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
  10     NAME */
  11
  12         AROS_LH2(float, SPPow,
  13
  14 /*  SYNOPSIS */
  15         AROS_LHA(float, fnum1, D1),
  16         AROS_LHA(float, fnum2, D0),
  17
  18 /*  LOCATION */
  19         struct Library *, MathTransBase, 15, MathTrans)
  20
  21 /*  FUNCTION
  22         Calculate fnum2 raised to the fnum1 power (fnum2^fnum1)
  23
  24     INPUTS
  25
  26     RESULT
  27         Motorola fast floating point number
  28
  29         flags:
  30         zero     : result is zero
  31         negative : result is negative
  32         overflow : result is too big
  33
  34     BUGS
  35
  36     INTERNALS
  37
  38 *****************************************************************************/
  39 {
  40     AROS_LIBFUNC_INIT
  41
  42     /*
  43         a     ^ b     = e^(b     * ln a    )
  44        fnum2 ^ fnum1 = e^(fnum1 * ln fnum2)
  45     */
  46
  47     ULONG Res;
  48     Res = SPLog( fnum2 & (FFPMantisse_Mask + FFPExponent_Mask) );
  49     Res = SPMul(Res, fnum1);
  50     Res = SPExp(Res);
  51
  52     if (0 == Res)
  53     {
  54         SetSR(Zero_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
  55         return 0;
  56     }
  57
  58     if ((char) Res < 0)
  59     {
  60         SetSR(Negative_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
  61     }
  62
  63     return Res;
  64
  65     AROS_LIBFUNC_EXIT
  66 }