Change semantics of image building in the layout code

If a layout file was specified, all regions not mentioned in the layout
file were taken from the new image instead of being preserved.
If regions overlap, the non-included regions won.

New behaviour:
If a layout file is specified, only the regions explicitly requested for
inclusion will be taken from the new image.
If regions overlap, the included regions win.

Corresponding to flashrom svn r1223.
Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
Acked-by: David Hendricks <dhendrix@google.com>

layout.c

@@ -22,6 +22,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <ctype.h>
+#include <limits.h>
 #include "flash.h"
 #include "programmer.h"
 
@@ -205,33 +206,62 @@ int find_romentry(char *name)
 	return -1;
 }
 
-int handle_romentries(struct flashchip *flash, uint8_t *oldcontents, uint8_t *newcontents)
+int find_next_included_romentry(unsigned int start)
 {
 	int i;
+	unsigned int best_start = UINT_MAX;
+	int best_entry = -1;
 
-	// This function does not save flash write cycles.
-	// 
-	// Also it does not cope with overlapping rom layout
-	// sections. 
-	// example:
-	// 00000000:00008fff gfxrom
-	// 00009000:0003ffff normal
-	// 00040000:0007ffff fallback
-	// 00000000:0007ffff all
-	//
-	// If you'd specify -i all the included flag of all other
-	// sections is still 0, so no changes will be made to the
-	// flash. Same thing if you specify -i normal -i all only 
-	// normal will be updated and the rest will be kept.
-
+	/* First come, first serve for overlapping regions. */
 	for (i = 0; i < romimages; i++) {
-		if (rom_entries[i].included)
+		if (!rom_entries[i].included)
 			continue;
-
-		memcpy(newcontents + rom_entries[i].start, 
-		       oldcontents + rom_entries[i].start,
-		       rom_entries[i].end - rom_entries[i].start + 1);
+		/* Already past the current entry? */
+		if (start > rom_entries[i].end)
+			continue;
+		/* Inside the current entry? */
+		if (start >= rom_entries[i].start)
+			return i;
+		/* Entry begins after start. */
+		if (best_start > rom_entries[i].start) {
+			best_start = rom_entries[i].start;
+			best_entry = i;
+		}
 	}
+	return best_entry;
+}
+
+int handle_romentries(struct flashchip *flash, uint8_t *oldcontents, uint8_t *newcontents)
+{
+	unsigned int start = 0;
+	int entry;
+	unsigned int size = flash->total_size * 1024;
 
+	/* If no layout file was specified or the layout file was empty, assume
+	 * that the user wants to flash the complete new image.
+	 */
+	if (!romimages)
+		return 0;
+	/* Non-included romentries are ignored.
+	 * The union of all included romentries is used from the new image.
+	 */
+	while (start < size) {
+		entry = find_next_included_romentry(start);
+		/* No more romentries for remaining region? */
+		if (entry < 0) {
+			memcpy(newcontents + start, oldcontents + start,
+			       size - start);
+			break;
+		}
+		if (rom_entries[entry].start > start)
+			memcpy(newcontents + start, oldcontents + start,
+			       rom_entries[entry].start - start);
+		/* Skip to location after current romentry. */
+		start = rom_entries[entry].end + 1;
+		/* Catch overflow. */
+		if (!start)
+			break;
+	}
+			
 	return 0;
 }