math/w_log2.c

   1 /*
   2  * wrapper log2(X)
   3  */
   4
   5 #include <math.h>
   6 #include "math_private.h"
   7
   8 double
   9 __log2 (double x)       /* wrapper log2 */
  10 {
  11 #ifdef _IEEE_LIBM
  12   return __ieee754_log2 (x);
  13 #else
  14   double z;
  15   z = __ieee754_log2 (x);
  16   if (_LIB_VERSION == _IEEE_ || __isnan (x)) return z;
  17   if (x <= 0.0)
  18     {
  19       if (x == 0.0)
  20         return __kernel_standard (x, x, 48); /* log2 (0) */
  21       else
  22         return __kernel_standard (x, x, 49); /* log2 (x < 0) */
  23     }
  24   else
  25     return z;
  26 #endif
  27 }
  28 weak_alias (__log2, log2)
  29 #ifdef NO_LONG_DOUBLE
  30 strong_alias (__log2, __log2l)
  31 weak_alias (__log2, log2l)
  32 #endif