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      1 /* Interface to byteswapping functions.
      2    Copyright (C) 2006-2026 Free Software Foundation, Inc.
      3 
      4    This file is part of libctf.
      5 
      6    libctf is free software; you can redistribute it and/or modify it under
      7    the terms of the GNU General Public License as published by the Free
      8    Software Foundation; either version 3, or (at your option) any later
      9    version.
     10 
     11    This program is distributed in the hope that it will be useful, but
     12    WITHOUT ANY WARRANTY; without even the implied warranty of
     13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
     14    See the GNU General Public License for more details.
     15 
     16    You should have received a copy of the GNU General Public License
     17    along with this program; see the file COPYING.  If not see
     18    <http://www.gnu.org/licenses/>.  */
     19 
     20 #ifndef _CTF_SWAP_H
     21 #define _CTF_SWAP_H
     22 
     23 #include "config.h"
     24 #include <stdint.h>
     25 #include <assert.h>
     26 
     27 #ifdef HAVE_BYTESWAP_H
     28 #include <byteswap.h>
     29 #endif /* defined(HAVE_BYTESWAP_H) */
     30 
     31 /* Provide our own versions of the byteswap functions.  */
     32 
     33 #if !HAVE_DECL_BSWAP_16
     34 static inline uint16_t
     35 bswap_16 (uint16_t v)
     36 {
     37   return ((v >> 8) & 0xff) | ((v & 0xff) << 8);
     38 }
     39 #endif /* !HAVE_DECL_BSWAP16 */
     40 
     41 #if !HAVE_DECL_BSWAP_32
     42 static inline uint32_t
     43 bswap_32 (uint32_t v)
     44 {
     45   return (  ((v & 0xff000000) >> 24)
     46 	  | ((v & 0x00ff0000) >>  8)
     47 	  | ((v & 0x0000ff00) <<  8)
     48 	  | ((v & 0x000000ff) << 24));
     49 }
     50 #endif /* !HAVE_DECL_BSWAP32 */
     51 
     52 #if !HAVE_DECL_BSWAP_64
     53 static inline uint64_t
     54 bswap_64 (uint64_t v)
     55 {
     56   return (  ((v & 0xff00000000000000ULL) >> 56)
     57 	  | ((v & 0x00ff000000000000ULL) >> 40)
     58 	  | ((v & 0x0000ff0000000000ULL) >> 24)
     59 	  | ((v & 0x000000ff00000000ULL) >>  8)
     60 	  | ((v & 0x00000000ff000000ULL) <<  8)
     61 	  | ((v & 0x0000000000ff0000ULL) << 24)
     62 	  | ((v & 0x000000000000ff00ULL) << 40)
     63 	  | ((v & 0x00000000000000ffULL) << 56));
     64 }
     65 #endif /* !HAVE_DECL_BSWAP64 */
     66 
     67 /* < C11? define away static assertions.  */
     68 
     69 #if !defined (__STDC_VERSION__) || __STDC_VERSION__ < 201112L
     70 #ifndef _Static_assert
     71 #define _Static_assert(cond, err)
     72 #endif
     73 #endif
     74 
     75 /* Swap the endianness of something.  */
     76 
     77 #define swap_thing(x)							\
     78   do									\
     79     {									\
     80       _Static_assert (sizeof (x) == 1 || (sizeof (x) % 2 == 0		\
     81 					  && sizeof (x) <= 8),		\
     82 		      "Invalid size, update endianness code");		\
     83       switch (sizeof (x)) {						\
     84       case 2: x = bswap_16 (x); break;					\
     85       case 4: x = bswap_32 (x); break;					\
     86       case 8: x = bswap_64 (x); break;					\
     87       case 1: /* Nothing needs doing */					\
     88 	break;								\
     89       }									\
     90     }									\
     91   while (0);
     92 
     93 
     94 #endif /* !defined(_CTF_SWAP_H) */
     95