workbench/libs/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
  10     NAME */
  11
  12         AROS_LH1(float, SPNeg,
  13
  14 /*  SYNOPSIS */
  15         AROS_LHA(float, fnum1, D0),
  16
  17 /*  LOCATION */
  18         struct LibHeader *, MathBase, 10, Mathffp)
  19
  20 /*  FUNCTION
  21         Calculate fnum1*(-1)
  22
  23     INPUTS
  24
  25     RESULT
  26         -fnum1
  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 zero if fnum == 0.
  38         Otherwise flip the sign-bit.
  39
  40 *****************************************************************************/
  41 {
  42     AROS_LIBFUNC_INIT
  43
  44     D(kprintf("SPNeg(%08x)\n", fnum1));
  45     if (0 == fnum1)
  46     {
  47         SetSR( Zero_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
  48         return 0;
  49     }
  50
  51     /* flip sign-bit */
  52     fnum1 ^= FFPSign_Mask;
  53
  54     if((char) fnum1 < 0)
  55     {
  56         /* result is negative */
  57         SetSR(Negative_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
  58     }
  59     else
  60     {
  61         /* result is positive */
  62         SetSR(0, Zero_Bit | Overflow_Bit | Negative_Bit );
  63     }
  64
  65     return fnum1;
  66
  67     AROS_LIBFUNC_EXIT
  68 }