xref: /xsrc/external/mit/xorg-server/dist/mi/midash.c

/***********************************************************

Copyright 1987, 1998  The Open Group

Permission to use, copy, modify, distribute, and sell this software and its
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all copies or substantial portions of the Software.

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in this Software without prior written authorization from The Open Group.


Copyright 1987 by Digital Equipment Corporation, Maynard, Massachusetts.

                        All Rights Reserved

Permission to use, copy, modify, and distribute this software and its
documentation for any purpose and without fee is hereby granted,
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 Digital not be
used in advertising or publicity pertaining to distribution of the
software without specific, written prior permission.

DIGITAL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
DIGITAL 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_DIX_CONFIG_H
#include <dix-config.h>
#endif

#include "regionstr.h"
#include "mistruct.h"
#include "mifpoly.h"

static miDashPtr CheckDashStorage(miDashPtr *ppseg, int nseg, int *pnsegMax);

#define NSEGDELTA 16

/* returns a pointer to the pseg[nseg-1], growing the storage as
necessary.  this interface seems unnecessarily cumbersome.

*/

static miDashPtr
CheckDashStorage(
    miDashPtr *ppseg,		/* base pointer */
    int nseg,			/* number of segment we want to write to */
    int *pnsegMax)		/* size (in segments) of list so far */
{
    if (nseg > *pnsegMax)
    {
	miDashPtr newppseg;

	*pnsegMax += NSEGDELTA;
	newppseg = (miDashPtr)xrealloc(*ppseg,
				       (*pnsegMax)*sizeof(miDashRec));
	if (!newppseg)
	{
	    xfree(*ppseg);
	    return (miDashPtr)NULL;
	}
	*ppseg = newppseg;
    }
    return(*ppseg+(nseg-1));
}

_X_EXPORT void
miStepDash (dist, pDashIndex, pDash, numInDashList, pDashOffset)
    int dist;			/* distance to step */
    int *pDashIndex;		/* current dash */
    unsigned char *pDash;	/* dash list */
    int numInDashList;		/* total length of dash list */
    int *pDashOffset;		/* offset into current dash */
{
    int	dashIndex, dashOffset;
    int totallen;
    int	i;

    dashIndex = *pDashIndex;
    dashOffset = *pDashOffset;
    if (dist < pDash[dashIndex] - dashOffset)
    {
	*pDashOffset = dashOffset + dist;
	return;
    }
    dist -= pDash[dashIndex] - dashOffset;
    if (++dashIndex == numInDashList)
	dashIndex = 0;
    totallen = 0;
    for (i = 0; i < numInDashList; i++)
	totallen += pDash[i];
    if (totallen <= dist)
	dist = dist % totallen;
    while (dist >= pDash[dashIndex])
    {
	dist -= pDash[dashIndex];
	if (++dashIndex == numInDashList)
	    dashIndex = 0;
    }
    *pDashIndex = dashIndex;
    *pDashOffset = dist;
}