crc--Cyclic redundancy Check code

The CRC is based on a checksum of modulo 2 operations.

N=k+r.

n is the length of the CRC code, K is the number of bits of the information code, and R is the number of bits of the checksum code.

2 R-Square >=k+r+1 (correct).

4 Useful information (1100) as a cyclic encoding, choose to generate a polynomial g (X) = 1011.

1. Move the information bit to the left r bit, i.e. add R 0 after the information bit.

Get 1100000.

2. Use 1100000 pairs of G (X) for modulo 2 to divide.

Get the remainder 010.

3. Modulo 2 Plus with remainder and 1100000.

Get 1100010.

Name	Generating a polynomial	Précis-Writers type *	Application examples
CRC-4	X4+x+1	3	ITU g.704
CRC-8	X8+x5+x4+1	31	Ds18b20
CRC-12	X12+x11+x3+x+1	5E
CRC-16	X16+x15+x2+1	8005	IBM SDLC
crc-itu**	X16+x12+x5+1	1021	ISO HDLC, ITU x. v.34/v.41/v.42, Ppp-fcs
CRC-32	X32+x26+x23+...+x2+x+1	04c11db7	ZIP, RAR, IEEE 802 lan/fddi, IEEE 1394, Ppp-fcs
crc-32c	X32+x28+x27+...+x8+x6+1	1edc6f41	Sctp

crc--Cyclic redundancy Check code