/** @file
  Routines that use BIOS to support INT 13 devices.

Copyright (c) 1999 - 2018, Intel Corporation. All rights reserved.<BR>

SPDX-License-Identifier: BSD-2-Clause-Patent

**/

#include "BiosBlkIo.h"

//
// Module global variables
//
//
// Address packet is a buffer under 1 MB for all version EDD calls
//
extern EDD_DEVICE_ADDRESS_PACKET  *mEddBufferUnder1Mb;

//
// This is a buffer for INT 13h func 48 information
//
extern BIOS_LEGACY_DRIVE          *mLegacyDriverUnder1Mb;

//
// Buffer of 0xFE00 bytes for EDD 1.1 transfer must be under 1 MB
//  0xFE00 bytes is the max transfer size supported.
//
extern VOID                       *mEdd11Buffer;


/**
  Initialize block I/O device instance

  @param  Dev   Instance of block I/O device instance

  @retval TRUE  Initialization succeeds.
  @retval FALSE Initialization fails.

**/
BOOLEAN
BiosInitBlockIo (
  IN  BIOS_BLOCK_IO_DEV         *Dev
  )
{
  EFI_BLOCK_IO_PROTOCOL *BlockIo;
  EFI_BLOCK_IO_MEDIA    *BlockMedia;
  BIOS_LEGACY_DRIVE     *Bios;

  BlockIo         = &Dev->BlockIo;
  BlockIo->Media  = &Dev->BlockMedia;
  BlockMedia      = BlockIo->Media;
  Bios            = &Dev->Bios;

  if (Int13GetDeviceParameters (Dev, Bios) != 0) {
    if (Int13Extensions (Dev, Bios) != 0) {
      BlockMedia->LastBlock = (EFI_LBA) Bios->Parameters.PhysicalSectors - 1;
      BlockMedia->BlockSize = (UINT32) Bios->Parameters.BytesPerSector;

      if ((Bios->Parameters.Flags & EDD_DEVICE_REMOVABLE) == EDD_DEVICE_REMOVABLE) {
        BlockMedia->RemovableMedia = TRUE;
      }

    } else {
      //
      // Legacy Interfaces
      //
      BlockMedia->BlockSize = 512;
      BlockMedia->LastBlock = (Bios->MaxHead + 1) * Bios->MaxSector * (Bios->MaxCylinder + 1) - 1;
    }

    DEBUG ((DEBUG_INIT, "BlockSize = %d  LastBlock = %d\n", BlockMedia->BlockSize, BlockMedia->LastBlock));

    BlockMedia->LogicalPartition  = FALSE;
    BlockMedia->WriteCaching      = FALSE;

    //
    // BugBug: Need to set this for removable media devices if they do not
    //  have media present
    //
    BlockMedia->ReadOnly      = FALSE;
    BlockMedia->MediaPresent  = TRUE;

    BlockIo->Reset            = BiosBlockIoReset;
    BlockIo->FlushBlocks      = BiosBlockIoFlushBlocks;

    if (!Bios->ExtendedInt13) {
      //
      // Legacy interfaces
      //
      BlockIo->ReadBlocks   = BiosReadLegacyDrive;
      BlockIo->WriteBlocks  = BiosWriteLegacyDrive;
    } else if ((Bios->EddVersion == EDD_VERSION_30) && (Bios->Extensions64Bit)) {
      //
      // EDD 3.0 Required for Device path, but extended reads are not required.
      //
      BlockIo->ReadBlocks   = Edd30BiosReadBlocks;
      BlockIo->WriteBlocks  = Edd30BiosWriteBlocks;
    } else {
      //
      // Assume EDD 1.1 - Read and Write functions.
      //  This could be EDD 3.0 without Extensions64Bit being set.
      // If it's EDD 1.1 this will work, but the device path will not
      //  be correct. This will cause confusion to EFI OS installation.
      //
      BlockIo->ReadBlocks   = Edd11BiosReadBlocks;
      BlockIo->WriteBlocks  = Edd11BiosWriteBlocks;
    }

    BlockMedia->LogicalPartition  = FALSE;
    BlockMedia->WriteCaching      = FALSE;

    return TRUE;
  }

  return FALSE;
}

/**
  Gets parameters of block I/O device.

  @param  BiosBlockIoDev Instance of block I/O device.
  @param  Drive          Legacy drive.

  @return  Result of device parameter retrieval.

**/
UINTN
Int13GetDeviceParameters (
  IN  BIOS_BLOCK_IO_DEV    *BiosBlockIoDev,
  IN  BIOS_LEGACY_DRIVE    *Drive
  )
{
  UINTN                 CarryFlag;
  UINT16                Cylinder;
  EFI_IA32_REGISTER_SET Regs;

  ZeroMem (&Regs, sizeof (EFI_IA32_REGISTER_SET));

  Regs.H.AH = 0x08;
  Regs.H.DL = Drive->Number;
  CarryFlag = BiosBlockIoDev->LegacyBios->Int86 (BiosBlockIoDev->LegacyBios, 0x13, &Regs);
  DEBUG ((DEBUG_INIT, "Int13GetDeviceParameters: INT 13 08 DL=%02x : CF=%d AH=%02x\n", Drive->Number, CarryFlag, Regs.H.AH));
  if (CarryFlag != 0 || Regs.H.AH != 0x00) {
    Drive->ErrorCode = Regs.H.AH;
    return FALSE;
  }

  if (Drive->Floppy) {
    if (Regs.H.BL == 0x10) {
      Drive->AtapiFloppy = TRUE;
    } else {
      Drive->MaxHead      = Regs.H.DH;
      Drive->MaxSector    = Regs.H.CL;
      Drive->MaxCylinder  = Regs.H.CH;
      if (Drive->MaxSector == 0) {
        //
        // BugBug: You can not trust the Carry flag.
        //
        return FALSE;
      }
    }
  } else {
    Drive->MaxHead  = (UINT8) (Regs.H.DH & 0x3f);
    Cylinder        = (UINT16) (((UINT16) Regs.H.DH & 0xc0) << 4);
    Cylinder        = (UINT16) (Cylinder | ((UINT16) Regs.H.CL & 0xc0) << 2);
    Drive->MaxCylinder  = (UINT16) (Cylinder + Regs.H.CH);
    Drive->MaxSector    = (UINT8) (Regs.H.CL & 0x3f);
  }

  return TRUE;
}

/**
  Extension of INT13 call.

  @param  BiosBlockIoDev Instance of block I/O device.
  @param  Drive          Legacy drive.

  @return  Result of this extension.

**/
UINTN
Int13Extensions (
  IN  BIOS_BLOCK_IO_DEV    *BiosBlockIoDev,
  IN  BIOS_LEGACY_DRIVE    *Drive
  )
{
  INTN                  CarryFlag;
  EFI_IA32_REGISTER_SET Regs;

  ZeroMem (&Regs, sizeof (EFI_IA32_REGISTER_SET));

  Regs.H.AH = 0x41;
  Regs.X.BX = 0x55aa;
  Regs.H.DL = Drive->Number;
  CarryFlag = BiosBlockIoDev->LegacyBios->Int86 (BiosBlockIoDev->LegacyBios, 0x13, &Regs);
  DEBUG ((DEBUG_INIT, "Int13Extensions: INT 13 41 DL=%02x : CF=%d BX=%04x\n", Drive->Number, CarryFlag, Regs.X.BX));
  if (CarryFlag != 0 || Regs.X.BX != 0xaa55) {
    Drive->ExtendedInt13            = FALSE;
    Drive->DriveLockingAndEjecting  = FALSE;
    Drive->Edd                      = FALSE;
    return FALSE;
  }

  Drive->EddVersion               = Regs.H.AH;
  Drive->ExtendedInt13            = (BOOLEAN) ((Regs.X.CX & 0x01) == 0x01);
  Drive->DriveLockingAndEjecting  = (BOOLEAN) ((Regs.X.CX & 0x02) == 0x02);
  Drive->Edd                      = (BOOLEAN) ((Regs.X.CX & 0x04) == 0x04);
  Drive->Extensions64Bit          = (BOOLEAN) (Regs.X.CX & 0x08);

  Drive->ParametersValid          = (UINT8) GetDriveParameters (BiosBlockIoDev, Drive);
  return TRUE;
}

/**
  Gets parameters of legacy drive.

