source: vbox/trunk/src/VBox/Devices/EFI/Firmware/MdePkg/Library/BaseLib/Math64.c@ 58786

/** @file
  Leaf math worker functions that require 64-bit arithmetic support from the
  compiler.

  Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR>
  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 "BaseLibInternals.h"

/**
  Shifts a 64-bit integer left between 0 and 63 bits. The low bits
  are filled with zeros. The shifted value is returned.

  This function shifts the 64-bit value Operand to the left by Count bits. The
  low Count bits are set to zero. The shifted value is returned.

  @param  Operand The 64-bit operand to shift left.
  @param  Count   The number of bits to shift left.

  @return Operand << Count.

**/
UINT64
EFIAPI
InternalMathLShiftU64 (
  IN      UINT64                    Operand,
  IN      UINTN                     Count
  )
{
  return Operand << Count;
}

/**
  Shifts a 64-bit integer right between 0 and 63 bits. This high bits
  are filled with zeros. The shifted value is returned.

  This function shifts the 64-bit value Operand to the right by Count bits. The
  high Count bits are set to zero. The shifted value is returned.

  @param  Operand The 64-bit operand to shift right.
  @param  Count   The number of bits to shift right.

  @return Operand >> Count.

**/
UINT64
EFIAPI
InternalMathRShiftU64 (
  IN      UINT64                    Operand,
  IN      UINTN                     Count
  )
{
  return Operand >> Count;
}

/**
  Shifts a 64-bit integer right between 0 and 63 bits. The high bits
  are filled with original integer's bit 63. The shifted value is returned.

  This function shifts the 64-bit value Operand to the right by Count bits. The
  high Count bits are set to bit 63 of Operand.  The shifted value is returned.

  @param  Operand The 64-bit operand to shift right.
  @param  Count   The number of bits to shift right.

  @return Operand arithmetically shifted right by Count.

**/
UINT64
EFIAPI
InternalMathARShiftU64 (
  IN      UINT64                    Operand,
  IN      UINTN                     Count
  )
{
  INTN  TestValue;

  //
  // Test if this compiler supports arithmetic shift
  //
  TestValue = (((-1) << (sizeof (-1) * 8 - 1)) >> (sizeof (-1) * 8 - 1));
  if (TestValue == -1) {
    //
    // Arithmetic shift is supported
    //
    return (UINT64)((INT64)Operand >> Count);
  }

  //
  // Arithmetic is not supported
  //
  return (Operand >> Count) |
         ((INTN)Operand < 0 ? ~((UINTN)-1 >> Count) : 0);
}


/**
  Rotates a 64-bit integer left between 0 and 63 bits, filling
  the low bits with the high bits that were rotated.

  This function rotates the 64-bit value Operand to the left by Count bits. The
  low Count bits are fill with the high Count bits of Operand. The rotated
  value is returned.

  @param  Operand The 64-bit operand to rotate left.
  @param  Count   The number of bits to rotate left.

  @return Operand <<< Count.

**/
UINT64
EFIAPI
InternalMathLRotU64 (
  IN      UINT64                    Operand,
  IN      UINTN                     Count
  )
{
  return (Operand << Count) | (Operand >> (64 - Count));
}

/**
  Rotates a 64-bit integer right between 0 and 63 bits, filling
  the high bits with the high low bits that were rotated.

  This function rotates the 64-bit value Operand to the right by Count bits.
  The high Count bits are fill with the low Count bits of Operand. The rotated
  value is returned.

  @param  Operand The 64-bit operand to rotate right.
  @param  Count   The number of bits to rotate right.

  @return Operand >>> Count.

**/
UINT64
EFIAPI
InternalMathRRotU64 (
  IN      UINT64                    Operand,
  IN      UINTN                     Count
  )
{
  return (Operand >> Count) | (Operand << (64 - Count));
}

/**
  Switches the endianess of a 64-bit integer.

  This function swaps the bytes in a 64-bit unsigned value to switch the value
  from little endian to big endian or vice versa. The byte swapped value is
  returned.

  @param  Operand A 64-bit unsigned value.

  @return The byte swapped Operand.

**/
UINT64
EFIAPI
InternalMathSwapBytes64 (
  IN      UINT64                    Operand
  )
{
  UINT64  LowerBytes;
  UINT64  HigherBytes;

  LowerBytes  = (UINT64) SwapBytes32 ((UINT32) Operand);
  HigherBytes = (UINT64) SwapBytes32 ((UINT32) (Operand >> 32));

  return (LowerBytes << 32 | HigherBytes);
}

/**
  Multiplies a 64-bit unsigned integer by a 32-bit unsigned integer
  and generates a 64-bit unsigned result.

  This function multiplies the 64-bit unsigned value Multiplicand by the 32-bit
  unsigned value Multiplier and generates a 64-bit unsigned result. This 64-
  bit unsigned result is returned.

  @param  Multiplicand  A 64-bit unsigned value.
  @param  Multiplier    A 32-bit unsigned value.

  @return Multiplicand * Multiplier

**/
UINT64
EFIAPI
InternalMathMultU64x32 (
  IN      UINT64                    Multiplicand,
  IN      UINT32                    Multiplier
  )
{
  return Multiplicand * Multiplier;
}


/**
  Multiplies a 64-bit unsigned integer by a 64-bit unsigned integer
  and generates a 64-bit unsigned result.

