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