rom/mathffp/spneg.c

   1 /*
   2     Copyright © 1995-2004, The AROS Development Team. All rights reserved.
   3     $Id$
   4 */
   5
   6 #include "mathffp_intern.h"
   7
   8 /*
   9     FUNCTION
  10         Calculate fnum1*(-1)
  11
  12     RESULT
  13         -fnum1
  14
  15         Flags:
  16           zero     : result is zero
  17           negative : result is negative
  18           overflow : 0
  19
  20     NOTES
  21
  22     EXAMPLE
  23
  24     BUGS
  25
  26     SEE ALSO
  27
  28
  29     INTERNALS
  30       ALGORITHM:
  31         Return zero if fnum == 0.
  32         Otherwise flip the sign-bit.
  33
  34     HISTORY
  35 */
  36
  37 AROS_LH1(float, SPNeg,
  38     AROS_LHA(float, fnum1, D0),
  39     struct LibHeader *, MathBase, 10, Mathffp
  40 )
  41 {
  42     AROS_LIBFUNC_INIT
  43
  44     if (0 == fnum1)
  45     {
  46         SetSR( Zero_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
  47         return 0;
  48     }
  49
  50     /* flip sign-bit */
  51     fnum1 ^= FFPSign_Mask;
  52
  53     if((char) fnum1 < 0)
  54     {
  55         /* result is negative */
  56         SetSR(Negative_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
  57     }
  58     else
  59     {
  60         /* result is positive */
  61         SetSR(0, Zero_Bit | Overflow_Bit | Negative_Bit );
  62     }
  63
  64     return fnum1;
  65
  66     AROS_LIBFUNC_EXIT
  67 }