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// Copyright 2011 Google Inc. All Rights Reserved.
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived from
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// this software without specific prior written permission.
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// Various stubs for the open-source version of Snappy.
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#ifndef UTIL_SNAPPY_OPENSOURCE_SNAPPY_STUBS_INTERNAL_H_
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#define UTIL_SNAPPY_OPENSOURCE_SNAPPY_STUBS_INTERNAL_H_
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#ifdef HAVE_SYS_MMAN_H
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#include "snappy-stubs-public.h"
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#if defined(__x86_64__)
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// Enable 64-bit optimized versions of some routines.
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// Needed by OS X, among others.
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#define MAP_ANONYMOUS MAP_ANON
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// Pull in std::min, std::ostream, and the likes. This is safe because this
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// header file is never used from any public header files.
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// The size of an array, if known at compile-time.
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// Will give unexpected results if used on a pointer.
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// We undefine it first, since some compilers already have a definition.
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#define ARRAYSIZE(a) (sizeof(a) / sizeof(*(a)))
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// Static prediction hints.
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#ifdef HAVE_BUILTIN_EXPECT
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#define PREDICT_FALSE(x) (__builtin_expect(x, 0))
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#define PREDICT_TRUE(x) (__builtin_expect(!!(x), 1))
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#define PREDICT_FALSE(x) x
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#define PREDICT_TRUE(x) x
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// This is only used for recomputing the tag byte table used during
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// decompression; for simplicity we just remove it from the open-source
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// version (anyone who wants to regenerate it can just do the call
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// themselves within main()).
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#define DEFINE_bool(flag_name, default_value, description) \
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bool FLAGS_ ## flag_name = default_value;
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#define DECLARE_bool(flag_name) \
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extern bool FLAGS_ ## flag_name;
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#define REGISTER_MODULE_INITIALIZER(name, code)
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static const uint32 kuint32max = static_cast<uint32>(0xFFFFFFFF);
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static const int64 kint64max = static_cast<int64>(0x7FFFFFFFFFFFFFFFLL);
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#define LOG(level) LogMessage()
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#define VLOG(level) true ? (void)0 : \
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snappy::LogMessageVoidify() & snappy::LogMessage()
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LogMessage& operator<<(const std::string& msg) {
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LogMessage& operator<<(int x) {
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// Asserts, both versions activated in debug mode only,
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// and ones that are always active.
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#define CRASH_UNLESS(condition) \
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PREDICT_TRUE(condition) ? (void)0 : \
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snappy::LogMessageVoidify() & snappy::LogMessageCrash()
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class LogMessageCrash : public LogMessage {
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LogMessageCrash() { }
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// This class is used to explicitly ignore values in the conditional
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// logging macros. This avoids compiler warnings like "value computed
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// is not used" and "statement has no effect".
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class LogMessageVoidify {
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LogMessageVoidify() { }
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// This has to be an operator with a precedence lower than << but
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void operator&(const LogMessage&) { }
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#define CHECK(cond) CRASH_UNLESS(cond)
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#define CHECK_LE(a, b) CRASH_UNLESS((a) <= (b))
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#define CHECK_GE(a, b) CRASH_UNLESS((a) >= (b))
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#define CHECK_EQ(a, b) CRASH_UNLESS((a) == (b))
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#define CHECK_NE(a, b) CRASH_UNLESS((a) != (b))
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#define CHECK_LT(a, b) CRASH_UNLESS((a) < (b))
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#define CHECK_GT(a, b) CRASH_UNLESS((a) > (b))
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#define DCHECK(cond) CRASH_UNLESS(true)
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#define DCHECK_LE(a, b) CRASH_UNLESS(true)
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#define DCHECK_GE(a, b) CRASH_UNLESS(true)
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#define DCHECK_EQ(a, b) CRASH_UNLESS(true)
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#define DCHECK_NE(a, b) CRASH_UNLESS(true)
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#define DCHECK_LT(a, b) CRASH_UNLESS(true)
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#define DCHECK_GT(a, b) CRASH_UNLESS(true)
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#define DCHECK(cond) CHECK(cond)
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#define DCHECK_LE(a, b) CHECK_LE(a, b)
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#define DCHECK_GE(a, b) CHECK_GE(a, b)
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#define DCHECK_EQ(a, b) CHECK_EQ(a, b)
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#define DCHECK_NE(a, b) CHECK_NE(a, b)
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#define DCHECK_LT(a, b) CHECK_LT(a, b)
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#define DCHECK_GT(a, b) CHECK_GT(a, b)
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// Potentially unaligned loads and stores.
