bitfield.c

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/*++

Copyright (c) 2004 - 2006, Intel Corporation                                                         
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.  


Module Name:

  BitField.c
  
Abstract: 

  Bit field functions of BaseLib.

--*/

#include "BaseLibInternal.h"

/**
  Worker function that returns a bit field from Operand

  Returns the bitfield specified by the StartBit and the EndBit from Operand.

  @param  Operand   Operand on which to perform the bitfield operation.
  @param  StartBit  The ordinal of the least significant bit in the bit field.
  @param  EndBit    The ordinal of the most significant bit in the bit field.

  @return The bit field read.

**/
unsigned int
BitFieldReadUint (
  IN      unsigned int              Operand,
  IN      UINTN                     StartBit,
  IN      UINTN                     EndBit
  )
{
  //
  // ~((unsigned int)-2 << EndBit) is a mask in which bit[0] thru bit[EndBit]
  // are 1's while bit[EndBit + 1] thru the most significant bit are 0's.
  //
  return (Operand & ~((unsigned int)-2 << EndBit)) >> StartBit;
}

/**
  Worker function that reads a bit field from Operand, performs a bitwise OR, 
  and returns the result.

  Performs a bitwise OR between the bit field specified by StartBit and EndBit
  in Operand and the value specified by AndData. All other bits in Operand are
  preserved. The new value is returned.

  @param  Operand   Operand on which to perform the bitfield operation.
  @param  StartBit  The ordinal of the least significant bit in the bit field.
  @param  EndBit    The ordinal of the most significant bit in the bit field.
  @param  OrData    The value to OR with the read value from the value

  @return The new value.

**/
unsigned int
BitFieldOrUint (
  IN      unsigned int              Operand,
  IN      UINTN                     StartBit,
  IN      UINTN                     EndBit,
  IN      unsigned int              OrData
  )
{
  //
  // ~((unsigned int)-2 << EndBit) is a mask in which bit[0] thru bit[EndBit]
  // are 1's while bit[EndBit + 1] thru the most significant bit are 0's.
  //
  return Operand | ((OrData << StartBit) & ~((unsigned int) -2 << EndBit));
}

/**
  Worker function that reads a bit field from Operand, performs a bitwise AND, 
  and returns the result.

  Performs a bitwise AND between the bit field specified by StartBit and EndBit
  in Operand and the value specified by AndData. All other bits in Operand are
  preserved. The new value is returned.

  @param  Operand   Operand on which to perform the bitfield operation.
  @param  StartBit  The ordinal of the least significant bit in the bit field.
  @param  EndBit    The ordinal of the most significant bit in the bit field.
  @param  AndData    The value to And with the read value from the value

  @return The new value.

**/
unsigned int
BitFieldAndUint (
  IN      unsigned int              Operand,
  IN      UINTN                     StartBit,
  IN      UINTN                     EndBit,
  IN      unsigned int              AndData
  )
{
  //
  // ~((unsigned int)-2 << EndBit) is a mask in which bit[0] thru bit[EndBit]
  // are 1's while bit[EndBit + 1] thru the most significant bit are 0's.
  //
  return Operand & ~((~AndData << StartBit) & ~((unsigned int) -2 << EndBit));
}

/**
  Returns a bit field from an 8-bit value.

  Returns the bitfield specified by the StartBit and the EndBit from Operand.

  If 8-bit operations are not supported, then ASSERT().
  If StartBit is greater than 7, then ASSERT().
  If EndBit is greater than 7, then ASSERT().
  If EndBit is less than StartBit, then ASSERT().

  @param  Operand   Operand on which to perform the bitfield operation.
  @param  StartBit  The ordinal of the least significant bit in the bit field.
                    Range 0..7.
  @param  EndBit    The ordinal of the most significant bit in the bit field.
                    Range 0..7.

  @return The bit field read.

**/
UINT8
EFIAPI
BitFieldRead8 (
  IN      UINT8                     Operand,
  IN      UINTN                     StartBit,
  IN      UINTN                     EndBit
  )
{
  ASSERT (EndBit < sizeof (Operand) * 8);
  ASSERT (StartBit <= EndBit);
  return (UINT8)BitFieldReadUint (Operand, StartBit, EndBit);
}

/**
  Writes a bit field to an 8-bit value, and returns the result.

  Writes Value to the bit field specified by the StartBit and the EndBit in
  Operand. All other bits in Operand are preserved. The new 8-bit value is
  returned.

  If 8-bit operations are not supported, then ASSERT().
  If StartBit is greater than 7, then ASSERT().
  If EndBit is greater than 7, then ASSERT().
  If EndBit is less than StartBit, then ASSERT().

