Package ghidra.app.plugin.assembler.sleigh.expr

Class MaskedLong

java.lang.Object
ghidra.app.plugin.assembler.sleigh.expr.MaskedLong
All Implemented Interfaces:
Comparable<MaskedLong>
public class MaskedLong extends Object implements Comparable<MaskedLong>
A 64-bit value where each bit is 0, 1, or x (undefined)

  • Field Details

    • ZERO

      public static final MaskedLong ZERO

    • UNKS

      public static final MaskedLong UNKS

    • ONES

      public static final MaskedLong ONES

    • msk

      protected long msk

    • val

      protected long val

  • Constructor Details

    • MaskedLong

      protected MaskedLong(long msk, long val)
      Create a masked long given a mask and value

  • Method Details

    • fromMaskAndValue

      public static MaskedLong fromMaskAndValue(long msk, long val)
      Create a masked value from a mask and a long

      Any positions in msk set to 0 create an x in the corresponding position of the result. Otherwise, the position takes the corresponding bit from val.

      Parameters:
      msk - the mask
      val - the value
      Returns:
      the constructed masked long

    • fromLong

      public static MaskedLong fromLong(long val)
      Create a fully-defined value from the bits of a long
      Parameters:
      val - the value to take
      Returns:
      the constructed masked long

    • longValue

      public long longValue()
      Obtain the value as a long, where all undefined bits are treated as 0
      Returns:
      the value as a long

    • getMask

      public long getMask()
      Get the mask as a long

      Positions with a defined bit are 1; positions with an undefined bit are 0.

      Returns:
      the mask as a long

    • isFullyDefined

      public boolean isFullyDefined()
      True iff there are no undefined bits
      Returns:
      true if fully-defined, false otherwise

    • isFullyUndefined

      public boolean isFullyUndefined()
      True iff there are no defined bits
      Returns:
      true if full-undefined, false otherwise

    • mask

      public MaskedLong mask(long mask)
      Apply an additional mask to this masked long

      Any 0 bit in msk will result in an undefined bit in the result. 1 bits result in a copy of the corresponding bit in the result.

      Parameters:
      mask - the mask to apply
      Returns:
      the result.

    • signExtend

      public MaskedLong signExtend()
      Sign extend the masked value, according to its mask, to a full long

      The leftmost defined bit is taken as the sign bit, and extended to the left.

      Returns:
      the sign-extended masked long

    • zeroExtend

      public MaskedLong zeroExtend()
      Zero extend the masked value, according to its mask, to a full long

      All bits to the left of the leftmost defined bit are set to 0.

      Returns:
      the zero-extended masked long

    • unknownExtend

      public MaskedLong unknownExtend(int n)
      Mask out all but the lowest n bits of the value
      Parameters:
      n - the number of bits to take (right-to-left)
      Returns:
      the unknown-extended masked long

    • signExtend

      public MaskedLong signExtend(int n)
      Sign extend the masked value as if of the given size in bits, to a full long
      Parameters:
      n - the number of bits to take (right-to-left)
      Returns:
      the sign-extended masked long

    • zeroExtend

      public MaskedLong zeroExtend(int n)
      Zero extend the masked value as if of the given size in bits, to a full long
      Parameters:
      n - the number of bits to take (right-to-left)
      Returns:
      the zero-extended masked long

    • combine

      public MaskedLong combine(MaskedLong that) throws SolverException
      Combine this and another masked long into one, by taking defined bits from either

      If this masked long agrees with the other, then the two are combined. For each bit position in the result, the defined bit from either corresponding position is taken. If neither is defined, then the position is undefined in the result. If both are defined, they must agree.

      Parameters:
      that - the other masked long
      Returns:
      the combined masked long
      Throws:
      SolverException - if this and the other masked long disagree

    • shiftCircular

      public MaskedLong shiftCircular(long n, int size, int dir)
      Shift size bits @{code n) positions circularly in a given direction

      The shifted bits are the least significant size bits. The remaining bits are unaffected.

