bswap_64(3)

1bswap(3)                   Library Functions Manual                   bswap(3)
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NAME

6       bswap_16, bswap_32, bswap_64 - reverse order of bytes
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LIBRARY

9       Standard C library (libc, -lc)
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SYNOPSIS

12       #include <byteswap.h>
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14       uint16_t bswap_16(uint16_t x);
15       uint32_t bswap_32(uint32_t x);
16       uint64_t bswap_64(uint64_t x);
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DESCRIPTION

19       These functions return a value in which the order of the bytes in their
20       2-, 4-, or 8-byte arguments is reversed.
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RETURN VALUE

23       These functions return the value of their argument with the  bytes  re‐
24       versed.
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ERRORS

27       These functions always succeed.
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STANDARDS

30       GNU.
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EXAMPLES

33       The program below swaps the bytes of the 8-byte integer supplied as its
34       command-line argument.  The following shell  session  demonstrates  the
35       use of the program:
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37           $ ./a.out 0x0123456789abcdef
38           0x123456789abcdef ==> 0xefcdab8967452301
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40   Program source
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42       #include <byteswap.h>
43       #include <inttypes.h>
44       #include <stdint.h>
45       #include <stdio.h>
46       #include <stdlib.h>
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48       int
49       main(int argc, char *argv[])
50       {
51           uint64_t x;
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53           if (argc != 2) {
54               fprintf(stderr, "Usage: %s <num>\n", argv[0]);
55               exit(EXIT_FAILURE);
56           }
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58           x = strtoull(argv[1], NULL, 0);
59           printf("%#" PRIx64 " ==> %#" PRIx64 "\n", x, bswap_64(x));
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61           exit(EXIT_SUCCESS);
62       }
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