workbench/libs/mathieeedoubbas/ieeedpneg.c

   1 /*
   2     Copyright © 1995-2003, The AROS Development Team. All rights reserved.
   3     $Id$
   4 */
   5
   6 #include "mathieeedoubbas_intern.h"
   7
   8 /*****************************************************************************
   9
  10     NAME */
  11
  12         AROS_LHQUAD1(double, IEEEDPNeg,
  13
  14 /*  SYNOPSIS */
  15         AROS_LHAQUAD(double, y, D0, D1),
  16
  17 /*  LOCATION */
  18         struct MathIeeeDoubBasBase *, MathIeeeDoubBasBase, 10, MathIeeeDoubBas)
  19
  20 /*  FUNCTION
  21         Switch the sign of the given IEEE double precision
  22         floating point number
  23
  24     INPUTS
  25
  26     RESULT
  27         -y
  28
  29         Flags:
  30           zero     : result is zero
  31           negative : result is negative
  32           overflow : 0
  33
  34     BUGS
  35
  36     INTERNALS
  37         ALGORITHM:
  38         Flip the sign-bit (even for zeroes).
  39
  40 *****************************************************************************/
  41 {
  42     AROS_LIBFUNC_INIT
  43
  44     QUAD * Qy = (QUAD *)&y;
  45
  46     /* change the sign-bit */
  47     XOR64QC(*Qy, IEEEDPSign_Mask_Hi, IEEEDPSign_Mask_Lo);
  48
  49     if
  50     (
  51            is_eqC(*Qy, 0x0, 0x0 )
  52         || is_eqC(*Qy, IEEEDPSign_Mask_Hi, IEEEDPSign_Mask_Lo)
  53     )
  54     {
  55         SetSR( Zero_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
  56         return y;
  57     }
  58
  59     /* if (y < 0) */
  60     if(is_lessSC(*Qy, 0x0, 0x0) )
  61     {
  62         /* result is negative */
  63         SetSR(Negative_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
  64     }
  65     else
  66     {
  67         /* result is positive */
  68         SetSR(0, Zero_Bit | Overflow_Bit | Negative_Bit );
  69     }
  70
  71     return y;
  72
  73     AROS_LIBFUNC_EXIT
  74 }