workbench/libs/mathieeesingbas/ieeespneg.c

   1 /*
   2     Copyright © 1995-2004, The AROS Development Team. All rights reserved.
   3     $Id$
   4 */
   5
   6 #include "mathieeesingbas_intern.h"
   7
   8 /*****************************************************************************
   9
  10     NAME */
  11
  12         AROS_LH1(float, IEEESPNeg,
  13
  14 /*  SYNOPSIS */
  15         AROS_LHA(float, y, D0),
  16
  17 /*  LOCATION */
  18         struct LibHeader *, MathIeeeSingBasBase, 10, Mathieeesingbas)
  19
  20 /*  FUNCTION
  21         Switch the sign of the given ieeesp number
  22
  23     INPUTS
  24
  25     RESULT
  26         -y
  27
  28         Flags:
  29           zero     : result is zero
  30           negative : result is negative
  31           overflow : 0
  32
  33     BUGS
  34
  35     INTERNALS
  36         ALGORITHM:
  37         Return -0 if y == 0.
  38         Otherwise flip the sign-bit.
  39
  40 *****************************************************************************/
  41 {
  42     AROS_LIBFUNC_INIT
  43
  44     if (0 == y || 0x80000000 == y)
  45     {
  46         SetSR( Zero_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
  47         return (IEEESPSign_Mask ^ y);
  48     }
  49
  50     /* flip sign-bit */
  51     y ^= IEEESPSign_Mask;
  52
  53     if(y < 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 y;
  65
  66     AROS_LIBFUNC_EXIT
  67 }