display: Don't run (rather slow) scroll code in ISR

3 files changed, 24 insertions, 4 deletions

diff --git a/src/display.cc b/src/display.cc
index 42710c9..82c5020 100644
--- a/src/display.cc
+++ b/src/display.cc
@@ -37,8 +37,6 @@ void Display::enable()
 void Display::multiplex()
 {
 	static uint16_t scroll;
-	uint8_t i, glyph_len;
-	uint8_t *glyph_addr;
 
 	/*
 	 * To avoid flickering, do not put any code (or expensive index
@@ -53,6 +51,15 @@ void Display::multiplex()
 
 	if (++scroll == scroll_delay) {
 		scroll = 0;
+		need_scroll = 1;
+	}
+}
+
+void Display::scroll() {
+	uint8_t i, glyph_len;
+	uint8_t *glyph_addr;
+	if (need_scroll) {
+		need_scroll = 0;
 
 		for (i = 0; i < 7; i++) {
 			disp_buf[i] = disp_buf[i+1];
@@ -87,6 +94,11 @@ void Display::reset()
 	char_pos = -1;
 }
 
+void Display::setString(const char *new_str)
+{
+	setString((char *)new_str);
+}
+
 void Display::setString(char *new_str)
 {
 	reset();
diff --git a/src/display.h b/src/display.h
index f0ea0a4..0887f72 100644
--- a/src/display.h
+++ b/src/display.h
@@ -7,6 +7,7 @@
 class Display {
 	private:
 		uint16_t scroll_delay;
+		uint8_t need_scroll;
 		uint8_t active_col;
 		uint8_t disp_buf[8];
 		uint8_t str_pos;
@@ -18,6 +19,8 @@ class Display {
 		void disable(void);
 		void multiplex(void);
 		void reset(void);
+		void scroll(void);
+		void setString(const char *str);
 		void setString(char *str);
 };
 
diff --git a/src/main.cc b/src/main.cc
index aefad1c..78cbd88 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -31,9 +31,14 @@ int main (void)
 		// nothing to do here, go to idle to save power
 		SMCR = _BV(SE);
 		asm("sleep");
-		// The display timer causes a wakeup after 256µs. Run the system
-		// loop after the timer's ISR is done.
+		/*
+		 * The display timer causes a wakeup after 256µs. Run the system
+		 * loop after the timer's ISR is done.
+		 * The Modem also causes wakeups, which is pretty convenient since
+		 * it means we can immediately process the received data.
+		 */
 		rocket.loop();
+		display.scroll();
 	}
 
 	return 0;