  @param  BiosBlockIoDev Instance of block I/O device.
  @param  Drive          Legacy drive.

  @return  Result of drive parameter retrieval.

**/
UINTN
GetDriveParameters (
  IN  BIOS_BLOCK_IO_DEV   *BiosBlockIoDev,
  IN  BIOS_LEGACY_DRIVE   *Drive
  )
{
  INTN                  CarryFlag;
  EFI_IA32_REGISTER_SET Regs;
  UINTN                 PointerMath;

  ZeroMem (&Regs, sizeof (EFI_IA32_REGISTER_SET));

  Regs.H.AH = 0x48;
  Regs.H.DL = Drive->Number;

  //
  // EDD Buffer must be passed in with max buffer size as first entry in the buffer
  //
  mLegacyDriverUnder1Mb->Parameters.StructureSize = (UINT16) sizeof (EDD_DRIVE_PARAMETERS);
  Regs.X.DS = EFI_SEGMENT ((UINTN)(&mLegacyDriverUnder1Mb->Parameters));
  Regs.X.SI = EFI_OFFSET ((UINTN)(&mLegacyDriverUnder1Mb->Parameters));
  CarryFlag = BiosBlockIoDev->LegacyBios->Int86 (BiosBlockIoDev->LegacyBios, 0x13, &Regs);
  DEBUG ((DEBUG_INIT, "GetDriveParameters: INT 13 48 DL=%02x : CF=%d AH=%02x\n", Drive->Number, CarryFlag, Regs.H.AH));
  if (CarryFlag != 0 || Regs.H.AH != 0x00) {
    Drive->ErrorCode = Regs.H.AH;
    SetMem (&Drive->Parameters, sizeof (Drive->Parameters), 0xaf);
    return FALSE;
  }
  //
  // We only have one buffer < 1MB, so copy into our instance data
  //
  CopyMem (
    &Drive->Parameters,
    &mLegacyDriverUnder1Mb->Parameters,
    sizeof (Drive->Parameters)
    );

  if (Drive->AtapiFloppy) {
    //
    // Sense Media Type
    //
    Regs.H.AH = 0x20;
    Regs.H.DL = Drive->Number;
    CarryFlag = BiosBlockIoDev->LegacyBios->Int86 (BiosBlockIoDev->LegacyBios, 0x13, &Regs);
    DEBUG ((DEBUG_INIT, "GetDriveParameters: INT 13 20 DL=%02x : CF=%d AL=%02x\n", Drive->Number, CarryFlag, Regs.H.AL));
    if (CarryFlag != 0) {
      //
      // Media not present or unknown media present
      //
      if ((Drive->Parameters.Flags & EDD_GEOMETRY_VALID) == EDD_GEOMETRY_VALID) {
        Drive->MaxHead    = (UINT8) (Drive->Parameters.MaxHeads - 1);
        Drive->MaxSector  = (UINT8) Drive->Parameters.SectorsPerTrack;
        ASSERT (Drive->MaxSector != 0);
        Drive->MaxCylinder = (UINT16) (Drive->Parameters.MaxCylinders - 1);
      } else {
        Drive->MaxHead      = 0;
        Drive->MaxSector    = 1;
        Drive->MaxCylinder  = 0;
      }

    } else {
      //
      // Media Present
      //
      switch (Regs.H.AL) {
      case 0x03:
        //
        // 720 KB
        //
        Drive->MaxHead      = 1;
        Drive->MaxSector    = 9;
        Drive->MaxCylinder  = 79;
        break;

      case 0x04:
        //
        // 1.44MB
        //
        Drive->MaxHead      = 1;
        Drive->MaxSector    = 18;
        Drive->MaxCylinder  = 79;
        break;

      case 0x06:
        //
        // 2.88MB
        //
        Drive->MaxHead      = 1;
        Drive->MaxSector    = 36;
        Drive->MaxCylinder  = 79;
        break;

      case 0x0C:
        //
        // 360 KB
        //
        Drive->MaxHead      = 1;
        Drive->MaxSector    = 9;
        Drive->MaxCylinder  = 39;
        break;

      case 0x0D:
        //
        // 1.2 MB
        //
        Drive->MaxHead      = 1;
        Drive->MaxSector    = 15;
        Drive->MaxCylinder  = 79;
        break;

      case 0x0E:
        //
        // Toshiba 3 mode
        //
      case 0x0F:
        //
        // NEC 3 mode
        //
      case 0x10:
        //
        // Default Media
        //
        if ((Drive->Parameters.Flags & EDD_GEOMETRY_VALID) == EDD_GEOMETRY_VALID) {
          Drive->MaxHead    = (UINT8) (Drive->Parameters.MaxHeads - 1);
          Drive->MaxSector  = (UINT8) Drive->Parameters.SectorsPerTrack;
          ASSERT (Drive->MaxSector != 0);
          Drive->MaxCylinder = (UINT16) (Drive->Parameters.MaxCylinders - 1);
        } else {
          Drive->MaxHead      = 0;
          Drive->MaxSector    = 1;
          Drive->MaxCylinder  = 0;
        }
        break;

      default:
        //
        // Unknown media type.
        //
        Drive->MaxHead      = 0;
        Drive->MaxSector    = 1;
        Drive->MaxCylinder  = 0;
        break;
      }
    }

    Drive->Parameters.PhysicalSectors = (Drive->MaxHead + 1) * Drive->MaxSector * (Drive->MaxCylinder + 1);
    Drive->Parameters.BytesPerSector  = 512;
  }
  //
  // This data comes from the BIOS so it may not allways be valid
  //  since the BIOS may reuse this buffer for future accesses
  //
  PointerMath = EFI_SEGMENT (Drive->Parameters.Fdpt) << 4;
  PointerMath += EFI_OFFSET (Drive->Parameters.Fdpt);
  Drive->FdptPointer = (VOID *) PointerMath;

  return TRUE;
}
//
// Block IO Routines
//

/**
  Read BufferSize bytes from Lba into Buffer.

  @param  This       Indicates a pointer to the calling context.
  @param  MediaId    Id of the media, changes every time the media is replaced.
  @param  Lba        The starting Logical Block Address to read from
  @param  BufferSize Size of Buffer, must be a multiple of device block size.
  @param  Buffer     A pointer to the destination buffer for the data. The caller is
                     responsible for either having implicit or explicit ownership of the buffer.

  @retval EFI_SUCCESS           The data was read correctly from the device.
  @retval EFI_DEVICE_ERROR      The device reported an error while performing the read.
  @retval EFI_NO_MEDIA          There is no media in the device.
  @retval EFI_MEDIA_CHANGED     The MediaId does not matched the current device.
  @retval EFI_BAD_BUFFER_SIZE   The Buffer was not a multiple of the block size of the device.
  @retval EFI_INVALID_PARAMETER The read request contains LBAs that are not valid,
                                or the buffer is not on proper alignment.

