vt: guide the compiler into optimizing the fast path

diff --git a/Kernel/vt.c b/Kernel/vt.c
index 68d7628..8a2c935 100644 (file)
--- a/Kernel/vt.c
+++ b/Kernel/vt.c
@@ -104,35 +104,38 @@ static void cursor_fix(void)
 
 static void charout(unsigned char c)
 {
-       if (c == 7) {
-               do_beep();
-               return;
-       }
-       if (c == 8) {
-               cursorx--;
-               goto fix;
-       }
-       if (c == 9) {
-               do {
-                       charout(' ');
-               } while (cursorx&7);
-               goto fix;
-       }
-       if (c == 10) {
-               cursory++;
-               goto fix;
-       }
-       if (c == 13) {
-               cursorx = 0;
-               return;
-       }
-       if (c == 0x1b) {
-               vtmode = 1;
-               return;
+       /* Fast path printable symbols */
+       if (c <= 0x1b) {
+               if (c == 7) {
+                       do_beep();
+                       return;
+               }
+               if (c == 8) {
+                       cursorx--;
+                       goto fix;
+               }
+               if (c == 9) {
+                       do {
+                               charout(' ');
+                       } while (cursorx&7);
+                       goto fix;
+               }
+               if (c == 10) {
+                       cursory++;
+                       goto fix;
+               }
+               if (c == 13) {
+                       cursorx = 0;
+                       return;
+               }
+               if (c == 0x1b) {
+                       vtmode = 1;
+                       return;
+               }
        }
        plot_char(cursory, cursorx, c);
        cursorx++;
-      fix:
+fix:
        cursor_fix();
 }