Package ghidra.util.bytesearch

Class DittedBitSequence

  • Direct Known Subclasses:
    Pattern
    public class DittedBitSequence
extends java.lang.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 Detail

      • popcount

        public static int[] popcount

    • Constructor Detail

      • DittedBitSequence

        public DittedBitSequence()

      • DittedBitSequence

        public DittedBitSequence​(java.lang.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:
        java.lang.IllegalArgumentException - if invalid dittedBitData specified

      • DittedBitSequence

        public DittedBitSequence​(java.lang.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"

    • Method Detail

      • 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 java.lang.Object

      • equals

        public boolean equals​(java.lang.Object obj)
        Overrides:
        equals in class java.lang.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​(java.lang.StringBuffer buf)

      • toString

        public java.lang.String toString()
        Overrides:
        toString in class java.lang.Object

      • getHexString

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

      • restoreXmlData

        protected int restoreXmlData​(XmlPullParser parser)
                      throws java.io.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:
        java.io.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