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diff --git a/mfb/mfbzerarc.c b/mfb/mfbzerarc.c
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+/************************************************************
+
+Copyright 1989, 1998 The Open Group
+
+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.
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+Except as contained in this notice, the name of The Open Group shall not be
+used in advertising or otherwise to promote the sale, use or other dealings
+in this Software without prior written authorization from The Open Group.
+
+********************************************************/
+
+/* $Xorg: mfbzerarc.c,v 1.4 2001/02/09 02:05:19 xorgcvs Exp $ */
+
+/* Derived from:
+ * "Algorithm for drawing ellipses or hyperbolae with a digital plotter"
+ * by M. L. V. Pitteway
+ * The Computer Journal, November 1967, Volume 10, Number 3, pp. 282-289
+ */
+
+#include "X.h"
+#include "Xprotostr.h"
+#include "miscstruct.h"
+#include "gcstruct.h"
+#include "pixmapstr.h"
+#include "scrnintstr.h"
+#include "mfb.h"
+#include "maskbits.h"
+#include "mizerarc.h"
+#include "mi.h"
+
+/*
+ * Note: LEFTMOST must be the bit leftmost in the actual screen
+ * representation. This depends also on the IMAGE_BYTE_ORDER.
+ * LONG2CHARS() takes care of the re-ordering as required. (DHD)
+ */
+#if (BITMAP_BIT_ORDER == MSBFirst)
+#define LEFTMOST ((PixelType) LONG2CHARS((1 << PLST)))
+#else
+#define LEFTMOST ((PixelType) LONG2CHARS(1))
+#endif
+
+#define PixelateWhite(addr,yoff,xoff) \
+ *mfbScanlineOffset(addr, (yoff)+((xoff)>>PWSH)) |= \
+ SCRRIGHT (LEFTMOST, ((xoff) & PIM))
+#define PixelateBlack(addr,yoff,xoff) \
+ *mfbScanlineOffset(addr, (yoff)+((xoff)>>PWSH)) &= \
+ ~(SCRRIGHT (LEFTMOST, ((xoff) & PIM)))
+
+#define Pixelate(base,yoff,xoff) \
+{ \
+ paddr = mfbScanlineOffset(base, (yoff) + ((xoff)>>PWSH)); \
+ pmask = SCRRIGHT(LEFTMOST, (xoff) & PIM); \
+ *paddr = (*paddr & ~pmask) | (pixel & pmask); \
+}
+
+#define DoPix(bit,base,yoff,xoff) if (mask & bit) Pixelate(base,yoff,xoff);
+
+static void
+mfbZeroArcSS(pDraw, pGC, arc)
+ DrawablePtr pDraw;
+ GCPtr pGC;
+ xArc *arc;
+{
+ miZeroArcRec info;
+ Bool do360;
+ register int x, y, a, b, d, mask;
+ register int k1, k3, dx, dy;
+ PixelType *addrl;
+ PixelType *yorgl, *yorgol;
+ PixelType pixel;
+ int nlwidth, yoffset, dyoffset;
+ PixelType pmask;
+ register PixelType *paddr;
+
+ if (((mfbPrivGC *)(pGC->devPrivates[mfbGCPrivateIndex].ptr))->rop ==
+ RROP_BLACK)
+ pixel = 0;
+ else
+ pixel = ~0;
+
+ mfbGetPixelWidthAndPointer(pDraw, nlwidth, addrl);
+ do360 = miZeroArcSetup(arc, &info, TRUE);
+ yorgl = addrl + ((info.yorg + pDraw->y) * nlwidth);
+ yorgol = addrl + ((info.yorgo + pDraw->y) * nlwidth);
+ info.xorg += pDraw->x;
+ info.xorgo += pDraw->x;
+ MIARCSETUP();
+ yoffset = y ? nlwidth : 0;
+ dyoffset = 0;
+ mask = info.initialMask;
+ if (!(arc->width & 1))
+ {
+ DoPix(2, yorgl, 0, info.xorgo);
+ DoPix(8, yorgol, 0, info.xorgo);
+ }
+ if (!info.end.x || !info.end.y)
+ {
+ mask = info.end.mask;
+ info.end = info.altend;
+ }
+ if (do360 && (arc->width == arc->height) && !(arc->width & 1))
+ {
+ int xoffset = nlwidth;
+ PixelType *yorghl = mfbScanlineDeltaNoBankSwitch(yorgl, info.h, nlwidth);
+ int xorghp = info.xorg + info.h;
+ int xorghn = info.xorg - info.h;
+
+ if (pixel)
+ {
+ while (1)
+ {
+ PixelateWhite(yorgl, yoffset, info.xorg + x);
+ PixelateWhite(yorgl, yoffset, info.xorg - x);
+ PixelateWhite(yorgol, -yoffset, info.xorg - x);
