Author: rodrigc
Date: Fri Jun 10 01:13:15 2011
New Revision: 222908
URL: http://svn.freebsd.org/changeset/base/222908
Log:
Obtain bswap64() function implementation from
version 1.3 of src/common/lib/libc/gen/bswap64.c in NetBSD.
Obtained from: NetBSD
Modified:
head/lib/libstand/bswap.c
Modified: head/lib/libstand/bswap.c
==============================================================================
--- head/lib/libstand/bswap.c Thu Jun 9 23:12:23 2011 (r222907)
+++ head/lib/libstand/bswap.c Fri Jun 10 01:13:15 2011 (r222908)
@@ -8,7 +8,7 @@ __FBSDID("$FreeBSD$");
#if defined(LIBC_SCCS) && !defined(lint)
static char *rcsid = "$NetBSD: bswap32.c,v 1.1 1997/10/09 15:42:33 bouyer Exp
$";
-static char *rcsid = "$NetBSD: bswap64.c,v 1.1 1997/10/09 15:42:33 bouyer Exp
$";
+static char *rcsid = "$NetBSD: bswap64.c,v 1.3 2009/03/16 05:59:21 cegger Exp
$";
#endif
#include <sys/types.h>
@@ -30,12 +30,28 @@ bswap32(u_int32_t x)
u_int64_t
bswap64(u_int64_t x)
-{
- u_int32_t *p = (u_int32_t*)&x;
- u_int32_t t;
- t = bswap32(p[0]);
- p[0] = bswap32(p[1]);
- p[1] = t;
- return 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
+}
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