mirror of https://github.com/acidanthera/audk.git
63 lines
1.4 KiB
C
63 lines
1.4 KiB
C
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/** @file
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This code fills in BDA (0x400) and EBDA (pointed to by 0x4xx)
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information. There is support for doing initializeation before
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Legacy16 is loaded and before a legacy boot is attempted.
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Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR>
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SPDX-License-Identifier: BSD-2-Clause-Patent
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**/
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#include "LegacyBiosInterface.h"
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/**
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Fill in the standard BDA and EBDA stuff before Legacy16 load
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@param Private Legacy BIOS Instance data
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@retval EFI_SUCCESS It should always work.
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**/
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EFI_STATUS
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LegacyBiosInitBda (
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IN LEGACY_BIOS_INSTANCE *Private
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)
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{
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BDA_STRUC *Bda;
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UINT8 *Ebda;
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Bda = (BDA_STRUC *) ((UINTN) 0x400);
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Ebda = (UINT8 *) ((UINTN) 0x9fc00);
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ACCESS_PAGE0_CODE (
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ZeroMem (Bda, 0x100);
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//
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// 640k-1k for EBDA
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//
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Bda->MemSize = 0x27f;
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Bda->KeyHead = 0x1e;
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Bda->KeyTail = 0x1e;
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Bda->FloppyData = 0x00;
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Bda->FloppyTimeout = 0xff;
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Bda->KeyStart = 0x001E;
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Bda->KeyEnd = 0x003E;
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Bda->KeyboardStatus = 0x10;
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Bda->Ebda = 0x9fc0;
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//
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// Move LPT time out here and zero out LPT4 since some SCSI OPROMS
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// use this as scratch pad (LPT4 is Reserved)
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//
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Bda->Lpt1_2Timeout = 0x1414;
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Bda->Lpt3_4Timeout = 0x1400;
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);
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ZeroMem (Ebda, 0x400);
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*Ebda = 0x01;
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return EFI_SUCCESS;
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}
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