workbench/libs/mathieeedoubbas/ieeedpfix.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(LONG, IEEEDPFix,
  13
  14 /*  SYNOPSIS */
  15         AROS_LHAQUAD(double, y, D0, D1),
  16
  17 /*  LOCATION */
  18         struct MathIeeeDoubBasBase *, MathIeeeDoubBasBase, 5, MathIeeeDoubBas)
  19
  20 /*  FUNCTION
  21         Converts an IEEE double precision floating point number to an integer.
  22
  23     INPUTS
  24         y - IEEE double precision floating point number.
  25
  26     RESULT
  27         x - the closest signed 32-bit integer to y.
  28
  29         Flags:
  30           zero     : result is zero
  31           negative : result is negative
  32           overflow : ieeedp out of integer-range
  33
  34     NOTES
  35
  36     EXAMPLE
  37
  38     BUGS
  39
  40     SEE ALSO
  41         IEEEDPFlt(), IEEEDPFloor(), IEEEDPCeil()
  42
  43     INTERNALS
  44
  45 *****************************************************************************/
  46 {
  47     AROS_LIBFUNC_INIT
  48
  49     LONG Res, Shift, tmp;
  50     QUAD y2;
  51     QUAD * Qy = (QUAD *)&y;
  52
  53     tmp = Get_High32of64(*Qy) & IEEEDPExponent_Mask_Hi;
  54
  55     if ( tmp > 0x41d00000 )
  56     {
  57     if( is_lessSC(*Qy, 0x0, 0x0))
  58     {
  59     SetSR(Overflow_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
  60     return 0x80000000;
  61     }
  62     else
  63     {
  64     SetSR(Overflow_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
  65     return 0x7fffffff;
  66     }
  67     }
  68
  69
  70     if(
  71            is_eqC(*Qy, 0x0, 0x0)
  72         || is_eqC(*Qy,IEEEDPSign_Mask_Hi, IEEEDPSign_Mask_Lo)
  73     ) /* y=+-0; */
  74     {
  75         SetSR(Zero_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
  76         return 0;
  77     }
  78
  79     Shift = (Get_High32of64(*Qy) & IEEEDPExponent_Mask_Hi) >> 20;
  80     Shift = 0x433 - Shift;
  81     tmp = Get_High32of64(*Qy);
  82     AND64QC(*Qy, IEEEDPMantisse_Mask_Hi, IEEEDPMantisse_Mask_Lo);
  83     OR64QC(*Qy, 0x00100000, 0x00000000);
  84     SHRU64(y2, *Qy , Shift);
  85     Res = Get_Low32of64(y2);
  86
  87     /* Test for a negative sign  */
  88     if (tmp < 0) /* y < 0 */
  89     {
  90         Res = -Res;
  91         SetSR(Negative_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
  92     }
  93
  94     return Res;
  95
  96     AROS_LIBFUNC_EXIT
  97 }