tvl-depot/absl/base/internal/endian.h
Abseil Team a4cb1c8ba6 Export of internal Abseil changes.
--
6fdf24a197b964f9bacbebd0ceca305aef1654fc by Shaindel Schwartz <shaindel@google.com>:

Internal change

PiperOrigin-RevId: 231627312

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65f7faf52bff01384171efb85fee159378dedf70 by CJ Johnson <johnsoncj@google.com>:

Relocates the definitions of the InputIterator-accepting parts of the InlinedVector API into the top-level. The removed functions had no other callers so there was no reason to keep the layer of indirection in the form of the function call.

PiperOrigin-RevId: 231527459

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30e105b749b5ecc50fdaf26c7da589617efce425 by CJ Johnson <johnsoncj@google.com>:

Relocates closing brace for absl namespace in InlinedVector to the correct end location

PiperOrigin-RevId: 231477871

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063c1e8b9d1f032662c46d574e20ecc357b87d0c by Eric Fiselier <ericwf@google.com>:

Cleanup std::hash probing metafunctions.

Previously there were two different ways to probe for
std::hash. One in hash.h and another in type_traits.h,
and they were both implemented differently, and neither
correctly worked around bad STL implementations.

This patch unifies the implementations into a single IsHashable trait.
It also:

* Correctly checks for old libc++ versions where this won't work.
* Avoids undefined behavior which resulted from calling std::is_constructible
  incomplete types.
* Unifies the feature test macro used in the headers and the tests.

Additionally it also slightly changes the behavior of when absl::variant
is hashable. Previously we disable hashing when std::hash<T>()(key) was
formed but when std::hash<T> couldn't be destructed. This seems wrong. If a
user provides a evil specialization of std::hash, then it's OK for variant's
hash to blow up.

PiperOrigin-RevId: 231468345

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05d75dd4b07c893de9b104731644d0d207b01253 by Abseil Team <absl-team@google.com>:

Import of CCTZ from GitHub.

PiperOrigin-RevId: 231397518

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a0ee9032f9e04039f3410ed17fcf45ae1a3868f5 by CJ Johnson <johnsoncj@google.com>:

Remove unused EnableIfAtLeastInputIterator from InlinedVector

PiperOrigin-RevId: 231348903

--
4dcd4e9a6780a81d7a6974c7bf22a037e6482b49 by Abseil Team <absl-team@google.com>:

Remove unnecessary register keyword from absl/base/internal/endian.h.

PiperOrigin-RevId: 231316570

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c8584836caa3a10f90a8604a85d4b831310b72ee by Abseil Team <absl-team@google.com>:

Fix hashtablez_sampler compilation on older Android NDK builds

PiperOrigin-RevId: 231283542
GitOrigin-RevId: 6fdf24a197b964f9bacbebd0ceca305aef1654fc
Change-Id: I185b12fb8347e3ad0ffcb2cbb83a53450e5eb938
2019-01-30 14:24:09 -05:00

