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

   1 /*
   2  * Public domain.
   3  */
   4
   5 #if defined(LIBM_SCCS) && !defined(lint)
   6 static char rcsid[] = "$NetBSD: $";
   7 #endif
   8
   9 /*
  10  * isinfl(x) returns 1 if x is inf, -1 if x is -inf, else 0;
  11  * no branching!
  12  * slightly dodgy in relying on signed shift right copying sign bit
  13  */
  14
  15 #include <math.h>
  16 #include <math_private.h>
  17 #include <math_ldbl_opt.h>
  18
  19 int
  20 ___isinfl (long double x)
  21 {
  22   double xhi;
  23   int64_t hx, mask;
  24
  25   xhi = ldbl_high (x);
  26   EXTRACT_WORDS64 (hx, xhi);
  27
  28   mask = (hx & 0x7fffffffffffffffLL) ^ 0x7ff0000000000000LL;
  29   mask |= -mask;
  30   mask >>= 63;
  31   return ~mask & (hx >> 62);
  32 }
  33 hidden_ver (___isinfl, __isinfl)
  34 #if !IS_IN (libm)
  35 weak_alias (___isinfl, ____isinfl)
  36 long_double_symbol (libc, ___isinfl, isinfl);
  37 long_double_symbol (libc, ____isinfl, __isinfl);
  38 #endif