/*	$NetBSD$	*/

/*-
 * Copyright (c) 2018 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */


#ifndef _SYS_UNALIGNED_H_
#define _SYS_UNALIGNED_H_

#include <sys/types.h>

#ifdef __clang__
//#define NO_SANITIZE_ALIGNMENT __attribute__((no_sanitize("alignment")))
#define NO_SANITIZE_ALIGNMENT __attribute__((no_sanitize_undefined))
#elif __GNUC__
#define NO_SANITIZE_ALIGNMENT __attribute__((no_sanitize_undefined))
#else
#define NO_SANITIZE_ALIGNMENT
#endif

#ifdef __NO_STRICT_ALIGNMENT
#define ___GET_UNALIGNED_TYPE(type, suffix)				\
NO_SANITIZE_ALIGNMENT static inline type				\
__get_unaligned_##suffix(const type *val)				\
{									\
	return *val;							\
}
#else

#if BYTE_ORDER == LITTLE_ENDIAN
#define __GET_UNALIGNED_FORLOOP	for (i = size; i-- > 0;)
#else /* BYTE_ORDER == BIG_ENDIAN */
#define __GET_UNALIGNED_FORLOOP for (i = 0; i < size; i++)
#endif

#define ___GET_UNALIGNED_TYPE(type, suffix)				\
static inline type							\
__get_unaligned_##suffix(const type *val)				\
{									\
	size_t i, size;							\
	type res = 0;							\
	size = sizeof(type);						\
	__GET_UNALIGNED_FORLOOP						\
		res |= (uintmax_t)(((char *)val)[i]) << (CHAR_BIT * i);	\
	return res;							\
}
#endif

#define __GET_UNALIGNED_TYPE(type, suffix) ___GET_UNALIGNED_TYPE(type, suffix)

/*
 * The char, signed and unsigned char types have the weekest alignment
 * and the operation on them should be always correctly aligned.
 */
__GET_UNALIGNED_TYPE(signed char, c)
__GET_UNALIGNED_TYPE(unsigned char, b)
__GET_UNALIGNED_TYPE(short, h)
__GET_UNALIGNED_TYPE(int, i)
__GET_UNALIGNED_TYPE(long, l)
__GET_UNALIGNED_TYPE(long long, q)
__GET_UNALIGNED_TYPE(unsigned short, H)
__GET_UNALIGNED_TYPE(unsigned int, I)
__GET_UNALIGNED_TYPE(unsigned long, L)
__GET_UNALIGNED_TYPE(unsigned long long, Q)

/*
 * This macro is GCC and Clang compatible, other incompatible
 * compilers could use a C11 variation using _Generic().
 */
#define get_unaligned(_val)						\
	__builtin_choose_expr(						\
	__builtin_types_compatible_p(typeof(*_val), signed char),	\
	__get_unaligned_c((const signed char *)_val),			\
	__builtin_choose_expr(						\
	__builtin_types_compatible_p(typeof(*_val), short),		\
	__get_unaligned_h((const short *)_val),				\
	__builtin_choose_expr(						\
	__builtin_types_compatible_p(typeof(*_val), int),		\
	__get_unaligned_i((const int *)_val),				\
	__builtin_choose_expr(						\
	__builtin_types_compatible_p(typeof(*_val), long),		\
	__get_unaligned_l((const long *)_val),				\
	__builtin_choose_expr(						\
	__builtin_types_compatible_p(typeof(*_val), long long),		\
	__get_unaligned_q((const long long *)_val),			\
	__builtin_choose_expr(						\
	__builtin_types_compatible_p(typeof(*_val), unsigned char),	\
	__get_unaligned_b((const unsigned char *)_val),			\
	__builtin_choose_expr(						\
	__builtin_types_compatible_p(typeof(*_val), unsigned short),	\
	__get_unaligned_H((const unsigned short *)_val),		\
	__builtin_choose_expr(						\
	__builtin_types_compatible_p(typeof(*_val), unsigned int),	\
	__get_unaligned_I((const unsigned int *)_val),			\
	__builtin_choose_expr(						\
	__builtin_types_compatible_p(typeof(*_val), unsigned long),	\
	__get_unaligned_L((const unsigned long *)_val),			\
	__builtin_choose_expr(						\
	__builtin_types_compatible_p(typeof(*_val), unsigned long long),\
	__get_unaligned_Q((const unsigned long long *)_val),		\
	(void)0))))))))))

#endif /* _SYS_UNALIGNED_H_ */