Add sanity check panic for CRTC interactions

02530a48 · Nathaniel Wesley Filardo · Frans Kaashoek · b019ac4f · 02530a48
--- a/console.c
+++ b/console.c
@@ -144,6 +144,9 @@ cgaputc(int c)
  } else
    crt[pos++] = (c&0xff) | 0x0700;  // black on white

+  if(pos > 25*80)
+    panic("pos overflow");
+  
  if((pos/80) >= 24){  // Scroll up.
    memmove(crt, crt+80, sizeof(crt[0])*23*80);
    pos -= 80;