diff options
Diffstat (limited to 'bits')
| -rw-r--r-- | bits/byteswap.h | 25 |
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 |