  @param  Operand   Operand on which to perform the bitfield operation.
  @param  StartBit  The ordinal of the least significant bit in the bit field.
                    Range 0..7.
  @param  EndBit    The ordinal of the most significant bit in the bit field.
                    Range 0..7.
  @param  Value     New value of the bit field.

  @return The new 8-bit value.

**/
UINT8
EFIAPI
BitFieldWrite8 (
  IN      UINT8                     Operand,
  IN      UINTN                     StartBit,
  IN      UINTN                     EndBit,
  IN      UINT8                     Value
  )
{
  ASSERT (EndBit < sizeof (Operand) * 8);
  ASSERT (StartBit <= EndBit);
  return BitFieldAndThenOr8 (Operand, StartBit, EndBit, 0, Value);
}

/**
  Reads a bit field from an 8-bit value, performs a bitwise OR, and returns the
  result.

  Performs a bitwise inclusive OR between the bit field specified by StartBit
  and EndBit in Operand and the value specified by OrData. All other bits in
  Operand are preserved. The new 8-bit value is returned.

  If 8-bit operations are not supported, then ASSERT().
  If StartBit is greater than 7, then ASSERT().
  If EndBit is greater than 7, then ASSERT().
  If EndBit is less than StartBit, then ASSERT().

  @param  Operand   Operand on which to perform the bitfield operation.
  @param  StartBit  The ordinal of the least significant bit in the bit field.
                    Range 0..7.
  @param  EndBit    The ordinal of the most significant bit in the bit field.
                    Range 0..7.
  @param  OrData    The value to OR with the read value from the value

  @return The new 8-bit value.

**/
UINT8
EFIAPI
BitFieldOr8 (
  IN      UINT8                     Operand,
  IN      UINTN                     StartBit,
  IN      UINTN                     EndBit,
  IN      UINT8                     OrData
  )
{
  ASSERT (EndBit < sizeof (Operand) * 8);
  ASSERT (StartBit <= EndBit);
  return (UINT8)BitFieldOrUint (Operand, StartBit, EndBit, OrData);
}

/**
  Reads a bit field from an 8-bit value, performs a bitwise AND, and returns
  the result.

  Performs a bitwise AND between the bit field specified by StartBit and EndBit
  in Operand and the value specified by AndData. All other bits in Operand are
  preserved. The new 8-bit value is returned.

  If 8-bit operations are not supported, then ASSERT().
  If StartBit is greater than 7, then ASSERT().
  If EndBit is greater than 7, then ASSERT().
  If EndBit is less than StartBit, then ASSERT().

  @param  Operand   Operand on which to perform the bitfield operation.
  @param  StartBit  The ordinal of the least significant bit in the bit field.
                    Range 0..7.
  @param  EndBit    The ordinal of the most significant bit in the bit field.
                    Range 0..7.
  @param  AndData   The value to AND with the read value from the value.

  @return The new 8-bit value.

**/
UINT8
EFIAPI
BitFieldAnd8 (
  IN      UINT8                     Operand,
  IN      UINTN                     StartBit,
  IN      UINTN                     EndBit,
  IN      UINT8                     AndData
  )
{
  ASSERT (EndBit < sizeof (Operand) * 8);
  ASSERT (StartBit <= EndBit);
  return (UINT8)BitFieldAndUint (Operand, StartBit, EndBit, AndData);
}

/**
  Reads a bit field from an 8-bit value, performs a bitwise AND followed by a
  bitwise OR, and returns the result.

  Performs a bitwise AND between the bit field specified by StartBit and EndBit
  in Operand and the value specified by AndData, followed by a bitwise
  inclusive OR with value specified by OrData. All other bits in Operand are
  preserved. The new 8-bit value is returned.

  If 8-bit operations are not supported, then ASSERT().
  If StartBit is greater than 7, then ASSERT().
  If EndBit is greater than 7, then ASSERT().
  If EndBit is less than StartBit, then ASSERT().

  @param  Operand   Operand on which to perform the bitfield operation.
  @param  StartBit  The ordinal of the least significant bit in the bit field.
                    Range 0..7.
  @param  EndBit    The ordinal of the most significant bit in the bit field.
                    Range 0..7.
  @param  AndData   The value to AND with the read value from the value.
  @param  OrData    The value to OR with the result of the AND operation.

  @return The new 8-bit value.

**/
UINT8
EFIAPI
BitFieldAndThenOr8 (
  IN      UINT8                     Operand,
  IN      UINTN                     StartBit,
  IN      UINTN                     EndBit,
  IN      UINT8                     AndData,
  IN      UINT8                     OrData
  )
{
  ASSERT (EndBit < sizeof (Operand) * 8);
  ASSERT (StartBit <= EndBit);
  return BitFieldOr8 (
           BitFieldAnd8 (Operand, StartBit, EndBit, AndData),
           StartBit,
           EndBit,
           OrData
           );
}

/**
  Returns a bit field from a 16-bit value.

