bignumber
javacardx.framework.math
Class BigNumber
public final class BigNumberextends Object
The BigNumber class encapsulates an unsigned number whose value is represented in internal hexadecimal format using an implementation specific maximum number of bytes. This class supports the BCD (binary coded decimal) format for I/O.
Since:
2.2.2
Field Summary | |
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static byte | FORMAT_BCD Constant to indicate a BCD (binary coded decimal) data format. |
static byte | FORMAT_HEX Constant to indicate a hexadecimal (simple binary) data format. |
Constructor Summary | |
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BigNumber (short maxBytes) Creates a BigNumber instance with initial value 0. |
Method Summary | |
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void | add (byte[] bArray,short bOff,short bLen,byte arrayFormat) Increments the internal big number by the specified operand value |
byte | compareTo (BigNumber operand) Compares the internal big number against the specified operand |
byte | compareTo (byte[] bArray,short bOff,short bLen,byte arrayFormat) Compares the internal big number against the specified operand. |
short | getByteLength (byte arrayFormat) Returns the number of bytes required to represent the big number using the desired format |
static short | getMaxBytesSupported () This method returns the byte length of the hex array that can store the biggest BigNumber supported. |
void | init (byte[] bArray,short bOff,short bLen,byte arrayFormat) Initializes the big number using the input data |
void | multiply (byte[] bArray,short bOff,short bLen,byte arrayFormat) Multiplies the internal big number by the specified operand value |
void | reset () Resets the big number to 0 |
void | setMaximum (byte[] maxValue,short bOff,short bLen,byte arrayFormat) Sets the maximum value that the BigNumber may contain. |
void | subtract (byte[] bArray,short bOff,short bLen,byte arrayFormat) Decrements the internal big number by the specified operand value |
void | toBytes (byte[] outBuf,short bOff,short numBytes,byte arrayFormat) Writes the internal big number out in the desired format. |
Methods inherited from class java.lang.Object |
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equals |
Field Detail |
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FORMAT_BCD
public static final byte FORMAT_BCD
Constant to indicate a BCD (binary coded decimal) data format. When this format is used a binary coded decimal digit is stored in 1 nibble (4 bits). A byte is packed with 2 BCD digits.
See Also:Constant Field Values
FORMAT_HEX
public static final byte FORMAT_HEX
Constant to indicate a hexadecimal (simple binary) data format.
See Also:Constant Field Values
Constructor Detail |
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BigNumber
public BigNumber(short maxBytes)
Creates a BigNumber instance with initial value 0. All implementations must support at least 8 byte length internal representation capacity.
Parameters:maxBytes - maximum number of bytes needed in the hexadecimal format for the largest unsigned big number. For example, maxBytes = 2 allows a big numberrepresentation range 0-65535.
Throws: ArithmeticException- if maxBytes is 0, negative or larger than the supported maximum
Method Detail |
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setMaximum
public void setMaximum(byte[] maxValue, short bOff, short bLen, byte arrayFormat)
Sets the maximum value that the BigNumber may contain. Attempts to increase beyond the maximum results in an exception. If this method is not called, the maximum value is the maximum hex value that fits within the configured maximum number of bytes. Note:
- This method may allocate internal storage to store the specified maximum value.
Parameters:maxValue - input byte array
bOff - offset within input byte array containing first byte (the high order byte)
bLen - byte length of input data
arrayFormat - indicates the format of the input data. Valid codes listed in FORMAT_* constants. See FORMAT_BCD .
Throws: NullPointerException- if maxValue is null
ArrayIndexOutOfBoundsException- if accessing the input array would cause access of data outside array bounds or if bLen is negative
ArithmeticException- for the following conditions:
- if the specified maximum value is smaller than the encapsulated big number
- if the specified maximum value is larger than will fit within the supported maximum number of bytes
- if the input byte array format is not conformant with the specified arrayFormat parameter
- if bLen is 0
- if arrayFormat is not one of the FORMAT_ constants.
getMaxBytesSupported
public static short getMaxBytesSupported()
This method returns the byte length of the hex array that can store the biggest BigNumber supported. This number is the maximum number in hex byte representation. All implementations must support at least 8 bytes.
Returns:the byte length of the biggest number supported
init
public void init(byte[] bArray, short bOff, short bLen, byte arrayFormat) throws NullPointerException , ArrayIndexOutOfBoundsException , ArithmeticException
Initializes the big number using the input data
Parameters:bArray - input byte array
bOff - offset within byte array containing first byte (the high order byte)
bLen - byte length of input data
arrayFormat - indicates the format of the input data. Valid codes listed in FORMAT_* constants. See FORMAT_BCD .
Throws: ArrayIndexOutOfBoundsException- if accessing the input array would cause access outside array bounds or if bLen is negative
NullPointerException- if bArray is null
ArithmeticException- for the following conditions:
- if the input byte array format is not conformant with the specified arrayFormat parameter
- if the specified input data represents a number which is larger than the maximum value configured or larger than will fit within the supported maximum number of bytes
- if bLen is 0
- if arrayFormat is not one of the FORMAT_ constants.
add
public void add(byte[] bArray, short bOff, short bLen, byte arrayFormat) throws NullPointerException , ArrayIndexOutOfBoundsException , ArithmeticException
Increments the internal big number by the specified operand value
Parameters:bArray - input byte array
bOff - offset within input byte array containing first byte (the high order byte)
bLen - byte length of input data
arrayFormat - indicates the format of the input data. Valid codes listed in FORMAT_* constants. See FORMAT_BCD .
