sysdeps/m68k/fpu/e_scalb.c

   1 /* Copyright (C) 1997, 1999 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Andreas Schwab <schwab@issan.informatik.uni-dortmund.de>.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <math.h>
  21 #include "math_private.h"
  22 #include "mathimpl.h"
  23
  24 #ifndef SUFF
  25 #define SUFF
  26 #endif
  27 #ifndef float_type
  28 #define float_type double
  29 #endif
  30
  31 #define CONCATX(a,b) __CONCAT(a,b)
  32 #define s(name) CONCATX(name,SUFF)
  33 #define m81(func) __m81_u(s(func))
  34
  35 float_type
  36 s(__ieee754_scalb) (float_type x, float_type fn)
  37 {
  38   float_type retval;
  39   unsigned long x_cond = __m81_test (x);
  40   unsigned long fn_cond = __m81_test (fn);
  41
  42   if ((x_cond | fn_cond) & __M81_COND_NAN)
  43     return x * fn;
  44
  45   if (fn_cond & __M81_COND_INF)
  46     {
  47       if (!(fn_cond & __M81_COND_NEG))
  48         return x * fn;
  49       else if (x_cond & __M81_COND_ZERO)
  50         return x;
  51       else
  52         return x / -fn;
  53     }
  54
  55   if (m81(__rint) (fn) != fn)
  56     return (x - x) / (x - x);
  57
  58   __asm ("fscale%.x %1, %0" : "=f" (retval) : "f" (fn), "0" (x));
  59   return retval;
  60 }