added jtag_add_statemove() helper fn(actual fn written by Dick Hollonbeck, I just...

[openocd.git] / src / jtag / jtag.c

diff --git a/src/jtag/jtag.c b/src/jtag/jtag.c
index c9167f41aec523696aaa0e831e19c7b1ad4688c7..4ed08971a47ae91737e8ddce79e60c84ddfc99e7 100644 (file)
--- a/src/jtag/jtag.c
+++ b/src/jtag/jtag.c
@@ -3719,3 +3719,90 @@ static int handle_tms_sequence_command(struct command_context_s *cmd_ctx, char *
 }
 
 /*-----</Cable Helper API>--------------------------------------*/
+
+
+/**
+ * Function jtag_add_statemove
+ * moves from the current state to the goal \a state. This needs
+ * to be handled according to the xsvf spec, see the XSTATE command
+ * description.
+ */
+int jtag_add_statemove(tap_state_t goal_state)
+{
+       int retval = ERROR_OK;
+
+       tap_state_t moves[8];
+       tap_state_t cur_state = cmd_queue_cur_state;
+       int i;
+       int tms_bits;
+       int     tms_count;
+
+       LOG_DEBUG( "cur_state=%s goal_state=%s",
+               tap_state_name(cur_state),
+               tap_state_name(goal_state) );
+
+
+       /*      From the XSVF spec, pertaining to XSTATE:
+
+               For special states known as stable states (Test-Logic-Reset,
+               Run-Test/Idle, Pause-DR, Pause- IR), an XSVF interpreter follows
+               predefined TAP state paths when the starting state is a stable state and
+               when the XSTATE specifies a new stable state (see the STATE command in
+               the [Ref 5] for the TAP state paths between stable states). For
+               non-stable states, XSTATE should specify a state that is only one TAP
+               state transition distance from the current TAP state to avoid undefined
+               TAP state paths. A sequence of multiple XSTATE commands can be issued to
+               transition the TAP through a specific state path.
+       */
+
+       if (goal_state==cur_state )
+               ;       /* nothing to do */
+
+       else if( goal_state==TAP_RESET )
+       {
+               jtag_add_tlr();
+       }
+
+       else if( tap_is_state_stable(cur_state) && tap_is_state_stable(goal_state) )
+       {
+               /*      note: unless tms_bits holds a path that agrees with [Ref 5] in above
+                       spec, then this code is not fully conformant to the xsvf spec.  This
+                       puts a burden on tap_get_tms_path() function from the xsvf spec.
+                       If in doubt, you should confirm that that burden is being met.
+               */
+
+               tms_bits  = tap_get_tms_path(cur_state, goal_state);
+               tms_count = tap_get_tms_path_len(cur_state, goal_state);
+
+               assert( (unsigned) tms_count < DIM(moves) );
+
+               for (i=0;   i<tms_count;   i++, tms_bits>>=1)
+               {
+                       bool bit = tms_bits & 1;
+
+                       cur_state = tap_state_transition(cur_state, bit);
+                       moves[i] = cur_state;
+               }
+
+               jtag_add_pathmove(tms_count, moves);
+       }
+
+       /*      else state must be immediately reachable in one clock cycle, and does not
+               need to be a stable state.
+       */
+       else if( tap_state_transition(cur_state, true)  == goal_state
+               ||   tap_state_transition(cur_state, false) == goal_state )
+       {
+               /* move a single state */
+               moves[0] = goal_state;
+               jtag_add_pathmove( 1, moves );
+       }
+
+       else
+       {
+               retval = ERROR_FAIL;
+       }
+
+       return retval;
+}
+