**/
EFI_STATUS
EFIAPI
Edd30BiosReadBlocks (
  IN  EFI_BLOCK_IO_PROTOCOL *This,
  IN  UINT32                MediaId,
  IN  EFI_LBA               Lba,
  IN  UINTN                 BufferSize,
  OUT VOID                  *Buffer
  )
{
  EFI_BLOCK_IO_MEDIA        *Media;
  BIOS_BLOCK_IO_DEV         *BiosBlockIoDev;
  EDD_DEVICE_ADDRESS_PACKET *AddressPacket;
  //
  // I exist only for readability
  //
  EFI_IA32_REGISTER_SET     Regs;
  UINT64                    TransferBuffer;
  UINTN                     NumberOfBlocks;
  UINTN                     TransferByteSize;
  UINTN                     BlockSize;
  BIOS_LEGACY_DRIVE         *Bios;
  UINTN                     CarryFlag;
  UINTN                     MaxTransferBlocks;
  EFI_BLOCK_IO_PROTOCOL     *BlockIo;

  Media     = This->Media;
  BlockSize = Media->BlockSize;

  ZeroMem (&Regs, sizeof (EFI_IA32_REGISTER_SET));

  if (MediaId != Media->MediaId) {
    return EFI_MEDIA_CHANGED;
  }

  if (Lba > Media->LastBlock) {
    return EFI_INVALID_PARAMETER;
  }

  if ((Lba + (BufferSize / BlockSize) - 1) > Media->LastBlock) {
    return EFI_INVALID_PARAMETER;
  }

  if (BufferSize % BlockSize != 0) {
    return EFI_BAD_BUFFER_SIZE;
  }

  if (Buffer == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  if (BufferSize == 0) {
    return EFI_SUCCESS;
  }

  BiosBlockIoDev    = BIOS_BLOCK_IO_FROM_THIS (This);
  AddressPacket     = mEddBufferUnder1Mb;

  MaxTransferBlocks = MAX_EDD11_XFER / BlockSize;

  TransferBuffer    = (UINT64)(UINTN) Buffer;
  for (; BufferSize > 0;) {
    NumberOfBlocks  = BufferSize / BlockSize;
    NumberOfBlocks  = NumberOfBlocks > MaxTransferBlocks ? MaxTransferBlocks : NumberOfBlocks;
    //
    // Max transfer MaxTransferBlocks
    //
    AddressPacket->PacketSizeInBytes  = (UINT8) sizeof (EDD_DEVICE_ADDRESS_PACKET);
    AddressPacket->Zero               = 0;
    AddressPacket->NumberOfBlocks     = (UINT8) NumberOfBlocks;
    AddressPacket->Zero2              = 0;
    AddressPacket->SegOffset          = 0xffffffff;
    AddressPacket->Lba                = (UINT64) Lba;
    AddressPacket->TransferBuffer     = TransferBuffer;

    Regs.H.AH                         = 0x42;
    Regs.H.DL                         = BiosBlockIoDev->Bios.Number;
    Regs.X.SI                         = EFI_OFFSET (AddressPacket);
    Regs.X.DS                         = EFI_SEGMENT (AddressPacket);

    CarryFlag                         = BiosBlockIoDev->LegacyBios->Int86 (BiosBlockIoDev->LegacyBios, 0x13, &Regs);
    DEBUG (
      (
      DEBUG_BLKIO, "Edd30BiosReadBlocks: INT 13 42 DL=%02x : CF=%d AH=%02x\n", BiosBlockIoDev->Bios.Number,
      CarryFlag, Regs.H.AH
      )
      );

    Media->MediaPresent = TRUE;
    if (CarryFlag != 0) {
      //
      // Return Error Status
      //
      BiosBlockIoDev->Bios.ErrorCode = Regs.H.AH;
      if (BiosBlockIoDev->Bios.ErrorCode == BIOS_DISK_CHANGED) {
        Media->MediaId++;
        Bios = &BiosBlockIoDev->Bios;
        if (Int13GetDeviceParameters (BiosBlockIoDev, Bios) != 0) {
          if (Int13Extensions (BiosBlockIoDev, Bios) != 0) {
            Media->LastBlock  = (EFI_LBA) Bios->Parameters.PhysicalSectors - 1;
            Media->BlockSize  = (UINT32) Bios->Parameters.BytesPerSector;
          } else {
            ASSERT (FALSE);
          }

          Media->ReadOnly = FALSE;
          gBS->HandleProtocol (BiosBlockIoDev->Handle, &gEfiBlockIoProtocolGuid, (VOID **) &BlockIo);
          gBS->ReinstallProtocolInterface (BiosBlockIoDev->Handle, &gEfiBlockIoProtocolGuid, BlockIo, BlockIo);
          return EFI_MEDIA_CHANGED;
        }
      }

      if (Media->RemovableMedia) {
        Media->MediaPresent = FALSE;
      }

      return EFI_DEVICE_ERROR;
    }

    TransferByteSize  = NumberOfBlocks * BlockSize;
    BufferSize        = BufferSize - TransferByteSize;
    TransferBuffer += TransferByteSize;
    Lba += NumberOfBlocks;
  }

  return EFI_SUCCESS;
}

/**
  Write BufferSize bytes from Lba into Buffer.

  @param  This       Indicates a pointer to the calling context.
  @param  MediaId    The media ID that the write request is for.
  @param  Lba        The starting logical block address to be written. The caller is
                     responsible for writing to only legitimate locations.
  @param  BufferSize Size of Buffer, must be a multiple of device block size.
  @param  Buffer     A pointer to the source buffer for the data.

  @retval EFI_SUCCESS           The data was written correctly to the device.
  @retval EFI_WRITE_PROTECTED   The device can not be written to.
  @retval EFI_DEVICE_ERROR      The device reported an error while performing the write.
  @retval EFI_NO_MEDIA          There is no media in the device.
  @retval EFI_MEDIA_CHNAGED     The MediaId does not matched the current device.
  @retval EFI_BAD_BUFFER_SIZE   The Buffer was not a multiple of the block size of the device.
  @retval EFI_INVALID_PARAMETER The write request contains LBAs that are not valid,
                                or the buffer is not on proper alignment.

**/
EFI_STATUS
EFIAPI
Edd30BiosWriteBlocks (
  IN  EFI_BLOCK_IO_PROTOCOL *This,
  IN  UINT32                MediaId,
  IN  EFI_LBA               Lba,
  IN  UINTN                 BufferSize,
  OUT VOID                  *Buffer
  )
{
  EFI_BLOCK_IO_MEDIA        *Media;
  BIOS_BLOCK_IO_DEV         *BiosBlockIoDev;
  EDD_DEVICE_ADDRESS_PACKET *AddressPacket;
  //
  // I exist only for readability
  //
  EFI_IA32_REGISTER_SET     Regs;
  UINT64                    TransferBuffer;
  UINTN                     NumberOfBlocks;
  UINTN                     TransferByteSize;
  UINTN                     BlockSize;
  BIOS_LEGACY_DRIVE         *Bios;
  UINTN                     CarryFlag;
  UINTN                     MaxTransferBlocks;
  EFI_BLOCK_IO_PROTOCOL     *BlockIo;

  Media     = This->Media;
  BlockSize = Media->BlockSize;

