[Add] laos base boot

laos/src/kernel/console.c

@@ -0,0 +1,28 @@
+#include "console.h"
+#include "memio.h"
+#include "memlayout.h"
+#include "spinlock.h"
+
+void consputc(int c) {
+    if (c == '\b') {
+        memb(SERIAL_ADDR) = '\b';
+        memb(SERIAL_ADDR) =  ' ';
+        memb(SERIAL_ADDR) = '\b';
+        return;
+    }
+
+    memb(SERIAL_ADDR) = c;
+}
+
+struct {
+  struct spinlock lock;
+  
+  // input
+#define INPUT_BUF_SIZE 128
+  char buf[INPUT_BUF_SIZE];
+  uint r;  // Read index
+  uint w;  // Write index
+  uint e;  // Edit index
+} cons;
+
+