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byteorder.h
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C/C++ Source or Header
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1993-06-04
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3KB
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134 lines
#ifndef _SYS_BYTEORDER_H
#define _SYS_BYTEORDER_H
/* Functions to convert `short' and `long' quantities from host byte order
to (internet) network byte order (i.e. big-endian).
Written by Ron Guilmette (rfg@ncd.com).
This isn't actually used by GCC. It is installed by fixinc.svr4.
For big-endian machines these functions are essentially no-ops.
For little-endian machines, we define the functions using specialized
asm sequences in cases where doing so yields better code (e.g. i386). */
#if !defined (__GNUC__) && !defined (__GNUG__)
#error You lose! This file is only useful with GNU compilers.
#endif
#ifdef __GNUC__
#define __STATIC static
#else
#define __STATIC
#endif
#ifdef __STDC__
__STATIC __inline__ unsigned long htonl (unsigned long);
__STATIC __inline__ unsigned short htons (unsigned int);
__STATIC __inline__ unsigned long ntohl (unsigned long);
__STATIC __inline__ unsigned short ntohs (unsigned int);
#endif /* defined (__STDC__) */
#if defined (__i386__)
/* Convert a host long to a network long. */
/* We must use a new-style function definition, so that this will also
be valid for C++. */
__STATIC __inline__ unsigned long
htonl (unsigned long __arg)
{
register unsigned long __result;
__asm__ ("xchg%B0 %b0,%h0\n\
ror%L0 $16,%0\n\
xchg%B0 %b0,%h0" : "=q" (__result) : "0" (__arg));
return __result;
}
/* Convert a host short to a network short. */
__STATIC __inline__ unsigned short
htons (unsigned int __arg)
{
register unsigned short __result;
__asm__ ("xchg%B0 %b0,%h0" : "=q" (__result) : "0" (__arg));
return __result;
}
#elif ((defined (__i860__) && !defined (__i860_big_endian__)) \
|| defined (__ns32k__) || defined (__vax__) \
|| defined (__spur__) || defined (__arm__))
/* For other little-endian machines, using C code is just as efficient as
using assembly code. */
/* Convert a host long to a network long. */
__STATIC __inline__ unsigned long
htonl (unsigned long __arg)
{
register unsigned long __result;
__result = (__arg >> 24) & 0x000000ff;
__result |= (__arg >> 8) & 0x0000ff00;
__result |= (__arg << 8) & 0x00ff0000;
__result |= (__arg << 24) & 0xff000000;
return __result;
}
/* Convert a host short to a network short. */
__STATIC __inline__ unsigned short
htons (unsigned int __arg)
{
register unsigned short __result;
__result = (__arg << 8) & 0xff00;
__result |= (__arg >> 8) & 0x00ff;
return __result;
}
#else /* must be a big-endian machine */
/* Convert a host long to a network long. */
__STATIC __inline__ unsigned long
htonl (unsigned long __arg)
{
return __arg;
}
/* Convert a host short to a network short. */
__STATIC __inline__ unsigned short
htons (unsigned int __arg)
{
return __arg;
}
#endif /* big-endian */
/* Convert a network long to a host long. */
__STATIC __inline__ unsigned long
ntohl (unsigned long __arg)
{
return htonl (__arg);
}
/* Convert a network short to a host short. */
__STATIC __inline__ unsigned short
ntohs (unsigned int __arg)
{
return htons (__arg);
}
#undef __STATIC
#endif /* !defined (_SYS_BYTEORDER_H) */