workbench/libs/mathtrans/sppow.c

   1 /*
   2     Copyright © 1995-2003, The AROS Development Team. All rights reserved.
   3     $Id$
   4 */
   5
   6 #include "mathtrans_intern.h"
   7
   8 /*
   9     FUNCTION
  10       Calculate fnum2 raised to the fnum1 power (fnum2^fnum1)
  11
  12     RESULT
  13       Motorola fast floating point number
  14
  15       flags:
  16         zero     : result is zero
  17         negative : result is negative
  18         overflow : result is too big
  19
  20     NOTES
  21
  22     EXAMPLE
  23
  24     BUGS
  25
  26     SEE ALSO
  27
  28     INTERNALS
  29
  30     HISTORY
  31 */
  32
  33 AROS_LH2(float, SPPow,
  34     AROS_LHA(float, fnum1, D1),
  35     AROS_LHA(float, fnum2, D0),
  36     struct Library *, MathTransBase, 15, MathTrans
  37 )
  38 {
  39     AROS_LIBFUNC_INIT
  40
  41     /*
  42         a     ^ b     = e^(b     * ln a    )
  43        fnum2 ^ fnum1 = e^(fnum1 * ln fnum2)
  44     */
  45
  46     ULONG Res;
  47     Res = SPLog( fnum2 & (FFPMantisse_Mask + FFPExponent_Mask) );
  48     Res = SPMul(Res, fnum1);
  49     Res = SPExp(Res);
  50
  51     if (0 == Res)
  52     {
  53         SetSR(Zero_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
  54         return 0;
  55     }
  56
  57     if ((char) Res < 0)
  58     {
  59         SetSR(Negative_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
  60     }
  61
  62     return Res;
  63
  64     AROS_LIBFUNC_EXIT
  65 }