+ PixelateWhite(yorgol, -yoffset, info.xorg + x);
+ if (a < 0)
+ break;
+ PixelateWhite(yorghl, -xoffset, xorghp - y);
+ PixelateWhite(yorghl, -xoffset, xorghn + y);
+ PixelateWhite(yorghl, xoffset, xorghn + y);
+ PixelateWhite(yorghl, xoffset, xorghp - y);
+ xoffset += nlwidth;
+ MIARCCIRCLESTEP(yoffset += nlwidth;);
+ }
+ }
+ else
+ {
+ while (1)
+ {
+ PixelateBlack(yorgl, yoffset, info.xorg + x);
+ PixelateBlack(yorgl, yoffset, info.xorg - x);
+ PixelateBlack(yorgol, -yoffset, info.xorg - x);
+ PixelateBlack(yorgol, -yoffset, info.xorg + x);
+ if (a < 0)
+ break;
+ PixelateBlack(yorghl, -xoffset, xorghp - y);
+ PixelateBlack(yorghl, -xoffset, xorghn + y);
+ PixelateBlack(yorghl, xoffset, xorghn + y);
+ PixelateBlack(yorghl, xoffset, xorghp - y);
+ xoffset += nlwidth;
+ MIARCCIRCLESTEP(yoffset += nlwidth;);
+ }
+ }
+ x = info.w;
+ yoffset = info.h * nlwidth;
+ }
+ else if (do360)
+ {
+ while (y < info.h || x < info.w)
+ {
+ MIARCOCTANTSHIFT(dyoffset = nlwidth;);
+ Pixelate(yorgl, yoffset, info.xorg + x);
+ Pixelate(yorgl, yoffset, info.xorgo - x);
+ Pixelate(yorgol, -yoffset, info.xorgo - x);
+ Pixelate(yorgol, -yoffset, info.xorg + x);
+ MIARCSTEP(yoffset += dyoffset;, yoffset += nlwidth;);
+ }
+ }
+ else
+ {
+ while (y < info.h || x < info.w)
+ {
+ MIARCOCTANTSHIFT(dyoffset = nlwidth;);
+ if ((x == info.start.x) || (y == info.start.y))
+ {
+ mask = info.start.mask;
+ info.start = info.altstart;
+ }
+ DoPix(1, yorgl, yoffset, info.xorg + x);
+ DoPix(2, yorgl, yoffset, info.xorgo - x);
+ DoPix(4, yorgol, -yoffset, info.xorgo - x);
+ DoPix(8, yorgol, -yoffset, info.xorg + x);
+ if ((x == info.end.x) || (y == info.end.y))
+ {
+ mask = info.end.mask;
+ info.end = info.altend;
+ }
+ MIARCSTEP(yoffset += dyoffset;, yoffset += nlwidth;);
+ }
+ }
+ if ((x == info.start.x) || (y == info.start.y))
+ mask = info.start.mask;
+ DoPix(1, yorgl, yoffset, info.xorg + x);
+ DoPix(4, yorgol, -yoffset, info.xorgo - x);
+ if (arc->height & 1)
+ {
+ DoPix(2, yorgl, yoffset, info.xorgo - x);
+ DoPix(8, yorgol, -yoffset, info.xorg + x);
+ }
+}
+
+void
+mfbZeroPolyArcSS(pDraw, pGC, narcs, parcs)
+ DrawablePtr pDraw;
+ GCPtr pGC;
+ int narcs;
+ xArc *parcs;
+{
+ register xArc *arc;
+ register int i;
+ BoxRec box;
+ int x2, y2;
+ RegionPtr cclip;
+
+ if (!pGC->planemask & 1)
+ return;
+ cclip = ((mfbPrivGC *)(pGC->devPrivates[mfbGCPrivateIndex].ptr))->pCompositeClip;
+ for (arc = parcs, i = narcs; --i >= 0; arc++)
+ {
+ if (miCanZeroArc(arc))
+ {
+ box.x1 = arc->x + pDraw->x;
+ box.y1 = arc->y + pDraw->y;
+ /*
+ * Because box.x2 and box.y2 get truncated to 16 bits, and the
+ * RECT_IN_REGION test treats the resulting number as a signed
+ * integer, the RECT_IN_REGION test alone can go the wrong way.
+ * This can result in a server crash because the rendering
+ * routines in this file deal directly with cpu addresses
+ * of pixels to be stored, and do not clip or otherwise check
+ * that all such addresses are within their respective pixmaps.
+ * So we only allow the RECT_IN_REGION test to be used for
+ * values that can be expressed correctly in a signed short.
+ */
+ x2 = box.x1 + (int)arc->width + 1;
+ box.x2 = x2;
+ y2 = box.y1 + (int)arc->height + 1;
+ box.y2 = y2;
+ if ( (x2 <= MAXSHORT) && (y2 <= MAXSHORT) &&
+ (RECT_IN_REGION(pDraw->pScreen, cclip, &box) == rgnIN) )
+ mfbZeroArcSS(pDraw, pGC, arc);
+ else
+ miZeroPolyArc(pDraw, pGC, 1, arc);
+ }
+ else
+ miPolyArc(pDraw, pGC, 1, arc);
+ }
+}
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