      Parameters:
      n - the number of positions
      size - the number of bits (least significant) to include in the shift
      dir - the direction to shift (0 for left, 1 for right)
      Returns:
      the result

    • shiftCircular

      public MaskedLong shiftCircular(MaskedLong n, int size, int dir)
      Shift size bits @{code n) positions circularly in a given direction

      The shifted bits are the least significant size bits. The remaining bits are unaffected.

      Parameters:
      n - the number of positions
      size - the number of bits (least significant) to include in the shift
      dir - the direction to shift (0 for left, 1 for right)
      Returns:
      the result

    • shiftLeft

      public MaskedLong shiftLeft(long n)
      Shift the bits @{code n} positions left

      This implements both a signed and unsigned shift.

      Parameters:
      n - the number of positions.
      Returns:
      the result.

    • shiftLeft

      public MaskedLong shiftLeft(MaskedLong n)
      Shift the bits n positions left

      This implements both a signed and unsigned shift.

      Parameters:
      n - the number of positions.
      Returns:
      the result.

    • invShiftLeft

      public MaskedLong invShiftLeft(long n) throws SolverException
      Invert a left shift of n positions, that is shift right

      This is different from a normal shift right, in that it inserts unknowns at the left. The normal right shift inserts zeros or sign bits. Additionally, if any ones would fall off the right, the inversion is undefined.

      Parameters:
      n - the number of positions
      Returns:
      the result
      Throws:
      SolverException - if the inversion is undefined

    • invShiftLeft

      public MaskedLong invShiftLeft(MaskedLong n) throws SolverException
      Invert a left shift of n positions, that is shift right

      This is different from a normal shift right, in that it inserts unknowns at the left. The normal right shift inserts zeros or sign bits. Additionally, if any ones would fall off the right, the inversion is undefined.

      Parameters:
      n - the number of positions
      Returns:
      the result
      Throws:
      SolverException - if the inversion is undefined

    • shiftRight

      public MaskedLong shiftRight(long n)
      Shift the bits arithmetically n positions right

      This implements a signed shift.

      Parameters:
      n - the number of positions.
      Returns:
      the result.

    • shiftRight

      public MaskedLong shiftRight(MaskedLong n)
      Shift the bits arithmetically n positions right

      This implements a signed shift.

      Parameters:
      n - the number of positions.
      Returns:
      the result.

    • invShiftRight

      public MaskedLong invShiftRight(long n) throws SolverException
      Invert an arithmetic right shift of n positions, that is shift left

      This is different from a normal shift left, in that it inserts unknowns at the right. The normal left shift inserts zeros. Additionally, all bits that fall off the left must match the resulting sign bit, or else the inversion is undefined.

      Parameters:
      n - the number of positions
      Returns:
      the result
      Throws:
      SolverException - if the inversion is undefined

    • invShiftRight

      public MaskedLong invShiftRight(MaskedLong n) throws SolverException
      Invert an arithmetic right shift of n positions, that is shift left

      This is different from a normal shift left, in that it inserts unknowns at the right. The normal left shift inserts zeros. Additionally, all bits that fall off the left must match the resulting sign bit, or else the inversion is undefined.

      Parameters:
      n - the number of positions
      Returns:
      the result
      Throws:
      SolverException - if the inversion is undefined

    • shiftRightLogical

      public MaskedLong shiftRightLogical(long n)
      Shift the bits logically n positions right

      This implements an unsigned shift.

      Parameters:
      n - the number of positions.
      Returns:
      the result.

    • shiftRightLogical

      public MaskedLong shiftRightLogical(MaskedLong n)
      Shift the bits logically n positions right

      This implements an unsigned shift.

      Parameters:
      n - the number of positions.
      Returns:
      the result.

