--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ueda/libuschem/graphblocks.c	Mon Jul 20 00:24:37 2015 +0000
@@ -0,0 +1,40 @@
+/*
+ * utility functions for working with graphical blocks
+ */
+
+#include <sys/param.h>
+#include <stdio.h>
+#include "schemstruct.h"
+
+FILE *
+reopen_schem_for_graphblocks(schem)
+	struct schem *schem;
+{
+	register FILE *f;
+
+	if (!schem->has_graphblocks)
+		return(NULL);
+	f = fopen(schem->orig_filename, "r");
+	if (!f) {
+		fprintf(stderr, "Unable to reopen %s for graphblocks: ",
+			schem->orig_filename);
+		perror(NULL);
+		exit(1);
+	}
+	return(f);
+}
+
+write_graphblock_to_file(blk, inf, outf)
+	struct graphblock *blk;
+	register FILE *inf, *outf;
+{
+	char buf[512];
+	register int cc, rem;
+
+	fseek(inf, blk->offset, 0);
+	for (rem = blk->length; rem; rem -= cc) {
+		cc = MIN(rem, sizeof buf);
+		fread(buf, 1, cc, inf);
+		fwrite(buf, 1, cc, outf);
+	}
+}