workbench/libs/mathieeesingbas/ieeespfix.c

   1 /*
   2     Copyright © 1995-2004, The AROS Development Team. All rights reserved.
   3     $Id$
   4 */
   5
   6 #include "mathieeesingbas_intern.h"
   7
   8 /*****************************************************************************
   9
  10     NAME */
  11
  12         AROS_LH1(LONG, IEEESPFix,
  13
  14 /*  SYNOPSIS */
  15         AROS_LHA(float, y, D0),
  16
  17 /*  LOCATION */
  18         struct LibHeader *, MathIeeeSingBasBase, 5, Mathieeesingbas)
  19
  20 /*  FUNCTION
  21         Convert ieeesp-number to integer
  22
  23     INPUTS
  24
  25     RESULT
  26         absolute value of y
  27
  28         Flags:
  29           zero     : result is zero
  30           negative : result is negative
  31           overflow : ieeesp out of integer-range
  32
  33     BUGS
  34
  35     INTERNALS
  36
  37 *****************************************************************************/
  38 {
  39     AROS_LIBFUNC_INIT
  40
  41     LONG Res;
  42     LONG Shift;
  43
  44     if ((y & IEEESPExponent_Mask) > 0x60000000 )
  45     {
  46         if(y < 0) /* don`t hurt the SR! */
  47         {
  48             SetSR(Overflow_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
  49             return 0x80000000;
  50         }
  51         else
  52         {
  53             SetSR(Overflow_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
  54             return 0x7fffffff;
  55         }
  56     }
  57
  58     if (0 == y || 0x80000000 == y) /* y=+-0; */
  59     {
  60         SetSR(Zero_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
  61         return 0;
  62     }
  63
  64     Shift = (y & IEEESPExponent_Mask) >> 23;
  65     Shift -=0x7e;
  66
  67     if ((char) Shift >= 25)
  68     {
  69         Res = ((y & IEEESPMantisse_Mask) | 0x00800000)  << (Shift-24);
  70     }
  71     else
  72     {
  73         Res = ((y & IEEESPMantisse_Mask) | 0x00800000)  >> (24 - Shift);
  74     }
  75
  76     /* Test for a negative sign  */
  77     if (y < 0)
  78     {
  79         Res = -Res;
  80         SetSR(Negative_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
  81     }
  82
  83     return Res;
  84
  85     AROS_LIBFUNC_EXIT
  86 }