Dick Hollenbeck <dick@softplc.com> - This patch adds JTAG state tracking to dummy.c

git-svn-id: svn://svn.berlios.de/openocd/trunk@1263 b42882b7-edfa-0310-969c-e2dbd0fdcd60

1 files changed, 129 insertions, 0 deletions

diff --git a/src/jtag/dummy.c b/src/jtag/dummy.c
index f6ca87c2..a3a0a1aa 100644
--- a/src/jtag/dummy.c
+++ b/src/jtag/dummy.c
@@ -26,6 +26,15 @@
 #include "jtag.h"

 #include "bitbang.h"

 

+

+/* my private tap controller state, which tracks state for calling code */

+static tap_state_t dummy_state = TAP_RESET;

+

+static int dummy_clock;         /* edge detector */

+

+static tap_state_t tap_state_transition(tap_state_t cur_state, int tms);

+

+

 int dummy_speed(int speed);

 int dummy_register_commands(struct command_context_s *cmd_ctx);

 int dummy_init(void);

@@ -70,12 +79,28 @@ int dummy_read(void)
 	return 1;

 }

 

+

 void dummy_write(int tck, int tms, int tdi)

 {

+	/* TAP standard: "state transitions occur on rising edge of clock" */

+	if( tck != dummy_clock )

+	{

+		if( tck )

+		{

+			int old_state = dummy_state;

+			dummy_state = tap_state_transition( dummy_state, tms );

+			if( old_state != dummy_state )

+				LOG_INFO( "dummy_tap=%s", jtag_state_name(dummy_state) );

+		}

+		dummy_clock = tck;

+	}

 }

 

 void dummy_reset(int trst, int srst)

 {

+	dummy_clock = 0;

+	dummy_state = TAP_RESET;

+	LOG_DEBUG( "reset to %s", jtag_state_name(dummy_state) );

 }

 

 static int dummy_khz(int khz, int *jtag_speed)

@@ -130,3 +155,107 @@ int dummy_quit(void)
 void dummy_led(int on)

 {

 }

+

+

+/**

+ * Function tap_state_transition

+ * takes a current TAP state and returns the next state according to the tms value.

+ *

+ * Even though there is code to duplicate this elsewhere, we do it here a little

+ * differently just to get a second opinion, i.e. a verification, on state tracking

+ * in that other logic. Plus array lookups without index checking are no favorite thing.

+ * This is educational for developers new to TAP controllers.

+ */

+static tap_state_t tap_state_transition(tap_state_t cur_state, int tms)

+{

+	tap_state_t new_state;

+

+	if (tms)

+	{

+		switch (cur_state)

+		{

+		case TAP_RESET:

+			new_state = cur_state;

+			break;

+		case TAP_IDLE:

+		case TAP_DRUPDATE:

+		case TAP_IRUPDATE:

+			new_state = TAP_DRSELECT;

+			break;

+		case TAP_DRSELECT:

+			new_state = TAP_IRSELECT;

+			break;

+		case TAP_DRCAPTURE:

+		case TAP_DRSHIFT:

+			new_state = TAP_DREXIT1;

+			break;

+		case TAP_DREXIT1:

+		case TAP_DREXIT2:

+			new_state = TAP_DRUPDATE;

+			break;

+		case TAP_DRPAUSE:

+			new_state = TAP_DREXIT2;

+			break;

+		case TAP_IRSELECT:

+			new_state = TAP_RESET;

+			break;

+		case TAP_IRCAPTURE:

+		case TAP_IRSHIFT:

+			new_state = TAP_IREXIT1;

+			break;

+		case TAP_IREXIT1:

+		case TAP_IREXIT2:

+			new_state = TAP_IRUPDATE;

+			break;

+		case TAP_IRPAUSE:

+			new_state = TAP_IREXIT2;

+			break;

+		default:

+			LOG_ERROR( "fatal: invalid argument cur_state=%d", cur_state );

+			exit(1);

+			break;

+		}

+	}

+	else

+	{

+		switch (cur_state)

+		{

+		case TAP_RESET:

+		case TAP_IDLE:

+		case TAP_DRUPDATE:

+		case TAP_IRUPDATE:

+			new_state = TAP_IDLE;

+			break;

+		case TAP_DRSELECT:

+			new_state = TAP_DRCAPTURE;

+			break;

+		case TAP_DRCAPTURE:

+		case TAP_DRSHIFT:

+		case TAP_DREXIT2:

+			new_state = TAP_DRSHIFT;

+			break;

+		case TAP_DREXIT1:

+		case TAP_DRPAUSE:

+			new_state = TAP_DRPAUSE;

+			break;

+		case TAP_IRSELECT:

+			new_state = TAP_IRCAPTURE;

+			break;

+		case TAP_IRCAPTURE:

+		case TAP_IRSHIFT:

+		case TAP_IREXIT2:

+			new_state = TAP_IRSHIFT;

+			break;

+		case TAP_IREXIT1:

+		case TAP_IRPAUSE:

+			new_state = TAP_IRPAUSE;

+			break;

+		default:

+			LOG_ERROR( "fatal: invalid argument cur_state=%d", cur_state );

+			exit(1);

+			break;

+		}

+	}

+

+	return new_state;

+}