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#if defined(__i386__) || defined(__x86_64__) || defined(__powerpc__)
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#define UNALIGNED_LOAD16(_p) (*reinterpret_cast<const uint16 *>(_p))
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#define UNALIGNED_LOAD32(_p) (*reinterpret_cast<const uint32 *>(_p))
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#define UNALIGNED_LOAD64(_p) (*reinterpret_cast<const uint64 *>(_p))
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#define UNALIGNED_STORE16(_p, _val) (*reinterpret_cast<uint16 *>(_p) = (_val))
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#define UNALIGNED_STORE32(_p, _val) (*reinterpret_cast<uint32 *>(_p) = (_val))
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#define UNALIGNED_STORE64(_p, _val) (*reinterpret_cast<uint64 *>(_p) = (_val))
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// These functions are provided for architectures that don't support
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// unaligned loads and stores.
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inline uint16 UNALIGNED_LOAD16(const void *p) {
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memcpy(&t, p, sizeof t);
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inline uint32 UNALIGNED_LOAD32(const void *p) {
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memcpy(&t, p, sizeof t);
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inline uint64 UNALIGNED_LOAD64(const void *p) {
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memcpy(&t, p, sizeof t);
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inline void UNALIGNED_STORE16(void *p, uint16 v) {
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memcpy(p, &v, sizeof v);
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inline void UNALIGNED_STORE32(void *p, uint32 v) {
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memcpy(p, &v, sizeof v);
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inline void UNALIGNED_STORE64(void *p, uint64 v) {
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memcpy(p, &v, sizeof v);
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// The following guarantees declaration of the byte swap functions.
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#ifdef WORDS_BIGENDIAN
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#define bswap_16(x) _byteswap_ushort(x)
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#define bswap_32(x) _byteswap_ulong(x)
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#define bswap_64(x) _byteswap_uint64(x)
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#elif defined(__APPLE__)
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// Mac OS X / Darwin features
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#include <libkern/OSByteOrder.h>
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#define bswap_16(x) OSSwapInt16(x)
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#define bswap_32(x) OSSwapInt32(x)
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#define bswap_64(x) OSSwapInt64(x)
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#include <byteswap.h>
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#endif // WORDS_BIGENDIAN
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// Convert to little-endian storage, opposite of network format.
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// Convert x from host to little endian: x = LittleEndian.FromHost(x);
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// convert x from little endian to host: x = LittleEndian.ToHost(x);
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// Store values into unaligned memory converting to little endian order:
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// LittleEndian.Store16(p, x);
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// Load unaligned values stored in little endian converting to host order:
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// x = LittleEndian.Load16(p);
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// Conversion functions.
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#ifdef WORDS_BIGENDIAN
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static uint16 FromHost16(uint16 x) { return bswap_16(x); }
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static uint16 ToHost16(uint16 x) { return bswap_16(x); }
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static uint32 FromHost32(uint32 x) { return bswap_32(x); }
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static uint32 ToHost32(uint32 x) { return bswap_32(x); }
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static bool IsLittleEndian() { return false; }
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#else // !defined(WORDS_BIGENDIAN)
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static uint16 FromHost16(uint16 x) { return x; }
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static uint16 ToHost16(uint16 x) { return x; }
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static uint32 FromHost32(uint32 x) { return x; }
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static uint32 ToHost32(uint32 x) { return x; }
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static bool IsLittleEndian() { return true; }
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#endif // !defined(WORDS_BIGENDIAN)
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// Functions to do unaligned loads and stores in little-endian order.
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static uint16 Load16(const void *p) {
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return ToHost16(UNALIGNED_LOAD16(p));
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static void Store16(void *p, uint16 v) {
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UNALIGNED_STORE16(p, FromHost16(v));
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static uint32 Load32(const void *p) {
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return ToHost32(UNALIGNED_LOAD32(p));
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static void Store32(void *p, uint32 v) {
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UNALIGNED_STORE32(p, FromHost32(v));
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// Some bit-manipulation functions.
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// Return floor(log2(n)) for positive integer n. Returns -1 iff n == 0.
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static int Log2Floor(uint32 n);
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// Return the first set least / most significant bit, 0-indexed. Returns an
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// undefined value if n == 0. FindLSBSetNonZero() is similar to ffs() except
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// that it's 0-indexed.
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static int FindLSBSetNonZero(uint32 n);
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static int FindLSBSetNonZero64(uint64 n);
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DISALLOW_COPY_AND_ASSIGN(Bits);
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#ifdef HAVE_BUILTIN_CTZ
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inline int Bits::Log2Floor(uint32 n) {
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return n == 0 ? -1 : 31 ^ __builtin_clz(n);
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inline int Bits::FindLSBSetNonZero(uint32 n) {
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return __builtin_ctz(n);
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inline int Bits::FindLSBSetNonZero64(uint64 n) {
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return __builtin_ctzll(n);
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#else // Portable versions.
