From 07e889209034ba94bfac9e765b8a50ef344daef2 Mon Sep 17 00:00:00 2001
From: Jeff Fan <jeff.fan@intel.com>
Date: Thu, 21 Apr 2016 10:28:17 +0800
Subject: UefiCpuPkg/MtrrLib: Remove the loop of calculating Fixed-MTRR Mask

Introduce the 32bit mask seeds to calculate Fixed-MTRR or&and mask values. It
could avoid the loop operation and 64bit shift operations.

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 | 39 +++++++++++++++++++++---------------
 1 file changed, 23 insertions(+), 16 deletions(-)

(limited to 'UefiCpuPkg')

diff --git a/UefiCpuPkg/Library/MtrrLib/MtrrLib.c b/UefiCpuPkg/Library/MtrrLib/MtrrLib.c
index 06a361bd84..c4a39b554d 100644
--- a/UefiCpuPkg/Library/MtrrLib/MtrrLib.c
+++ b/UefiCpuPkg/Library/MtrrLib/MtrrLib.c
@@ -20,6 +20,9 @@
 #include <Library/BaseMemoryLib.h>
 #include <Library/DebugLib.h>
 
+#define OR_SEED      0x01010101
+#define CLEAR_SEED   0xFFFFFFFF
+
 //
 // Context to save and restore when MTRRs are programmed
 //
@@ -460,11 +463,12 @@ ProgramFixedMtrr (
 {
   UINT32  MsrNum;
   UINT32  ByteShift;
-  UINT64  OrMask;
-  UINT64  ClearMask;
+  UINT32  OrMask[2];
+  UINT32  ClearMask[2];
+  UINT64  SubLength;
 
-  OrMask    = 0;
-  ClearMask = 0;
+  *(UINT64 *)OrMask    = 0;
+  *(UINT64 *)ClearMask = 0;
 
   for (MsrNum = *LastMsrNum + 1; MsrNum < MTRR_NUMBER_OF_FIXED_MTRR; MsrNum++) {
     if ((*Base >= mMtrrLibFixedMtrrTable[MsrNum].BaseAddress) &&
@@ -493,24 +497,27 @@ ProgramFixedMtrr (
     return RETURN_UNSUPPORTED;
   }
 
-  for (
-        ;
-        ((ByteShift < 8) && (*Length >= mMtrrLibFixedMtrrTable[MsrNum].Length));
-        ByteShift++
-      ) {
-    OrMask |= LShiftU64 ((UINT64) MemoryCacheType, (UINT32) (ByteShift * 8));
-    ClearMask |= LShiftU64 ((UINT64) 0xFF, (UINT32) (ByteShift * 8));
-    *Length -= mMtrrLibFixedMtrrTable[MsrNum].Length;
-    *Base += mMtrrLibFixedMtrrTable[MsrNum].Length;
+  if (ByteShift < 4) {
+    OrMask[0]    = OR_SEED * (UINT32)MemoryCacheType;
+    ClearMask[0] = CLEAR_SEED;
+    OrMask[1]    = (OR_SEED * (UINT32)MemoryCacheType) >> ((4 - ByteShift) * 8);
+    ClearMask[1] = CLEAR_SEED >> ((4 - ByteShift) * 8);
+  } else {
+    OrMask[0]    = (OR_SEED * (UINT32)MemoryCacheType) >> ((8 - ByteShift) * 8);
+    ClearMask[0] = CLEAR_SEED >> ((8 - ByteShift) * 8);
   }
 
-  if (ByteShift < 8 && (*Length != 0)) {
+  SubLength = mMtrrLibFixedMtrrTable[MsrNum].Length * (8 - ByteShift);
+  if (*Length < SubLength) {
     return RETURN_UNSUPPORTED;
   }
 
+  *Length -= SubLength;
+  *Base   += SubLength;
+
   *LastMsrNum      = MsrNum;
-  *ReturnClearMask = ClearMask;
-  *ReturnOrMask    = OrMask;
+  *ReturnClearMask = *(UINT64 *)ClearMask;
+  *ReturnOrMask    = *(UINT64 *)OrMask;
 
   return RETURN_SUCCESS;
 }
-- 
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