workbench/libs/mathieeedoubbas/ieeedpfloor.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     FUNCTION
  10         Calculates the floor-value of a IEEE double precision number
  11
  12     RESULT
  13        <code>
  14        +1 : y > z
  15         0 : y = z
  16        -1 : y < z
  17
  18         Flags:
  19           zero     : y = z
  20           negative : y < z
  21           overflow : 0
  22        </code>
  23
  24     NOTES
  25
  26     EXAMPLE
  27
  28     BUGS
  29
  30     SEE ALSO
  31
  32     INTERNALS
  33
  34     HISTORY
  35 */
  36
  37 AROS_LHQUAD1(double, IEEEDPFloor,
  38     AROS_LHAQUAD(double, y, D0, D1),
  39     struct MathIeeeDoubBasBase *, MathIeeeDoubBasBase, 15, MathIeeeDoubBas
  40 )
  41 {
  42     AROS_LIBFUNC_INIT
  43
  44     QUAD Mask;
  45     QUAD y_tmp,y2;
  46     int shift;
  47     QUAD * Qy = (QUAD *)&y;
  48
  49     if (is_eqC(*Qy,0,0)) return *Qy;
  50
  51     Set_Value64(y_tmp, *Qy);
  52     AND64QC(y_tmp, IEEEDPExponent_Mask_Hi, IEEEDPExponent_Mask_Lo );
  53
  54     if (is_lessC(y_tmp, one_Hi, one_Lo ))
  55     {
  56         if (is_lessSC(*Qy,0,0))
  57         {
  58             SetSR(Negative_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
  59             Set_Value64C
  60             (
  61                 *Qy,
  62                 one_Hi | IEEEDPSign_Mask_Hi,
  63                 one_Lo | IEEEDPSign_Mask_Lo
  64             );
  65             return y;
  66         }
  67         else
  68         {
  69             SetSR(Zero_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
  70             Set_Value64C(*Qy, 0,0);
  71             return y;
  72         }
  73     }
  74
  75     /* |fnum| >= 1 */
  76     Set_Value64C(Mask, 0x80000000, 0x00000000);
  77     SHRU32(shift, y_tmp, 52);
  78     SHRS64(Mask, Mask, (shift-0x3ff+11));  /* leave the () there! StormC 1.1 needs 'em! */
  79
  80     /* y is negative */
  81     if (is_leqSC(*Qy, 0x0, 0x0))
  82     {
  83         QUAD Mask2;
  84         NOT64(Mask2, Mask);
  85         Set_Value64(y2,*Qy);
  86         AND64Q(y2, Mask2);
  87         if (is_neqC(y2,0x0,0x0))
  88         {
  89             QUAD minusone;
  90             double * Dminusone = (double *)&minusone;
  91             Set_Value64C
  92             (
  93                 minusone,
  94                 one_Hi | IEEEDPSign_Mask_Hi,
  95                 one_Lo | IEEEDPSign_Mask_Lo
  96             );
  97             *Qy = IEEEDPAdd(*Qy, *Dminusone);
  98             Set_Value64C(Mask, 0x80000000, 0x00000000);
  99             SHRU32(shift, y_tmp, 52);
 100             SHRS64(Mask, Mask, (shift-0x3ff+11)); /* leave the () there! StormC 1.1 needs 'em! */
 101         }
 102     }
 103
 104     if (is_lessSC(*Qy,0x0,0x0))
 105     {
 106         SetSR(Negative_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
 107     }
 108
 109     AND64Q(*Qy, Mask);
 110
 111     return y;
 112
 113     AROS_LIBFUNC_EXIT
 114 }