From af091674a6105c9f0d0a7e4e4c5b9cde611f4309 Mon Sep 17 00:00:00 2001
From: Nathan Cannon <neviynhd@gmail.com>
Date: Sun, 22 Oct 2017 02:02:19 +0100
Subject: [PATCH] Reduced number of calculations performed in terminalScroll.

---
 kernel/arch/i386/tty.nim | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/kernel/arch/i386/tty.nim b/kernel/arch/i386/tty.nim
index bb1ab1e..fbbf421 100644
--- a/kernel/arch/i386/tty.nim
+++ b/kernel/arch/i386/tty.nim
@@ -32,11 +32,10 @@ proc terminalInitialize*() =
 
 proc terminalScroll() =
   for y in 0..< (vgaHeight - 1):
+    let base1 = y * vgaWidth
+    let base2 = (y + 1) * vgaWidth
     for x in 0..<vgaWidth:
-      let xval = x * 2
-      let index1 = y * vgaWidth + x
-      let index2 = (y + 1) * vgaWidth + x
-      vgaMem[index1] = vgaMem[index2]
+      vgaMem[base1 + x] = vgaMem[base2 + x]
   for x in 0..<vgaWidth: # Blank the "new" bottom line
     terminalWriteAtPoint(' ', terminalColour, x, vgaHeight - 1)