Moved the MdePkg to OldMdePkg so that new code in MdePkg does not break existing...

[mirror_edk2.git] / OldMdePkg / Library / BaseLib / Ia32 / WriteDr4.asm

diff --git a/OldMdePkg/Library/BaseLib/Ia32/WriteDr4.asm b/OldMdePkg/Library/BaseLib/Ia32/WriteDr4.asm
new file mode 100644 (file)
index 0000000..9c10305
--- /dev/null
+++ b/OldMdePkg/Library/BaseLib/Ia32/WriteDr4.asm
@@ -0,0 +1,48 @@
+;------------------------------------------------------------------------------\r
+;\r
+; Copyright (c) 2006, Intel Corporation\r
+; All rights reserved. This program and the accompanying materials\r
+; are licensed and made available under the terms and conditions of the BSD License\r
+; which accompanies this distribution.  The full text of the license may be found at\r
+; http://opensource.org/licenses/bsd-license.php\r
+;\r
+; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
+; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
+;\r
+; Module Name:\r
+;\r
+;   WriteDr4.Asm\r
+;\r
+; Abstract:\r
+;\r
+;   AsmWriteDr4 function\r
+;\r
+; Notes:\r
+;\r
+;------------------------------------------------------------------------------\r
+\r
+    .586p\r
+    .model  flat,C\r
+    .code\r
+\r
+;------------------------------------------------------------------------------\r
+; UINTN\r
+; EFIAPI\r
+; AsmWriteDr4 (\r
+;   IN UINTN Value\r
+;   );\r
+;------------------------------------------------------------------------------\r
+AsmWriteDr4 PROC\r
+    mov     eax, [esp + 4]\r
+    ;\r
+    ; DR4 is alias to DR6 only if DE (in CR4) is cleared. Otherwise, writing to\r
+    ; this register will cause a #UD exception.\r
+    ;\r
+    ; MS assembler doesn't support this instruction since no one would use it\r
+    ; under normal circustances. Here opcode is used.\r
+    ;\r
+    DB      0fh, 23h, 0e0h\r
+    ret\r
+AsmWriteDr4 ENDP\r
+\r
+    END\r