NetBSD/sys/lib/libkern/bswap64.c

46 lines
1.1 KiB
C

/* $NetBSD: bswap64.c,v 1.5 2003/12/04 13:57:31 keihan Exp $ */
/*
* Written by Manuel Bouyer <bouyer@NetBSD.org>.
* Public domain.
*/
#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: bswap64.c,v 1.5 2003/12/04 13:57:31 keihan Exp $");
#endif /* LIBC_SCCS and not lint */
#include <sys/types.h>
#include <machine/bswap.h>
#undef bswap64
u_int64_t
bswap64(x)
u_int64_t x;
{
#ifdef _LP64
/*
* Assume we have wide enough registers to do it without touching
* memory.
*/
return ( (x << 56) & 0xff00000000000000UL ) |
( (x << 40) & 0x00ff000000000000UL ) |
( (x << 24) & 0x0000ff0000000000UL ) |
( (x << 8) & 0x000000ff00000000UL ) |
( (x >> 8) & 0x00000000ff000000UL ) |
( (x >> 24) & 0x0000000000ff0000UL ) |
( (x >> 40) & 0x000000000000ff00UL ) |
( (x >> 56) & 0x00000000000000ffUL );
#else
/*
* Split the operation in two 32bit steps.
*/
u_int32_t tl, th;
th = bswap32((u_int32_t)(x & 0x00000000ffffffffULL));
tl = bswap32((u_int32_t)((x >> 32) & 0x00000000ffffffffULL));
return ((u_int64_t)th << 32) | tl;
#endif
}