usbblaster clock() rate improved, using byte shift mode

git-svn-id: https://urjtag.svn.sourceforge.net/svnroot/urjtag/trunk@1176 b68d4a1b-bc3d-0410-92ed-d4ac073336b7

jtag/ChangeLog

@@ -1,5 +1,7 @@
 2008-04-19  Kolja Waschk <kawk>
 
+   * src/tap/cable/usbblaster.c: clock() at highest possible rate
+     using the byte shift mode for n>=8 (Thanks M. Banditt)
    * include/cmd.h, src/cmd/cmd.c, src/jtag.c: [ 1946331 ] command
      completion support (by Mike Frysinger)
    * configure.ac, acinclude.m4: [ 1946114 ] make AC_PROG_SED

jtag/THANKS

@@ -5,6 +5,7 @@ or someone is missing who should be listed there!
 
 Shaju Abraham
 Beregnyei Balazs
+Michael Banditt
 Krzysztof Blaszkowski
 Eugene Boldenkov
 Uwe Bonnes
@@ -14,6 +15,7 @@ Ian Campbell
 Jeff Carr
 Alex (d18c7db)
 Jerome Debard
+Kris Dickie
 Alexander Didebulidze
 Rainer Dörken
 Andrew Dyer

jtag/src/tap/cable/usbblaster.c

@@ -63,14 +63,38 @@ usbblaster_init( cable_t *cable )
 static void
 usbblaster_clock( cable_t *cable, int tms, int tdi, int n )
 {
-	int i;
+	int i, m;
 
 	tms = tms ? (1<<TMS) : 0;
 	tdi = tdi ? (1<<TDI) : 0;
 
 	// printf("clock: %d %d %d\n", tms, tdi, n);
 
-	for (i = 0; i < n; i++) {
+	m = n;
+	if (tms == 0 && m >= 8)
+	{
+		unsigned char tdis = tdi ? 0xFF : 0;
+
+		parport_set_control( cable->link.port, 0 ); // noflush
+
+		while (m >= 8)
+		{
+			int i;
+			int chunkbytes = (m >> 3);
+			if(chunkbytes > 63) chunkbytes = 63;
+
+			parport_set_data( cable->link.port,(1<<SHMODE)|(0<<READ)|chunkbytes);
+
+			for (i=0; i<chunkbytes; i++)
+			{
+				parport_set_data( cable->link.port, tdis);
+			}
+
+			m -= (chunkbytes << 3);
+		}
+	}
+			
+	for (i = 0; i < m; i++) {
 		parport_set_data( cable->link.port, OTHERS | (0 << TCK) | tms | tdi );
 		parport_set_data( cable->link.port, OTHERS | (1 << TCK) | tms | tdi );
 		parport_set_control( cable->link.port, 1 ); // flush
@@ -189,7 +213,7 @@ usbblaster_transfer( cable_t *cable, int len, char *in, char *out )
 static void
 usbblaster_flush( cable_t *cable, cable_flush_amount_t how_much )
 {
-    if( how_much == OPTIONALLY ) return;
+	if( how_much == OPTIONALLY ) return;
 
 	while (cable->todo.num_items > 0)
 	{