ShellPkg: Refine the code format.

1. Add function header comment.
2. Non-Boolean comparisons should explicitly use a compare operator.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Qiu Shumin <shumin.qiu@intel.com>
Reviewed-by: Ruiyu Ni <ruiyu.ni@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19424 6f19259b-4bc3-4df7-8a09-765794883524

ShellPkg/Application/Shell/ShellManParser.c

@@ -15,7 +15,26 @@
 
 #include "Shell.h"
 
-CHAR16 EFIAPI InternalShellCharToUpper (IN CHAR16  Char);
+/**
+  Convert a Unicode character to upper case only if
+  it maps to a valid small-case ASCII character.
+
+  This internal function only deal with Unicode character
+  which maps to a valid small-case ASCII character, i.e.
+  L'a' to L'z'. For other Unicode character, the input character
+  is returned directly.
+
+  @param  Char  The character to convert.
+
+  @retval LowerCharacter   If the Char is with range L'a' to L'z'.
+  @retval Unchanged        Otherwise.
+
+**/
+CHAR16
+EFIAPI 
+InternalShellCharToUpper (
+  IN CHAR16  Char
+  );
 
 /**
   Verifies that the filename has .MAN on the end.
@@ -630,7 +649,7 @@ ManFileFindTitleSection(
   // Do not pass any leading path information that may be present to IsTitleHeader().
   //
   Start = StrLen(Command);
-  while (Start
+  while ((Start != 0)
          && (*(Command + Start - 1) != L'\\')
          && (*(Command + Start - 1) != L'/')
          && (*(Command + Start - 1) != L':')) {