# HG changeset patch
# User Thinker K.F. Li <thinker@branda.to>
# Date 1235282150 -28800
# Node ID eb14cac68cbbed67701bfd5b9a145d793de6dbab
# Parent  6b1594fb668f35e81addcb5a4b36faba465758ec
Transite TAP controller to shift state.
- shift commands will transite state machine of TAP controller to
  shift state before starting shifting.

diff -r 6b1594fb668f -r eb14cac68cbb src/jtag.c
--- a/src/jtag.c	Sun Feb 22 12:54:45 2009 +0800
+++ b/src/jtag.c	Sun Feb 22 13:55:50 2009 +0800
@@ -30,6 +30,11 @@
     } while(0)
 #define GET_TDO() (JTAG_PIN & _BV(JTAG_TDO))
 
+/*!
+ * Before shifting registers, TAP controller must move to last state before
+ * shift state.  The state machine transite to shift state when shifting
+ * starts.
+ */
 void jtag_tms(char *buf, int nbits) {
     int i;
     int nbytes, byte;
@@ -88,6 +93,11 @@
     int byteoff, bitoff;
     int bit;
     
+    /* Transite to shift state.
+     * \sa jtag_tms()
+     */
+    pin_lo(JTAG_PORT, JTAG_TMS);
+
     nbytes = nbits / 8;
     for(i = 0; i < nbytes; i++) {
 	byte = buf[i];
@@ -143,6 +153,11 @@
     int byteoff, bitoff;
     int bit;
     
+    /* Transite to shift state.
+     * \sa jtag_tms()
+     */
+    pin_lo(JTAG_PORT, JTAG_TMS);
+
     nbytes = nbits / 8;
     for(i = 0; i < nbytes; i++) {
 	byte = ibuf[i];