/* $XFree86: xc/programs/Xserver/hw/xfree86/drivers/ati/atiutil.c,v 1.8 2003/01/01 19:16:34 tsi Exp $ *//* * Copyright 1997 through 2004 by Marc Aurele La France (TSI @ UQV), tsi@xfree86.org * * Permission to use, copy, modify, distribute, and sell this software and its * documentation for any purpose is hereby granted without fee, provided that * the above copyright notice appear in all copies and that both that copyright * notice and this permission notice appear in supporting documentation, and * that the name of Marc Aurele La France not be used in advertising or * publicity pertaining to distribution of the software without specific, * written prior permission.  Marc Aurele La France makes no representations * about the suitability of this software for any purpose.  It is provided * "as-is" without express or implied warranty. * * MARC AURELE LA FRANCE DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.  IN NO * EVENT SHALL MARC AURELE LA FRANCE BE LIABLE FOR ANY SPECIAL, INDIRECT OR * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR * PERFORMANCE OF THIS SOFTWARE. */#ifdef HAVE_CONFIG_H#include "config.h"#endif#include "atiutil.h"/* * ATIReduceRatio -- * * Reduce a fraction by factoring out the largest common divider of the * fraction's numerator and denominator. */voidATIReduceRatio(    int *Numerator,    int *Denominator){    int Multiplier, Divider, Remainder;    Multiplier = *Numerator;    Divider = *Denominator;    while ((Remainder = Multiplier % Divider))    {        Multiplier = Divider;        Divider = Remainder;    }    *Numerator /= Divider;    *Denominator /= Divider;}/* * ATIDivide -- * * Using integer arithmetic and avoiding overflows, this function finds the * rounded integer that best approximates * *         Numerator      Shift *        ----------- * 2 *        Denominator * * using the specified rounding (floor (<0), nearest (=0) or ceiling (>0)). */intATIDivide(    int       Numerator,    int       Denominator,    int       Shift,    const int RoundingKind){    int Rounding = 0;                           /* Default to floor */#define MaxInt ((int)((unsigned int)(-1) >> 2))    ATIReduceRatio(&Numerator, &Denominator);    /* Deal with left shifts but try to keep the denominator even */    if (Denominator & 1)    {        if (Denominator <= MaxInt)        {            Denominator <<= 1;            Shift++;        }    }    else while ((Shift > 0) && !(Denominator & 3))    {        Denominator >>= 1;        Shift--;    }    /* Deal with right shifts */    while (Shift < 0)    {        if ((Numerator & 1) && (Denominator <= MaxInt))            Denominator <<= 1;        else            Numerator >>= 1;        Shift++;    }    if (!RoundingKind)                          /* Nearest */        Rounding = Denominator >> 1;    else if (RoundingKind > 0)                  /* Ceiling */        Rounding = Denominator - 1;    return ((Numerator / Denominator) << Shift) +            ((((Numerator % Denominator) << Shift) + Rounding) / Denominator);}