sysdeps/libm-ieee754/s_isinf.c

   1 /*
   2  * Written by J.T. Conklin <jtc@netbsd.org>.
   3  * Changed to return -1 for -Inf by Ulrich Drepper <drepper@cygnus.com>.
   4  * Public domain.
   5  */
   6
   7 #if defined(LIBM_SCCS) && !defined(lint)
   8 static char rcsid[] = "$NetBSD: s_isinf.c,v 1.3 1995/05/11 23:20:14 jtc Exp $";
   9 #endif
  10
  11 /*
  12  * isinf(x) returns 1 is x is inf, -1 if x is -inf, else 0;
  13  * no branching!
  14  */
  15
  16 #include "math.h"
  17 #include "math_private.h"
  18
  19 #ifdef __STDC__
  20         int __isinf(double x)
  21 #else
  22         int __isinf(x)
  23         double x;
  24 #endif
  25 {
  26         u_int32_t hx;
  27         int32_t lx;
  28         EXTRACT_WORDS(hx,lx,x);
  29         lx |= (hx & 0x7fffffff) ^ 0x7ff00000;
  30         lx |= -lx;
  31         return ~(lx >> 31) & (1 - ((hx >> 30) & 2));
  32 }
  33 weak_alias (__isinf, isinf)
  34 #ifdef NO_LONG_DOUBLE
  35 strong_alias (__isinf, __isinfl)
  36 weak_alias (__isinf, isinfl)
  37 #endif