I have the below function that I call in a parallel loop. I have declared the union
inside the below function for thread safety. The issue is that doing so slow things a lot. My question is whether there is a way to turn the double
into an uin64_t
(the same way as union
does) but in a faster way? Thank you.
uint64_t flip(double d) {
union {double d; uint64_t u64;} u;
u.d = d;
return u.u64 ^ (-(u.u64 >> 63) | 0x8000000000000000ULL);
}
I am using gcc to compile the code.
You might try re-doing this as a macro to eliminate the call
and return
overhead for the function:
#define DOUBLE_TO_UINT64(d) ((*(uint64_t *)(&(d))) ^ (-( (*(uint64_t *)(&(d))) >> 63) | 0x8000000000000000ULL))
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