  ZeroMem (&Regs, sizeof (EFI_IA32_REGISTER_SET));

  if (MediaId != Media->MediaId) {
    return EFI_MEDIA_CHANGED;
  }

  if (Lba > Media->LastBlock) {
    return EFI_DEVICE_ERROR;
  }

  if ((Lba + (BufferSize / BlockSize) - 1) > Media->LastBlock) {
    return EFI_INVALID_PARAMETER;
  }

  if (BufferSize % BlockSize != 0) {
    return EFI_BAD_BUFFER_SIZE;
  }

  if (Buffer == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  if (BufferSize == 0) {
    return EFI_SUCCESS;
  }

  BiosBlockIoDev    = BIOS_BLOCK_IO_FROM_THIS (This);
  AddressPacket     = mEddBufferUnder1Mb;

  MaxTransferBlocks = MAX_EDD11_XFER / BlockSize;

  TransferBuffer    = (UINT64)(UINTN) Buffer;
  for (; BufferSize > 0;) {
    NumberOfBlocks  = BufferSize / BlockSize;
    NumberOfBlocks  = NumberOfBlocks > MaxTransferBlocks ? MaxTransferBlocks : NumberOfBlocks;
    //
    // Max transfer MaxTransferBlocks
    //
    AddressPacket->PacketSizeInBytes  = (UINT8) sizeof (EDD_DEVICE_ADDRESS_PACKET);
    AddressPacket->Zero               = 0;
    AddressPacket->NumberOfBlocks     = (UINT8) NumberOfBlocks;
    AddressPacket->Zero2              = 0;
    AddressPacket->SegOffset          = 0xffffffff;
    AddressPacket->Lba                = (UINT64) Lba;
    AddressPacket->TransferBuffer     = TransferBuffer;

    Regs.H.AH                         = 0x43;
    Regs.H.AL                         = 0x00;
    //
    // Write Verify Off
    //
    Regs.H.DL = (UINT8) (BiosBlockIoDev->Bios.Number);
    Regs.X.SI = EFI_OFFSET (AddressPacket);
    Regs.X.DS = EFI_SEGMENT (AddressPacket);

    CarryFlag = BiosBlockIoDev->LegacyBios->Int86 (BiosBlockIoDev->LegacyBios, 0x13, &Regs);
    DEBUG (
      (
      DEBUG_BLKIO, "Edd30BiosWriteBlocks: INT 13 43 DL=%02x : CF=%d AH=%02x\n", BiosBlockIoDev->Bios.Number,
      CarryFlag, Regs.H.AH
      )
      );

    Media->MediaPresent = TRUE;
    if (CarryFlag != 0) {
      //
      // Return Error Status
      //
      BiosBlockIoDev->Bios.ErrorCode = Regs.H.AH;
      if (BiosBlockIoDev->Bios.ErrorCode == BIOS_DISK_CHANGED) {
        Media->MediaId++;
        Bios = &BiosBlockIoDev->Bios;
        if (Int13GetDeviceParameters (BiosBlockIoDev, Bios) != 0) {
          if (Int13Extensions (BiosBlockIoDev, Bios) != 0) {
            Media->LastBlock  = (EFI_LBA) Bios->Parameters.PhysicalSectors - 1;
            Media->BlockSize  = (UINT32) Bios->Parameters.BytesPerSector;
          } else {
            ASSERT (FALSE);
          }

          Media->ReadOnly = FALSE;
          gBS->HandleProtocol (BiosBlockIoDev->Handle, &gEfiBlockIoProtocolGuid, (VOID **) &BlockIo);
          gBS->ReinstallProtocolInterface (BiosBlockIoDev->Handle, &gEfiBlockIoProtocolGuid, BlockIo, BlockIo);
          return EFI_MEDIA_CHANGED;
        }
      } else if (BiosBlockIoDev->Bios.ErrorCode == BIOS_WRITE_PROTECTED) {
        Media->ReadOnly = TRUE;
        return EFI_WRITE_PROTECTED;
      }

      if (Media->RemovableMedia) {
        Media->MediaPresent = FALSE;
      }

      return EFI_DEVICE_ERROR;
    }

    Media->ReadOnly   = FALSE;
    TransferByteSize  = NumberOfBlocks * BlockSize;
    BufferSize        = BufferSize - TransferByteSize;
    TransferBuffer += TransferByteSize;
    Lba += NumberOfBlocks;
  }

  return EFI_SUCCESS;
}

/**
  Flush the Block Device.

  @param  This              Indicates a pointer to the calling context.

  @retval EFI_SUCCESS       All outstanding data was written to the device
  @retval EFI_DEVICE_ERROR  The device reported an error while writting back the data
  @retval EFI_NO_MEDIA      There is no media in the device.

**/
EFI_STATUS
EFIAPI
BiosBlockIoFlushBlocks (
  IN  EFI_BLOCK_IO_PROTOCOL  *This
  )
{
  return EFI_SUCCESS;
}

/**
  Reset the Block Device.

  @param  This                 Indicates a pointer to the calling context.
  @param  ExtendedVerification Driver may perform diagnostics on reset.

  @retval EFI_SUCCESS          The device was reset.
  @retval EFI_DEVICE_ERROR     The device is not functioning properly and could
                               not be reset.

**/
EFI_STATUS
EFIAPI
BiosBlockIoReset (
  IN  EFI_BLOCK_IO_PROTOCOL *This,
  IN  BOOLEAN               ExtendedVerification
  )
{
  BIOS_BLOCK_IO_DEV     *BiosBlockIoDev;
  EFI_IA32_REGISTER_SET Regs;
  UINTN                 CarryFlag;

  BiosBlockIoDev  = BIOS_BLOCK_IO_FROM_THIS (This);

  ZeroMem (&Regs, sizeof (EFI_IA32_REGISTER_SET));

  Regs.H.AH       = 0x00;
  Regs.H.DL       = BiosBlockIoDev->Bios.Number;
  CarryFlag       = BiosBlockIoDev->LegacyBios->Int86 (BiosBlockIoDev->LegacyBios, 0x13, &Regs);
  DEBUG (
    (
    DEBUG_INIT, "BiosBlockIoReset: INT 13 00 DL=%02x : CF=%d AH=%02x\n", BiosBlockIoDev->Bios.Number, CarryFlag,
    Regs.H.AH
    )
    );
  if (CarryFlag != 0) {
    if (Regs.H.AL == BIOS_RESET_FAILED) {
      Regs.H.AH = 0x00;
      Regs.H.DL = BiosBlockIoDev->Bios.Number;
      CarryFlag = BiosBlockIoDev->LegacyBios->Int86 (BiosBlockIoDev->LegacyBios, 0x13, &Regs);
      DEBUG (
        (
        DEBUG_INIT, "BiosBlockIoReset: INT 13 00 DL=%02x : CF=%d AH=%02x\n", BiosBlockIoDev->Bios.Number, CarryFlag,
        Regs.H.AH
        )
        );
      if (CarryFlag != 0) {
        BiosBlockIoDev->Bios.ErrorCode = Regs.H.AH;
        return EFI_DEVICE_ERROR;
      }
    }
  }

  return EFI_SUCCESS;
}
//
//
// These functions need to double buffer all data under 1MB!
//
//

/**
  Read BufferSize bytes from Lba into Buffer.

  @param  This       Indicates a pointer to the calling context.
  @param  MediaId    Id of the media, changes every time the media is replaced.
  @param  Lba        The starting Logical Block Address to read from
  @param  BufferSize Size of Buffer, must be a multiple of device block size.
  @param  Buffer     A pointer to the destination buffer for the data. The caller is
                     responsible for either having implicit or explicit ownership of the buffer.

