From a33f60fea30c931207aa05c933dab4bd992a40c2 Mon Sep 17 00:00:00 2001
From: Robert Morris <rtm@csail.mit.edu>
Date: Sat, 27 Jul 2019 05:47:19 -0400
Subject: console/uart tweaks

---
 kernel/uart.c | 4 ++++
 1 file changed, 4 insertions(+)

(limited to 'kernel/uart.c')

diff --git a/kernel/uart.c b/kernel/uart.c
index b8dd664..ba66237 100644
--- a/kernel/uart.c
+++ b/kernel/uart.c
@@ -43,6 +43,7 @@ uartinit(void)
   *R(1) = 0x01;
 }
 
+// write one output character to the UART.
 void
 uartputc(int c)
 {
@@ -52,6 +53,8 @@ uartputc(int c)
   *R(0) = c;
 }
 
+// read one input character from the UART.
+// return -1 if none is waiting.
 int
 uartgetc(void)
 {
@@ -63,6 +66,7 @@ uartgetc(void)
   }
 }
 
+// trap.c calls here when the uart interrupts.
 void
 uartintr(void)
 {
-- 
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