Package ghidra.util.bytesearch

Class DittedBitSequence

java.lang.Object
ghidra.util.bytesearch.DittedBitSequence
Direct Known Subclasses:
Pattern
public class DittedBitSequence extends Object
A pattern of bits/mask to match to a stream of bytes. The bits/mask can be of any length. The sequence can be initialized by: a string an array of bytes (no mask) an array of bytes and for mask The dits represent bits(binary) or nibbles(hex) that are don't care, for example: 0x..d.4de2 ....0000 .1...... 00101101 11101001 where 0x starts a hex number and '.' is a don't care nibble (hex) or bit (binary)

  • Field Details

    • popcount

      public static int[] popcount

  • Constructor Details

    • DittedBitSequence

      public DittedBitSequence()

    • DittedBitSequence

      public DittedBitSequence(String dittedBitData)
      Constructor from a ditted-bit-sequence string where white space is ignored (e.g., "10..11.0");
      Parameters:
      dittedBitData - ditted sequence specified as a string
      Throws:
      IllegalArgumentException - if invalid dittedBitData specified

    • DittedBitSequence

      public DittedBitSequence(String dittedBitData, boolean hex)
      Constructor from a ditted-bit string where white space is ignored. If there are no dits, hex is true, and hex does not begin with {code 0x}, 0x will be prepended to the string before constructing the DittedBitSequence.
      Parameters:
      dittedBitData - string of bits and dits or hex numbers and dits (e.g., 0.1..0, 0xAB..)
      hex - true to force hex on the sequence

    • DittedBitSequence

      public DittedBitSequence(DittedBitSequence op2)
      Copy contructor
      Parameters:
      op2 - is bit sequence being copied

    • DittedBitSequence

      public DittedBitSequence(byte[] bytes)
      Construct a sequence of bytes to search for. No bits are masked off.
      Parameters:
      bytes - byte values that must match

    • DittedBitSequence

      public DittedBitSequence(byte[] bytes, byte[] mask)
      Construct a bit pattern to search for consisting of 0 bits, 1 bits, and don't care bits
      Parameters:
      bytes - is an array of bytes indicating the 0 and 1 bits that are cared about
      mask - is an array of bytes masking off the bits that should be cared about, a 0 indicates a "don't care"

    • DittedBitSequence

      public DittedBitSequence(DittedBitSequence s1, DittedBitSequence s2)

  • Method Details

    • getValueBytes

      public byte[] getValueBytes()
      Returns:
      value bytes

    • getMaskBytes

      public byte[] getMaskBytes()
      Returns:
      mask bytes which correspond to value bytes

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object

    • equals

      public boolean equals(Object obj)
      Overrides:
      equals in class Object

    • concatenate

      public DittedBitSequence concatenate(DittedBitSequence toConat)
      Concatenates a sequence to the end of another sequence and returns a new sequence.
      Parameters:
      toConat - sequence to concatenate to this sequence
      Returns:
      a new sequence that is the concat of this and toConcat

    • isMatch

      public boolean isMatch(int pos, int val)
      Check for a match of a value at a certain offset in the pattern. An outside matcher will keep track of the match position within this ditted bit sequence. Then call this method to match.
      Parameters:
      pos - position in the pattern to match
      val - a byte to be match at the given byte offset in the pattern
      Returns:
      true if the byte matches the sequence mask/value

    • setIndex

      public void setIndex(int index)
      Set a an index in a larger sequence, or identifing id on this pattern
      Parameters:
      index - - index in match sequence, or unique id

    • getIndex

      public int getIndex()
      Get the index or identifying id attached to this pattern
      Returns:
      index or unique id attached to this sequence

    • getSize

      public int getSize()
      get the size of this sequence in bytes
      Returns:
      size in bytes

    • getNumFixedBits

      public int getNumFixedBits()
      Get number of bits that must be 0/1
      Returns:
      number of bits that are not don't care (ditted)

    • getNumUncertainBits

      public int getNumUncertainBits()
      Get number of bits that are ditted (don't care)
      Returns:
      number of ditted bits (don't care)

    • writeBits

      public void writeBits(StringBuffer buf)

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • getHexString

      public String getHexString()
      get a ditted hex string representing this sequence
      Returns:
      ditted hex string

    • restoreXmlData

      protected int restoreXmlData(XmlPullParser parser) throws IOException
      restore ditted string from XML stream with hex/binary ditted sequences in the form: 0x..d.4de2 ....0000 .1...... 00101101 11101001 where 0x starts a hex number and '.' is a don't care nibble (hex) or bit (binary)
      Parameters:
      parser - XML pull parser stream
      Returns:
      number of bytes read from XML tag
      Throws:
      IOException - if XML read has an error

    • getNumInitialFixedBits

      public int getNumInitialFixedBits(int marked)
      Get the number of bits that are fixed, not ditted (don't care)
      Parameters:
      marked - number of bytes in the pattern to check
      Returns:
      number of initial fixed bits