newlib/libm/common/s_isinf.c

   1 /*
   2  * isinf(x) returns 1 if x is infinity, else 0;
   3  * no branching!
   4  *
   5  * isinf is a <math.h> macro in the C99 standard.  It was previously
   6  * implemented as a function by newlib and is declared as such in
   7  * <math.h>.  Newlib supplies it here as a function if the user
   8  * chooses to use it instead of the C99 macro.
   9  */
  10
  11 #include "fdlibm.h"
  12 #include <ieeefp.h>
  13
  14 #ifndef _DOUBLE_IS_32BITS
  15
  16 #undef isinf
  17
  18 int
  19 isinf (double x)
  20 {
  21         __int32_t hx,lx;
  22         EXTRACT_WORDS(hx,lx,x);
  23         hx &= 0x7fffffff;
  24         hx |= (__uint32_t)(lx|(-lx))>>31;
  25         hx = 0x7ff00000 - hx;
  26         return 1 - (int)((__uint32_t)(hx|(-hx))>>31);
  27 }
  28
  29 #endif /* _DOUBLE_IS_32BITS */