8478bcb501f8c278278f63466d44501f3ca3f951
markd
  Tue Nov 28 01:37:05 2023 -0800
make frameIncr function available to other code

diff --git src/hg/inc/frame.h src/hg/inc/frame.h
new file mode 100644
index 0000000..92e2f04
--- /dev/null
+++ src/hg/inc/frame.h
@@ -0,0 +1,20 @@
+/* frame - frame increment and manipulation.  Static functions to inline */
+
+/* Copyright (C) 2006 The Regents of the University of California 
+ * See kent/LICENSE or http://genome.ucsc.edu/license/ for licensing information. */
+
+#ifndef FRAME_H
+#define FRAME_H
+/* Increment a frame by the specified amount, which maybe negative. frame
+ * of -1 always returns -1. */
+INLINE int frameIncr(int frame, int amt) {
+    if (frame < 0) {
+        return frame;  /* no frame not changed */
+    } else if (amt >= 0) {
+        return (frame + amt) % 3;
+    } else {
+        int amt3 = ((-amt)%3);
+        return (frame - (amt-amt3)) % 3;
+    }
+}
+#endif