X-Git-Url: https://review.openocd.org/gitweb?a=blobdiff_plain;ds=sidebyside;f=src%2Fjtag%2Fjtag.c;h=4ed08971a47ae91737e8ddce79e60c84ddfc99e7;hb=7662bbeaa5da95abc1be2ca5dc686825fbeafccc;hp=c9167f41aec523696aaa0e831e19c7b1ad4688c7;hpb=414245c9ce4ec112dc704664f56b268d27be3218;p=openocd.git

diff --git a/src/jtag/jtag.c b/src/jtag/jtag.c
index c9167f41ae..4ed08971a4 100644
--- 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;
+}
+