From 6966eb287f160c68c597105e60b191806a63b9ba Mon Sep 17 00:00:00 2001
From: David Lamparter <equinox@diac24.net>
Date: Sat, 22 Sep 2012 23:02:15 +0200
Subject: can: handle interrupt asynchronously

---
 can.c       | 22 ++++++++++++++--------
 door.c      |  4 ----
 lightctrl.c | 11 ++++-------
 3 files changed, 18 insertions(+), 19 deletions(-)

diff --git a/can.c b/can.c
index 6deff37..255cf14 100644
--- a/can.c
+++ b/can.c
@@ -24,13 +24,6 @@
 #ifndef R0KET
 #define spi_ss(x)	PORTB = ((x) << B_SS) | 0x3;
 
-static volatile bool canint = false;
-
-ISR(INT0_vect)
-{
-	canint = true;
-}
-
 static uint8_t spi_wrrd(uint8_t out)
 {
 	SPDR = out;
@@ -152,6 +145,9 @@ union {
 } can_rx_addr;
 uint8_t can_rx_dlc, can_rx_data[8];
 
+#define can_rx_avail()		(can_rx_addr.u)
+#define can_rx_pop()		do { can_rx_addr.u = 0; } while (0)
+
 static void can_rxh(uint8_t buffer)
 {
 	uint8_t c, byte;
@@ -162,6 +158,14 @@ static void can_rxh(uint8_t buffer)
 		uart_puts("can: RX0IF\n");
 	spi_ss(0);
 	spi_wrrd(0x90 + 0x04 * buffer);
+
+	if (can_rx_addr.u) {
+		spi_wrrd(0xff);
+		spi_ss(1);
+		uart_puts("-- CAN RX overrun\n");
+		return;
+	};
+
 	c = 0;
 #define rdaddr() byte = spi_wrrd(0xff); uart_puthex(byte); can_rx_addr.b[c++] = byte
 	rdaddr();
@@ -180,7 +184,7 @@ static void can_rxh(uint8_t buffer)
 	spi_ss(1);
 }
 
-static void can_int(void)
+ISR(INT0_vect)
 {
 	uint8_t canintf, eflg, canstat;
 
@@ -230,6 +234,8 @@ static void can_int(void)
 
 static void can_preinit(void)
 {
+	can_rx_addr.u = 0;
+
 	spi_ss(1);
 #ifndef R0KET
 	DDRB |= (1 << B_SCK) | (1 << B_MOSI) | (1 << B_SS);
diff --git a/door.c b/door.c
index 8780e81..561289f 100644
--- a/door.c
+++ b/door.c
@@ -107,10 +107,6 @@ int main(void)
 	TCCR1B = (1 << WGM12) | (1 << CS11);
 
 	while (1) {
-		if (canint) {
-			canint = false;
-			can_int();
-		}
 		_delay_ms(1);
 	}
 }
diff --git a/lightctrl.c b/lightctrl.c
index 2a82ad3..e901714 100644
--- a/lightctrl.c
+++ b/lightctrl.c
@@ -223,15 +223,12 @@ int main(void)
 
 	while (1) {
 		wdt_reset();
-		if (canint) {
-			canint = false;
-			can_int();
 
-			if (can_rx_addr.b[0]) {
-				can_rx_exec();
-				can_rx_addr.u = 0;
-			}
+		if (can_rx_avail()) {
+			can_rx_exec();
+			can_rx_pop();
 		}
+
 		_delay_ms(5);
 		do_tick();
 
-- 
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