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author | Anton Samokhvalov <pg83@yandex.ru> | 2022-02-10 16:45:15 +0300 |
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committer | Daniil Cherednik <dcherednik@yandex-team.ru> | 2022-02-10 16:45:15 +0300 |
commit | 72cb13b4aff9bc9cf22e49251bc8fd143f82538f (patch) | |
tree | da2c34829458c7d4e74bdfbdf85dff449e9e7fb8 /contrib/libs/snappy/snappy-stubs-internal.h | |
parent | 778e51ba091dc39e7b7fcab2b9cf4dbedfb6f2b5 (diff) | |
download | ydb-72cb13b4aff9bc9cf22e49251bc8fd143f82538f.tar.gz |
Restoring authorship annotation for Anton Samokhvalov <pg83@yandex.ru>. Commit 1 of 2.
Diffstat (limited to 'contrib/libs/snappy/snappy-stubs-internal.h')
-rw-r--r-- | contrib/libs/snappy/snappy-stubs-internal.h | 720 |
1 files changed, 360 insertions, 360 deletions
diff --git a/contrib/libs/snappy/snappy-stubs-internal.h b/contrib/libs/snappy/snappy-stubs-internal.h index 4854689d17..48b40bac98 100644 --- a/contrib/libs/snappy/snappy-stubs-internal.h +++ b/contrib/libs/snappy/snappy-stubs-internal.h @@ -1,46 +1,46 @@ -// 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. - +// Copyright 2011 Google Inc. All Rights Reserved. +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are +// met: +// +// * Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// * Redistributions in binary form must reproduce the above +// copyright notice, this list of conditions and the following disclaimer +// in the documentation and/or other materials provided with the +// distribution. +// * Neither the name of Google Inc. nor the names of its +// contributors may be used to endorse or promote products derived from +// this software without specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +// +// Various stubs for the open-source version of Snappy. + #ifndef THIRD_PARTY_SNAPPY_OPENSOURCE_SNAPPY_STUBS_INTERNAL_H_ #define THIRD_PARTY_SNAPPY_OPENSOURCE_SNAPPY_STUBS_INTERNAL_H_ - + #ifdef HAVE_CONFIG_H #include "config.h" -#endif - +#endif + #include <string> - -#include <assert.h> -#include <stdlib.h> -#include <string.h> - + +#include <assert.h> +#include <stdlib.h> +#include <string.h> + #ifdef HAVE_SYS_MMAN_H #include <sys/mman.h> #endif @@ -65,13 +65,13 @@ #define SNAPPY_ANNOTATE_MEMORY_IS_INITIALIZED(address, size) /* empty */ #endif // __has_feature(memory_sanitizer) -#include "snappy-stubs-public.h" - -#if defined(__x86_64__) - -// Enable 64-bit optimized versions of some routines. -#define ARCH_K8 1 - +#include "snappy-stubs-public.h" + +#if defined(__x86_64__) + +// Enable 64-bit optimized versions of some routines. +#define ARCH_K8 1 + #elif defined(__ppc64__) #define ARCH_PPC 1 @@ -80,21 +80,21 @@ #define ARCH_ARM 1 -#endif - -// Needed by OS X, among others. -#ifndef MAP_ANONYMOUS -#define MAP_ANONYMOUS MAP_ANON -#endif - -// 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))) - +#endif + +// Needed by OS X, among others. +#ifndef MAP_ANONYMOUS +#define MAP_ANONYMOUS MAP_ANON +#endif + +// 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 SNAPPY_PREDICT_FALSE(x) (__builtin_expect(x, 0)) @@ -103,44 +103,44 @@ #define SNAPPY_PREDICT_FALSE(x) x #define SNAPPY_PREDICT_TRUE(x) x #endif - -// This is only used for recomputing the tag byte table used during -// decompression; for simplicity we just remove it from the open-source -// version (anyone who wants to regenerate it can just do the call -// themselves within main()). -#define DEFINE_bool(flag_name, default_value, description) \ - bool FLAGS_ ## flag_name = default_value -#define