/* 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