    • shiftRightPositional

      public MaskedLong shiftRightPositional(long n)
      Shift the bits positionally n positions right

      This fills the left with unknown bits

      Parameters:
      n -
      Returns:

    • invShiftRightLogical

      public MaskedLong invShiftRightLogical(long n) throws SolverException
      Invert a logical right shift of n positions, that is shift left

      This is different from a normal shift left, in that it inserts unknowns at the right. The normal left shift inserts zeros. Additionally, if any ones would fall off the left, the inversion is undefined.

      Parameters:
      n - the number of positions
      Returns:
      the result
      Throws:
      SolverException - if the inversion is undefined

    • invShiftRightLogical

      public MaskedLong invShiftRightLogical(MaskedLong n) throws SolverException
      Invert a logical right shift of n positions, that is shift left

      This is different from a normal shift left, in that it inserts unknowns at the right. The normal left shift inserts zeros. Additionally, if any ones would fall off the left, the inversion is undefined.

      Parameters:
      n - the number of positions
      Returns:
      the result
      Throws:
      SolverException - if the inversion is undefined

    • byteSwap

      public MaskedLong byteSwap(int n)
      Reverse the least significant n bytes

      This interprets the bits as an n-byte value and changes the endianness. Any bits outside of the interpretation are truncated, i.e., become unknown.

      Parameters:
      n - the size, in bytes, of the interpreted value.
      Returns:
      the result.

    • and

      public MaskedLong and(MaskedLong that)
      Compute the bitwise AND of this and another masked long

      To handle unknown bits, the result is derived from the following truth table: 

      
   0 x 1 <= A (this)
 0 0 0 0
 x 0 x x
 1 0 x 1
 ^
 B (that)
      Parameters:
      that - the other masked long (B).
      Returns:
      the result.

    • invAnd

      public MaskedLong invAnd(MaskedLong that) throws SolverException
      Solves the expression A & B = C, for B, given C and A

      To handle unknown bits, the solution is derived from the following truth table, where * indicates no solution: 

      
   0 x 1 <= A (that)
 0 x x 0
 x x x x
 1 * 1 1
 ^
 B (this)
      Parameters:
      that - the other masked long (B).
      Returns:
      the result.
      Throws:
      SolverException - if no solution exists.

    • or

      public MaskedLong or(MaskedLong that)
      Compute the bitwise OR of this and another masked long

      To handle unknown bits, the result is derived from the following truth table: 

      
   0 x 1 <= A (this)
 0 0 x 1
 x x x 1
 1 1 1 1
 ^
 B (that)
      Parameters:
      that - the other masked long (B).
      Returns:
      the result.

    • invOr

      public MaskedLong invOr(MaskedLong that) throws SolverException
      Solves the expression A | B = C, for B, given C and A

      To handle unknown bits, the solution is derived from the following truth table, where * indicates no solution: 

      
   0 x 1 <= A (that)
 0 0 0 *
 x x x x
 1 1 x x
 ^
 B (this)
      Parameters:
      that - the other masked long (B).
      Returns:
      the result.
      Throws:
      SolverException - if not solution exists.

    • xor

      public MaskedLong xor(MaskedLong that)
      Compute the bitwise XOR of this and another masked long

      To handle unknown bits, the result is derived from the following truth table: 

      
   0 x 1 <= A (this)
 0 0 x 1
 x x x x
 1 1 x 0
 ^
 B (that)
      Parameters:
      that - the other masked long (B).
      Returns:
      the result.

    • negate

      public MaskedLong negate()
      Negate the value
      Returns:
      the result.

    • not

      public MaskedLong not()
      Compute the bitwise NOT

      To handle unknown bits, the result is derived from the following truth table: 

      
 0 x 1 <= A (this)
 1 x 0
      Returns:
      the result.

    • add

      public MaskedLong add(MaskedLong that)
      Compute the arithmetic sum of this and another masked long
      Parameters:
      that - the other masked long.
      Returns:
      the result.

