cryptix.util.math

Class BigRegister

java.lang.Object
- cryptix.util.math.BigRegister

Implemented Interfaces:: Cloneable, Serializable

Known Direct Subclasses:: TrinomialLFSR

public class BigRegister

extends java.lang.Object

implements Cloneable, Serializable

Utility class to manage a large bit-register of a given size as a mutable object.

The bits are indexed from 0 (rightmost) to size - 1, (leftmost) where size is this register's designated (at instantiation time) bit capacity.

$Revision: 1.2 $

Author:: Raif S. Naffah

Field Summary
`static int`	`MAXIMUM_SIZE` Maximum allowed number of bits in a `BigRegister` object.

Constructor Summary
`BigRegister(int size)` Instantiate a `BigRegister` of a given `size` with all its bits set to zeroes.

Method Summary
`void`	`and(BigRegister source)` Compute `this &= source`.
`void`	`andNot(BigRegister source)` Compute `this &= ~source`.
`void`	`atRandom()` Fill `this BigRegister` object with random data generated from the default source.
`void`	`atRandom(SecureRandom source)` Fill `this BigRegister` object with random data generated from a designated source.
`int`	`byteValue()` Return the rightmost byte value in `this BigRegister`.
`void`	`clearBit(int n)` Set the bit at the designated position to 0; ie.
`Object`	`clone()` Return a reference to a duplicate of `this`.
`int`	`compareTo(BigRegister x)` Compare `this BigRegister`'s contents to that of the argument, returning -1, 0 or 1 for less than, equal to, or greater than comparison result.
`int`	`countSetBits()` Return the number of bits set (to 1) in `this`.
`void`	`flipBit(int n)` Flip the value of the bit at the designated position.
`int`	`getBit(int n)` Return 1 or 0 if the designated bit was set or cleared respectively.
`long`	`getBits(int n, int count)` Return `count` bits starting at offset `n` framed in a `long`, right justified and left padded with binary zeroes.
`int`	`getSize()` Return the `size` of `this` object as specified at its instantiation time.
`int`	`highestSetBit()` Return the index of the leftmost non-zero bit in `this`.
`int`	`intValue()` Return the rightmost 32-bit value in `this BigRegister` as an `int`.
`void`	`invertOrder()` Invert the bit order of the current contents of `this`.
`boolean`	`isSameValue(BigRegister x)` Return true if the parameters of the BigRegister x (`size` and `bits`) are equal to this one; false otherwise.
`void`	`load(byte[] source)` Copy the bit values from a byte array into `this`.
`void`	`load(BigRegister source)` Copy the argument's value into `this`.
`long`	`longValue()` Return the rightmost 64-bit value in `this BigRegister` as a `long`.
`int`	`lowestSetBit()` Return the index of the rightmost non-zero bit in `this`.
`void`	`not()` Compute `this = ~this`.
`void`	`or(BigRegister source)` Compute `this \|= source`.
`void`	`reset()` Reset to zeroes all `this BigRegister`'s bits.
`void`	`rotateLeft(int n)` Circular left shift over the `size` of `this` register.
`void`	`rotateRight(int n)` Circular right shift over the `size` of `this` register.
`void`	`setBit(int n)` Set the bit at the designated position to 1.
`void`	`setBits(int n, int count, long value)` Set `count` bits starting at offset `n` to a given `value`.
`void`	`shiftLeft(int n)` Execute a left shift of `this BigRegister`'s contents by a given number of bit positions.
`void`	`shiftRight(int n)` Execute a right shift of `this BigRegister`'s contents by a given number of bit positions.
`boolean`	`testBit(int n)` Return true if the designated bit is set or false otherwise.
`byte[]`	`toByteArray()` Return a copy of `this BigRegister`'s contents in a byte array with the LSB at index position 0.
`String`	`toString()` Return a formatted `String` representation of the binary contents of `this`.
`BigRegister`	`valueOf(long n)` Return a `BigRegister`, of the same `size` as `this` set to the specified value.
`void`	`xor(BigRegister source)` Compute `this ^= source`.

MAXIMUM_SIZE

public static final int MAXIMUM_SIZE

Maximum allowed number of bits in a BigRegister object.
Field Value:
4096

BigRegister

public BigRegister(int size)

Instantiate a BigRegister of a given size with all its bits set to zeroes.
Parameters:
size - Number of meaningful bits in this object.
See Also:
MAXIMUM_SIZE

and

public void and(BigRegister source)

Compute this &= source.

andNot

public void andNot(BigRegister source)

Compute this &= ~source.

atRandom

public void atRandom()

Fill this BigRegister object with random data generated from the default source.

atRandom

public void atRandom(SecureRandom source)

Fill this BigRegister object with random data generated from a designated source.

byteValue

public int byteValue()

Return the rightmost byte value in this BigRegister.
Returns:
The rightmost byte value in this.

clearBit

public void clearBit(int n)

Set the bit at the designated position to 0; ie. clear it.
Parameters:
n - The bit position to alter.

clone

public Object clone()

Return a reference to a duplicate of this.

compareTo

public int compareTo(BigRegister x)

Compare this BigRegister's contents to that of the argument, returning -1, 0 or 1 for less than, equal to, or greater than comparison result.
Parameters:
x - A BigRegister object to compare to.
Returns:
-1, 0, +1 If the contents of this object are respectively less than, equal to, or greater than those of the argument.

