workbench/libs/mathieeedoubbas/ieeedpfloor.c

   1 /*
   2     Copyright © 1995-2017, 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 an IEEE double precision number.
  22
  23     INPUTS
  24         y - IEEE double precision floating point number.
  25
  26     RESULT
  27         x - floor of y.
  28
  29         Flags:
  30           zero     : result is zero
  31           negative : result is negative
  32           overflow : 0
  33
  34     NOTES
  35
  36     EXAMPLE
  37
  38     BUGS
  39
  40     SEE ALSO
  41         IEEEDPCeil(), IEEEDPFix()
  42
  43     INTERNALS
  44
  45 *****************************************************************************/
  46 {
  47     AROS_LIBFUNC_INIT
  48
  49     QUAD Mask;
  50     QUAD y_tmp,y2;
  51     int shift;
  52     QUAD * Qy = (QUAD *)&y;
  53
  54     if (is_eqC(*Qy,0,0)) return *Qy;
  55
  56     Set_Value64(y_tmp, *Qy);
  57     AND64QC(y_tmp, IEEEDPExponent_Mask_Hi, IEEEDPExponent_Mask_Lo );
  58
  59     if (is_lessC(y_tmp, one_Hi, one_Lo ))
  60     {
  61         if (is_lessSC(*Qy,0,0))
  62         {
  63             SetSR(Negative_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
  64             Set_Value64C
  65             (
  66                 *Qy,
  67                 one_Hi | IEEEDPSign_Mask_Hi,
  68                 one_Lo | IEEEDPSign_Mask_Lo
  69             );
  70             return y;
  71         }
  72         else
  73         {
  74             SetSR(Zero_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
  75             Set_Value64C(*Qy, 0,0);
  76             return y;
  77         }
  78     }
  79
  80     /* |fnum| >= 1 */
  81     Set_Value64C(Mask, 0x80000000, 0x00000000);
  82     SHRU32(shift, y_tmp, 52);
  83     SHRS64(Mask, Mask, (shift-0x3ff+11));  /* leave the () there! StormC 1.1 needs 'em! */
  84
  85     /* y is negative */
  86     if (is_leqSC(*Qy, 0x0, 0x0))
  87     {
  88         QUAD Mask2;
  89         NOT64(Mask2, Mask);
  90         Set_Value64(y2,*Qy);
  91         AND64Q(y2, Mask2);
  92         if (is_neqC(y2,0x0,0x0))
  93         {
  94             QUAD minusone;
  95             double * Dminusone = (double *)&minusone;
  96             Set_Value64C
  97             (
  98                 minusone,
  99                 one_Hi | IEEEDPSign_Mask_Hi,
 100                 one_Lo | IEEEDPSign_Mask_Lo
 101             );
 102             *Qy = IEEEDPAdd(*Qy, *Dminusone);
 103             Set_Value64C(Mask, 0x80000000, 0x00000000);
 104             SHRU32(shift, y_tmp, 52);
 105             SHRS64(Mask, Mask, (shift-0x3ff+11)); /* leave the () there! StormC 1.1 needs 'em! */
 106         }
 107     }
 108
 109     if (is_lessSC(*Qy,0x0,0x0))
 110     {
 111         SetSR(Negative_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
 112     }
 113
 114     AND64Q(*Qy, Mask);
 115
 116     return y;
 117
 118     AROS_LIBFUNC_EXIT
 119 }