to_copy = std::min(output_iov_[curr_iov_index_].iov_len -
- curr_iov_written_,
- len);
- if (to_copy == 0) {
- // This iovec is full. Go to the next one.
- if (curr_iov_index_ + 1 >= output_iov_count_) {
- return false;
- }
- ++curr_iov_index_;
- curr_iov_written_ = 0;
- continue;
- }
- if (to_copy > len) {
- to_copy = len;
- }
- IncrementalCopy(GetIOVecPointer(from_iov_index, from_iov_offset),
- GetIOVecPointer(curr_iov_index_, curr_iov_written_),
- to_copy);
- curr_iov_written_ += to_copy;
- from_iov_offset += to_copy;
- total_written_ += to_copy;
- len -= to_copy;
- }
- }
-
- return true;
- }
-
-};
-
-bool RawUncompressToIOVec(const char* compressed, size_t compressed_length,
- const struct iovec* iov, size_t iov_cnt) {
- ByteArraySource reader(compressed, compressed_length);
- return RawUncompressToIOVec(&reader, iov, iov_cnt);
-}
-
-bool RawUncompressToIOVec(Source* compressed, const struct iovec* iov,
- size_t iov_cnt) {
- SnappyIOVecWriter output(iov, iov_cnt);
- return InternalUncompress(compressed, &output);
-}
-
-// -----------------------------------------------------------------------
-// Flat array interfaces
-// -----------------------------------------------------------------------
-
-// A type that writes to a flat array.
-// Note that this is not a "ByteSink", but a type that matches the
-// Writer template argument to SnappyDecompressor::DecompressAllTags().
-class SnappyArrayWriter {
- private:
- char* base_;
- char* op_;
- char* op_limit_;
-
- public:
- inline explicit SnappyArrayWriter(char* dst)
- : base_(dst),
- op_(dst) {
- }
-
- inline void SetExpectedLength(size_t len) {
- op_limit_ = op_ + len;
- }
-
- inline bool CheckLength() const {
- return op_ == op_limit_;
- }
-
- inline bool Append(const char* ip, size_t len) {
- char* op = op_;
- const size_t space_left = op_limit_ - op;
- if (space_left < len) {
- return false;
- }
- memcpy(op, ip, len);
- op_ = op + len;
- return true;
- }
-
- inline bool TryFastAppend(const char* ip, size_t available, size_t len) {
- char* op = op_;
- const size_t space_left = op_limit_ - op;
- if (len <= 16 && available >= 16 + kMaximumTagLength && space_left >= 16) {
- // Fast path, used for the majority (about 95%) of invocations.
- UnalignedCopy64(ip, op);
- UnalignedCopy64(ip + 8, op + 8);
- op_ = op + len;
- return true;
- } else {
- return false;
- }
- }
-
- inline bool AppendFromSelf(size_t offset, size_t len) {
- char* op = op_;
- const size_t space_left = op_limit_ - op;
-
- // Check if we try to append from before the start of the buffer.
- // Normally this would just be a check for "produced < offset",
- // but "produced <= offset - 1u" is equivalent for every case
- // except the one where offset==0, where the right side will wrap around
- // to a very big number. This is convenient, as offset==0 is another
- // invalid case that we also want to catch, so that we do not go
- // into an infinite loop.
- assert(op >= base_);
- size_t produced = op - base_;
- if (produced <= offset - 1u) {
- return false;
- }
- if (len <= 16 && offset >= 8 && space_left >= 16) {
- // Fast path, used for the majority (70-80%) of dynamic invocations.
- UnalignedCopy64(op - offset, op);
- UnalignedCopy64(op - offset + 8, op + 8);
- } else {
- if (space_left >= len + kMaxIncrementCopyOverflow) {
- IncrementalCopyFastPath(op - offset, op, len);
- } else {
- if (space_left < len) {
- return false;
- }
- IncrementalCopy(op - offset, op, len);
- }
- }
-
- op_ = op + len;
- return true;
- }
-};
-
-bool RawUncompress(const char* compressed, size_t n, char* uncompressed) {
- ByteArraySource reader(compressed, n);
- return RawUncompress(&reader, uncompressed);
-}
-
-bool RawUncompress(Source* compressed, char* uncompressed) {
- SnappyArrayWriter output(uncompressed);
- return InternalUncompress(compressed, &output);
-}
-
-bool Uncompress(const char* compressed, size_t n, string* uncompressed) {
- size_t ulength;
- if (!GetUncompressedLength(compressed, n, &ulength)) {
- return false;
- }
- // On 32-bit builds: max_size() < kuint32max. Check for that instead
- // of crashing (e.g., consider externally specified compressed data).
- if (ulength > uncompressed->max_size()) {
- return false;
- }
- STLStringResizeUninitialized(uncompressed, ulength);
- return RawUncompress(compressed, n, string_as_array(uncompressed));
-}
-
-
-// A Writer that drops everything on the floor and just does validation
-class SnappyDecompressionValidator {
- private:
- size_t expected_;
- size_t produced_;
-
- public:
- inline SnappyDecompressionValidator() : produced_(0) { }
- inline void SetExpectedLength(size_t len) {
- expected_ = len;
- }
- inline bool CheckLength() const {
- return expected_ == produced_;
- }
- inline bool Append(const char* ip, size_t len) {
- produced_ += len;
- return produced_ <= expected_;
- }
- inline bool TryFastAppend(const char* ip, size_t available, size_t length) {
- return false;
- }
- inline bool AppendFromSelf(size_t offset, size_t len) {
- // See SnappyArrayWriter::AppendFromSelf for an explanation of
- // the "offset - 1u" trick.
- if (produced_ <= offset - 1u) return false;
- produced_ += len;
- return produced_ <= expected_;
- }
-};
-
-bool IsValidCompressedBuffer(const char* compressed, size_t n) {
- ByteArraySource reader(compressed, n);
- SnappyDecompressionValidator writer;
- return InternalUncompress(&reader, &writer);
-}
-
-void RawCompress(const char* input,
- size_t input_length,
- char* compressed,
- size_t* compressed_length) {
- ByteArraySource reader(input, input_length);
- UncheckedByteArraySink writer(compressed);
- Compress(&reader, &writer);
-
- // Compute how many bytes were added
- *compressed_length = (writer.CurrentDestination() - compressed);
-}
-
-size_t Compress(const char* input, size_t input_length, string* compressed) {
- // Pre-grow the buffer to the max length of the compressed output
- compressed->resize(MaxCompressedLength(input_length));
-
- size_t compressed_length;
- RawCompress(input, input_length, string_as_array(compressed),
- &compressed_length);
- compressed->resize(compressed_length);
- return compressed_length;
-}
-
-
-} // end namespace snappy
-
http://git-wip-us.apache.org/repos/asf/orc/blob/590245a0/c++/libs/snappy-1.1.2/snappy.h
----------------------------------------------------------------------
diff --git a/c++/libs/snappy-1.1.2/snappy.h b/c++/libs/snappy-1.1.2/snappy.h
deleted file mode 100644
index e879e79..0000000
--- a/c++/libs/snappy-1.1.2/snappy.h
+++ /dev/null
@@ -1,184 +0,0 @@
-// 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 UTIL_SNAPPY_SNAPPY_H__
-#define UTIL_SNAPPY_SNAPPY_H__
-
-#include <stddef.h>
-#include <string>
-
-#include "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);
-
-
- // ------------------------------------------------------------------------
- // 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);
-
- // 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 // UTIL_SNAPPY_SNAPPY_H__