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/* SPDX-License-Identifier: copyleft-next-0.3.1 */
/* Copyright 2021 - 2022, Kim Kuparinen < kimi.h.kuparinen@gmail.com > */
#ifndef KMI_UNALIGNED_H
#define KMI_UNALIGNED_H
/**
* @file unaligned.h
* Helpers for unaligned memory accesses. Largely lifted from Linux.
*/
#include <kmi/types.h>
#include <kmi/attrs.h>
/**
* Get unaligned value. Type of value is deduced from pointer type.
*
* @param ptr Pointer to possibly unaligned value to read.
* @return Value pointed to by \c ptr.
*/
#define get_unaligned(ptr) \
_Generic(*(ptr), \
uint8_t: get_unaligned_uint8_t, \
uint16_t: get_unaligned_uint16_t, \
uint32_t: get_unaligned_uint32_t, \
uint64_t: get_unaligned_uint64_t, \
\
int8_t: get_unaligned_int8_t, \
int16_t: get_unaligned_int16_t, \
int32_t: get_unaligned_int32_t, \
int64_t: get_unaligned_int64_t)((void *)ptr)
/**
* Put unaligned value. Type of value is deduced from pointer type.
*
* @param val Value to write to memory.
* @param ptr Pointer to possibly unaligned address.
*/
#define put_unaligned(val, ptr) \
_Generic(*(ptr), \
uint8_t: put_unaligned_uint8_t, \
uint16_t: put_unaligned_uint16_t, \
uint32_t: put_unaligned_uint32_t, \
uint64_t: put_unaligned_uint64_t, \
\
int8_t: put_unaligned_int8_t, \
int16_t: put_unaligned_int16_t, \
int32_t: put_unaligned_int32_t, \
int64_t: put_unaligned_int64_t)(val, (void *)ptr)
/**
* Helper macro for defining an unaligned value reader.
*
* @param type Type of value reader to define.
*/
#define DEFINE_GET(type) \
static inline type get_unaligned_##type(void *ptr) \
{ \
const struct __packed { \
type x; \
} *__pptr = ptr; \
return __pptr->x; \
}
/**
* Read possibly unaligned \ref uint8_t.
*
* Technically speaking a byte can't be unaligned, but this is just here for
* cohesion.
*
* @warning Prefer using \ref get_unaligned().
*
* @param ptr Pointer to \ref uint8_t to read.
* @return Value pointed to by \c ptr.
*/
DEFINE_GET(uint8_t);
/**
* Read possibly unaligned \ref uint16_t.
*
* @warning Prefer using \ref get_unaligned().
*
* @param ptr Pointer to \ref uint16_t to read.
* @return Value pointed to by \c ptr.
*/
DEFINE_GET(uint16_t);
/**
* Read possibly unaligned \ref uint32_t.
*
* @warning Prefer using \ref get_unaligned().
*
* @param ptr Pointer to \ref uint32_t to read.
* @return Value pointed to by \c ptr.
*/
DEFINE_GET(uint32_t);
/**
* Read possibly unaligned \ref uint64_t.
*
* @warning Prefer using \ref get_unaligned().
*
* @param ptr Pointer to \ref uint64_t to read.
* @return Value pointed to by \c ptr.
*/
DEFINE_GET(uint64_t);
/**
* Read possibly unaligned \ref int8_t.
*
* Technically speaking a byte can't be unaligned, but this is just here for
* cohesion.
*
* @warning Prefer using \ref get_unaligned().
*
* @param ptr Pointer to \ref int8_t to read.
* @return Value pointed to by \c ptr.
*/
DEFINE_GET(int8_t);
/**
* Read possibly unaligned \ref int16_t.
*
* @warning Prefer using \ref get_unaligned().
*
* @param ptr Pointer to \ref int16_t to read.
* @return Value pointed to by \c ptr.
*/
DEFINE_GET(int16_t);
/**
* Read possibly unaligned \ref int32_t.
*
* @warning Prefer using \ref get_unaligned().
*
* @param ptr Pointer to \ref int32_t to read.
* @return Value pointed to by \c ptr.
*/
DEFINE_GET(int32_t);
/**
* Read possibly unaligned \ref int64_t.
*
* @warning Prefer using \ref get_unaligned().
*
* @param ptr Pointer to \ref int64_t to read.
* @return Value pointed to by \c ptr.
*/
DEFINE_GET(int64_t);
#undef DEFINE_GET
/**
* Helper macro for defining an unaligned writer.
*
* @param type Type of value to write.
*/
#define DEFINE_PUT(type) \
static inline void put_unaligned_##type(type val, void *ptr) \
{ \
struct __packed { \
type x; \
} *__pptr = ptr; \
__pptr->x = val; \
}
/**
* Write possibly unaligned \ref uint8_t.
*
* Technically speaking a byte can't be unaligned, but this is just here for
* cohesion.
*
* @warning Prefer using \ref put_unaligned().
*
* @param val Value to write.
* @param ptr Address to write to.
*/
DEFINE_PUT(uint8_t);
/**
* Write possibly unaligned \ref uint16_t.
*
* @warning Prefer using \ref put_unaligned().
*
* @param val Value to write.
* @param ptr Address to write to.
*/
DEFINE_PUT(uint16_t);
/**
* Write possibly unaligned \ref uint32_t.
*
* @warning Prefer using \ref put_unaligned().
*
* @param val Value to write.
* @param ptr Address to write to.
*/
DEFINE_PUT(uint32_t);
/**
* Write possibly unaligned \ref uint64_t.
*
* @warning Prefer using \ref put_unaligned().
*
* @param val Value to write.
* @param ptr Address to write to.
*/
DEFINE_PUT(uint64_t);
/**
* Write possibly unaligned \ref int8_t.
*
* Technically speaking a byte can't be unaligned, but this is just here for
* cohesion.
*
* @warning Prefer using \ref put_unaligned().
*
* @param val Value to write.
* @param ptr Address to write to.
*/
DEFINE_PUT(int8_t);
/**
* Write possibly unaligned \ref int16_t.
*
* @warning Prefer using \ref put_unaligned().
*
* @param val Value to write.
* @param ptr Address to write to.
*/
DEFINE_PUT(int16_t);
/**
* Write possibly unaligned \ref int32_t.
*
* @warning Prefer using \ref put_unaligned().
*
* @param val Value to write.
* @param ptr Address to write to.
*/
DEFINE_PUT(int32_t);
/**
* Write possibly unaligned \ref int64_t.
*
* @warning Prefer using \ref put_unaligned().
*
* @param val Value to write.
* @param ptr Address to write to.
*/
DEFINE_PUT(int64_t);
#undef DEFINE_PUT
#endif /* KMI_UNALIGNED_H */
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