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authorUlrich Drepper <drepper@redhat.com>2000-12-27 20:01:21 +0000
committerUlrich Drepper <drepper@redhat.com>2000-12-27 20:01:21 +0000
commit3d7f417bdeeebe0373c0c60ef234065189220f25 (patch)
treeb39efa870a67347951d72e0d2b5715a7f77f11fd /bits
parented073f0e6249dc1bcecb3f72fa941d01b516be3f (diff)
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(__bswap_64): Handle constant argument case separately.
Diffstat (limited to 'bits')
-rw-r--r--bits/byteswap.h25
1 files changed, 20 insertions, 5 deletions
diff --git a/bits/byteswap.h b/bits/byteswap.h
index b193ea19ec..ec2051ace2 100644
--- a/bits/byteswap.h
+++ b/bits/byteswap.h
@@ -53,12 +53,27 @@ __bswap_32 (unsigned int __bsx)
#if defined __GNUC__ && __GNUC__ >= 2
/* Swap bytes in 64 bit value. */
+#define __bswap_constant_64(x) \
+ ((((x) & 0xff00000000000000ull) >> 56) \
+ | (((x) & 0x00ff000000000000ull) >> 40) \
+ | (((x) & 0x0000ff0000000000ull) >> 24) \
+ | (((x) & 0x000000ff00000000ull) >> 8) \
+ | (((x) & 0x00000000ff000000ull) << 8) \
+ | (((x) & 0x0000000000ff0000ull) << 24) \
+ | (((x) & 0x000000000000ff00ull) << 40) \
+ | (((x) & 0x00000000000000ffull) << 56))
+
# define __bswap_64(x) \
(__extension__ \
- ({ union { unsigned long long int __ll; \
- unsigned int __l[2]; } __v, __r; \
- __v.__ll = (x); \
- __r.__l[0] = __bswap_32 (__v.__l[1]); \
- __r.__l[1] = __bswap_32 (__v.__l[0]); \
+ ({ union { __extension__ unsigned long long int __ll; \
+ unsigned long int __l[2]; } __w, __r; \
+ if (__builtin_constant_p (x)) \
+ __r.__ll = __bswap_constant_64 (x); \
+ else \
+ { \
+ __w.__ll = (x); \
+ __r.__l[0] = __bswap_32 (__w.__l[1]); \
+ __r.__l[1] = __bswap_32 (__w.__l[0]); \
+ } \
__r.__ll; }))
#endif