mirror of https://github.com/mkerrisk/man-pages
84 lines
2.5 KiB
Groff
84 lines
2.5 KiB
Groff
.\" Copyright (C) 2016 Michael Kerrisk <mtk.manpages@gmail.com>
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.\"
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.\" %%%LICENSE_START(VERBATIM)
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\" %%%LICENSE_END
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.\"
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.TH BSWAP 3 2020-11-01 "Linux" "Linux Programmer's Manual"
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.SH NAME
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bswap_16, bswap_32, bswap_64 \- reverse order of bytes
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.SH SYNOPSIS
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.nf
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.B #include <byteswap.h>
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.PP
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.BI "uint16_t bswap_16(uint16_t " x );
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.BI "uint32_t bswap_32(uint32_t " x );
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.BI "uint64_t bswap_64(uint64_t " x );
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.fi
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.SH DESCRIPTION
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These functions return a value in which the order of the bytes
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in their 2-, 4-, or 8-byte arguments is reversed.
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.SH RETURN VALUE
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These functions return the value of their argument with the bytes reversed.
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.SH ERRORS
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These functions always succeed.
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.SH CONFORMING TO
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These functions are GNU extensions.
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.SH EXAMPLES
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The program below swaps the bytes of the 8-byte integer supplied as
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its command-line argument.
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The following shell session demonstrates the use of the program:
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.PP
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.in +4n
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.EX
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$ \fB./a.out 0x0123456789abcdef\fP
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0x123456789abcdef ==> 0xefcdab8967452301
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.EE
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.in
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.SS Program source
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\&
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.EX
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#include <stdio.h>
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#include <stdint.h>
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#include <stdlib.h>
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#include <inttypes.h>
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#include <byteswap.h>
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int
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main(int argc, char *argv[])
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{
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uint64_t x;
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if (argc != 2) {
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fprintf(stderr, "Usage: %s <num>\en", argv[0]);
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exit(EXIT_FAILURE);
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}
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x = strtoull(argv[1], NULL, 0);
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printf("%#" PRIx64 " ==> %#" PRIx64 "\en", x, bswap_64(x));
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exit(EXIT_SUCCESS);
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}
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.EE
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.SH SEE ALSO
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.BR byteorder (3),
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.BR endian (3)
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