Revision created by MOE tool push_codebase.

MOE_MIGRATION=


git-svn-id: http://snappy.googlecode.com/svn/trunk@2 03e5f5b5-db94-4691-08a0-1a8bf15f6143

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diff --git a/snappy-stubs-internal.h b/snappy-stubs-internal.h
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+// Copyright 2011 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+//      Unless required by applicable law or agreed to in writing, software
+//      distributed under the License is distributed on an "AS IS" BASIS,
+//      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//      See the License for the specific language governing permissions and
+//      limitations under the License.
+//
+// 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_
+
+#include <iostream>
+#include <string>
+
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+
+#include "config.h"
+#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;
+#define REGISTER_MODULE_INITIALIZER(name, code)
+
+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 _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)
+
+#else
+#include <byteswap.h>
+#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_