audk/MdeModulePkg/Core/RuntimeDxe/Crc32.c

/** @file
  CalculateCrc32 Boot Services as defined in DXE CIS.

  This Boot Services is in the Runtime Driver because this service is
  also required by SetVirtualAddressMap() when the EFI System Table and
  EFI Runtime Services Table are converted from physical address to
  virtual addresses.	This requires that the 32-bit CRC be recomputed.

Copyright (c) 2006, Intel Corporation. <BR>
All rights reserved. This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD License
which accompanies this distribution.  The full text of the license may be found at
http://opensource.org/licenses/bsd-license.php

THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.

**/


#include <Uefi.h>

UINT32  mCrcTable[256];

/**
  Calculate CRC32 for target data.

  @param  Data                  The target data.
  @param  DataSize              The target data size.
  @param  CrcOut                The CRC32 for target data.

  @retval EFI_SUCCESS           The CRC32 for target data is calculated successfully.
  @retval EFI_INVALID_PARAMETER Some parameter is not valid, so the CRC32 is not
                                calculated.

**/
EFI_STATUS
EFIAPI
RuntimeDriverCalculateCrc32 (
  IN  VOID    *Data,
  IN  UINTN   DataSize,
  OUT UINT32  *CrcOut
  )
{
  UINT32  Crc;
  UINTN   Index;
  UINT8   *Ptr;

  if (Data == NULL || DataSize == 0 || CrcOut == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  Crc = 0xffffffff;
  for (Index = 0, Ptr = Data; Index < DataSize; Index++, Ptr++) {
    Crc = (Crc >> 8) ^ mCrcTable[(UINT8) Crc ^ *Ptr];
  }

  *CrcOut = Crc ^ 0xffffffff;
  return EFI_SUCCESS;
}


/**
  Reverse bits for 32bit data.
  This is a internal function.

  @param  Value                 The data to be reversed.

  @return                       Data reversed.

**/
UINT32
ReverseBits (
  UINT32  Value
  )
{
  UINTN   Index;
  UINT32  NewValue;

  NewValue = 0;
  for (Index = 0; Index < 32; Index++) {
    if ((Value & (1 << Index)) != 0) {
      NewValue = NewValue | (1 << (31 - Index));
    }
  }

  return NewValue;
}

/**
  Initialize CRC32 table.
**/
VOID
RuntimeDriverInitializeCrc32Table (
  VOID
  )
{
  UINTN   TableEntry;
  UINTN   Index;
  UINT32  Value;

  for (TableEntry = 0; TableEntry < 256; TableEntry++) {
    Value = ReverseBits ((UINT32) TableEntry);
    for (Index = 0; Index < 8; Index++) {
      if ((Value & 0x80000000) != 0) {
        Value = (Value << 1) ^ 0x04c11db7;
      } else {
        Value = Value << 1;
      }
    }

    mCrcTable[TableEntry] = ReverseBits (Value);
  }
}