  @retval EFI_SUCCESS           The data was read correctly from the device.
  @retval EFI_DEVICE_ERROR      The device reported an error while performing the read.
  @retval EFI_NO_MEDIA          There is no media in the device.
  @retval EFI_MEDIA_CHANGED     The MediaId does not matched the current device.
  @retval EFI_BAD_BUFFER_SIZE   The Buffer was not a multiple of the block size of the device.
  @retval EFI_INVALID_PARAMETER The read request contains LBAs that are not valid,
                                or the buffer is not on proper alignment.

**/
EFI_STATUS
EFIAPI
Edd11BiosReadBlocks (
  IN  EFI_BLOCK_IO_PROTOCOL *This,
  IN  UINT32                MediaId,
  IN  EFI_LBA               Lba,
  IN  UINTN                 BufferSize,
  OUT VOID                  *Buffer
  )
{
  EFI_BLOCK_IO_MEDIA        *Media;
  BIOS_BLOCK_IO_DEV         *BiosBlockIoDev;
  EDD_DEVICE_ADDRESS_PACKET *AddressPacket;
  //
  // I exist only for readability
  //
  EFI_IA32_REGISTER_SET     Regs;
  UINT64                    TransferBuffer;
  UINTN                     NumberOfBlocks;
  UINTN                     TransferByteSize;
  UINTN                     BlockSize;
  BIOS_LEGACY_DRIVE         *Bios;
  UINTN                     CarryFlag;
  UINTN                     MaxTransferBlocks;
  EFI_BLOCK_IO_PROTOCOL     *BlockIo;

  Media     = This->Media;
  BlockSize = Media->BlockSize;

  ZeroMem (&Regs, sizeof (EFI_IA32_REGISTER_SET));

  if (MediaId != Media->MediaId) {
    return EFI_MEDIA_CHANGED;
  }

  if (Lba > Media->LastBlock) {
    return EFI_INVALID_PARAMETER;
  }

  if ((Lba + (BufferSize / BlockSize) - 1) > Media->LastBlock) {
    return EFI_INVALID_PARAMETER;
  }

  if (BufferSize % BlockSize != 0) {
    return EFI_BAD_BUFFER_SIZE;
  }

  if (Buffer == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  if (BufferSize == 0) {
    return EFI_SUCCESS;
  }

  BiosBlockIoDev    = BIOS_BLOCK_IO_FROM_THIS (This);
  AddressPacket     = mEddBufferUnder1Mb;

  MaxTransferBlocks = MAX_EDD11_XFER / BlockSize;

  TransferBuffer    = (UINT64)(UINTN) mEdd11Buffer;
  for (; BufferSize > 0;) {
    NumberOfBlocks  = BufferSize / BlockSize;
    NumberOfBlocks  = NumberOfBlocks > MaxTransferBlocks ? MaxTransferBlocks : NumberOfBlocks;
    //
    // Max transfer MaxTransferBlocks
    //
    AddressPacket->PacketSizeInBytes  = (UINT8) sizeof (EDD_DEVICE_ADDRESS_PACKET);
    AddressPacket->Zero               = 0;
    AddressPacket->NumberOfBlocks     = (UINT8) NumberOfBlocks;
    AddressPacket->Zero2              = 0;
    //
    // TransferBuffer has been 4KB alignment. Normalize TransferBuffer to make offset as 0 in seg:offset
    // format to transfer maximum 127 blocks of data.
    // Otherwise when offset adding data size exceeds 0xFFFF, if OpROM does not normalize TransferBuffer,
    // INT13 function 42H will return data boundary error 09H.
    //
    AddressPacket->SegOffset = (UINT32) LShiftU64 (RShiftU64(TransferBuffer, 4), 16);
    AddressPacket->Lba  = (UINT64) Lba;

    Regs.H.AH           = 0x42;
    Regs.H.DL           = BiosBlockIoDev->Bios.Number;
    Regs.X.SI           = EFI_OFFSET (AddressPacket);
    Regs.X.DS           = EFI_SEGMENT (AddressPacket);

    CarryFlag           = BiosBlockIoDev->LegacyBios->Int86 (BiosBlockIoDev->LegacyBios, 0x13, &Regs);
    DEBUG (
      (
      DEBUG_BLKIO, "Edd11BiosReadBlocks: INT 13 42 DL=%02x : CF=%d AH=%02x : LBA 0x%lx  Block(s) %0d \n",
      BiosBlockIoDev->Bios.Number, CarryFlag, Regs.H.AH, Lba, NumberOfBlocks
      )
      );
    Media->MediaPresent = TRUE;
    if (CarryFlag != 0) {
      //
      // Return Error Status
      //
      BiosBlockIoDev->Bios.ErrorCode = Regs.H.AH;
      if (BiosBlockIoDev->Bios.ErrorCode == BIOS_DISK_CHANGED) {
        Media->MediaId++;
        Bios = &BiosBlockIoDev->Bios;
        if (Int13GetDeviceParameters (BiosBlockIoDev, Bios) != 0) {
          if (Int13Extensions (BiosBlockIoDev, Bios) != 0) {
            Media->LastBlock  = (EFI_LBA) Bios->Parameters.PhysicalSectors - 1;
            Media->BlockSize  = (UINT32) Bios->Parameters.BytesPerSector;
          } else {
            ASSERT (FALSE);
          }

          Media->ReadOnly = FALSE;
          gBS->HandleProtocol (BiosBlockIoDev->Handle, &gEfiBlockIoProtocolGuid, (VOID **) &BlockIo);
          gBS->ReinstallProtocolInterface (BiosBlockIoDev->Handle, &gEfiBlockIoProtocolGuid, BlockIo, BlockIo);
          return EFI_MEDIA_CHANGED;
        }
      }

      if (Media->RemovableMedia) {
        Media->MediaPresent = FALSE;
      }

      return EFI_DEVICE_ERROR;
    }

    TransferByteSize = NumberOfBlocks * BlockSize;
    CopyMem (Buffer, (VOID *) (UINTN) TransferBuffer, TransferByteSize);
    BufferSize  = BufferSize - TransferByteSize;
    Buffer      = (VOID *) ((UINT8 *) Buffer + TransferByteSize);
    Lba += NumberOfBlocks;
  }

  return EFI_SUCCESS;
}

/**
  Write BufferSize bytes from Lba into Buffer.

  @param  This       Indicates a pointer to the calling context.
  @param  MediaId    The media ID that the write request is for.
  @param  Lba        The starting logical block address to be written. The caller is
                     responsible for writing to only legitimate locations.
  @param  BufferSize Size of Buffer, must be a multiple of device block size.
  @param  Buffer     A pointer to the source buffer for the data.

  @retval EFI_SUCCESS           The data was written correctly to the device.
  @retval EFI_WRITE_PROTECTED   The device can not be written to.
  @retval EFI_DEVICE_ERROR      The device reported an error while performing the write.
  @retval EFI_NO_MEDIA          There is no media in the device.
  @retval EFI_MEDIA_CHNAGED     The MediaId does not matched the current device.
  @retval EFI_BAD_BUFFER_SIZE   The Buffer was not a multiple of the block size of the device.
  @retval EFI_INVALID_PARAMETER The write request contains LBAs that are not valid,
                                or the buffer is not on proper alignment.

