From 90b9086a79ce1b24a4efa7390b6920c1d2ea7393 Mon Sep 17 00:00:00 2001
From: Jakob Odersky <jodersky@gmail.com>
Date: Tue, 8 Apr 2014 15:25:11 +0200
Subject: fix problem with locks

---
 kernel/include/mux/lock.h     | 5 +++--
 kernel/mcu/atmega2560/usart.c | 9 ++++-----
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/kernel/include/mux/lock.h b/kernel/include/mux/lock.h
index b5ac4d9..252237e 100644
--- a/kernel/include/mux/lock.h
+++ b/kernel/include/mux/lock.h
@@ -2,11 +2,12 @@
 #define MUX_LOCK_H
 
 #include "mux/sched.h"
+#include <avr/interrupt.h>
 
 typedef volatile char spin_lock_t;
 
-#define SPIN_LOCK_UNLOCKED 0
-#define SPIN_LOCK_LOCKED 0
+#define SPIN_LOCK_UNLOCKED (volatile char) 0
+#define SPIN_LOCK_LOCKED (volatile char) 1
 
 static inline void spin_lock(spin_lock_t* lock) {
   while(*lock != SPIN_LOCK_UNLOCKED) {yield();};
diff --git a/kernel/mcu/atmega2560/usart.c b/kernel/mcu/atmega2560/usart.c
index f07e137..803c204 100644
--- a/kernel/mcu/atmega2560/usart.c
+++ b/kernel/mcu/atmega2560/usart.c
@@ -2,6 +2,7 @@
 #include "mux/list.h"
 #include "mux/rbuffer.h"
 #include "mux/sched.h"
+#include "mux/lock.h"
 #include "mcu/usart.h"
 #include "mcu/context.h"
 #include <avr/interrupt.h>
@@ -72,11 +73,13 @@ ssize_t usart_write(struct file* usart, const char* const buffer, size_t length)
         sei();
         *ucsrxb |= write_enable;
     } while (r == 0 && wrote < length);
+
     return wrote;
 }
 
 ssize_t usart_read(struct file* usart, char* const buffer, size_t length) {
     struct usart_private* priv = (struct usart_private*) usart->private_data;
+
     while (rbuffer_empty(&priv->rx_buffer)) {
         sleep_queue(&priv->rx_queue);
         yield();
@@ -104,7 +107,7 @@ struct file_operations usart_fops = {
     .close = usart_close
 };
 
-struct usart_private _usart0 = {
+static struct usart_private _usart0 = {
     .ucsrxa = &UCSR0A,
     .ubrrxh = &UBRR0H,
     .ubrrxl = &UBRR0L,
@@ -135,14 +138,10 @@ ISR(USART0_UDRE_vect) {
 
 //called when byte is received
 ISR(USART0_RX_vect) {
-    //context_save();
 
     struct usart_private* priv = (struct usart_private*) usart0.private_data;
     
     char c = UDR0;
     rbuffer_write(&priv->rx_buffer, c);
     wake_all_queue(&priv->rx_queue);
-
-    //context_restore();
-    //asm volatile ("reti");
 }
\ No newline at end of file
-- 
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