  Returns the bitfield specified by the StartBit and the EndBit from Operand.

  If 16-bit operations are not supported, then ASSERT().
  If StartBit is greater than 15, then ASSERT().
  If EndBit is greater than 15, then ASSERT().
  If EndBit is less than StartBit, then ASSERT().

  @param  Operand   Operand on which to perform the bitfield operation.
  @param  StartBit  The ordinal of the least significant bit in the bit field.
                    Range 0..15.
  @param  EndBit    The ordinal of the most significant bit in the bit field.
                    Range 0..15.

  @return The bit field read.

**/
UINT16
EFIAPI
BitFieldRead16 (
  IN      UINT16                    Operand,
  IN      UINTN                     StartBit,
  IN      UINTN                     EndBit
  )
{
  ASSERT (EndBit < sizeof (Operand) * 8);
  ASSERT (StartBit <= EndBit);
  return (UINT16)BitFieldReadUint (Operand, StartBit, EndBit);
}

/**
  Writes a bit field to a 16-bit value, and returns the result.

  Writes Value to the bit field specified by the StartBit and the EndBit in
  Operand. All other bits in Operand are preserved. The new 16-bit value is
  returned.

  If 16-bit operations are not supported, then ASSERT().
  If StartBit is greater than 15, then ASSERT().
  If EndBit is greater than 15, then ASSERT().
  If EndBit is less than StartBit, then ASSERT().

  @param  Operand   Operand on which to perform the bitfield operation.
  @param  StartBit  The ordinal of the least significant bit in the bit field.
                    Range 0..15.
  @param  EndBit    The ordinal of the most significant bit in the bit field.
                    Range 0..15.
  @param  Value     New value of the bit field.

  @return The new 16-bit value.

**/
UINT16
EFIAPI
BitFieldWrite16 (
  IN      UINT16                    Operand,
  IN      UINTN                     StartBit,
  IN      UINTN                     EndBit,
  IN      UINT16                    Value
  )
{
  ASSERT (EndBit < sizeof (Operand) * 8);
  ASSERT (StartBit <= EndBit);
  return BitFieldAndThenOr16 (Operand, StartBit, EndBit, 0, Value);
}

/**
  Reads a bit field from a 16-bit value, performs a bitwise OR, and returns the
  result.

  Performs a bitwise inclusive OR between the bit field specified by StartBit
  and EndBit in Operand and the value specified by OrData. All other bits in
  Operand are preserved. The new 16-bit value is returned.

  If 16-bit operations are not supported, then ASSERT().
  If StartBit is greater than 15, then ASSERT().
  If EndBit is greater than 15, then ASSERT().
  If EndBit is less than StartBit, then ASSERT().

  @param  Operand   Operand on which to perform the bitfield operation.
  @param  StartBit  The ordinal of the least significant bit in the bit field.
                    Range 0..15.
  @param  EndBit    The ordinal of the most significant bit in the bit field.
                    Range 0..15.
  @param  OrData    The value to OR with the read value from the value

  @return The new 16-bit value.

**/
UINT16
EFIAPI
BitFieldOr16 (
  IN      UINT16                    Operand,
  IN      UINTN                     StartBit,
  IN      UINTN                     EndBit,
  IN      UINT16                    OrData
  )
{
  ASSERT (EndBit < sizeof (Operand) * 8);
  ASSERT (StartBit <= EndBit);
  return (UINT16)BitFieldOrUint (Operand, StartBit, EndBit, OrData);
}

/**
  Reads a bit field from a 16-bit value, performs a bitwise AND, and returns
  the result.

  Performs a bitwise AND between the bit field specified by StartBit and EndBit
  in Operand and the value specified by AndData. All other bits in Operand are
  preserved. The new 16-bit value is returned.

  If 16-bit operations are not supported, then ASSERT().
  If StartBit is greater than 15, then ASSERT().
  If EndBit is greater than 15, then ASSERT().
  If EndBit is less than StartBit, then ASSERT().

  @param  Operand   Operand on which to perform the bitfield operation.
  @param  StartBit  The ordinal of the least significant bit in the bit field.
                    Range 0..15.
  @param  EndBit    The ordinal of the most significant bit in the bit field.
                    Range 0..15.
  @param  AndData   The value to AND with the read value from the value

  @return The new 16-bit value.

**/
UINT16
EFIAPI
BitFieldAnd16 (
  IN      UINT16                    Operand,