workbench/libs/mathtrans/sptieee.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        Convert FFP number to single precision ieee number
  11
  12     RESULT
  13        IEEE Single Precision Floating Point
  14
  15        flags:
  16          zero     : result is zero
  17          negative : result is negative
  18          overflow : exponent of the ieee-number was out of range for ffp
  19
  20     NOTES
  21
  22     EXAMPLE
  23
  24     BUGS
  25
  26     SEE ALSO
  27
  28     INTERNALS
  29
  30     HISTORY
  31 */
  32
  33 AROS_LH1(float, SPTieee,
  34     AROS_LHA(float, fnum, D0),
  35     struct Library *, MathTransBase, 17, MathTrans
  36 )
  37 {
  38     AROS_LIBFUNC_INIT
  39
  40     LONG Res;
  41     LONG Exponent;
  42     if (0 == fnum)
  43     {
  44         SetSR(Zero_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
  45         return 0;
  46     }
  47
  48     Exponent = (fnum & FFPExponent_Mask) - 0x40 + 126;
  49
  50     Res = ( Exponent << (30-7) );
  51     Res |= (((ULONG)fnum & 0x7fffff00) >> 8);
  52
  53     if ((char) fnum < 0)
  54     {
  55         SetSR(Negative_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
  56         Res |= IEEESPSign_Mask;
  57     }
  58
  59     return Res;
  60
  61     AROS_LIBFUNC_EXIT
  62 }