**/
EFI_STATUS
EFIAPI
Edd11BiosWriteBlocks (
  IN  EFI_BLOCK_IO_PROTOCOL *This,
  IN  UINT32                MediaId,
  IN  EFI_LBA               Lba,
  IN  UINTN                 BufferSize,
  OUT VOID                  *Buffer
  )
{
  EFI_BLOCK_IO_MEDIA        *Media;
  BIOS_BLOCK_IO_DEV         *BiosBlockIoDev;
  EDD_DEVICE_ADDRESS_PACKET *AddressPacket;
  //
  // I exist only for readability
  //
  EFI_IA32_REGISTER_SET     Regs;
  UINT64                    TransferBuffer;
  UINTN                     NumberOfBlocks;
  UINTN                     TransferByteSize;
  UINTN                     BlockSize;
  BIOS_LEGACY_DRIVE         *Bios;
  UINTN                     CarryFlag;
  UINTN                     MaxTransferBlocks;
  EFI_BLOCK_IO_PROTOCOL     *BlockIo;

  Media     = This->Media;
  BlockSize = Media->BlockSize;

  ZeroMem (&Regs, sizeof (EFI_IA32_REGISTER_SET));

  if (MediaId != Media->MediaId) {
    return EFI_MEDIA_CHANGED;
  }

  if (Lba > Media->LastBlock) {
    return EFI_INVALID_PARAMETER;
  }

  if ((Lba + (BufferSize / BlockSize) - 1) > Media->LastBlock) {
    return EFI_INVALID_PARAMETER;
  }

  if (BufferSize % BlockSize != 0) {
    return EFI_BAD_BUFFER_SIZE;
  }

  if (Buffer == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  if (BufferSize == 0) {
    return EFI_SUCCESS;
  }

  BiosBlockIoDev    = BIOS_BLOCK_IO_FROM_THIS (This);
  AddressPacket     = mEddBufferUnder1Mb;

  MaxTransferBlocks = MAX_EDD11_XFER / BlockSize;

  TransferBuffer    = (UINT64)(UINTN) mEdd11Buffer;
  for (; BufferSize > 0;) {
    NumberOfBlocks  = BufferSize / BlockSize;
    NumberOfBlocks  = NumberOfBlocks > MaxTransferBlocks ? MaxTransferBlocks : NumberOfBlocks;
    //
    // Max transfer MaxTransferBlocks
    //
    AddressPacket->PacketSizeInBytes  = (UINT8) sizeof (EDD_DEVICE_ADDRESS_PACKET);
    AddressPacket->Zero               = 0;
    AddressPacket->NumberOfBlocks     = (UINT8) NumberOfBlocks;
    AddressPacket->Zero2              = 0;
    //
    // TransferBuffer has been 4KB alignment. Normalize TransferBuffer to make offset as 0 in seg:offset
    // format to transfer maximum 127 blocks of data.
    // Otherwise when offset adding data size exceeds 0xFFFF, if OpROM does not normalize TransferBuffer,
    // INT13 function 42H will return data boundary error 09H.
    //
    AddressPacket->SegOffset = (UINT32) LShiftU64 (RShiftU64(TransferBuffer, 4), 16);
    AddressPacket->Lba  = (UINT64) Lba;

    Regs.H.AH           = 0x43;
    Regs.H.AL           = 0x00;
    //
    // Write Verify disable
    //
    Regs.H.DL         = BiosBlockIoDev->Bios.Number;
    Regs.X.SI         = EFI_OFFSET (AddressPacket);
    Regs.X.DS         = EFI_SEGMENT (AddressPacket);

    TransferByteSize  = NumberOfBlocks * BlockSize;
    CopyMem ((VOID *) (UINTN) TransferBuffer, Buffer, TransferByteSize);

    CarryFlag = BiosBlockIoDev->LegacyBios->Int86 (BiosBlockIoDev->LegacyBios, 0x13, &Regs);
    DEBUG (
      (
      DEBUG_BLKIO, "Edd11BiosWriteBlocks: INT 13 43 DL=%02x : CF=%d AH=%02x\n: LBA 0x%lx  Block(s) %0d \n",
      BiosBlockIoDev->Bios.Number, CarryFlag, Regs.H.AH, Lba, NumberOfBlocks
      )
      );
    Media->MediaPresent = TRUE;
    if (CarryFlag != 0) {
      //
      // Return Error Status
      //
      BiosBlockIoDev->Bios.ErrorCode = Regs.H.AH;
      if (BiosBlockIoDev->Bios.ErrorCode == BIOS_DISK_CHANGED) {
        Media->MediaId++;
        Bios = &BiosBlockIoDev->Bios;
        if (Int13GetDeviceParameters (BiosBlockIoDev, Bios) != 0) {
          if (Int13Extensions (BiosBlockIoDev, Bios) != 0) {
            Media->LastBlock  = (EFI_LBA) Bios->Parameters.PhysicalSectors - 1;
            Media->BlockSize  = (UINT32) Bios->Parameters.BytesPerSector;
          } else {
            ASSERT (FALSE);
          }

          Media->ReadOnly = FALSE;
          gBS->HandleProtocol (BiosBlockIoDev->Handle, &gEfiBlockIoProtocolGuid, (VOID **) &BlockIo);
          gBS->ReinstallProtocolInterface (BiosBlockIoDev->Handle, &gEfiBlockIoProtocolGuid, BlockIo, BlockIo);
          return EFI_MEDIA_CHANGED;
        }
      } else if (BiosBlockIoDev->Bios.ErrorCode == BIOS_WRITE_PROTECTED) {
        Media->ReadOnly = TRUE;
        return EFI_WRITE_PROTECTED;
      }

      if (Media->RemovableMedia) {
        Media->MediaPresent = FALSE;
      }

      return EFI_DEVICE_ERROR;
    }

    Media->ReadOnly = FALSE;
    BufferSize      = BufferSize - TransferByteSize;
    Buffer          = (VOID *) ((UINT8 *) Buffer + TransferByteSize);
    Lba += NumberOfBlocks;
  }

  return EFI_SUCCESS;
}

/**
  Read BufferSize bytes from Lba into Buffer.

  @param  This       Indicates a pointer to the calling context.
  @param  MediaId    Id of the media, changes every time the media is replaced.
  @param  Lba        The starting Logical Block Address to read from
  @param  BufferSize Size of Buffer, must be a multiple of device block size.
  @param  Buffer     A pointer to the destination buffer for the data. The caller is
                     responsible for either having implicit or explicit ownership of the buffer.

  @retval EFI_SUCCESS           The data was read correctly from the device.
  @retval EFI_DEVICE_ERROR      The device reported an error while performing the read.
  @retval EFI_NO_MEDIA          There is no media in the device.
  @retval EFI_MEDIA_CHANGED     The MediaId does not matched the current device.
  @retval EFI_BAD_BUFFER_SIZE   The Buffer was not a multiple of the block size of the device.
  @retval EFI_INVALID_PARAMETER The read request contains LBAs that are not valid,
                                or the buffer is not on proper alignment.

