revision 26772, Mon May 14 03:18:42 2007 UTC

[Timo Kreuzer]

It should probably be
+ Exp -= (1 - EXCESS);
in EFtoF() and
+ Exp += (1 - EXCESS);
in FtoEF(). The other way round.

Suggestion to make it a little clearer:
#define BIAS 127
Exp -+= (BIAS - 2);

jimtabor wrote:

>   ---
> trunk/reactos/dll/win32/gdi32/objects/painting.c	2006/12/28 22:36:53	25235
>  +++ trunk/reactos/dll/win32/gdi32/objects/painting.c	2007/05/14 03:18:42	26772
>  @@ -1,15 +1,66 @@
>     
[...]
>   +/* the following deal with IEEE single-precision
> numbers */
>  +#define EXCESS          126L
>  +#define SIGNBIT         0x80000000L
>  +#define SIGN(fp)        ((fp) & SIGNBIT)
>  +#define EXP(fp)         (((fp) >> 23L) & 0xFF)
>  +#define MANT(fp)        ((fp) & 0x7FFFFFL)
>  +#define PACK(s,e,m)     ((s) | ((e) << 23L) | (m))
>     
[...]
>   +LONG
>  +FASTCALL
>  +EFtoF( EFLOAT_S * efp)
>  +{
>  + long Mant, Exp, Sign = 0;
>  +
>  + if (!efp->lMant) return 0;
>  +
>  + Mant = efp->lMant;
>  + Exp = efp->lExp;
>  + Sign = SIGN(Mant);
>  +
>  +//// M$ storage emulation
>  + Mant = ((Mant & 0x3fffffff) >> 7);
>  + Exp += (1 - EXCESS);
>  +////
>  + Mant = MANT(Mant);
>  + return PACK(Sign, Exp, Mant);
>  +}
>  +
>  +VOID
>  +FASTCALL
>  +FtoEF( EFLOAT_S * efp, FLOATL f)
>  +{
>  + long Mant, Exp;
>  + gxf_long worker;
>  +
>  +#ifdef _X86_
>  + worker.l = f; // It's a float stored in a long.
>  +#else
>  + worker.f = f;
>  +#endif
>  +
>  + Exp = EXP(worker.l);
>  + Mant = MANT(worker.l); 
>  +
>  +//// M$ storage emulation
>  + Mant = ((Mant << 7) | 0x40000000 | SIGN(worker.l));
>  + Exp -= (1 - EXCESS);
>  +//// 
>  + efp->lMant = Mant;
>  + efp->lExp = Exp;
>  +}
>