Update

src/devices/input.c

+#include "devices/input.h"
+#include <debug.h>
+#include "devices/intq.h"
+#include "devices/serial.h"
+
+/* Stores keys from the keyboard and serial port. */
+static struct intq buffer;
+
+/* Initializes the input buffer. */
+void
+input_init (void) 
+{
+  intq_init (&buffer);
+}
+
+/* Adds a key to the input buffer.
+   Interrupts must be off and the buffer must not be full. */
+void
+input_putc (uint8_t key) 
+{
+  ASSERT (intr_get_level () == INTR_OFF);
+  ASSERT (!intq_full (&buffer));
+
+  intq_putc (&buffer, key);
+  serial_notify ();
+}
+
+/* Retrieves a key from the input buffer.
+   If the buffer is empty, waits for a key to be pressed. */
+uint8_t
+input_getc (void) 
+{
+  enum intr_level old_level;
+  uint8_t key;
+
+  old_level = intr_disable ();
+  key = intq_getc (&buffer);
+  serial_notify ();
+  intr_set_level (old_level);
+  
+  return key;
+}
+
+/* Returns true if the input buffer is full,
+   false otherwise.
+   Interrupts must be off. */
+bool
+input_full (void) 
+{
+  ASSERT (intr_get_level () == INTR_OFF);
+  return intq_full (&buffer);
+}