**/
EFI_STATUS
EFIAPI
BiosReadLegacyDrive (
  IN  EFI_BLOCK_IO_PROTOCOL *This,
  IN  UINT32                MediaId,
  IN  EFI_LBA               Lba,
  IN  UINTN                 BufferSize,
  OUT VOID                  *Buffer
  )
{
  EFI_BLOCK_IO_MEDIA    *Media;
  BIOS_BLOCK_IO_DEV     *BiosBlockIoDev;
  EFI_IA32_REGISTER_SET Regs;
  UINTN                 UpperCylinder;
  UINTN                 Temp;
  UINTN                 Cylinder;
  UINTN                 Head;
  UINTN                 Sector;
  UINTN                 NumberOfBlocks;
  UINTN                 TransferByteSize;
  UINTN                 ShortLba;
  UINTN                 CheckLba;
  UINTN                 BlockSize;
  BIOS_LEGACY_DRIVE     *Bios;
  UINTN                 CarryFlag;
  UINTN                 Retry;
  EFI_BLOCK_IO_PROTOCOL *BlockIo;

  Media     = This->Media;
  BlockSize = Media->BlockSize;

  ZeroMem (&Regs, sizeof (EFI_IA32_REGISTER_SET));

  if (MediaId != Media->MediaId) {
    return EFI_MEDIA_CHANGED;
  }

  if (Lba > Media->LastBlock) {
    return EFI_INVALID_PARAMETER;
  }

  if ((Lba + (BufferSize / BlockSize) - 1) > Media->LastBlock) {
    return EFI_INVALID_PARAMETER;
  }

  if (BufferSize % BlockSize != 0) {
    return EFI_BAD_BUFFER_SIZE;
  }

  if (Buffer == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  if (BufferSize == 0) {
    return EFI_SUCCESS;
  }

  BiosBlockIoDev  = BIOS_BLOCK_IO_FROM_THIS (This);
  ShortLba        = (UINTN) Lba;

  while (BufferSize != 0) {
    //
    // Compute I/O location in Sector, Head, Cylinder format
    //
    Sector    = (ShortLba % BiosBlockIoDev->Bios.MaxSector) + 1;
    Temp      = ShortLba / BiosBlockIoDev->Bios.MaxSector;
    Head      = Temp % (BiosBlockIoDev->Bios.MaxHead + 1);
    Cylinder  = Temp / (BiosBlockIoDev->Bios.MaxHead + 1);

    //
    // Limit transfer to this Head & Cylinder
    //
    NumberOfBlocks  = BufferSize / BlockSize;
    Temp            = BiosBlockIoDev->Bios.MaxSector - Sector + 1;
    NumberOfBlocks  = NumberOfBlocks > Temp ? Temp : NumberOfBlocks;

    Retry           = 3;
    do {
      //
      // Perform the IO
      //
      Regs.H.AH     = 2;
      Regs.H.AL     = (UINT8) NumberOfBlocks;
      Regs.H.DL     = BiosBlockIoDev->Bios.Number;

      UpperCylinder = (Cylinder & 0x0f00) >> 2;

      CheckLba      = Cylinder * (BiosBlockIoDev->Bios.MaxHead + 1) + Head;
      CheckLba      = CheckLba * BiosBlockIoDev->Bios.MaxSector + Sector - 1;

      DEBUG (
        (DEBUG_BLKIO,
        "RLD: LBA %x (%x), Sector %x (%x), Head %x (%x), Cyl %x, UCyl %x\n",
        ShortLba,
        CheckLba,
        Sector,
        BiosBlockIoDev->Bios.MaxSector,
        Head,
        BiosBlockIoDev->Bios.MaxHead,
        Cylinder,
        UpperCylinder)
        );
      ASSERT (CheckLba == ShortLba);

      Regs.H.CL = (UINT8) ((Sector & 0x3f) + (UpperCylinder & 0xff));
      Regs.H.DH = (UINT8) (Head & 0x3f);
      Regs.H.CH = (UINT8) (Cylinder & 0xff);

      Regs.X.BX = EFI_OFFSET (mEdd11Buffer);
      Regs.X.ES = EFI_SEGMENT (mEdd11Buffer);

      DEBUG (
        (DEBUG_BLKIO,
        "INT 13h: AX:(02%02x) DX:(%02x%02x) CX:(%02x%02x) BX:(%04x) ES:(%04x)\n",
        Regs.H.AL,
        (UINT8) (Head & 0x3f),
        Regs.H.DL,
        (UINT8) (Cylinder & 0xff),
        (UINT8) ((Sector & 0x3f) + (UpperCylinder & 0xff)),
        EFI_OFFSET (mEdd11Buffer),
        EFI_SEGMENT (mEdd11Buffer))
        );

      CarryFlag = BiosBlockIoDev->LegacyBios->Int86 (BiosBlockIoDev->LegacyBios, 0x13, &Regs);
      DEBUG (
        (
        DEBUG_BLKIO, "BiosReadLegacyDrive: INT 13 02 DL=%02x : CF=%d AH=%02x\n", BiosBlockIoDev->Bios.Number,
        CarryFlag, Regs.H.AH
        )
        );
      Retry--;
    } while (CarryFlag != 0 && Retry != 0 && Regs.H.AH != BIOS_DISK_CHANGED);

    Media->MediaPresent = TRUE;
    if (CarryFlag != 0) {
      //
      // Return Error Status
      //
      BiosBlockIoDev->Bios.ErrorCode = Regs.H.AH;
      if (BiosBlockIoDev->Bios.ErrorCode == BIOS_DISK_CHANGED) {
        Media->MediaId++;
        Bios = &BiosBlockIoDev->Bios;
        if (Int13GetDeviceParameters (BiosBlockIoDev, Bios) != 0) {
          //
          // If the size of the media changed we need to reset the disk geometry
          //
          if (Int13Extensions (BiosBlockIoDev, Bios) != 0) {
            Media->LastBlock  = (EFI_LBA) Bios->Parameters.PhysicalSectors - 1;
            Media->BlockSize  = (UINT32) Bios->Parameters.BytesPerSector;
          } else {
            //
            // Legacy Interfaces
            //
            Media->LastBlock  = (Bios->MaxHead + 1) * Bios->MaxSector * (Bios->MaxCylinder + 1) - 1;
            Media->BlockSize  = 512;
          }

          Media->ReadOnly = FALSE;
          gBS->HandleProtocol (BiosBlockIoDev->Handle, &gEfiBlockIoProtocolGuid, (VOID **) &BlockIo);
          gBS->ReinstallProtocolInterface (BiosBlockIoDev->Handle, &gEfiBlockIoProtocolGuid, BlockIo, BlockIo);
          return EFI_MEDIA_CHANGED;
        }
      }

      if (Media->RemovableMedia) {
        Media->MediaPresent = FALSE;
      }

      return EFI_DEVICE_ERROR;
    }

    TransferByteSize = NumberOfBlocks * BlockSize;
    CopyMem (Buffer, mEdd11Buffer, TransferByteSize);

    ShortLba    = ShortLba + NumberOfBlocks;
    BufferSize  = BufferSize - TransferByteSize;
    Buffer      = (VOID *) ((UINT8 *) Buffer + TransferByteSize);
  }

  return EFI_SUCCESS;
}

/**
  Write BufferSize bytes from Lba into Buffer.

  @param  This       Indicates a pointer to the calling context.
  @param  MediaId    The media ID that the write request is for.
  @param  Lba        The starting logical block address to be written. The caller is
                     responsible for writing to only legitimate locations.
  @param  BufferSize Size of Buffer, must be a multiple of device block size.
  @param  Buffer     A pointer to the source buffer for the data.

  @retval EFI_SUCCESS           The data was written correctly to the device.
  @retval EFI_WRITE_PROTECTED   The device can not be written to.
  @retval EFI_DEVICE_ERROR      The device reported an error while performing the write.
  @retval EFI_NO_MEDIA          There is no media in the device.
  @retval EFI_MEDIA_CHNAGED     The MediaId does not matched the current device.
  @retval EFI_BAD_BUFFER_SIZE   The Buffer was not a multiple of the block size of the device.
  @retval EFI_INVALID_PARAMETER The write request contains LBAs that are not valid,
                                or the buffer is not on proper alignment.

