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<!-- Copyright (C) 2003 Red Hat, Inc. --> <!-- This material may be distributed only subject to the terms --> <!-- and conditions set forth in the Open Publication License, v1.0 --> <!-- or later (the latest version is presently available at --> <!-- http://www.opencontent.org/openpub/). --> <!-- Distribution of the work or derivative of the work in any --> <!-- standard (paper) book form is prohibited unless prior --> <!-- permission is obtained from the copyright holder. --> <HTML ><HEAD ><TITLE >byteorder</TITLE ><meta name="MSSmartTagsPreventParsing" content="TRUE"> <META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ "><LINK REL="HOME" TITLE="eCos Reference Manual" HREF="ecos-ref.html"><LINK REL="UP" TITLE="TCP/IP Library Reference" HREF="tcpip-library-reference.html"><LINK REL="PREVIOUS" TITLE="gethostname" HREF="net-common-tcpip-manpages-gethostname.html"><LINK REL="NEXT" TITLE="ethers" HREF="net-common-tcpip-manpages-ethers.html"></HEAD ><BODY CLASS="SECT1" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#840084" ALINK="#0000FF" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >eCos Reference Manual</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="net-common-tcpip-manpages-gethostname.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" >Chapter 38. TCP/IP Library Reference</TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="net-common-tcpip-manpages-ethers.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECT1" ><H1 CLASS="SECT1" ><A NAME="NET-COMMON-TCPIP-MANPAGES-BYTEORDER">byteorder</H1 ><TABLE BORDER="5" BGCOLOR="#E0E0F0" WIDTH="70%" ><TR ><TD ><PRE CLASS="SCREEN" >BYTEORDER(3) System Library Functions Manual BYTEORDER(3) NAME htonl, htons, ntohl, ntohs, htobe32, htobe16, betoh32, betoh16, htole32, htole16, letoh32, letoh16, swap32, swap16 - convert values between dif- ferent byte orderings SYNOPSIS #include <sys/types.h> #include <machine/endian.h> u_int32_t htonl(u_int32_t host32); u_int16_t htons(u_int16_t host16); u_int32_t ntohl(u_int32_t net32); u_int16_t ntohs(u_int16_t net16); u_int32_t htobe32(u_int32_t host32); u_int16_t htobe16(u_int16_t host16); u_int32_t betoh32(u_int32_t big32); u_int16_t betoh16(u_int16_t big16); u_int32_t htole32(u_int32_t host32); u_int16_t htole16(u_int16_t host16); u_int32_t letoh32(u_int32_t little32); u_int16_t letoh16(u_int16_t little16); u_int32_t swap32(u_int32_t val32); u_int16_t swap16(u_int16_t val16); DESCRIPTION These routines convert 16- and 32-bit quantities between different byte orderings. The ``swap'' functions reverse the byte ordering of the given quantity, the others converts either from/to the native byte order used by the host to/from either little- or big-endian (a.k.a network) order. Apart from the swap functions, the names can be described by this form: {src-order}to{dst-order}{size}. Both {src-order} and {dst-order} can take the following forms: h Host order. n Network order (big-endian). be Big-endian (most significant byte first). le Little-endian (least significant byte first). One of the specified orderings must be `h'. {size} will take these forms: l Long (32-bit, used in conjunction with forms involving `n'). s Short (16-bit, used in conjunction with forms involving `n'). 16 16-bit. 32 32-bit. The swap functions are of the form: swap{size}. Names involving `n' convert quantities between network byte order and host byte order. The last letter (`s' or `l') is a mnemonic for the tra- ditional names for such quantities, short and long, respectively. Today, the C concept of short and long integers need not coincide with this tra- ditional misunderstanding. On machines which have a byte order which is the same as the network order, routines are defined as null macros. The functions involving either ``be'', ``le'', or ``swap'' use the num- bers 16 and 32 for specifying the bitwidth of the quantities they operate on. Currently all supported architectures are either big- or little- endian so either the ``be'' or ``le'' variants are implemented as null macros. The routines mentioned above which have either {src-order} or {dst-order} set to `n' are most often used in conjunction with Internet addresses and ports as returned by gethostbyname(3) and getservent(3). SEE ALSO gethostbyname(3), getservent(3) HISTORY The byteorder functions appeared in 4.2BSD. BUGS On the vax, alpha, i386, and so far mips, bytes are handled backwards from most everyone else in the world. This is not expected to be fixed in the near future. BSD June 4, 1993 BSD </PRE ></TD ></TR ></TABLE ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="net-common-tcpip-manpages-gethostname.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="ecos-ref.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="net-common-tcpip-manpages-ethers.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >gethostname</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="tcpip-library-reference.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >ethers</TD ></TR ></TABLE ></DIV ></BODY ></HTML >
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