man3/bswap.3

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  25 .TH BSWAP 3 2019-03-06 "Linux" "Linux Programmer's Manual"
  26 .SH NAME
  27 bswap_16, bswap_32, bswap_64 \- reverse order of bytes
  28 .SH SYNOPSIS
  29 .nf
  30 .B #include <byteswap.h>
  31 .PP
  32 .BI bswap_16( x );
  33 .BI bswap_32( x );
  34 .BI bswap_64( x );
  35 .fi
  36 .SH DESCRIPTION
  37 These macros return a value in which the order of the bytes
  38 in their 2-, 4-, or 8-byte arguments is reversed.
  39 .SH RETURN VALUE
  40 These macros return the value of their argument with the bytes reversed.
  41 .SH ERRORS
  42 These macros always succeed.
  43 .SH CONFORMING TO
  44 These macros are GNU extensions.
  45 .SH EXAMPLES
  46 The program below swaps the bytes of the 8-byte integer supplied as
  47 its command-line argument.
  48 The following shell session demonstrates the use of the program:
  49 .PP
  50 .in +4n
  51 .EX
  52 $ \fB./a.out 0x0123456789abcdef\fP
  53 0x123456789abcdef ==> 0xefcdab8967452301
  54 .EE
  55 .in
  56 .SS Program source
  57 \&
  58 .EX
  59 #include <stdio.h>
  60 #include <stdint.h>
  61 #include <stdlib.h>
  62 #include <inttypes.h>
  63 #include <byteswap.h>
  64
  65 int
  66 main(int argc, char *argv[])
  67 {
  68     uint64_t x;
  69
  70     if (argc != 2) {
  71         fprintf(stderr, "Usage: %s <num>\en", argv[0]);
  72         exit(EXIT_FAILURE);
  73     }
  74
  75     x = strtoul(argv[1], NULL, 0);
  76     printf("0x%" PRIx64 " ==> 0x%" PRIx64 "\en", x, bswap_64(x));
  77
  78     exit(EXIT_SUCCESS);
  79 }
  80 .EE
  81 .SH SEE ALSO
  82 .BR byteorder (3),
  83 .BR endian (3)