    • subtract

      public MaskedLong subtract(MaskedLong that)
      Compute the arithmetic difference: this masked long minus another
      Parameters:
      that - the other masked long.
      Returns:
      the result.

    • multiply

      public MaskedLong multiply(MaskedLong that)
      Compute the arithmetic product of this and another masked long
      Parameters:
      that - the other masked long.
      Returns:
      the result.

    • divideSigned

      public MaskedLong divideSigned(MaskedLong that)

    • divideUnsigned

      public MaskedLong divideUnsigned(MaskedLong that)
      Compute the unsigned arithmetic quotient: this masked long divided by another
      Parameters:
      that - the other masked long.
      Returns:
      the result.

    • invMultiplyUnsigned

      public MaskedLong invMultiplyUnsigned(MaskedLong that) throws SolverException
      Compute the arithmetic quotient as a solution to unsigned multiplication

      This is slightly different than divideUnsigned(MaskedLong) in its treatment of unknowns.

      Parameters:
      that - the known factor
      Returns:
      a solution to that*x == this, if possible
      Throws:
      SolverException

    • agrees

      public boolean agrees(MaskedLong that)
      Checks if this and another masked long agree

      Two masked longs agree iff their corresponding defined bit positions are equal. Where either or both positions are undefined, no check is applied. In the case that both masked longs are fully-defined, this is the same as an equality check on the values.

      Parameters:
      that - the other masked long.
      Returns:
      true if this and that agree.

    • agrees

      public boolean agrees(long that)
      Checks if this and a long agree

      The masked long agrees with the given long iff the masked long's defined bit positions agree with the corresponding bit positions in the given long. Where there are undefined bits, no check is applied. In the case that the masked long is fully-defined, this is the same as an equality check on the value.

      Parameters:
      that - the long
      Returns:
      true if this and that agree.

    • agrees

      public boolean agrees(Object that)
      Check if this and another object agree
      Parameters:
      that - a MaskedLong or Long to check.
      Returns:
      true if this and that agree.
      See Also:

    • isInRange

      public boolean isInRange(long max, boolean signed)
      Check if the masked value falls within a given range

      The range is defined by a maximum and a signedness. The maximum must be one less than a positive power of 2. In other words, it defines a maximum number of bits, including the sign bit if applicable.

      The defined bits of this masked long are then checked to fall in the given range. The effective value is derived by sign/zero extending the value according to its mask. In general, if any 1 bits exist outside of the given max, the value is rejected, unless that 1 is purely a result of signedness.

      Parameters:
      max - the maximum value, taken as an unsigned long.
      signed - true to interpret the masked value as signed.
      Returns:
      true if the masked value "fits" into the given range.

    • compareTo

      public int compareTo(MaskedLong that)
      "Compare" two masked longs

      This is not meant to reflect a numerical comparison. Rather, this is just to impose an ordering for the sake of storing these in sorted collections.

      Specified by:
      compareTo in interface Comparable<MaskedLong>

    • equals

      public boolean equals(Object other)
      Check for equality

      This will only return true if the other object is a masked long, even if this one is fully-defined, and the value is equal to a given long (or Long). The other masked long must have the same mask and value to be considered equal. For other sorts of "equality" checks, see agrees(Object) and friends.

      Overrides:
      equals in class Object

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • signExtend

      protected static long signExtend(long val, int bits)
      Sign extend a number of the given size in bits, to a full long
      Parameters:
      val - the value to extend
      bits - the number of bits to take (right-to-left)
      Returns:
      the sign-extended value as a long

    • zeroExtend

      protected static long zeroExtend(long val, int bits)
      Zero extend a number of the given size in bits, to a full long
      Parameters:
      val - the value to extend
      bits - the number of bits to take (right-to-left)
      Returns:
      the zero-extended value as a long

    • fillMask

      public MaskedLong fillMask()
      Set all undefined bits to 0
      Returns:
      the result