workbench/libs/mathieeedoubtrans/ieeedptieee.c

   1 /*
   2     Copyright © 1995-2003, The AROS Development Team. All rights reserved.
   3     $Id$
   4 */
   5
   6 #include "mathieeedoubtrans_intern.h"
   7
   8 /*****************************************************************************
   9
  10     NAME */
  11
  12         AROS_LHQUAD1(LONG, IEEEDPTieee,
  13
  14 /*  SYNOPSIS */
  15         AROS_LHAQUAD(double, y, D0, D1),
  16
  17 /*  LOCATION */
  18         struct MathIeeeDoubTransBase *, MathIeeeDoubTransBase, 17, MathIeeeDoubTrans)
  19
  20 /*  FUNCTION
  21         Convert IEEE double to IEEE single precision number
  22
  23     INPUTS
  24
  25     RESULT
  26         IEEE single precision number
  27
  28         Flags:
  29           zero     : result is zero
  30           negative : result is negative
  31           overflow : value was out of range for IEEE single precision
  32
  33     BUGS
  34
  35     INTERNALS
  36
  37 *****************************************************************************/
  38 {
  39     AROS_LIBFUNC_INIT
  40
  41     LONG Res, tmp;
  42
  43     SetSR(0, Zero_Bit | Overflow_Bit | Negative_Bit );
  44
  45     if (is_eqC(y, 0x0, 0x0))
  46     {
  47         SetSR(Zero_Bit, Zero_Bit | Overflow_Bit | Negative_Bit );
  48         return 0;
  49     }
  50
  51     SHRU32(Res, y, 52 );
  52     SHRU32(tmp, y, 29 );
  53     /* calculate the exponent */
  54     Res &=0x7ff;
  55     Res = Res + 0x7e - 0x3fe;
  56     Res <<= 23;
  57
  58     Res |= (tmp & IEEESPMantisse_Mask);
  59
  60     if (is_lessSC(y, 0x0, 0x0))
  61     {
  62         SetSR(Negative_Bit, Zero_Bit | Overflow_Bit | Negative_Bit );
  63         Res |= IEEESPSign_Mask;
  64     }
  65
  66     return Res;
  67
  68     AROS_LIBFUNC_EXIT
  69 }