Package de.tilman_neumann.jml.base

Class UnsignedBigInt

java.lang.Object
de.tilman_neumann.jml.base.UnsignedBigInt
public class UnsignedBigInt
extends java.lang.Object
A very limited unsigned big integer implementation. Currently the only implemented arithmetic methods are division and modulus of big integers by small integers. These methods are notably faster than using BigInteger.divide(BigInteger), like factor 2.5 for BigIntegers with 100 bit, factor 1.8 at 200 bit, factor 1.6 at 300 bit.

  • Constructor Summary

    Constructors
    Constructor Description
    UnsignedBigInt​(int[] buffer)
    Constructor using the given buffer.
    UnsignedBigInt​(UnsignedBigInt N)
    Copy constructor
    UnsignedBigInt​(java.math.BigInteger N)
    Shortcut constructor for new UnsignedBigInt(); set(N);

  • Method Summary

    Modifier and Type Method Description
    int bitLength()  
    int divideAndRemainder​(int divisor, UnsignedBigInt quotient)
    Divide this by the given divisor, store the quotient in quotient and return the remainder.
    int divideAndRemainder_v1​(int divisor, UnsignedBigInt quotient)
    Deprecated.
    boolean equals​(java.lang.Object o)  
    int hashCode()  
    int intLength()  
    int intValue()  
    boolean isOne()
    Test for 1.
    boolean isZero()
    Test for 0.
    long longValue()  
    int mod​(int divisor)
    Compute the remainder of this modulo divisor.
    void set​(java.math.BigInteger N)
    Sets this to the given BigInteger N.
    java.math.BigInteger toBigInteger()  
    java.lang.String toBinaryString()  
    java.lang.String toString()  

    Methods inherited from class java.lang.Object

    clone, finalize, getClass, notify, notifyAll, wait, wait, wait

  • Constructor Details

    • UnsignedBigInt

      public UnsignedBigInt​(UnsignedBigInt N)
      Copy constructor
      Parameters:
      N - original unsigned big int

    • UnsignedBigInt

      public UnsignedBigInt​(java.math.BigInteger N)
      Shortcut constructor for new UnsignedBigInt(); set(N);
      Parameters:
      N -

    • UnsignedBigInt

      public UnsignedBigInt​(int[] buffer)
      Constructor using the given buffer. The numbers to work on must be set using the set(BigInteger) method.
      Parameters:
      buffer - a buffer big enough to represent all numbers that will be set using set(BigInteger).

  • Method Details

    • set

      public void set​(java.math.BigInteger N)
      Sets this to the given BigInteger N. This method must be called before any arithmetic operation. If a buffer has been passed to the constructor then it should be big enough to represent N.
      Parameters:
      N -

    • isZero

      public boolean isZero()
      Test for 0. The caller must make sure that set(BigInteger) has been invoked before.
      Returns:
      true if this==0, false else

    • isOne

      public boolean isOne()
      Test for 1. The caller must make sure that set(BigInteger) has been invoked before.
      Returns:
      true if this==1, false else

    • intLength

      public int intLength()

    • bitLength

      public int bitLength()

    • divideAndRemainder_v1

      @Deprecated public int divideAndRemainder_v1​(int divisor, UnsignedBigInt quotient)
      Deprecated.
      Divide this by the given divisor, store the quotient in quotient and return the remainder. The caller must make sure that set(BigInteger) has been invoked before.
      Parameters:
      divisor -
      quotient - output
      Returns:
      remainder

    • divideAndRemainder

      public int divideAndRemainder​(int divisor, UnsignedBigInt quotient)
      Divide this by the given divisor, store the quotient in quotient and return the remainder. The caller must make sure that set(BigInteger) has been invoked before.
      Parameters:
      divisor -
      quotient - output
      Returns:
      remainder

    • mod

      public int mod​(int divisor)
      Compute the remainder of this modulo divisor. The caller must make sure that set(BigInteger) has been invoked before. This simple implementation seems to be amazingly fast, like 100 times faster than BigInteger.mod(d), where BigInteger d = BigInteger.valueOf(divisor) has been created before the performance test loop. Here, Barrett reduction has no chance to shine...
      Parameters:
      divisor -
      Returns:
      remainder

    • equals

      public boolean equals​(java.lang.Object o)
      Overrides:
      equals in class java.lang.Object

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class java.lang.Object

    • intValue

      public int intValue()

    • longValue

      public long longValue()

    • toBigInteger

      public java.math.BigInteger toBigInteger()

    • toString

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

    • toBinaryString

      public java.lang.String toBinaryString()