DECLARE_bool(flag_name) \ - extern bool FLAGS_ ## flag_name - -namespace snappy { - -static const uint32 kuint32max = static_cast<uint32>(0xFFFFFFFF); -static const int64 kint64max = static_cast<int64>(0x7FFFFFFFFFFFFFFFLL); - -// Potentially unaligned loads and stores. - + +// This is only used for recomputing the tag byte table used during +// decompression; for simplicity we just remove it from the open-source +// version (anyone who wants to regenerate it can just do the call +// themselves within main()). +#define DEFINE_bool(flag_name, default_value, description) \ + bool FLAGS_ ## flag_name = default_value +#define DECLARE_bool(flag_name) \ + extern bool FLAGS_ ## flag_name + +namespace snappy { + +static const uint32 kuint32max = static_cast<uint32>(0xFFFFFFFF); +static const int64 kint64max = static_cast<int64>(0x7FFFFFFFFFFFFFFFLL); + +// Potentially unaligned loads and stores. + // x86, PowerPC, and ARM64 can simply do these loads and stores native. - + #if defined(__i386__) || defined(__x86_64__) || defined(__powerpc__) || \ defined(__aarch64__) - -#define UNALIGNED_LOAD16(_p) (*reinterpret_cast<const uint16 *>(_p)) -#define UNALIGNED_LOAD32(_p) (*reinterpret_cast<const uint32 *>(_p)) -#define UNALIGNED_LOAD64(_p) (*reinterpret_cast<const uint64 *>(_p)) - -#define UNALIGNED_STORE16(_p, _val) (*reinterpret_cast<uint16 *>(_p) = (_val)) -#define UNALIGNED_STORE32(_p, _val) (*reinterpret_cast<uint32 *>(_p) = (_val)) -#define UNALIGNED_STORE64(_p, _val) (*reinterpret_cast<uint64 *>(_p) = (_val)) - -// ARMv7 and newer support native unaligned accesses, but only of 16-bit -// and 32-bit values (not 64-bit); older versions either raise a fatal signal, -// do an unaligned read and rotate the words around a bit, or do the reads very -// slowly (trip through kernel mode). There's no simple #define that says just -// “ARMv7 or higher”, so we have to filter away all ARMv5 and ARMv6 -// sub-architectures. -// -// This is a mess, but there's not much we can do about it. + +#define UNALIGNED_LOAD16(_p) (*reinterpret_cast<const uint16 *>(_p)) +#define UNALIGNED_LOAD32(_p) (*reinterpret_cast<const uint32 *>(_p)) +#define UNALIGNED_LOAD64(_p) (*reinterpret_cast<const uint64 *>(_p)) + +#define UNALIGNED_STORE16(_p, _val) (*reinterpret_cast<uint16 *>(_p) = (_val)) +#define UNALIGNED_STORE32(_p, _val) (*reinterpret_cast<uint32 *>(_p) = (_val)) +#define UNALIGNED_STORE64(_p, _val) (*reinterpret_cast<uint64 *>(_p) = (_val)) + +// ARMv7 and newer support native unaligned accesses, but only of 16-bit +// and 32-bit values (not 64-bit); older versions either raise a fatal signal, +// do an unaligned read and rotate the words around a bit, or do the reads very +// slowly (trip through kernel mode). There's no simple #define that says just +// “ARMv7 or higher”, so we have to filter away all ARMv5 and ARMv6 +// sub-architectures. +// +// This is a mess, but there's not much we can do about it. // // To further complicate matters, only LDR instructions (single reads) are // allowed to be unaligned, not LDRD (two reads) or LDM (many reads). Unless we @@ -150,30 +150,30 @@ static const int64 kint64max = static_cast<int64>(0x7FFFFFFFFFFFFFFFLL); // (it ignores __attribute__((packed)) on individual variables). However, // we can tell it that a _struct_ is unaligned, which has the same effect, // so we do that. - -#elif defined(__arm__) && \ + +#elif defined(__arm__) && \ !defined(__ARM_ARCH_4__) && \ !defined(__ARM_ARCH_4T__) && \ - !defined(__ARM_ARCH_5__) && \ - !defined(__ARM_ARCH_5T__) && \ - !defined(__ARM_ARCH_5TE__) && \ - !defined(__ARM_ARCH_5TEJ__) && \ - !defined(__ARM_ARCH_6__) && \ - !defined(__ARM_ARCH_6J__) && \ - !defined(__ARM_ARCH_6K__) && \ - !defined(__ARM_ARCH_6Z__) && \ - !defined(__ARM_ARCH_6ZK__) && \ - !defined(__ARM_ARCH_6T2__) - + !defined(__ARM_ARCH_5__) && \ + !defined(__ARM_ARCH_5T__) && \ + !defined(__ARM_ARCH_5TE__) && \ + !defined(__ARM_ARCH_5TEJ__) && \ + !defined(__ARM_ARCH_6__) && \ + !defined(__ARM_ARCH_6J__) && \ + !defined(__ARM_ARCH_6K__) && \ + !defined(__ARM_ARCH_6Z__) && \ + !defined(__ARM_ARCH_6ZK__) && \ + !defined(__ARM_ARCH_6T2__) + #if __GNUC__ #define ATTRIBUTE_PACKED __attribute__((__packed__)) #else #define ATTRIBUTE_PACKED #endif - + namespace base { namespace internal { - + struct Unaligned16Struct { uint16 value; uint8 dummy; // To make the size non-power-of-two. @@ -200,59 +200,59 @@ struct Unaligned32Struct { (_val)) // TODO: NEON supports unaligned 64-bit loads and stores. -// See if that would be more efficient on platforms supporting it, -// at least for copies. - -inline uint64 UNALIGNED_LOAD64(const void *p) { - uint64 t; - memcpy(&t, p, sizeof t); - return t; -} - -inline void UNALIGNED_STORE64(void *p, uint64 v) { - memcpy(p, &v, sizeof v); -} - -#else - -// These functions are provided for architectures that don't support -// unaligned loads and stores. - -inline uint16 UNALIGNED_LOAD16(const void *p) { - uint16 t; - memcpy(&t, p, sizeof t); - return t; -} - -inline uint32 UNALIGNED_LOAD32(const void *p) { - uint32 t; - memcpy(&t, p, sizeof t); - return t; -} - -inline uint64 UNALIGNED_LOAD64(const void *p) { - uint64 t; - memcpy(&t, p, sizeof t); - return t; -} - -inline void UNALIGNED_STORE16(void *p, uint16 v) { - memcpy(p, &v, sizeof v); -} - -inline void UNALIGNED_STORE32(void *p, uint32 v) { - memcpy(p, &v, sizeof v); -} - -inline void UNALIGNED_STORE64(void *p, uint64 v) { - memcpy(p, &v, sizeof v); -} - -#endif - +// See if that would be more efficient on platforms supporting it, +// at least for copies. + +inline uint64 UNALIGNED_LOAD64(const void *p) { + uint64 t; + memcpy(&t, p, sizeof t); + return t; +} + +inline void UNALIGNED_STORE64(void *p, uint64 v) { + memcpy(p, &v, sizeof v); +} + +#else + +// These functions are provided for architectures that don't support +// unaligned loads and stores. + +inline uint16 UNALIGNED_LOAD16(const void *p) { + uint16 t; + memcpy(&t, p, sizeof t); + return t; +} + +inline uint32 UNALIGNED_LOAD32(const void *p) { + uint32 t; + memcpy(&t, p, sizeof t); + return t; +} + +inline uint64 UNALIGNED_LOAD64(const void *p) { + uint64 t; + memcpy(&t, p, sizeof t); + return t; +} + +inline void UNALIGNED_STORE16(void *p, uint16 v) { + memcpy(p, &v, sizeof v); +} + +inline void UNALIGNED_STORE32(void *p, uint32 v) { + memcpy(p, &v, sizeof v); +} + +inline void UNALIGNED_STORE64(void *p, uint64 v) { + memcpy(p, &v, sizeof v); +} + +#endif + // The following guarantees declaration of the byte swap functions. #if defined(SNAPPY_IS_BIG_ENDIAN) - + #ifdef HAVE_SYS_BYTEORDER_H #include <sys/byteorder.h> #endif @@ -293,8 +293,8 @@ inline void UNALIGNED_STORE64(void *p, uint64 v) { 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); @@ -310,28 +310,28 @@ inline uint64 bswap_64(uint64 x) { #endif // defined(SNAPPY_IS_BIG_ENDIAN) -// 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. +// 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. #if defined(SNAPPY_IS_BIG_ENDIAN) - + 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; } - + static bool IsLittleEndian() { return false; } + #else // !defined(SNAPPY_IS_BIG_ENDIAN) static uint16 FromHost16(uint16 x) { return x; } @@ -344,50 +344,50 @@ class LittleEndian { #endif // !defined(SNAPPY_IS_BIG_ENDIAN) - // 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: + // 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. static int Log2FloorNonZero(uint32 n); - // 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); + // 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); #if defined(ARCH_K8) || defined(ARCH_PPC) || defined(ARCH_ARM) - static int FindLSBSetNonZero64(uint64 n); + static int FindLSBSetNonZero64(uint64 n); #endif // defined(ARCH_K8) || defined(ARCH_PPC) || defined(ARCH_ARM) - - private: + + private: // No copying Bits(const Bits&); void operator=(const Bits&); -}; - -#ifdef HAVE_BUILTIN_CTZ - +}; + +#ifdef HAVE_BUILTIN_CTZ + inline int Bits::Log2FloorNonZero(uint32 n) { assert(n != 0); // (31 ^ x) is equivalent to (31 - x) for x in [0, 31]. An easy proof @@ -399,22 +399,22 @@ inline int Bits::Log2FloorNonZero(uint32 n) { return 31 ^ __builtin_clz(n); } -inline int Bits::Log2Floor(uint32 n) { +inline int Bits::Log2Floor(uint32 n) { return (n == 0) ? -1 : Bits::Log2FloorNonZero(n); -} - -inline int Bits::FindLSBSetNonZero(uint32 n) { +} + +inline int Bits::FindLSBSetNonZero(uint32 n) { assert(n != 0); - return __builtin_ctz(n); -} - + return __builtin_ctz(n); +} + #if defined(ARCH_K8) || defined(ARCH_PPC) || defined(ARCH_ARM) -inline int Bits::FindLSBSetNonZero64(uint64 n) { +inline int Bits::FindLSBSetNonZero64(uint64 n) { assert(n != 0); - return __builtin_ctzll(n); -} + return __builtin_ctzll(n); +} #endif // defined(ARCH_K8) || defined(ARCH_PPC) || defined(ARCH_ARM) - + #elif defined(_MSC_VER) inline int Bits::Log2FloorNonZero(uint32 n) { @@ -449,158 +449,158 @@ inline int Bits::FindLSBSetNonZero64(uint64 n) { } #endif // defined(ARCH_K8) || defined(ARCH_PPC) || defined(ARCH_ARM) -#else // Portable versions. - +#else // Portable versions. + inline int Bits::Log2FloorNonZero(uint32 n) { assert(n != 0); - 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; -} - + 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::Log2Floor(uint32 n) { return (n == 0) ? -1 : Bits::Log2FloorNonZero(n); } -inline int Bits::FindLSBSetNonZero(uint32 n) { +inline int Bits::FindLSBSetNonZero(uint32 n) { assert(n != 0); - 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; -} - + 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; +} + #if defined(ARCH_K8) || defined(ARCH_PPC) || defined(ARCH_ARM) -// FindLSBSetNonZero64() is defined in terms of FindLSBSetNonZero(). -inline int Bits::FindLSBSetNonZero64(uint64 n) { +// FindLSBSetNonZero64() is defined in terms of FindLSBSetNonZero(). +inline int Bits::FindLSBSetNonZero64(uint64 n) { assert(n != 0); - 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); - } -} + 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 // defined(ARCH_K8) || defined(ARCH_PPC) || defined(ARCH_ARM) - -#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". + +#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(std::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); -} - +}; + +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. +// 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(std::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. +} + +// 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(std::string* str) { return str->empty() ? NULL : &*str->begin(); -} - -} // namespace snappy - +} + +} // namespace snappy + #endif // THIRD_PARTY_SNAPPY_OPENSOURCE_SNAPPY_STUBS_INTERNAL_H_ |