reactos/dll/win32/gdi32/objects/efloat.c

   1 /*
   2  * COPYRIGHT:       See COPYING in the top level directory
   3  * PROJECT:         ReactOS System Libraries
   4  * FILE:            dll/gdi32/objects/coord.c
   5  * PURPOSE:         Functions to convert between FLOAT and EFLOAT
   6  * PROGRAMMER:      James Tabor
   7  */
   8 #include "precomp.h"
   9
  10 /* the following deal with IEEE single-precision numbers */
  11 #define EXCESS          126L
  12 #define SIGNBIT         0x80000000L
  13 #define SIGN(fp)        ((fp) & SIGNBIT)
  14 #define EXP(fp)         (((fp) >> 23L) & 0xFF)
  15 #define MANT(fp)        ((fp) & 0x7FFFFFL)
  16 #define PACK(s,e,m)     ((s) | ((e) << 23L) | (m))
  17
  18 FLOATL
  19 FASTCALL
  20 EFtoF(EFLOAT_S * efp)
  21 {
  22     ULONG Mant, Exp, Sign;
  23
  24     if (!efp->lMant) return 0;
  25
  26     Mant = efp->lMant;
  27     Exp = efp->lExp;
  28     Sign = SIGN(Mant);
  29
  30     if (Sign) Mant = -Mant;
  31     Mant >>= 7;
  32     Exp += (EXCESS-1);
  33
  34     Mant = MANT(Mant);
  35     return PACK(Sign, Exp, Mant);
  36 }
  37
  38 VOID
  39 FASTCALL
  40 FtoEF( EFLOAT_S * efp, FLOATL f)
  41 {
  42     ULONG Mant, Exp, Sign = 0;
  43     gxf_long worker;
  44
  45 #ifdef _X86_
  46     worker.l = f; // It's a float stored in a long.
  47 #else
  48     worker.f = f;
  49 #endif
  50
  51     Exp = EXP(worker.l);
  52     Mant = MANT(worker.l);
  53     if (SIGN(worker.l)) Sign = -1;
  54
  55     Mant = ((Mant << 7) | 0x40000000);
  56     Mant ^= Sign;
  57     Mant -= Sign;
  58     Exp -= (EXCESS-1);
  59
  60     efp->lMant = Mant;
  61     efp->lExp = Exp;
  62 }