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Diffstat (limited to 'third_party/abseil_cpp/absl/base/internal/endian.h')
| -rw-r--r-- | third_party/abseil_cpp/absl/base/internal/endian.h | 266 |
1 files changed, 266 insertions, 0 deletions
diff --git a/third_party/abseil_cpp/absl/base/internal/endian.h b/third_party/abseil_cpp/absl/base/internal/endian.h new file mode 100644 index 000000000000..9677530e8de3 --- /dev/null +++ b/third_party/abseil_cpp/absl/base/internal/endian.h @@ -0,0 +1,266 @@ +// 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 +// +// https://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(__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 { +ABSL_NAMESPACE_BEGIN + +// 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); +} + +#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 // intrinsics 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 + +ABSL_NAMESPACE_END +} // namespace absl + +#endif // ABSL_BASE_INTERNAL_ENDIAN_H_ |