Module crc 

Cyclic redundancy checks.

A CRC of degree $L$ appends the remainder of $D^{L} a(D)$ divided by the generator polynomial $g(D)$ to the information bits $a(D)$ (most significant bit first, zero initial state, no reflection, no final XOR — the convention of 3GPP TS 38.212, Sec. 5.1). The polynomials of 5G NR are provided.

Constructor	$g(D)$	Use in NR
Crc::crc24a	0x864CFB	transport blocks
Crc::crc24b	0x800063	code blocks
Crc::crc24c	0xB2B117	downlink control (polar)
Crc::crc16	0x1021	small transport blocks
Crc::crc11	0x621	uplink control (polar)
Crc::crc6	0x21	uplink control (polar)

Examples

use comnum_fec::crc::Crc;
let crc = Crc::crc24a();
let mut word = crc.attach(&[1, 0, 1, 1, 0, 0, 1]);
assert_eq!(word.len(), 7 + 24);
assert!(crc.check(&word));
word[3] ^= 1;
assert!(!crc.check(&word));

References

1. 3GPP TS 38.212, NR; Multiplexing and channel coding, Sec. 5.1.
2. W. W. Peterson and D. T. Brown, “Cyclic codes for error detection,” Proc. IRE, 49(1), 228–235, 1961.

Structs

Crc

A cyclic redundancy check of degree width and generator poly (without its leading term), valid by construction (Crc::new checks them).