rom/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     FUNCTION
  10         Convert ieeesp-number to integer
  11
  12     RESULT
  13         absolute value of y
  14
  15         Flags:
  16           zero     : result is zero
  17           negative : result is negative
  18           overflow : ieeesp out of integer-range
  19
  20     NOTES
  21
  22     EXAMPLE
  23
  24     BUGS
  25
  26     SEE ALSO
  27
  28
  29     INTERNALS
  30
  31     HISTORY
  32 */
  33
  34 AROS_LH1(LONG, IEEESPFix,
  35     AROS_LHA(float, y, D0),
  36     struct LibHeader *, MathIeeeSingBasBase, 5, Mathieeesingbas
  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 }