Throws: ArrayIndexOutOfBoundsException- if accessing the input array would cause access of data outside array bounds or if bLen is negative
NullPointerException- if bArray is null
ArithmeticException- for the following conditions:
- if the input byte array format is not conformant with the specified arrayFormat parameter
- if the result of the addition results in a big number which cannot be represented within the maximum supported bytes or is greater than the configured max value. The internal big number is left unchanged.
- if bLen is 0
- if arrayFormat is not one of the FORMAT_ constants
subtract
public void subtract(byte[] bArray, short bOff, short bLen, byte arrayFormat) throws ArithmeticException
Decrements the internal big number by the specified operand value
Parameters:bArray - input byte array
bOff - offset within input byte array containing first byte (the high order byte)
bLen - byte length of input data
arrayFormat - indicates the format of the input data. Valid codes listed in FORMAT_* constants. See FORMAT_BCD .
Throws: ArrayIndexOutOfBoundsException- if accessing the input array would cause access of data outside array bounds or if bLen is negative
NullPointerException- if bArray is null
ArithmeticException- for the following conditions:
- if the input byte array format is not conformant with the specified arrayFormat parameter
- if the result of the subtraction results in a negative number. The internal big number is left unchanged.
- if bLen is 0
- if arrayFormat is not one of the FORMAT_ constants.
multiply
public void multiply(byte[] bArray, short bOff, short bLen, byte arrayFormat) throws ArithmeticException
Multiplies the internal big number by the specified operand value
Parameters:bArray - input byte array
bOff - offset within input byte array containing first byte (the high order byte)
bLen - byte length of input data
arrayFormat - indicates the format of the input data. Valid codes listed in FORMAT_* constants. See FORMAT_BCD .
Throws: ArrayIndexOutOfBoundsException- if accessing the input array would cause access of data outside array bounds or if bLen is negative
NullPointerException- if bArray is null
ArithmeticException- for the following conditions:
- if the input byte array format is not conformant with the specified arrayFormat parameter
- if the result of the multiplication results in a big number which cannot be represented within the maximum supported bytes or is greater than the configured max value. The internal big number is left unchanged.
- if bLen is 0
- if arrayFormat is not one of the FORMAT_ constants.
compareTo
public byte compareTo(BigNumber operand)
Compares the internal big number against the specified operand
Parameters:operand - contains the BigNumber operand
Returns:the result of the comparison as follows:
- 0 if equal
- -1 if the internal big number is less than the specified operand
- 1 if the internal big number is greater than the specified operand
Throws: NullPointerException- if operand is null
compareTo
public byte compareTo(byte[] bArray, short bOff, short bLen, byte arrayFormat)
Compares the internal big number against the specified operand. The operand is specified in an input byte array.
Parameters:bArray - input byte array
bOff - offset within input byte array containing first byte (the high order byte)
bLen - byte length of input data
arrayFormat - indicates the format of the input data. Valid codes listed in FORMAT_* constants. See FORMAT_BCD .
Returns:the result of the comparison as follows:
- 0 if equal
- -1 if the internal big number is less than the specified operand
- 1 if the internal big number is greater than the specified operand
Throws: ArrayIndexOutOfBoundsException- if accessing the input array would cause access of data outside array bounds or if bLen is negative
NullPointerException- if bArray is null
ArithmeticException- for the following conditions:
- if the input byte array format is not conformant with the specified arrayFormat parameter
- if bLen is 0
- if arrayFormat is not one of the FORMAT_ constants.
toBytes
public void toBytes(byte[] outBuf, short bOff, short numBytes, byte arrayFormat) throws ArrayIndexOutOfBoundsException , NullPointerException
Writes the internal big number out in the desired format. Note that the value output into the specified byte array is right justified for the number of requested bytes. BCD 0 nibbles are prepended to the output BCD data written out.
Parameters:outBuf - output byte array
bOff - offset within byte array containing first byte (the high order byte)
numBytes - number of output bytes required
arrayFormat - indicates the format of the input data. Valid codes listed in FORMAT_* constants. See FORMAT_BCD .
Throws: ArrayIndexOutOfBoundsException- if accessing the output array would cause access of data outside array bounds or if numBytes is negative
NullPointerException- if outBuf is null
ArithmeticException- for the following conditions:
- if numBytes is not sufficient to represent the big number in the desired format
- if numBytes is 0
- if arrayFormat is not one of the FORMAT_ constants.
getByteLength
public short getByteLength(byte arrayFormat)
Returns the number of bytes required to represent the big number using the desired format
Parameters:arrayFormat - indicates the format of the output data. Valid codes listed in FORMAT_* constants. See FORMAT_BCD .
Returns:the byte length of big number
Throws: ArithmeticException- if arrayFormat is not one of the FORMAT_ constants.
reset
public void reset()
Resets the big number to 0