R6.6 is the Xorg base-line

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diff --git a/mi/miscanfill.h b/mi/miscanfill.h
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+/* $Xorg: miscanfill.h,v 1.4 2001/02/09 02:05:21 xorgcvs Exp $ */
+/*
+
+Copyright 1987, 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.
+
+*/
+
+
+#ifndef SCANFILLINCLUDED
+#define SCANFILLINCLUDED
+/*
+ *     scanfill.h
+ *
+ *     Written by Brian Kelleher; Jan 1985
+ *
+ *     This file contains a few macros to help track
+ *     the edge of a filled object.  The object is assumed
+ *     to be filled in scanline order, and thus the
+ *     algorithm used is an extension of Bresenham's line
+ *     drawing algorithm which assumes that y is always the
+ *     major axis.
+ *     Since these pieces of code are the same for any filled shape,
+ *     it is more convenient to gather the library in one
+ *     place, but since these pieces of code are also in
+ *     the inner loops of output primitives, procedure call
+ *     overhead is out of the question.
+ *     See the author for a derivation if needed.
+ */
+
+
+/*
+ *  In scan converting polygons, we want to choose those pixels
+ *  which are inside the polygon.  Thus, we add .5 to the starting
+ *  x coordinate for both left and right edges.  Now we choose the
+ *  first pixel which is inside the pgon for the left edge and the
+ *  first pixel which is outside the pgon for the right edge.
+ *  Draw the left pixel, but not the right.
+ *
+ *  How to add .5 to the starting x coordinate:
+ *      If the edge is moving to the right, then subtract dy from the
+ *  error term from the general form of the algorithm.
+ *      If the edge is moving to the left, then add dy to the error term.
+ *
+ *  The reason for the difference between edges moving to the left
+ *  and edges moving to the right is simple:  If an edge is moving
+ *  to the right, then we want the algorithm to flip immediately.
+ *  If it is moving to the left, then we don't want it to flip until
+ *  we traverse an entire pixel.
+ */
+#define BRESINITPGON(dy, x1, x2, xStart, d, m, m1, incr1, incr2) { \
+    int dx;      /* local storage */ \
+\
+    /* \
+     *  if the edge is horizontal, then it is ignored \
+     *  and assumed not to be processed.  Otherwise, do this stuff. \
+     */ \
+    if ((dy) != 0) { \
+        xStart = (x1); \
+        dx = (x2) - xStart; \
+        if (dx < 0) { \
+            m = dx / (dy); \
+            m1 = m - 1; \
+            incr1 = -2 * dx + 2 * (dy) * m1; \
+            incr2 = -2 * dx + 2 * (dy) * m; \
+            d = 2 * m * (dy) - 2 * dx - 2 * (dy); \
+        } else { \
+            m = dx / (dy); \
+            m1 = m + 1; \
+            incr1 = 2 * dx - 2 * (dy) * m1; \
+            incr2 = 2 * dx - 2 * (dy) * m; \
+            d = -2 * m * (dy) + 2 * dx; \
+        } \
+    } \
+}
+
+#define BRESINCRPGON(d, minval, m, m1, incr1, incr2) { \
+    if (m1 > 0) { \
+        if (d > 0) { \
+            minval += m1; \
+            d += incr1; \
+        } \
+        else { \
+            minval += m; \
+            d += incr2; \
+        } \
+    } else {\
+        if (d >= 0) { \
+            minval += m1; \
+            d += incr1; \
+        } \
+        else { \
+            minval += m; \
+            d += incr2; \
+        } \
+    } \
+}
+
+
+/*
+ *     This structure contains all of the information needed
+ *     to run the bresenham algorithm.
+ *     The variables may be hardcoded into the declarations
+ *     instead of using this structure to make use of
+ *     register declarations.
+ */
+typedef struct {
+    int minor;         /* minor axis        */
+    int d;           /* decision variable */
+    int m, m1;       /* slope and slope+1 */
+    int incr1, incr2; /* error increments */
+} BRESINFO;
+
+
+#define BRESINITPGONSTRUCT(dmaj, min1, min2, bres) \
+	BRESINITPGON(dmaj, min1, min2, bres.minor, bres.d, \
+                     bres.m, bres.m1, bres.incr1, bres.incr2)
+
+#define BRESINCRPGONSTRUCT(bres) \
+        BRESINCRPGON(bres.d, bres.minor, bres.m, bres.m1, bres.incr1, bres.incr2)
+
+
+#endif