get_unaligned.h File Reference

Read little-endian values through possibly unaligned pointers. More...

#include "CxxUtils/restrict.h"
#include <cstring>
#include <stdint.h>

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Namespaces
	CxxUtils

Functions
uint16_t	CxxUtils::htole16 (uint16_t x)
uint32_t	CxxUtils::htole32 (uint32_t x)
uint64_t	CxxUtils::htole64 (uint64_t x)
uint16_t	CxxUtils::get_unaligned16 (const uint8_t *ATH_RESTRICT &p)
	Read a 2-byte little-endian value from a possibly unaligned pointer. More...
uint32_t	CxxUtils::get_unaligned32 (const uint8_t *ATH_RESTRICT &p)
	Read a 4-byte little-endian value from a possibly unaligned pointer. More...
uint64_t	CxxUtils::get_unaligned64 (const uint8_t *ATH_RESTRICT &p)
	Read a 8-byte little-endian value from a possibly unaligned pointer. More...
float	CxxUtils::get_unaligned_float (const uint8_t *ATH_RESTRICT &p)
	Read little-endian float value from a possibly unaligned pointer. More...
double	CxxUtils::get_unaligned_double (const uint8_t *ATH_RESTRICT &p)
	Read little-endian float value from a possibly unaligned pointer. More...
template<class T >
T	CxxUtils::get_unaligned (const uint8_t *ATH_RESTRICT &p)
	Define templated versions of the above functions. More...
template<>
uint8_t	CxxUtils::get_unaligned< uint8_t > (const uint8_t *ATH_RESTRICT &p)
template<>
uint16_t	CxxUtils::get_unaligned< uint16_t > (const uint8_t *ATH_RESTRICT &p)
template<>
uint32_t	CxxUtils::get_unaligned< uint32_t > (const uint8_t *ATH_RESTRICT &p)
template<>
uint64_t	CxxUtils::get_unaligned< uint64_t > (const uint8_t *ATH_RESTRICT &p)
template<>
float	CxxUtils::get_unaligned< float > (const uint8_t *ATH_RESTRICT &p)
template<>
double	CxxUtils::get_unaligned< double > (const uint8_t *ATH_RESTRICT &p)
template<>
int8_t	CxxUtils::get_unaligned< int8_t > (const uint8_t *ATH_RESTRICT &p)
template<>
int16_t	CxxUtils::get_unaligned< int16_t > (const uint8_t *ATH_RESTRICT &p)
template<>
int32_t	CxxUtils::get_unaligned< int32_t > (const uint8_t *ATH_RESTRICT &p)
template<>
int64_t	CxxUtils::get_unaligned< int64_t > (const uint8_t *ATH_RESTRICT &p)

Detailed Description

Read little-endian values through possibly unaligned pointers.

Author

scott snyder snyde.nosp@m.r@bn.nosp@m.l.gov

Date

May, 2019 Doing, eg,

char* p = ...;
int* ip = reinterpret_cast<int*>(p);
int i = *ip++;

is undefined if p isn't aligned to an int boundary. It further will read the value using the host endianness, which is an issue for the common use case of reading persistent data.

The functions here allow reading little-endian data via possibly unaligned pointers regardless of the host byte ordering and without relying on undefined behavior.

Definition in file get_unaligned.h.