From 51b98461202a3aedb9cbc8ea6fab95a140770e78 Mon Sep 17 00:00:00 2001
From: "R. Timothy Edwards" <tim@opencircuitdesign.com>
Date: Thu, 30 Oct 2025 12:07:29 -0400
Subject: [PATCH] Made a correction to the DRC error checking on a
 non-Manhattan edge.  This was catching geometry unrelated to the error when
 doing a spacing check between geometry on different planes.  In the
 reverse-edge case, magic needed to run an additional search over the area on
 the other side of the original edge that triggered the rule to effectively
 clip that corner of the triangle from the search area.

---
 VERSION        |  2 +-
 drc/DRCbasic.c | 88 +++++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 88 insertions(+), 2 deletions(-)

diff --git a/VERSION b/VERSION
index 970db810..d671d5db 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-8.3.570
+8.3.571
diff --git a/drc/DRCbasic.c b/drc/DRCbasic.c
index 3c2afed8..755cb08a 100644
--- a/drc/DRCbasic.c
+++ b/drc/DRCbasic.c
@@ -36,6 +36,7 @@ static char rcsid[] __attribute__ ((unused)) = "$Header: /usr/cvsroot/magic-8.0/
 #include "utils/signals.h"
 #include "utils/maxrect.h"
 #include "utils/malloc.h"
+#include "textio/textio.h"
 
 int dbDRCDebug = 0;
 
@@ -284,12 +285,53 @@ areaCheck(tile, arg)
     return 0;
 }
 
+/*
+ * ----------------------------------------------------------------------------
+ *
+ * areaNMReject ---
+ *
+ *	Trivial callback function used by areaNMCheck to see if a tile
+ *	found in the error area of a reverse non-manhattan check exists
+ *	only on the other side of the original check boundary.  If it
+ *	is found in this search, return 1 to immediately stop the search.
+ *
+ * Results:
+ *	Returns 1 if the tile indicated in the ClientData argument was
+ *	found in the check area, otherwise return 0 to keep looking.
+ *
+ * Side effects:
+ *	None.
+ *
+ * ----------------------------------------------------------------------------
+ */
+
+int
+areaNMReject(tile, arg)
+    Tile *tile;
+    ClientData *arg;
+{
+    Tile *checktile = (Tile *)arg;
+
+    if (tile == checktile)
+	return 1;
+
+    return 0;
+}
+
 /*
  * ----------------------------------------------------------------------------
  *
  * areaNMCheck ---
  *
- *  Check for errors in triangular area of a tile
+ *	Check for errors in triangular area of a tile.
+ *
+ * Results:
+ *	Return 0 always to keep the search going.
+ *
+ * Side effects:
+ *	If the tile is not rejected due to being outside of the various
+ *	clip areas, then call the function specified in the drcClientData
+ *	argument.	
  *
  * ----------------------------------------------------------------------------
  */
@@ -320,6 +362,26 @@ areaNMCheck(tile, arg)
     if ((rect.r_xbot >= rect.r_xtop) || (rect.r_ybot >= rect.r_ytop))
 	return 0;
 
+    if (arg->dCD_entries & TT_DIAGONAL)
+    {
+	TileTypeBitMask mask;
+	int dinfo = arg->dCD_entries;
+
+	/* In the DRC_REVERSE case, the area being searched extends
+	 * behind the edge that triggered the DRC check, but any
+	 * tile that is outside that edge should be ignored.  This
+	 * requires a separate check.
+	 */
+
+	TTMaskSetOnlyType(&mask, TiGetLeftType(tile));
+	TTMaskSetType(&mask, TiGetRightType(tile));
+	if (DBSrPaintNMArea((Tile *)tile,
+		arg->dCD_celldef->cd_planes[arg->dCD_plane],
+		dinfo, arg->dCD_rlist,
+		&mask, areaNMReject, (ClientData)tile) == 0)
+	    return 0;
+    }
+
     (*(arg->dCD_function))(arg->dCD_celldef, &rect, arg->dCD_cptr,
 			arg->dCD_clientData);
     (*(arg->dCD_errors))++;
@@ -555,6 +617,23 @@ drcTile (tile, arg)
 		/* Split side changes in the reverse case */
 		dinfo |= TT_SIDE;
 	    }
+	    else
+	    {
+		/* The area to check is bounded between the diagonals of
+		 * tile and errRect (which is the tile area, offset).
+		 * Pass errRect and dinfo to areaNMCheck using the
+		 * ClientData structure arg->dCD_rlist and arg->dCD_entries,
+		 * which are not used by areaNMCheck.  This is only needed
+		 * for the DRC_REVERSE case.
+		 */
+		arg->dCD_rlist = (Rect *)mallocMagic(sizeof(Rect));
+		*(arg->dCD_rlist) = errRect;
+		arg->dCD_entries = dinfo;
+		if (dinfo & TT_SIDE)
+		    arg->dCD_entries &= ~TT_SIDE;
+		else
+		    arg->dCD_entries |= TT_SIDE;
+	    }
 
 	    /* errRect is the tile area offset by (deltax, deltay) */
 	    errRect.r_xbot += deltax;
@@ -565,6 +644,13 @@ drcTile (tile, arg)
 	    DBSrPaintNMArea((Tile *) NULL,
 			arg->dCD_celldef->cd_planes[cptr->drcc_plane], dinfo,
 			&errRect, &tmpMask, areaNMCheck, (ClientData) arg);
+
+	    if (cptr->drcc_flags & DRC_REVERSE)
+	    {
+		arg->dCD_entries = 0;
+		freeMagic(arg->dCD_rlist);
+		arg->dCD_rlist = (Rect *)NULL;
+	    }
 	}
 	DRCstatEdges++;
     }