  This function multiplies the 64-bit unsigned value Multiplicand by the 64-bit
  unsigned value Multiplier and generates a 64-bit unsigned result. This 64-
  bit unsigned result is returned.

  @param  Multiplicand  A 64-bit unsigned value.
  @param  Multiplier    A 64-bit unsigned value.

  @return Multiplicand * Multiplier.

**/
UINT64
EFIAPI
InternalMathMultU64x64 (
  IN      UINT64                    Multiplicand,
  IN      UINT64                    Multiplier
  )
{
  return Multiplicand * Multiplier;
}

/**
  Divides a 64-bit unsigned integer by a 32-bit unsigned integer and
  generates a 64-bit unsigned result.

  This function divides the 64-bit unsigned value Dividend by the 32-bit
  unsigned value Divisor and generates a 64-bit unsigned quotient. This
  function returns the 64-bit unsigned quotient.

  @param  Dividend  A 64-bit unsigned value.
  @param  Divisor   A 32-bit unsigned value.

  @return Dividend / Divisor.

**/
UINT64
EFIAPI
InternalMathDivU64x32 (
  IN      UINT64                    Dividend,
  IN      UINT32                    Divisor
  )
{
  return Dividend / Divisor;
}

/**
  Divides a 64-bit unsigned integer by a 32-bit unsigned integer and
  generates a 32-bit unsigned remainder.

  This function divides the 64-bit unsigned value Dividend by the 32-bit
  unsigned value Divisor and generates a 32-bit remainder. This function
  returns the 32-bit unsigned remainder.

  @param  Dividend  A 64-bit unsigned value.
  @param  Divisor   A 32-bit unsigned value.

  @return Dividend % Divisor.

**/
UINT32
EFIAPI
InternalMathModU64x32 (
  IN      UINT64                    Dividend,
  IN      UINT32                    Divisor
  )
{
  return (UINT32)(Dividend % Divisor);
}

/**
  Divides a 64-bit unsigned integer by a 32-bit unsigned integer and
  generates a 64-bit unsigned result and an optional 32-bit unsigned remainder.

  This function divides the 64-bit unsigned value Dividend by the 32-bit
  unsigned value Divisor and generates a 64-bit unsigned quotient. If Remainder
  is not NULL, then the 32-bit unsigned remainder is returned in Remainder.
  This function returns the 64-bit unsigned quotient.

  @param  Dividend  A 64-bit unsigned value.
  @param  Divisor   A 32-bit unsigned value.
  @param  Remainder A pointer to a 32-bit unsigned value. This parameter is
                    optional and may be NULL.

  @return Dividend / Divisor.

**/
UINT64
EFIAPI
InternalMathDivRemU64x32 (
  IN      UINT64                    Dividend,
  IN      UINT32                    Divisor,
  OUT     UINT32                    *Remainder OPTIONAL
  )
{
  if (Remainder != NULL) {
    *Remainder = (UINT32)(Dividend % Divisor);
  }
  return Dividend / Divisor;
}

/**
  Divides a 64-bit unsigned integer by a 64-bit unsigned integer and
  generates a 64-bit unsigned result and an optional 64-bit unsigned remainder.

  This function divides the 64-bit unsigned value Dividend by the 64-bit
  unsigned value Divisor and generates a 64-bit unsigned quotient. If Remainder
  is not NULL, then the 64-bit unsigned remainder is returned in Remainder.
  This function returns the 64-bit unsigned quotient.

  @param  Dividend  A 64-bit unsigned value.
  @param  Divisor   A 64-bit unsigned value.
  @param  Remainder A pointer to a 64-bit unsigned value. This parameter is
                    optional and may be NULL.

  @return Dividend / Divisor

**/
UINT64
EFIAPI
InternalMathDivRemU64x64 (
  IN      UINT64                    Dividend,
  IN      UINT64                    Divisor,
  OUT     UINT64                    *Remainder OPTIONAL
  )
{
  if (Remainder != NULL) {
    *Remainder = Dividend % Divisor;
  }
  return Dividend / Divisor;
}

/**
  Divides a 64-bit signed integer by a 64-bit signed integer and
  generates a 64-bit signed result and an optional 64-bit signed remainder.

  This function divides the 64-bit signed value Dividend by the 64-bit
  signed value Divisor and generates a 64-bit signed quotient. If Remainder
  is not NULL, then the 64-bit signed remainder is returned in Remainder.
  This function returns the 64-bit signed quotient.

  @param  Dividend  A 64-bit signed value.
  @param  Divisor   A 64-bit signed value.
  @param  Remainder A pointer to a 64-bit signed value. This parameter is
                    optional and may be NULL.

  @return Dividend / Divisor.

**/
INT64
EFIAPI
InternalMathDivRemS64x64 (
  IN      INT64                     Dividend,
  IN      INT64                     Divisor,
  OUT     INT64                     *Remainder  OPTIONAL
  )
{
  if (Remainder != NULL) {
    *Remainder = Dividend % Divisor;
  }
  return Dividend / Divisor;
}