272 lines
8.5 KiB
C++

// Copyright 2017 The Abseil Authors.
//
// 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.
//
#ifndef ABSL_BASE_INTERNAL_ENDIAN_H_
#define ABSL_BASE_INTERNAL_ENDIAN_H_
// The following guarantees declaration of the byte swap functions
#ifdef _MSC_VER
#include <stdlib.h> // NOLINT(build/include)
#elif defined(__APPLE__)
// Mac OS X / Darwin features
#include <libkern/OSByteOrder.h>
#elif defined(__FreeBSD__)
#include <sys/endian.h>
#elif defined(__GLIBC__)
#include <byteswap.h> // IWYU pragma: export
#endif
#include <cstdint>
#include "absl/base/config.h"
#include "absl/base/internal/unaligned_access.h"
#include "absl/base/port.h"
namespace absl {
// Use compiler byte-swapping intrinsics if they are available. 32-bit
// and 64-bit versions are available in Clang and GCC as of GCC 4.3.0.
// The 16-bit version is available in Clang and GCC only as of GCC 4.8.0.
// For simplicity, we enable them all only for GCC 4.8.0 or later.
#if defined(__clang__) || \
(defined(__GNUC__) && \
((__GNUC__ == 4 && __GNUC_MINOR__ >= 8) || __GNUC__ >= 5))
inline uint64_t gbswap_64(uint64_t host_int) {
return __builtin_bswap64(host_int);
}
inline uint32_t gbswap_32(uint32_t host_int) {
return __builtin_bswap32(host_int);
}
inline uint16_t gbswap_16(uint16_t host_int) {
return __builtin_bswap16(host_int);
}
#elif defined(_MSC_VER)
inline uint64_t gbswap_64(uint64_t host_int) {
return _byteswap_uint64(host_int);
}
inline uint32_t gbswap_32(uint32_t host_int) {
return _byteswap_ulong(host_int);
}
inline uint16_t gbswap_16(uint16_t host_int) {
return _byteswap_ushort(host_int);
}
#elif defined(__APPLE__)
inline uint64_t gbswap_64(uint64_t host_int) { return OSSwapInt16(host_int); }
inline uint32_t gbswap_32(uint32_t host_int) { return OSSwapInt32(host_int); }
inline uint16_t gbswap_16(uint16_t host_int) { return OSSwapInt64(host_int); }
#else
inline uint64_t gbswap_64(uint64_t host_int) {
#if defined(__GNUC__) && defined(__x86_64__) && !defined(__APPLE__)
// Adapted from /usr/include/byteswap.h. Not available on Mac.
if (__builtin_constant_p(host_int)) {
return __bswap_constant_64(host_int);
} else {
uint64_t result;
__asm__("bswap %0" : "=r"(result) : "0"(host_int));
return result;
}
#elif defined(__GLIBC__)
return bswap_64(host_int);
#else
return (((host_int & uint64_t{0xFF}) << 56) |
((host_int & uint64_t{0xFF00}) << 40) |
((host_int & uint64_t{0xFF0000}) << 24) |
((host_int & uint64_t{0xFF000000}) << 8) |
((host_int & uint64_t{0xFF00000000}) >> 8) |
((host_int & uint64_t{0xFF0000000000}) >> 24) |
((host_int & uint64_t{0xFF000000000000}) >> 40) |
((host_int & uint64_t{0xFF00000000000000}) >> 56));
#endif // bswap_64
}
inline uint32_t gbswap_32(uint32_t host_int) {
#if defined(__GLIBC__)
return bswap_32(host_int);
#else
return (((host_int & uint32_t{0xFF}) << 24) |
((host_int & uint32_t{0xFF00}) << 8) |
((host_int & uint32_t{0xFF0000}) >> 8) |
((host_int & uint32_t{0xFF000000}) >> 24));
#endif
}
inline uint16_t gbswap_16(uint16_t host_int) {
#if defined(__GLIBC__)
return bswap_16(host_int);
#else
return (((host_int & uint16_t{0xFF}) << 8) |
((host_int & uint16_t{0xFF00}) >> 8));
#endif
}
#endif // intrinics available
#ifdef ABSL_IS_LITTLE_ENDIAN
// Definitions for ntohl etc. that don't require us to include
// netinet/in.h. We wrap gbswap_32 and gbswap_16 in functions rather
// than just #defining them because in debug mode, gcc doesn't
// correctly handle the (rather involved) definitions of bswap_32.
// gcc guarantees that inline functions are as fast as macros, so
// this isn't a performance hit.
inline uint16_t ghtons(uint16_t x) { return gbswap_16(x); }
inline uint32_t ghtonl(uint32_t x) { return gbswap_32(x); }
inline uint64_t ghtonll(uint64_t x) { return gbswap_64(x); }
#elif defined ABSL_IS_BIG_ENDIAN
// These definitions are simpler on big-endian machines
// These are functions instead of macros to avoid self-assignment warnings
// on calls such as "i = ghtnol(i);". This also provides type checking.
