math/w_exp2.c

   1 /*
   2  * wrapper exp2(x)
   3  */
   4
   5 #include <float.h>
   6 #include <math.h>
   7 #include "math_private.h"
   8
   9 static const double o_threshold= (double) DBL_MAX_EXP;
  10 static const double u_threshold= (double) (DBL_MIN_EXP - DBL_MANT_DIG - 1);
  11
  12 double
  13 __exp2 (double x)               /* wrapper exp2 */
  14 {
  15 #ifdef _IEEE_LIBM
  16   return __ieee754_exp2 (x);
  17 #else
  18   double z;
  19   z = __ieee754_exp2 (x);
  20   if (_LIB_VERSION != _IEEE_ && __finite (x))
  21     {
  22       if (x > o_threshold)
  23         /* exp2 overflow */
  24         return __kernel_standard (x, x, 44);
  25       else if (x <= u_threshold)
  26         /* exp2 underflow */
  27         return __kernel_standard (x, x, 45);
  28     }
  29   return z;
  30 #endif
  31 }
  32 weak_alias (__exp2, exp2)
  33 #ifdef NO_LONG_DOUBLE
  34 strong_alias (__exp2, __exp2l)
  35 weak_alias (__exp2, exp2l)
  36 #endif