From aaa1e579a5109a868863c8a3c7a51580f83b4c38 Mon Sep 17 00:00:00 2001
From: Jeff Fan <jeff.fan@intel.com>
Date: Wed, 20 Apr 2016 16:58:24 +0800
Subject: [PATCH] UefiCpuPkg/MtrrLib: Remove the loop of calculating byte
 offset in MSR

Calculate byte offset in MSR directly and removing the loop.

Cc: Feng Tian <feng.tian@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jeff Fan <jeff.fan@intel.com>
Reviewed-by: Feng Tian <feng.tian@intel.com>
---
 UefiCpuPkg/Library/MtrrLib/MtrrLib.c | 14 +++-----------
 1 file changed, 3 insertions(+), 11 deletions(-)

diff --git a/UefiCpuPkg/Library/MtrrLib/MtrrLib.c b/UefiCpuPkg/Library/MtrrLib/MtrrLib.c
index 609aca5c3e..06a361bd84 100644
--- a/UefiCpuPkg/Library/MtrrLib/MtrrLib.c
+++ b/UefiCpuPkg/Library/MtrrLib/MtrrLib.c
@@ -486,18 +486,10 @@ ProgramFixedMtrr (
   //
   // We found the fixed MTRR to be programmed
   //
-  for (ByteShift = 0; ByteShift < 8; ByteShift++) {
-    if (*Base ==
-         (
-           mMtrrLibFixedMtrrTable[MsrNum].BaseAddress +
-           (ByteShift * mMtrrLibFixedMtrrTable[MsrNum].Length)
-         )
-       ) {
-      break;
-    }
-  }
+  ByteShift = ((UINT32)*Base - mMtrrLibFixedMtrrTable[MsrNum].BaseAddress)
+               / mMtrrLibFixedMtrrTable[MsrNum].Length;
 
-  if (ByteShift == 8) {
+  if (ByteShift >= 8) {
     return RETURN_UNSUPPORTED;
   }