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inline int Bits::Log2Floor(uint32 n) {
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for (int i = 4; i >= 0; --i) {
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int shift = (1 << i);
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uint32 x = value >> shift;
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inline int Bits::FindLSBSetNonZero(uint32 n) {
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for (int i = 4, shift = 1 << 4; i >= 0; --i) {
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const uint32 x = n << shift;
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// FindLSBSetNonZero64() is defined in terms of FindLSBSetNonZero().
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inline int Bits::FindLSBSetNonZero64(uint64 n) {
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const uint32 bottombits = static_cast<uint32>(n);
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if (bottombits == 0) {
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// Bottom bits are zero, so scan in top bits
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return 32 + FindLSBSetNonZero(static_cast<uint32>(n >> 32));
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return FindLSBSetNonZero(bottombits);
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#endif // End portable versions.
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// Variable-length integer encoding.
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// Maximum lengths of varint encoding of uint32.
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static const int kMax32 = 5;
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// Attempts to parse a varint32 from a prefix of the bytes in [ptr,limit-1].
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// Never reads a character at or beyond limit. If a valid/terminated varint32
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// was found in the range, stores it in *OUTPUT and returns a pointer just
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// past the last byte of the varint32. Else returns NULL. On success,
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// "result <= limit".
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static const char* Parse32WithLimit(const char* ptr, const char* limit,
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// REQUIRES "ptr" points to a buffer of length sufficient to hold "v".
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// EFFECTS Encodes "v" into "ptr" and returns a pointer to the
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// byte just past the last encoded byte.
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static char* Encode32(char* ptr, uint32 v);
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// EFFECTS Appends the varint representation of "value" to "*s".
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static void Append32(string* s, uint32 value);
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inline const char* Varint::Parse32WithLimit(const char* p,
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const unsigned char* ptr = reinterpret_cast<const unsigned char*>(p);
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const unsigned char* limit = reinterpret_cast<const unsigned char*>(l);
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if (ptr >= limit) return NULL;
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b = *(ptr++); result = b & 127; if (b < 128) goto done;
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if (ptr >= limit) return NULL;
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b = *(ptr++); result |= (b & 127) << 7; if (b < 128) goto done;
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if (ptr >= limit) return NULL;
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b = *(ptr++); result |= (b & 127) << 14; if (b < 128) goto done;
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if (ptr >= limit) return NULL;
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b = *(ptr++); result |= (b & 127) << 21; if (b < 128) goto done;
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if (ptr >= limit) return NULL;
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b = *(ptr++); result |= (b & 127) << 28; if (b < 16) goto done;
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return NULL; // Value is too long to be a varint32
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return reinterpret_cast<const char*>(ptr);
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inline char* Varint::Encode32(char* sptr, uint32 v) {
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// Operate on characters as unsigneds
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unsigned char* ptr = reinterpret_cast<unsigned char*>(sptr);
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static const int B = 128;
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} else if (v < (1<<14)) {
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} else if (v < (1<<21)) {
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*(ptr++) = (v>>7) | B;
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} else if (v < (1<<28)) {
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*(ptr++) = (v>>7) | B;
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*(ptr++) = (v>>14) | B;
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*(ptr++) = (v>>7) | B;
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*(ptr++) = (v>>14) | B;
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*(ptr++) = (v>>21) | B;
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return reinterpret_cast<char*>(ptr);
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// If you know the internal layout of the std::string in use, you can
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// replace this function with one that resizes the string without
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// filling the new space with zeros (if applicable) --
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// it will be non-portable but faster.
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inline void STLStringResizeUninitialized(string* s, size_t new_size) {
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// Return a mutable char* pointing to a string's internal buffer,
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// which may not be null-terminated. Writing through this pointer will
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// modify the string.
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// string_as_array(&str)[i] is valid for 0 <= i < str.size() until the
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// next call to a string method that invalidates iterators.
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// As of 2006-04, there is no standard-blessed way of getting a
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// mutable reference to a string's internal buffer. However, issue 530
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// (http://www.open-std.org/JTC1/SC22/WG21/docs/lwg-defects.html#530)
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// proposes this as the method. It will officially be part of the standard
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// for C++0x. This should already work on all current implementations.
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inline char* string_as_array(string* str) {
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return str->empty() ? NULL : &*str->begin();
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} // namespace snappy
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#endif // UTIL_SNAPPY_OPENSOURCE_SNAPPY_STUBS_INTERNAL_H_
added
removed
cppForSwig/leveldbwin/snappy_src/snappy-stubs-internal.h
