sysdeps/ieee754/ldbl-128ibm/s_isinf_nsl.c

   1 /*
   2  * __isinf_nsl(x) returns != 0 if x is ±inf, else 0;
   3  * no branching!
   4  * slightly dodgy in relying on signed shift right copying sign bit
   5  */
   6
   7 #include <math.h>
   8 #include <math_private.h>
   9
  10 int
  11 __isinf_nsl (long double x)
  12 {
  13   double xhi;
  14   int64_t hx, mask;
  15
  16   xhi = ldbl_high (x);
  17   EXTRACT_WORDS64 (hx, xhi);
  18
  19   mask = (hx & 0x7fffffffffffffffLL) ^ 0x7ff0000000000000LL;
  20   mask |= -mask;
  21   mask >>= 63;
  22   return ~mask;
  23 }