MdeModulePkg: 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: Feng Tian <feng.tian@intel.com>

1 files changed, 10 insertions, 10 deletions

diff --git a/MdeModulePkg/Universal/HiiDatabaseDxe/Font.c b/MdeModulePkg/Universal/HiiDatabaseDxe/Font.c
index 9bef0642af..b85cf88f54 100644
--- a/MdeModulePkg/Universal/HiiDatabaseDxe/Font.c
+++ b/MdeModulePkg/Universal/HiiDatabaseDxe/Font.c
@@ -2,7 +2,7 @@
 Implementation for EFI_HII_FONT_PROTOCOL.

 

 

-Copyright (c) 2007 - 2016, Intel Corporation. All rights reserved.<BR>

+Copyright (c) 2007 - 2017, Intel Corporation. All rights reserved.<BR>

 This program and the accompanying materials

 are licensed and made available under the terms and conditions of the BSD License

 which accompanies this distribution.  The full text of the license may be found at

@@ -411,7 +411,7 @@ GlyphToBlt (
   // The glyph's upper left hand corner pixel is the most significant bit of the

   // first bitmap byte.

   //

-  for (Ypos = 0; Ypos < Cell->Height && ((UINTN) (Ypos + YposOffset) < RowHeight); Ypos++) {

+  for (Ypos = 0; Ypos < Cell->Height && (((UINT32) Ypos + YposOffset) < RowHeight); Ypos++) {

     OffsetY = BITMAP_LEN_1_BIT (Cell->Width, Ypos);

 

     //

@@ -419,7 +419,7 @@ GlyphToBlt (
     //

     for (Xpos = 0; Xpos < Cell->Width / 8; Xpos++) {

       Data  = *(GlyphBuffer + OffsetY + Xpos);

-      for (Index = 0; Index < 8 && ((UINTN) (Xpos * 8 + Index + Cell->OffsetX) < RowWidth); Index++) {

+      for (Index = 0; Index < 8 && (((UINT32) Xpos * 8 + Index + Cell->OffsetX) < RowWidth); Index++) {

         if ((Data & (1 << (8 - Index - 1))) != 0) {

           BltBuffer[Ypos * ImageWidth + Xpos * 8 + Index] = Foreground;

         } else {

@@ -435,7 +435,7 @@ GlyphToBlt (
       // There are some padding bits in this byte. Ignore them.

       //

       Data  = *(GlyphBuffer + OffsetY + Xpos);

-      for (Index = 0; Index < Cell->Width % 8 && ((UINTN) (Xpos * 8 + Index + Cell->OffsetX) < RowWidth); Index++) {

+      for (Index = 0; Index < Cell->Width % 8 && (((UINT32) Xpos * 8 + Index + Cell->OffsetX) < RowWidth); Index++) {

         if ((Data & (1 << (8 - Index - 1))) != 0) {

           BltBuffer[Ypos * ImageWidth + Xpos * 8 + Index] = Foreground;

         } else {

@@ -1927,7 +1927,7 @@ HiiStringToImage (
     // If this character is the last character of a row, we need not

     // draw its (AdvanceX - Width - OffsetX) for next character.

     //

-    LineWidth -= (UINTN) (Cell[Index].AdvanceX - Cell[Index].Width - Cell[Index].OffsetX);

+    LineWidth -= (Cell[Index].AdvanceX - Cell[Index].Width - Cell[Index].OffsetX);

 

     //

     // Clip the right-most character if cannot fit when EFI_HII_OUT_FLAG_CLEAN_X is set.

@@ -1950,8 +1950,8 @@ HiiStringToImage (
         //

         // Don't draw the last char on this row. And, don't draw the second last char (AdvanceX - Width - OffsetX).

         //

-        LineWidth -= (UINTN) (Cell[Index].Width + Cell[Index].OffsetX);

-        LineWidth -= (UINTN) (Cell[Index - 1].AdvanceX - Cell[Index - 1].Width - Cell[Index - 1].OffsetX);

+        LineWidth -= (Cell[Index].Width + Cell[Index].OffsetX);

+        LineWidth -= (Cell[Index - 1].AdvanceX - Cell[Index - 1].Width - Cell[Index - 1].OffsetX);

         RowInfo[RowIndex].EndIndex       = Index - 1;

         RowInfo[RowIndex].LineWidth      = LineWidth;

         RowInfo[RowIndex].LineHeight     = LineHeight;

@@ -2008,7 +2008,7 @@ HiiStringToImage (
           if (Index1 == RowInfo[RowIndex].StartIndex) {

             LineWidth = 0;

           } else {

-            LineWidth -= (UINTN) (Cell[Index1 - 1].AdvanceX - Cell[Index1 - 1].Width - Cell[Index1 - 1].OffsetX);

+            LineWidth -= (Cell[Index1 - 1].AdvanceX - Cell[Index1 - 1].Width - Cell[Index1 - 1].OffsetX);

           }

           RowInfo[RowIndex].LineWidth = LineWidth;

         }

@@ -2025,8 +2025,8 @@ HiiStringToImage (
             //

             // Don't draw the last char on this row. And, don't draw the second last char (AdvanceX - Width - OffsetX).

             //

-            LineWidth -= (UINTN) (Cell[Index1].Width + Cell[Index1].OffsetX);

-            LineWidth -= (UINTN) (Cell[Index1 - 1].AdvanceX - Cell[Index1 - 1].Width - Cell[Index1 - 1].OffsetX);

+            LineWidth -= (Cell[Index1].Width + Cell[Index1].OffsetX);

+            LineWidth -= (Cell[Index1 - 1].AdvanceX - Cell[Index1 - 1].Width - Cell[Index1 - 1].OffsetX);

             RowInfo[RowIndex].EndIndex       = Index1 - 1;

             RowInfo[RowIndex].LineWidth      = LineWidth;

           } else {