Package org.apache.commons.codec.digest

Class Crc16

java.lang.Object

org.apache.commons.codec.digest.Crc16

All Implemented Interfaces:

java.util.zip.Checksum

public final class Crc16
extends java.lang.Object
implements java.util.zip.Checksum

CRC-16 checksum implementations you can customize with a table and init value.

Since there are so many CRC-16 variants, we do not pick a default.

For example, to create a create a custom variant of CRC16-MODBUS with an init value of 0x0000, use:

 Checksum crc16 = CRC16.builder().setTable(CRC16.getModbusTable()).setInit(0x0000).get();
 

Since:

1.20.0

See Also:

Cyclic redundancy check, Catalogue of parametrised CRC algorithms with 16 bits, On-line CRC calculation and free library, crccalc

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	Crc16.Builder	Builds Crc16 instances.

Method Summary

Modifier and Type	Method	Description
static Crc16	arc()	Creates a new CRC16-CCITT Checksum.
static Crc16.Builder	builder()	Creates a new builder.
static Crc16	ccitt()	Creates a new CRC16-CCITT Checksum.
static Crc16	dnp()	Creates a new CRC16-DNP Checksum.
static int[]	getArcTable()	Gets a copy of the CRC16-CCITT table.
static int[]	getCcittTable()	Gets a copy of the CRC16-CCITT table.
static int[]	getDnpTable()	Gets a copy of the CRC16-DNP table.
static int[]	getIbmSdlcTable()	Gets a copy of the CRC16-IBM-SDLC table.
static int[]	getMaximTable()	Gets a copy of the CRC16-MAXIM table.
static int[]	getMcrf4xxTable()	Gets a copy of the CRC16-MCRF4XX table.
static int[]	getModbusTable()	Gets a copy of the CRC16-MODBUS table.
static int[]	getNrsc5Table()	Gets a copy of the CRC16-NRSC-5 table.
long	getValue()
static Crc16	ibmSdlc()	Creates a new CRC16-IBM-SDLC Checksum.
static Crc16	maxim()	Creates a new instance for CRC16-MAXIM Checksum.
static Crc16	mcrf4xx()	Creates a new instance for CRC16-MCRF4XX Checksum.
static Crc16	modbus()	Creates a new instance for CRC16-MODBUS Checksum.
static Crc16	nrsc5()	Creates a new instance for CRC16-NRSC-5 Checksum.
void	reset()
java.lang.String	toString()
void	update(byte[] b, int off, int len)
void	update(int b)
static Crc16	usb()	Creates a new instance for CRC16-USB Checksum.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.zip.Checksum

update, update

Method Detail

arc

public static Crc16 arc()

Creates a new CRC16-CCITT Checksum.

• The init value is 0x0000.
• The XorOut value is 0x0000.

Also known as:

• CRC-16/ARC
• ARC
• CRC-16
• CRC-16/LHA
• CRC-IBM

Returns:

a new CRC16-CCITT Checksum.

builder

public static Crc16.Builder builder()

Creates a new builder.

Since there are so many CRC-16 variants, we do not pick a default.

Returns:

a new builder.

ccitt

public static Crc16 ccitt()

Creates a new CRC16-CCITT Checksum.

• The init value is 0x0000.
• The XorOut value is 0x0000.

Also known as:

• CRC-16/KERMIT
• CRC-16/BLUETOOTH
• CRC-16/CCITT
• CRC-16/CCITT-TRUE
• CRC-16/V-41-LSB
• CRC-CCITT
• KERMIT

Returns:

a new CRC16-CCITT Checksum.

dnp

public static Crc16 dnp()

Creates a new CRC16-DNP Checksum.

• The init value is 0x0000.
• The XorOut value is 0xFFFF.

Returns:

a new CRC16-DNP Checksum.

getArcTable

public static int[] getArcTable()

Gets a copy of the CRC16-CCITT table.

Returns:

a copy of the CCRC16-CITT table.

getCcittTable

public static int[] getCcittTable()

Gets a copy of the CRC16-CCITT table.

Returns:

a copy of the CCRC16-CITT table.

getDnpTable

public static int[] getDnpTable()

Gets a copy of the CRC16-DNP table.

Returns:

a copy of the CCRC16-DNP table.

getIbmSdlcTable

public static int[] getIbmSdlcTable()

Gets a copy of the CRC16-IBM-SDLC table.

Returns:

a copy of the CRC16-IBM-SDLC table.

getMaximTable

public static int[] getMaximTable()

Gets a copy of the CRC16-MAXIM table.

Returns:

a copy of the CRC16-MAXIM table.

getMcrf4xxTable

public static int[] getMcrf4xxTable()

Gets a copy of the CRC16-MCRF4XX table.

Returns:

a copy of the CRC16-MCRF4XX table.

getModbusTable

public static int[] getModbusTable()

Gets a copy of the CRC16-MODBUS table.

Returns:

a copy of the CRC16-MODBUS table.

getNrsc5Table

public static int[] getNrsc5Table()

Gets a copy of the CRC16-NRSC-5 table.

Returns:

a copy of the CRC16-NRSC-5 table.

ibmSdlc

public static Crc16 ibmSdlc()

Creates a new CRC16-IBM-SDLC Checksum.

• The init value is 0xFFFF.
• The XorOut value is 0xFFFF.

Also known as:

• CRC-16/IBM-SDLC
• CRC-16/ISO-HDLC
• CRC-16/ISO-IEC-14443-3-B
• CRC-16/X-25
• CRC-B
• X-25

Returns:

a new CRC16-IBM-SDLC Checksum.

maxim

public static Crc16 maxim()

Creates a new instance for CRC16-MAXIM Checksum.

CRC-16 checksum implementation based on polynomial x<sup>16</spu> + x^15 + x^2 + 1 (0x8005).

• The init value is 0xFFFF.
• The XorOut value is 0xFFFF.

Also known as:

• CRC-16/MAXIM-DOW

Returns:

a new CRC16-MAXIM Checksum.

mcrf4xx

public static Crc16 mcrf4xx()

Creates a new instance for CRC16-MCRF4XX Checksum.

• The init value is 0xFFFF.
• The XorOut value is 0x0000.

Returns:

a new CRC16-MCRF4XX Checksum.

modbus

public static Crc16 modbus()

Creates a new instance for CRC16-MODBUS Checksum.

CRC-16 checksum implementation based on polynomial x<sup>16</spu> + x^15 + x^2 + 1 (0x8005).

• The init value is 0xFFFF.
• The XorOut value is 0x0000.

Also known as:

• CRC-16/MODBUST
• MODBUST

Returns:

a new CRC16-MODBUS Checksum.

nrsc5

public static Crc16 nrsc5()

Creates a new instance for CRC16-NRSC-5 Checksum.

• The init value is 0xFFFF.
• The XorOut value is 0x0000.

Returns:

a new CRC16-NRSC-5 Checksum.

usb

public static Crc16 usb()

Creates a new instance for CRC16-USB Checksum.

• The init value is 0xFFFF.
• The XorOut value is 0xFFFF.

Returns:

a new CRC16-USB Checksum.

getValue

public long getValue()

Specified by:

getValue in interface java.util.zip.Checksum

reset

public void reset()

Specified by:

reset in interface java.util.zip.Checksum

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

update

public void update(byte[] b,
                   int off,
                   int len)

Specified by:

update in interface java.util.zip.Checksum

update

public void update(int b)

Specified by:

update in interface java.util.zip.Checksum