1 /* $NetBSD: bswap64.c,v 1.5 2003/12/04 13:57:31 keihan Exp $ */
2
3 /*
4 * Written by Manuel Bouyer <bouyer@NetBSD.org>.
5 * Public domain.
6 */
7
8 #include <sys/cdefs.h>
9 #if defined(LIBC_SCCS) && !defined(lint)
10 __RCSID("$NetBSD: bswap64.c,v 1.5 2003/12/04 13:57:31 keihan Exp $");
11 #endif /* LIBC_SCCS and not lint */
12
13 #include <sys/types.h>
14 #include <machine/bswap.h>
15
16 #undef bswap64
17
18 u_int64_t
19 bswap64(x)
20 u_int64_t x;
21 {
22 #ifdef _LP64
23 /*
24 * Assume we have wide enough registers to do it without touching
25 * memory.
26 */
27 return ( (x << 56) & 0xff00000000000000UL ) |
28 ( (x << 40) & 0x00ff000000000000UL ) |
29 ( (x << 24) & 0x0000ff0000000000UL ) |
30 ( (x << 8) & 0x000000ff00000000UL ) |
31 ( (x >> 8) & 0x00000000ff000000UL ) |
32 ( (x >> 24) & 0x0000000000ff0000UL ) |
33 ( (x >> 40) & 0x000000000000ff00UL ) |
34 ( (x >> 56) & 0x00000000000000ffUL );
35 #else
36 /*
37 * Split the operation in two 32bit steps.
38 */
39 u_int32_t tl, th;
40
41 th = bswap32((u_int32_t)(x & 0x00000000ffffffffULL));
42 tl = bswap32((u_int32_t)((x >> 32) & 0x00000000ffffffffULL));
43 return ((u_int64_t)th << 32) | tl;
44 #endif
45 }
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