**/
EFI_STATUS
EFIAPI
BiosWriteLegacyDrive (
  IN  EFI_BLOCK_IO_PROTOCOL *This,
  IN  UINT32                MediaId,
  IN  EFI_LBA               Lba,
  IN  UINTN                 BufferSize,
  OUT VOID                  *Buffer
  )
{
  EFI_BLOCK_IO_MEDIA    *Media;
  BIOS_BLOCK_IO_DEV     *BiosBlockIoDev;
  EFI_IA32_REGISTER_SET Regs;
  UINTN                 UpperCylinder;
  UINTN                 Temp;
  UINTN                 Cylinder;
  UINTN                 Head;
  UINTN                 Sector;
  UINTN                 NumberOfBlocks;
  UINTN                 TransferByteSize;
  UINTN                 ShortLba;
  UINTN                 CheckLba;
  UINTN                 BlockSize;
  BIOS_LEGACY_DRIVE     *Bios;
  UINTN                 CarryFlag;
  UINTN                 Retry;
  EFI_BLOCK_IO_PROTOCOL *BlockIo;

  Media     = This->Media;
  BlockSize = Media->BlockSize;

  ZeroMem (&Regs, sizeof (EFI_IA32_REGISTER_SET));

  if (MediaId != Media->MediaId) {
    return EFI_MEDIA_CHANGED;
  }

  if (Lba > Media->LastBlock) {
    return EFI_INVALID_PARAMETER;
  }

  if ((Lba + (BufferSize / BlockSize) - 1) > Media->LastBlock) {
    return EFI_INVALID_PARAMETER;
  }

  if (BufferSize % BlockSize != 0) {
    return EFI_BAD_BUFFER_SIZE;
  }

  if (Buffer == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  if (BufferSize == 0) {
    return EFI_SUCCESS;
  }

  BiosBlockIoDev  = BIOS_BLOCK_IO_FROM_THIS (This);
  ShortLba        = (UINTN) Lba;

  while (BufferSize != 0) {
    //
    // Compute I/O location in Sector, Head, Cylinder format
    //
    Sector    = (ShortLba % BiosBlockIoDev->Bios.MaxSector) + 1;
    Temp      = ShortLba / BiosBlockIoDev->Bios.MaxSector;
    Head      = Temp % (BiosBlockIoDev->Bios.MaxHead + 1);
    Cylinder  = Temp / (BiosBlockIoDev->Bios.MaxHead + 1);

    //
    // Limit transfer to this Head & Cylinder
    //
    NumberOfBlocks  = BufferSize / BlockSize;
    Temp            = BiosBlockIoDev->Bios.MaxSector - Sector + 1;
    NumberOfBlocks  = NumberOfBlocks > Temp ? Temp : NumberOfBlocks;

    Retry           = 3;
    do {
      //
      // Perform the IO
      //
      Regs.H.AH     = 3;
      Regs.H.AL     = (UINT8) NumberOfBlocks;
      Regs.H.DL     = BiosBlockIoDev->Bios.Number;

      UpperCylinder = (Cylinder & 0x0f00) >> 2;

      CheckLba      = Cylinder * (BiosBlockIoDev->Bios.MaxHead + 1) + Head;
      CheckLba      = CheckLba * BiosBlockIoDev->Bios.MaxSector + Sector - 1;

      DEBUG (
        (DEBUG_BLKIO,
        "RLD: LBA %x (%x), Sector %x (%x), Head %x (%x), Cyl %x, UCyl %x\n",
        ShortLba,
        CheckLba,
        Sector,
        BiosBlockIoDev->Bios.MaxSector,
        Head,
        BiosBlockIoDev->Bios.MaxHead,
        Cylinder,
        UpperCylinder)
        );
      ASSERT (CheckLba == ShortLba);

      Regs.H.CL         = (UINT8) ((Sector & 0x3f) + (UpperCylinder & 0xff));
      Regs.H.DH         = (UINT8) (Head & 0x3f);
      Regs.H.CH         = (UINT8) (Cylinder & 0xff);

      Regs.X.BX         = EFI_OFFSET (mEdd11Buffer);
      Regs.X.ES         = EFI_SEGMENT (mEdd11Buffer);

      TransferByteSize  = NumberOfBlocks * BlockSize;
      CopyMem (mEdd11Buffer, Buffer, TransferByteSize);

      DEBUG (
        (DEBUG_BLKIO,
        "INT 13h: AX:(03%02x) DX:(%02x%02x) CX:(%02x%02x) BX:(%04x) ES:(%04x)\n",
        Regs.H.AL,
        (UINT8) (Head & 0x3f),
        Regs.H.DL,
        (UINT8) (Cylinder & 0xff),
        (UINT8) ((Sector & 0x3f) + (UpperCylinder & 0xff)),
        EFI_OFFSET (mEdd11Buffer),
        EFI_SEGMENT (mEdd11Buffer))
        );

      CarryFlag = BiosBlockIoDev->LegacyBios->Int86 (BiosBlockIoDev->LegacyBios, 0x13, &Regs);
      DEBUG (
        (
        DEBUG_BLKIO, "BiosWriteLegacyDrive: INT 13 03 DL=%02x : CF=%d AH=%02x\n", BiosBlockIoDev->Bios.Number,
        CarryFlag, Regs.H.AH
        )
        );
      Retry--;
    } while (CarryFlag != 0 && Retry != 0 && Regs.H.AH != BIOS_DISK_CHANGED);

    Media->MediaPresent = TRUE;
    if (CarryFlag != 0) {
      //
      // Return Error Status
      //
      BiosBlockIoDev->Bios.ErrorCode = Regs.H.AH;
      if (BiosBlockIoDev->Bios.ErrorCode == BIOS_DISK_CHANGED) {
        Media->MediaId++;
        Bios = &BiosBlockIoDev->Bios;
        if (Int13GetDeviceParameters (BiosBlockIoDev, Bios) != 0) {
          if (Int13Extensions (BiosBlockIoDev, Bios) != 0) {
            Media->LastBlock  = (EFI_LBA) Bios->Parameters.PhysicalSectors - 1;
            Media->BlockSize  = (UINT32) Bios->Parameters.BytesPerSector;
          } else {
            //
            // Legacy Interfaces
            //
            Media->LastBlock  = (Bios->MaxHead + 1) * Bios->MaxSector * (Bios->MaxCylinder + 1) - 1;
            Media->BlockSize  = 512;
          }
          //
          // If the size of the media changed we need to reset the disk geometry
          //
          Media->ReadOnly = FALSE;
          gBS->HandleProtocol (BiosBlockIoDev->Handle, &gEfiBlockIoProtocolGuid, (VOID **) &BlockIo);
          gBS->ReinstallProtocolInterface (BiosBlockIoDev->Handle, &gEfiBlockIoProtocolGuid, BlockIo, BlockIo);
          return EFI_MEDIA_CHANGED;
        }
      } else if (BiosBlockIoDev->Bios.ErrorCode == BIOS_WRITE_PROTECTED) {
        Media->ReadOnly = TRUE;
        return EFI_WRITE_PROTECTED;
      }

      if (Media->RemovableMedia) {
        Media->MediaPresent = FALSE;
      }

      return EFI_DEVICE_ERROR;
    }

    Media->ReadOnly = FALSE;
    ShortLba        = ShortLba + NumberOfBlocks;
    BufferSize      = BufferSize - TransferByteSize;
    Buffer          = (VOID *) ((UINT8 *) Buffer + TransferByteSize);
  }

  return EFI_SUCCESS;
}