mirror of https://github.com/acidanthera/audk.git
48 lines
1.3 KiB
NASM
48 lines
1.3 KiB
NASM
;------------------------------------------------------------------------------
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;
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; Copyright (c) 2006, Intel Corporation
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; All rights reserved. This program and the accompanying materials
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; are licensed and made available under the terms and conditions of the BSD License
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; which accompanies this distribution. The full text of the license may be found at
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; http://opensource.org/licenses/bsd-license.php
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;
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; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
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; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
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;
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; Module Name:
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;
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; ReadDr4.Asm
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;
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; Abstract:
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;
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; AsmReadDr4 function
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;
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; Notes:
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;
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;------------------------------------------------------------------------------
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.586p
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.model flat,C
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.code
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;------------------------------------------------------------------------------
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; UINTN
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; EFIAPI
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; AsmReadDr4 (
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; VOID
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; );
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;------------------------------------------------------------------------------
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AsmReadDr4 PROC
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;
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; DR4 is alias to DR6 only if DE (in CR4) is cleared. Otherwise, reading
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; this register will cause a #UD exception.
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;
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; MS assembler doesn't support this instruction since no one would use it
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; under normal circustances. Here opcode is used.
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;
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DB 0fh, 21h, 0e0h
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ret
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AsmReadDr4 ENDP
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END
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