workbench/libs/mathffp/spfix.c

   1 /*
   2     Copyright © 1995-2004, The AROS Development Team. All rights reserved.
   3     $Id$
   4 */
   5
   6 #include "mathffp_intern.h"
   7
   8 /*****************************************************************************
   9
  10     NAME */
  11
  12         AROS_LH1(LONG, SPFix,
  13
  14 /*  SYNOPSIS */
  15         AROS_LHA(float, fnum, D0),
  16
  17 /*  LOCATION */
  18         struct LibHeader *, MathBase, 5, Mathffp)
  19
  20 /*  FUNCTION
  21         Convert ffp-number to integer
  22
  23     INPUTS
  24
  25     RESULT
  26         absolute value of fnum1
  27
  28         Flags:
  29           zero     : result is zero
  30           negative : result is negative
  31           overflow : ffp out of integer-range
  32
  33     BUGS
  34
  35     INTERNALS
  36
  37 *****************************************************************************/
  38 {
  39     AROS_LIBFUNC_INIT
  40
  41     LONG Res;
  42     BYTE Shift;
  43
  44     if ((fnum & FFPExponent_Mask) > 0x60 )
  45     {
  46         if(fnum < 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
  59     Shift = (fnum & FFPExponent_Mask) - 0x40;
  60     if (Shift > 0) /* > 32 bit LONG shift = undefined */
  61         Res = ((ULONG)(fnum & FFPMantisse_Mask)) >> (32 - Shift);
  62     else
  63         Res = 0;
  64
  65     if (0 == Res)
  66     {
  67         SetSR(Zero_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
  68         return 0;
  69     }
  70
  71     if (0x80000000 == Res) return 0x7fffffff;
  72
  73
  74     /* Test for a negative sign */
  75     if ((char)fnum < 0)
  76     {
  77         Res = -Res;
  78         SetSR(Negative_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
  79     }
  80
  81     D(kprintf("SPFix(%x) = %d\n", fnum, Res));
  82
  83     return Res;
  84
  85     AROS_LIBFUNC_EXIT
  86 }