mirror of https://github.com/acidanthera/audk.git
45 lines
1.3 KiB
NASM
45 lines
1.3 KiB
NASM
;------------------------------------------------------------------------------
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;
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; Copyright (c) 2006, Intel Corporation. All rights reserved.<BR>
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; 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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SECTION .text
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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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global ASM_PFX(AsmReadDr4)
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ASM_PFX(AsmReadDr4):
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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 0xf, 0x21, 0xe0
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ret
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