inline uint16_t ghtons(uint16_t x) { return x; }
inline uint32_t ghtonl(uint32_t x) { return x; }
inline uint64_t ghtonll(uint64_t x) { return x; }
#else
#error \
"Unsupported byte order: Either ABSL_IS_BIG_ENDIAN or " \
"ABSL_IS_LITTLE_ENDIAN must be defined"
#endif // byte order
inline uint16_t gntohs(uint16_t x) { return ghtons(x); }
inline uint32_t gntohl(uint32_t x) { return ghtonl(x); }
inline uint64_t gntohll(uint64_t x) { return ghtonll(x); }
// Utilities to convert numbers between the current hosts's native byte
// order and little-endian byte order
//
// Load/Store methods are alignment safe
namespace little_endian {
// Conversion functions.
#ifdef ABSL_IS_LITTLE_ENDIAN
inline uint16_t FromHost16(uint16_t x) { return x; }
inline uint16_t ToHost16(uint16_t x) { return x; }
inline uint32_t FromHost32(uint32_t x) { return x; }
inline uint32_t ToHost32(uint32_t x) { return x; }
inline uint64_t FromHost64(uint64_t x) { return x; }
inline uint64_t ToHost64(uint64_t x) { return x; }
inline constexpr bool IsLittleEndian() { return true; }
#elif defined ABSL_IS_BIG_ENDIAN
inline uint16_t FromHost16(uint16_t x) { return gbswap_16(x); }
inline uint16_t ToHost16(uint16_t x) { return gbswap_16(x); }
inline uint32_t FromHost32(uint32_t x) { return gbswap_32(x); }
inline uint32_t ToHost32(uint32_t x) { return gbswap_32(x); }
inline uint64_t FromHost64(uint64_t x) { return gbswap_64(x); }
inline uint64_t ToHost64(uint64_t x) { return gbswap_64(x); }
inline constexpr bool IsLittleEndian() { return false; }
#endif /* ENDIAN */
// Functions to do unaligned loads and stores in little-endian order.
inline uint16_t Load16(const void *p) {
return ToHost16(ABSL_INTERNAL_UNALIGNED_LOAD16(p));
}
inline void Store16(void *p, uint16_t v) {
ABSL_INTERNAL_UNALIGNED_STORE16(p, FromHost16(v));
}
inline uint32_t Load32(const void *p) {
return ToHost32(ABSL_INTERNAL_UNALIGNED_LOAD32(p));
}
inline void Store32(void *p, uint32_t v) {
ABSL_INTERNAL_UNALIGNED_STORE32(p, FromHost32(v));
}
inline uint64_t Load64(const void *p) {
return ToHost64(ABSL_INTERNAL_UNALIGNED_LOAD64(p));
}
inline void Store64(void *p, uint64_t v) {
ABSL_INTERNAL_UNALIGNED_STORE64(p, FromHost64(v));
}
} // namespace little_endian
// Utilities to convert numbers between the current hosts's native byte
// order and big-endian byte order (same as network byte order)
//
// Load/Store methods are alignment safe
namespace big_endian {
#ifdef ABSL_IS_LITTLE_ENDIAN
inline uint16_t FromHost16(uint16_t x) { return gbswap_16(x); }
inline uint16_t ToHost16(uint16_t x) { return gbswap_16(x); }
inline uint32_t FromHost32(uint32_t x) { return gbswap_32(x); }
inline uint32_t ToHost32(uint32_t x) { return gbswap_32(x); }
inline uint64_t FromHost64(uint64_t x) { return gbswap_64(x); }
inline uint64_t ToHost64(uint64_t x) { return gbswap_64(x); }
inline constexpr bool IsLittleEndian() { return true; }
#elif defined ABSL_IS_BIG_ENDIAN
inline uint16_t FromHost16(uint16_t x) { return x; }
inline uint16_t ToHost16(uint16_t x) { return x; }
inline uint32_t FromHost32(uint32_t x) { return x; }
inline uint32_t ToHost32(uint32_t x) { return x; }
inline uint64_t FromHost64(uint64_t x) { return x; }
inline uint64_t ToHost64(uint64_t x) { return x; }
inline constexpr bool IsLittleEndian() { return false; }
#endif /* ENDIAN */
// Functions to do unaligned loads and stores in big-endian order.
inline uint16_t Load16(const void *p) {
return ToHost16(ABSL_INTERNAL_UNALIGNED_LOAD16(p));
}
inline void Store16(void *p, uint16_t v) {
ABSL_INTERNAL_UNALIGNED_STORE16(p, FromHost16(v));
}
inline uint32_t Load32(const void *p) {
return ToHost32(ABSL_INTERNAL_UNALIGNED_LOAD32(p));
}
inline void Store32(void *p, uint32_t v) {
ABSL_INTERNAL_UNALIGNED_STORE32(p, FromHost32(v));
}
inline uint64_t Load64(const void *p) {
return ToHost64(ABSL_INTERNAL_UNALIGNED_LOAD64(p));
}
inline void Store64(void *p, uint64_t v) {
ABSL_INTERNAL_UNALIGNED_STORE64(p, FromHost64(v));
}
} // namespace big_endian
} // namespace absl
#endif // ABSL_BASE_INTERNAL_ENDIAN_H_