From aa5f60ae41f0fa1b4816071704ab6669b0fe94c1 Mon Sep 17 00:00:00 2001
From: Hao Wu <hao.a.wu@intel.com>
Date: Mon, 23 Jan 2017 11:24:50 +0800
Subject: IntelFrameworkModulePkg: Refine casting expression result to bigger
 size

There are cases that the operands of an expression are all with rank less
than UINT64/INT64 and the result of the expression is explicitly cast to
UINT64/INT64 to fit the target size.

An example will be:
UINT32 a,b;
// a and b can be any unsigned int type with rank less than UINT64, like
// UINT8, UINT16, etc.
UINT64 c;
c = (UINT64) (a + b);

Some static code checkers may warn that the expression result might
overflow within the rank of "int" (integer promotions) and the result is
then cast to a bigger size.

The commit refines codes by the following rules:
1). When the expression is possible to overflow the range of unsigned int/
int:
c = (UINT64)a + b;

2). When the expression will not overflow within the rank of "int", remove
the explicit type casts:
c = a + b;

3). When the expression will be cast to pointer of possible greater size:
UINT32 a,b;
VOID *c;
c = (VOID *)(UINTN)(a + b); --> c = (VOID *)((UINTN)a + b);

4). When one side of a comparison expression contains only operands with
rank less than UINT32:
UINT8 a;
UINT16 b;
UINTN c;
if ((UINTN)(a + b) > c) {...} --> if (((UINT32)a + b) > c) {...}

For rule 4), if we remove the 'UINTN' type cast like:
if (a + b > c) {...}
The VS compiler will complain with warning C4018 (signed/unsigned
mismatch, level 3 warning) due to promoting 'a + b' to type 'int'.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
Reviewed-by: Jeff Fan <jeff.fan@intel.com>
---
 IntelFrameworkModulePkg/Csm/BiosThunk/Snp16Dxe/BiosSnp16.c |  4 ++--
 IntelFrameworkModulePkg/Csm/BiosThunk/Snp16Dxe/Misc.c      | 14 +++++++-------
 2 files changed, 9 insertions(+), 9 deletions(-)

(limited to 'IntelFrameworkModulePkg/Csm/BiosThunk/Snp16Dxe')

diff --git a/IntelFrameworkModulePkg/Csm/BiosThunk/Snp16Dxe/BiosSnp16.c b/IntelFrameworkModulePkg/Csm/BiosThunk/Snp16Dxe/BiosSnp16.c
index a2a7797f07..b586a91c7b 100644
--- a/IntelFrameworkModulePkg/Csm/BiosThunk/Snp16Dxe/BiosSnp16.c
+++ b/IntelFrameworkModulePkg/Csm/BiosThunk/Snp16Dxe/BiosSnp16.c
@@ -1,6 +1,6 @@
 /** @file
 
-Copyright (c) 1999 - 2014, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 1999 - 2017, Intel Corporation. All rights reserved.<BR>
 
 This program and the accompanying materials
 are licensed and made available under the terms and conditions
@@ -1858,7 +1858,7 @@ Undi16SimpleNetworkIsr (
 
       CopyMem (
         Frame,
-        (VOID *)(UINTN) ((SimpleNetworkDevice->Isr.FrameSegSel << 4) + SimpleNetworkDevice->Isr.FrameOffset),
+        (VOID *) (((UINTN) SimpleNetworkDevice->Isr.FrameSegSel << 4) + SimpleNetworkDevice->Isr.FrameOffset),
         SimpleNetworkDevice->Isr.BufferLength
         );
       Frame = Frame + SimpleNetworkDevice->Isr.BufferLength;
diff --git a/IntelFrameworkModulePkg/Csm/BiosThunk/Snp16Dxe/Misc.c b/IntelFrameworkModulePkg/Csm/BiosThunk/Snp16Dxe/Misc.c
index 4750b2f99d..a1dc86786b 100644
--- a/IntelFrameworkModulePkg/Csm/BiosThunk/Snp16Dxe/Misc.c
+++ b/IntelFrameworkModulePkg/Csm/BiosThunk/Snp16Dxe/Misc.c
@@ -1,7 +1,7 @@
 /** @file
   Helper Routines that use a PXE-enabled NIC option ROM.
  
-Copyright (c) 1999 - 2014, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 1999 - 2017, Intel Corporation. All rights reserved.<BR>
 
 This program and the accompanying materials
 are licensed and made available under the terms and conditions
@@ -49,7 +49,7 @@ CacheVectorAddress (
 {
   UINT32  *Address;
 
-  Address                          = (UINT32 *)(UINTN) (IVT_BASE + VectorNumber * 4);
+  Address                          = (UINT32 *) ((UINTN) IVT_BASE + VectorNumber * 4);
   CachedVectorAddress[VectorNumber] = *Address;
   return EFI_SUCCESS;
 }
@@ -68,7 +68,7 @@ RestoreCachedVectorAddress (
 {
   UINT32  *Address;
 
-  Address  = (UINT32 *)(UINTN) (IVT_BASE + VectorNumber * 4);
+  Address  = (UINT32 *) ((UINTN) IVT_BASE + VectorNumber * 4);
   *Address = CachedVectorAddress[VectorNumber];
   return EFI_SUCCESS;
 }
@@ -469,7 +469,7 @@ LaunchBaseCode (
 
   RomIdTableAddress = (UNDI_ROMID_T *) (RomAddress + OPTION_ROM_PTR->PxeRomIdOffset);
 
-  if ((UINTN) (OPTION_ROM_PTR->PxeRomIdOffset + RomIdTableAddress->StructLength) > RomLength) {
+  if (((UINT32)OPTION_ROM_PTR->PxeRomIdOffset + RomIdTableAddress->StructLength) > RomLength) {
     DEBUG ((DEBUG_ERROR, "ROM ID Offset Error\n\r"));
     return EFI_NOT_FOUND;
   }
@@ -754,10 +754,10 @@ LaunchBaseCode (
   Print_Undi_Loader_Table (UndiLoaderTable);
 
   DEBUG ((DEBUG_NET, "Display the PXENV+ and !PXE tables exported by NIC\n\r"));
-  Print_PXENV_Table ((VOID *)(UINTN)((UndiLoaderTable->PXENVptr.Segment << 4) | UndiLoaderTable->PXENVptr.Offset));
-  Print_PXE_Table ((VOID *)(UINTN)((UndiLoaderTable->PXEptr.Segment << 4) + UndiLoaderTable->PXEptr.Offset));
+  Print_PXENV_Table ((VOID *)(((UINTN)UndiLoaderTable->PXENVptr.Segment << 4) | UndiLoaderTable->PXENVptr.Offset));
+  Print_PXE_Table ((VOID *)(((UINTN)UndiLoaderTable->PXEptr.Segment << 4) + UndiLoaderTable->PXEptr.Offset));
 
-  Pxe = (PXE_T *)(UINTN)((UndiLoaderTable->PXEptr.Segment << 4) + UndiLoaderTable->PXEptr.Offset);
+  Pxe = (PXE_T *)(((UINTN)UndiLoaderTable->PXEptr.Segment << 4) + UndiLoaderTable->PXEptr.Offset);
   SimpleNetworkDevice->Nii.Id = (UINT64)(UINTN) Pxe;
 
   gBS->FreePool (Buffer);
-- 
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