libm/s_ldexp.c

   1 /*
   2  * ====================================================
   3  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   4  *
   5  * Developed at SunPro, a Sun Microsystems, Inc. business.
   6  * Permission to use, copy, modify, and distribute this
   7  * software is freely granted, provided that this notice
   8  * is preserved.
   9  * ====================================================
  10  */
  11
  12 #include "math.h"
  13 #include "math_private.h"
  14 #include <errno.h>
  15
  16 /* TODO: POSIX says:
  17  *
  18  * "If the integer expression (math_errhandling & MATH_ERRNO) is non-zero,
  19  * then errno shall be set to [ERANGE]. If the integer expression
  20  * (math_errhandling & MATH_ERREXCEPT) is non-zero, then the underflow
  21  * floating-point exception shall be raised."
  22  *
  23  * *And it says the same about scalbn*! Thus these two functions
  24  * are the same and can be just aliased.
  25  *
  26  * Currently, ldexp tries to be vaguely POSIX compliant while scalbn
  27  * does not (it does not set ERRNO).
  28  */
  29
  30 double ldexp(double value, int _exp)
  31 {
  32         if (!isfinite(value) || value == 0.0)
  33                 return value;
  34         value = scalbn(value, _exp);
  35         if (!isfinite(value) || value == 0.0)
  36                 errno = ERANGE;
  37         return value;
  38 }
  39 libm_hidden_def(ldexp)