countSetBits

public int countSetBits()

Return the number of bits set (to 1) in this.
Returns:
The number of set bits in this.

flipBit

public void flipBit(int n)

Flip the value of the bit at the designated position.
Parameters:
n - The bit position to alter.

getBit

public int getBit(int n)

Return 1 or 0 if the designated bit was set or cleared respectively.
Parameters:
n - The index of the bit to retrieve.

getBits

public long getBits(int n,
                    int count)

Return count bits starting at offset n framed in a long, right justified and left padded with binary zeroes.
Parameters:
n - The index of the first bit to retrieve.
count - Number of bits to retrieve.
Returns:
Right justified count bits starting from bit index n in a java long.

getSize

public int getSize()

Return the size of this object as specified at its instantiation time.
Returns:
The size of this object as specified at its instantiation time.

highestSetBit

public int highestSetBit()

Return the index of the leftmost non-zero bit in this.
Returns:
Index of the leftmost non-zero bit in this, or -1 if all bits are zeroes.

intValue

public int intValue()

Return the rightmost 32-bit value in this BigRegister as an int.
Returns:
The rightmost 32-bit value in this as an int.

invertOrder

public void invertOrder()

Invert the bit order of the current contents of this.

isSameValue

public boolean isSameValue(BigRegister x)

Return true if the parameters of the BigRegister x (size and bits) are equal to this one; false otherwise.
NOTE: the equals method is not used, because this is a mutable object (see the requirements for equals in the Java Language Spec).
Parameters:
x - BigRegister to test for equality.
Returns:
true iff x has equal size and contents.

load

public void load(byte[] source)

Copy the bit values from a byte array into this. Byte array order is assumed to have its Least Significant Byte (LSB) at index position 0. This format mirrors that of the output returned by the toByteArray() method.
Bits unprovided for in the source array are cleared. It is a more tolerant way of initialising a register than that obtained by invoking the same method with a BigRegister argument.
Parameters:
source - The source bits organised in a byte array with their LSB at index 0.
See Also:
toByteArray()

load

public void load(BigRegister source)

Copy the argument's value into this.

longValue

public long longValue()

Return the rightmost 64-bit value in this BigRegister as a long.
Returns:
The rightmost 64-bit value in this as a long.

lowestSetBit

public int lowestSetBit()

Return the index of the rightmost non-zero bit in this.
Returns:
Index of the rightmost non-zero bit in this, or -1 if all bits are zeroes.

not

public void not()

Compute this = ~this.

or

public void or(BigRegister source)

Compute this |= source.

reset

public void reset()

Reset to zeroes all this BigRegister's bits.

rotateLeft

public void rotateLeft(int n)

Circular left shift over the size of this register.
Effectively compute this = this << n | this >> (size - n).
If the number of positions to rotate by is negative, then a right instead of left rotation is executed.

rotateRight

public void rotateRight(int n)

Circular right shift over the size of this register.
Effectively compute this = this >> n | this << (size - n).
If the number of positions to rotate by is negative, then a left instead of right rotation is executed.

setBit

public void setBit(int n)

Set the bit at the designated position to 1.
Parameters:
n - The bit position to alter.

setBits

public void setBits(int n,
                    int count,
                    long value)

Set count bits starting at offset n to a given value.
Parameters:
n - The index of the first bit to set.
count - Number of bits to set.
value - New bits value, right justified in a long.

shiftLeft

public void shiftLeft(int n)

Execute a left shift of this BigRegister's contents by a given number of bit positions. If the number is negative, a right shift is executed.
Parameters:
n - Number of bit positions to shift by. If this value is negative then a shift in the opposite direction is executed.

shiftRight

public void shiftRight(int n)

Execute a right shift of this BigRegister's contents by a given number of bit positions. If the number is negative, a left shift is executed.
Parameters:
n - Number of bit positions to shift by. If this value is negative then a shift in the opposite direction is executed.

testBit

public boolean testBit(int n)

Return true if the designated bit is set or false otherwise.
Parameters:
n - Index of the bit to test.
Returns:
true if the designated bit is set or false otherwise.

toByteArray

public byte[] toByteArray()

Return a copy of this BigRegister's contents in a byte array with the LSB at index position 0. This format is compatible with the load([B) method of this class.
Returns:
The bits of this in a byte array with the LSB at index position 0.

toString

public String toString()

Return a formatted String representation of the binary contents of this.
Returns:
A formatted string representation of the binary contents of this.

valueOf

public BigRegister valueOf(long n)

Return a BigRegister, of the same size as this set to the specified value.
Returns:
A BigRegister, of the same size as this set to the specified value.

xor

public void xor(BigRegister source)

Compute this ^= source.

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cryptix.util.math

Class BigRegister

Field Summary

Constructor Summary

Method Summary

Field Details

MAXIMUM_SIZE

Constructor Details

BigRegister

Method Details

and

andNot

atRandom

atRandom

byteValue

clearBit

clone

compareTo

countSetBits

flipBit

getBit

getBits

getSize

highestSetBit

intValue

invertOrder

isSameValue

load

load

longValue

lowestSetBit

not

or

reset

rotateLeft

rotateRight

setBit

setBits

shiftLeft

shiftRight

testBit

toByteArray

toString

valueOf

xor