- Added HD44780 incremental LCD update.

- Minor fix to 4bit.

server/drivers/hd44780-4bit.c

@@ -117,9 +117,9 @@ hd_init_4bit (HD44780_functions * hd44780_functions, lcd_logical_driver * driver
 		enableLines |= EN3;
 		port_out (lptPort + 2, 0 ^ OUTMASK);
 	}
-
 	port_out (lptPort, 0x03);
 	if( delayBus ) hd44780_functions->uPause (1);
+
 	port_out (lptPort, enableLines | 0x03);
 	if (extIF)
 		port_out (lptPort + 2, ALLEXT ^ OUTMASK);
@@ -148,6 +148,9 @@ hd_init_4bit (HD44780_functions * hd44780_functions, lcd_logical_driver * driver
 	hd44780_functions->uPause (40);
 
 	// now in 8-bit mode...  set 4-bit mode
+	port_out (lptPort, 0x02);
+	if( delayBus ) hd44780_functions->uPause (1);
+
 	port_out (lptPort, enableLines | 0x02);
 	if (extIF)
 		port_out (lptPort + 2, ALLEXT ^ OUTMASK);
@@ -157,6 +160,10 @@ hd_init_4bit (HD44780_functions * hd44780_functions, lcd_logical_driver * driver
 		port_out (lptPort + 2, 0 ^ OUTMASK);
 	hd44780_functions->uPause (40);
 
+	// Set up two-line, small character (5x8) mode
+	hd44780_functions->senddata (0, RS_INSTR, FUNCSET | TWOLINE | SMALLCHAR );
+	hd44780_functions->uPause (40);
+
 	common_init ();
 
 	if (have_keypad) {

server/drivers/hd44780.c

@@ -151,6 +151,9 @@ static char pressed_key = 0;
 static int pressed_key_repetitions = 0;
 static struct timeval pressed_key_time;
 
+// for incremental updates store last lcd contents
+static char * lcd_contents = (char *) 0;
+
 // function declarations
 void HD44780_close ();
 void HD44780_flush ();
@@ -272,6 +275,15 @@ HD44780_init (lcd_logical_driver * driver, char *args)
 		//HD44780_close();
 		return -1;
 	}
+
+	// Allocate and clear the buffer for incremental updates
+	lcd_contents = (unsigned char *) malloc (HD44780->wid * HD44780->hgt);
+	if (!lcd_contents) {
+		return -1;
+	}
+	memset(lcd_contents, ' ', HD44780->wid * HD44780->hgt);
+
+
 	// Set the functions the driver supports...
 	// These are the default HD44780 functions
 	driver->init = HD44780_init;
@@ -384,6 +396,8 @@ uPause (int usecs)
 //
 void HD44780_close()
 {
+	free( HD44780->framebuf );
+	free( lcd_contents );
 }
 
 /////////////////////////////////////////////////////////////////
@@ -813,21 +827,30 @@ void
 HD44780_draw_frame (char *dat)
 {
 	int x, y;
+	int wid = HD44780->wid;
+	char drawing;
 
 	if (!dat)
 		return;
 
+	// Update LCD incrementally by comparing with last contents
 	for (y=0; y<HD44780->hgt; y++) {
-		//printf("\n%d :",y);
+		drawing = 0;
-		for (x = 0; x < HD44780->wid; x++) {
+		for (x=0 ; x<wid; x++) {
-
+			if( dat[(y*wid)+x] != lcd_contents[(y*wid)+x] ) {
-			if( x % 8 == 0 )
+				if( !drawing || x % 8 == 0 ) { // x%8 for 16x1 displays
+					drawing = 1;
 					HD44780_position(x,y);
-			hd44780_functions->senddata (spanList[y], RS_DATA, HD44780_charmap[(unsigned char)dat[(y * HD44780->wid) + x]]);
+				}
+				hd44780_functions->senddata( spanList[y], RS_DATA, HD44780_charmap[(unsigned char)dat[(y * wid) + x]]);
 				hd44780_functions->uPause (40);  // Minimum exec time for all commands
+				lcd_contents[(y*wid)+x] = dat[(y*wid)+x];
+			}
+			else {
+				drawing = 0;
+			}
 		}
 	}
-
 }
 
 /////////////////////////////////////////////////////////////