From 1e4725e569960b1107c11df6c404312d26129eab Mon Sep 17 00:00:00 2001
From: Jiaxin Wu <jiaxin.wu@intel.com>
Date: Tue, 2 Jan 2018 11:29:03 +0800
Subject: [PATCH] NetworkPkg/HttpDxe: Fix build warning error if CHAR8 is
 unsigned.

This patch is to fix the compiler warning error: C4245. The issue will happen
if the below build option is enabled:
  *_*_*_CC_FLAGS = -J.

That's because the value of ('A' - 'a') is a negative value, which will
be converted to an unsigned type if CHAR8 is treated as unsigned:
  Src -= ('A' - 'a');

The above issue is also recorded at:
https://bugzilla.tianocore.org/show_bug.cgi?id=815.

Cc: Ye Ting <ting.ye@intel.com>
Cc: Fu Siyuan <siyuan.fu@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Wu Jiaxin <jiaxin.wu@intel.com>
Reviewed-by: Fu Siyuan <siyuan.fu@intel.com>
---
 NetworkPkg/HttpDxe/HttpsSupport.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/NetworkPkg/HttpDxe/HttpsSupport.c b/NetworkPkg/HttpDxe/HttpsSupport.c
index e6f4d5a6cc..6aed61a3a4 100644
--- a/NetworkPkg/HttpDxe/HttpsSupport.c
+++ b/NetworkPkg/HttpDxe/HttpsSupport.c
@@ -67,11 +67,11 @@ AsciiStrCaseStr (
       Dst = *SearchStringTmp;
 
       if ((Src >= 'A') && (Src <= 'Z')) {
-        Src -= ('A' - 'a');
+        Src += ('a' - 'A');
       }
 
       if ((Dst >= 'A') && (Dst <= 'Z')) {
-        Dst -= ('A' - 'a');
+        Dst += ('a' - 'A');
       }
 
       if (Src != Dst) {