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// Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
// Encoding independent of machine byte order:
// * Fixed-length numbers are encoded with least-significant byte first
// (little endian, native order on Intel and others)
//
// More functions in coding.h
#pragma once
#include <cstdint>
#include <cstring>
#include "port/port.h" // for port::kLittleEndian
namespace ROCKSDB_NAMESPACE {
// Lower-level versions of Put... that write directly into a character buffer
// REQUIRES: dst has enough space for the value being written
// -- Implementation of the functions declared above
inline void EncodeFixed16(char* buf, uint16_t value) {
if (port::kLittleEndian) {
memcpy(buf, &value, sizeof(value));
} else {
buf[0] = value & 0xff;
buf[1] = (value >> 8) & 0xff;
}
}
inline void EncodeFixed32(char* buf, uint32_t value) {
if (port::kLittleEndian) {
memcpy(buf, &value, sizeof(value));
} else {
buf[0] = value & 0xff;
buf[1] = (value >> 8) & 0xff;
buf[2] = (value >> 16) & 0xff;
buf[3] = (value >> 24) & 0xff;
}
}
inline void EncodeFixed64(char* buf, uint64_t value) {
if (port::kLittleEndian) {
memcpy(buf, &value, sizeof(value));
} else {
buf[0] = value & 0xff;
buf[1] = (value >> 8) & 0xff;
buf[2] = (value >> 16) & 0xff;
buf[3] = (value >> 24) & 0xff;
buf[4] = (value >> 32) & 0xff;
buf[5] = (value >> 40) & 0xff;
buf[6] = (value >> 48) & 0xff;
buf[7] = (value >> 56) & 0xff;
}
}
// Lower-level versions of Get... that read directly from a character buffer
// without any bounds checking.
inline uint16_t DecodeFixed16(const char* ptr) {
if (port::kLittleEndian) {
// Load the raw bytes
uint16_t result;
memcpy(&result, ptr, sizeof(result)); // gcc optimizes this to a plain load
return result;
} else {
return ((static_cast<uint16_t>(static_cast<unsigned char>(ptr[0]))) |
(static_cast<uint16_t>(static_cast<unsigned char>(ptr[1])) << 8));
}
}
inline uint32_t DecodeFixed32(const char* ptr) {
if (port::kLittleEndian) {
// Load the raw bytes
uint32_t result;
memcpy(&result, ptr, sizeof(result)); // gcc optimizes this to a plain load
return result;
} else {
return ((static_cast<uint32_t>(static_cast<unsigned char>(ptr[0]))) |
(static_cast<uint32_t>(static_cast<unsigned char>(ptr[1])) << 8) |
(static_cast<uint32_t>(static_cast<unsigned char>(ptr[2])) << 16) |
(static_cast<uint32_t>(static_cast<unsigned char>(ptr[3])) << 24));
}
}
inline uint64_t DecodeFixed64(const char* ptr) {
if (port::kLittleEndian) {
// Load the raw bytes
uint64_t result;
memcpy(&result, ptr, sizeof(result)); // gcc optimizes this to a plain load
return result;
} else {
uint64_t lo = DecodeFixed32(ptr);
uint64_t hi = DecodeFixed32(ptr + 4);
return (hi << 32) | lo;
}
}
} // namespace ROCKSDB_NAMESPACE
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