+//extern tap_transition_t tap_transitions[16]; /* describe the TAP state diagram */
+
+
+/*-----<Cable Helper API>-------------------------------------------*/
+
+/* The "Cable Helper API" is what the cable drivers can use to help implement
+ * their "Cable API". So a Cable Helper API is a set of helper functions used by
+ * cable drivers, and this is different from a Cable API. A "Cable API" is what
+ * higher level code used to talk to a cable.
+ */
+
+
+/** implementation of wrapper function tap_set_state() */
+void tap_set_state_impl(tap_state_t new_state);
+
+/**
+ * Function tap_set_state
+ * sets the state of a "state follower" which tracks the state of the TAPs connected to the
+ * cable. The state follower is hopefully always in the same state as the actual
+ * TAPs in the jtag chain, and will be so if there are no bugs in the tracking logic within that
+ * cable driver. All the cable drivers call this function to indicate the state they think
+ * the TAPs attached to their cables are in. Because this function can also log transitions,
+ * it will be helpful to call this function with every transition that the TAPs being manipulated
+ * are expected to traverse, not just end points of a multi-step state path.
+ * @param new_state is the state we think the TAPs are currently in or are about to enter.
+ */
+#if defined(_DEBUG_JTAG_IO_)
+#define tap_set_state(new_state) \
+ do { \
+ LOG_DEBUG( "tap_set_state(%s)", tap_state_name(new_state) ); \
+ tap_set_state_impl(new_state); \
+ } while (0)
+#else
+static inline void tap_set_state(tap_state_t new_state)
+{
+ tap_set_state_impl(new_state);
+}
+
+#endif
+
+/**
+ * Function tap_get_state
+ * gets the state of the "state follower" which tracks the state of the TAPs connected to
+ * the cable.
+ * @see tap_set_state
+ * @return tap_state_t - The state the TAPs are in now.
+ */
+tap_state_t tap_get_state(void);
+
+/**
+ * Function tap_set_end_state
+ * sets the state of an "end state follower" which tracks the state that any cable driver
+ * thinks will be the end (resultant) state of the current TAP SIR or SDR operation. At completion
+ * of that TAP operation this value is copied into the state follower via tap_set_state().
+ * @param new_end_state is that state the TAPs should enter at completion of a pending TAP operation.
+ */
+void tap_set_end_state(tap_state_t new_end_state);
+
+/**
+ * Function tap_get_end_state
+ * @see tap_set_end_state
+ * @return tap_state_t - The state the TAPs should be in at completion of the current TAP operation.
+ */
+tap_state_t tap_get_end_state(void);
+
+/**
+ * Function tap_get_tms_path
+ * returns a 7 bit long "bit sequence" indicating what has to be done with TMS
+ * during a sequence of seven TAP clock cycles in order to get from
+ * state \a "from" to state \a "to".
+ * @param from is the starting state
+ * @param to is the resultant or final state
+ * @return int - a 7 bit sequence, with the first bit in the sequence at bit 0.
+ */
+int tap_get_tms_path(tap_state_t from, tap_state_t to);
+
+
+/**
+ * Function int tap_get_tms_path_len
+ * returns the total number of bits that represents a TMS path
+ * transition as given by the function tap_get_tms_path().
+ *
+ * For at least one interface (JLink) it's not OK to simply "pad" TMS sequences
+ * to fit a whole byte. (I suspect this is a general TAP problem within OOCD.)
+ * Padding TMS causes all manner of instability that's not easily
+ * discovered. Using this routine we can apply EXACTLY the state transitions
+ * required to make something work - no more - no less.
+ *
+ * @param from is the starting state
+ * @param to is the resultant or final state
+ * @return int - the total number of bits in a transition.
+ */
+int tap_get_tms_path_len(tap_state_t from, tap_state_t to);
+
+
+/**
+ * Function tap_move_ndx
+ * when given a stable state, returns an index from 0-5. The index corresponds to a
+ * sequence of stable states which are given in this order: <p>
+ * { TAP_RESET, TAP_IDLE, TAP_DRSHIFT, TAP_DRPAUSE, TAP_IRSHIFT, TAP_IRPAUSE }
+ * <p>
+ * This sequence corresponds to look up tables which are used in some of the
+ * cable drivers.
+ * @param astate is the stable state to find in the sequence. If a non stable
+ * state is passed, this may cause the program to output an error message
+ * and terminate.
+ * @return int - the array (or sequence) index as described above
+ */
+int tap_move_ndx(tap_state_t astate);