byteswap.h (2450B) - Raw
1 /* Macros and inline functions to swap the order of bytes in integer values. 2 Copyright (C) 1997-2025 Free Software Foundation, Inc. 3 This file is part of the GNU C Library. 4 5 The GNU C Library is free software; you can redistribute it and/or 6 modify it under the terms of the GNU Lesser General Public 7 License as published by the Free Software Foundation; either 8 version 2.1 of the License, or (at your option) any later version. 9 10 The GNU C Library is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 13 Lesser General Public License for more details. 14 15 You should have received a copy of the GNU Lesser General Public 16 License along with the GNU C Library; if not, see 17 <https://www.gnu.org/licenses/>. */ 18 19 #if !defined _BYTESWAP_H && !defined _NETINET_IN_H && !defined _ENDIAN_H 20 # error "Never use <bits/byteswap.h> directly; include <byteswap.h> instead." 21 #endif 22 23 #ifndef _BITS_BYTESWAP_H 24 #define _BITS_BYTESWAP_H 1 25 26 #include <features.h> 27 #include <bits/types.h> 28 29 /* Swap bytes in 16-bit value. */ 30 #define __bswap_constant_16(x) \ 31 ((__uint16_t) ((((x) >> 8) & 0xff) | (((x) & 0xff) << 8))) 32 33 static __inline __uint16_t 34 __bswap_16 (__uint16_t __bsx) 35 { 36 #if __GNUC_PREREQ (4, 8) 37 return __builtin_bswap16 (__bsx); 38 #else 39 return __bswap_constant_16 (__bsx); 40 #endif 41 } 42 43 /* Swap bytes in 32-bit value. */ 44 #define __bswap_constant_32(x) \ 45 ((((x) & 0xff000000u) >> 24) | (((x) & 0x00ff0000u) >> 8) \ 46 | (((x) & 0x0000ff00u) << 8) | (((x) & 0x000000ffu) << 24)) 47 48 static __inline __uint32_t 49 __bswap_32 (__uint32_t __bsx) 50 { 51 #if __GNUC_PREREQ (4, 3) 52 return __builtin_bswap32 (__bsx); 53 #else 54 return __bswap_constant_32 (__bsx); 55 #endif 56 } 57 58 /* Swap bytes in 64-bit value. */ 59 #define __bswap_constant_64(x) \ 60 ((((x) & 0xff00000000000000ull) >> 56) \ 61 | (((x) & 0x00ff000000000000ull) >> 40) \ 62 | (((x) & 0x0000ff0000000000ull) >> 24) \ 63 | (((x) & 0x000000ff00000000ull) >> 8) \ 64 | (((x) & 0x00000000ff000000ull) << 8) \ 65 | (((x) & 0x0000000000ff0000ull) << 24) \ 66 | (((x) & 0x000000000000ff00ull) << 40) \ 67 | (((x) & 0x00000000000000ffull) << 56)) 68 69 __extension__ static __inline __uint64_t 70 __bswap_64 (__uint64_t __bsx) 71 { 72 #if __GNUC_PREREQ (4, 3) 73 return __builtin_bswap64 (__bsx); 74 #else 75 return __bswap_constant_64 (__bsx); 76 #endif 77 } 78 79 #endif /* _BITS_BYTESWAP_H */