endian.h

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/*
 * Copyright (C) 2024 Otto-von-Guericke-Universität Magdeburg
 *
 * This file is subject to the terms and conditions of the GNU Lesser General
 * Public License v2.1. See the file LICENSE in the top level directory for more
 * details.
 */
 
#ifndef ENDIAN_H
#define ENDIAN_H
 
#include <stdint.h>
 
#ifdef __cplusplus
extern "C" {
#endif
 
#ifdef DOXYGEN
#define LITTLE_ENDIAN   magic-number
 
#define BIG_ENDIAN      magic-number
 
#define PDP_ENDIAN      magic-number
 
#define BYTE_ORDER      <LITTLE_ENDIAN or BIG_ENDIAN>
 
uint16_t htobe16(uint16_t host_16bits);         
uint16_t htole16(uint16_t host_16bits);         
uint16_t be16toh(uint16_t big_endian_16bits);   
uint16_t le16toh(uint16_t little_endian_16bits);
uint32_t htobe32(uint32_t host_32bits);         
uint32_t htole32(uint32_t host_32bits);         
uint32_t be32toh(uint32_t big_endian_32bits);   
uint32_t le32toh(uint32_t little_endian_32bits);
uint64_t htobe64(uint64_t host_64bits);         
uint64_t htole64(uint64_t host_64bits);         
uint64_t be64toh(uint64_t big_endian_64bits);   
uint64_t le64toh(uint64_t little_endian_64bits);
#else /* DOXYGEN */
 
/* Depending on the version of newlib used, newlib may provide them indirectly
 * as well. We don't want to redefine them in this case */
#ifndef LITTLE_ENDIAN
#  define LITTLE_ENDIAN 1234
#endif
#ifndef BIG_ENDIAN
#  define BIG_ENDIAN    4321
#endif
#ifndef PDP_ENDIAN
#  define PDP_ENDIAN    3412
#endif
#ifndef BYTE_ORDER
#  define BYTE_ORDER    __BYTE_ORDER__
#endif
 
/* But to avoid lots of pain in the ass: Let's at least make sure everyone
 * agrees on what magic number is what */
#if (LITTLE_ENDIAN != 1234) || (BIG_ENDIAN != 4321) || (PDP_ENDIAN != 3412)
#  error "Mismatching magic numbers to refer to endianness"
#endif
 
#if BYTE_ORDER == LITTLE_ENDIAN
#  define htobe16(_x) __builtin_bswap16(_x)
#  define htole16(_x) ((uint16_t)(_x))
#  define be16toh(_x) __builtin_bswap16(_x)
#  define le16toh(_x) ((uint16_t)(_x))
#  define htobe32(_x) __builtin_bswap32(_x)
#  define htole32(_x) ((uint32_t)(_x))
#  define be32toh(_x) __builtin_bswap32(_x)
#  define le32toh(_x) ((uint32_t)(_x))
#  define htobe64(_x) __builtin_bswap64(_x)
#  define htole64(_x) ((uint64_t)(_x))
#  define be64toh(_x) __builtin_bswap64(_x)
#  define le64toh(_x) ((uint64_t)(_x))
#elif BYTE_ORDER == BIG_ENDIAN
#  define htole16(_x) __builtin_bswap16(_x)
#  define htobe16(_x) ((uint16_t)(_x))
#  define le16toh(_x) __builtin_bswap16(_x)
#  define be16toh(_x) ((uint16_t)(_x))
#  define htole32(_x) __builtin_bswap32(_x)
#  define htobe32(_x) ((uint32_t)(_x))
#  define le32toh(_x) __builtin_bswap32(_x)
#  define be32toh(_x) ((uint32_t)(_x))
#  define htole64(_x) __builtin_bswap64(_x)
#  define htobe64(_x) ((uint64_t)(_x))
#  define le64toh(_x) __builtin_bswap64(_x)
#  define be64toh(_x) ((uint64_t)(_x))
#else
#  error "Byte order not supported"
#endif
 
#endif /* DOXYGEN */
 
#ifdef __cplusplus
}
#endif
 
#endif /* ENDIAN_H */