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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 UTIL_SNAPPY_OPENSOURCE_SNAPPY_STUBS_INTERNAL_H_

 #define UTIL_SNAPPY_OPENSOURCE_SNAPPY_STUBS_INTERNAL_H_

 #ifdef HAVE_CONFIG_H

 #include "config.h"

 #endif

 #include <iostream>

 #include <string>

 #include <assert.h>

 #include <stdlib.h>

 #include <string.h>

 #ifdef HAVE_SYS_MMAN_H

 #include <sys/mman.h>

 #endif

 #include "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);

 // 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))

 #ifdef NDEBUG

 #define DCHECK(cond) CRASH_UNLESS(true)

 #define DCHECK_LE(a, b) CRASH_UNLESS(true)

 #define DCHECK_GE(a, b) CRASH_UNLESS(true)

 #define DCHECK_EQ(a, b) CRASH_UNLESS(true)

 #define DCHECK_NE(a, b) CRASH_UNLESS(true)

 #define DCHECK_LT(a, b) CRASH_UNLESS(true)

 #define DCHECK_GT(a, b) CRASH_UNLESS(true)

 #else

 #define DCHECK(cond) CHECK(cond)

 #define DCHECK_LE(a, b) CHECK_LE(a, b)

 #define DCHECK_GE(a, b) CHECK_GE(a, b)

 #define DCHECK_EQ(a, b) CHECK_EQ(a, b)

 #define DCHECK_NE(a, b) CHECK_NE(a, b)

 #define DCHECK_LT(a, b) CHECK_LT(a, b)

 #define DCHECK_GT(a, b) CHECK_GT(a, b)

 #endif

 // Potentially unaligned loads and stores.

 #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))

 #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

 // 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  // UTIL_SNAPPY_OPENSOURCE_SNAPPY_STUBS_INTERNAL_H_