#include <GenericCrc.h>

Collaboration diagram for GenericCrc:

Public Member Functions
	GenericCrc ()
	Provides a library of known CRC(like) algorithms. More...

	~GenericCrc ()

uint32_t	crc9fibre (const std::vector< uint32_t > &inwords, size_t num_bits) const
	Functions calculating CRC over input data. More...

uint32_t	crc20rod (const std::vector< uint32_t > &inwords, size_t num_bits) const

Detailed Description

Definition at line 9 of file GenericCrc.h.

Constructor & Destructor Documentation

◆ GenericCrc()

GenericCrc::GenericCrc ( )

inline

Provides a library of known CRC(like) algorithms.

GenericCrc is a stateless class which just provides a collection of CRC-like functions for various stages of data processing

Definition at line 20 of file GenericCrc.h.

20 {}

◆ ~GenericCrc()

GenericCrc::~GenericCrc ( )

inline

Definition at line 21 of file GenericCrc.h.

21 {}

Member Function Documentation

◆ crc20rod()

uint32_t GenericCrc::crc20rod	(	const std::vector< uint32_t > &	inwords,
		size_t	num_bits
	)		const

Definition at line 33 of file GenericCrc.cxx.

 {
   int order = 20;
   uint32_t val  = 0xfffff;
   //<<uint32_t poly = 0x18349f;   // Old, wrong, polynomial used until December 2021
   uint32_t poly = 0x18359f;
   size_t num_words = inwords.size();
   if ( (num_bits+31)/32 > num_words )
   {
     std::cout << "ERROR: not enough words (" << num_words << ") for " << num_bits << "-bit CRC calculation." << std::endl;
     return 0;
   }
   for ( int i = 0 ; i < order ; ++i )
   {
     int flip = val&1;
     val >>= 1;
     if ( flip )
       val ^= (poly>>1);
   }
   for ( size_t i = 0 ; i < num_bits ; ++i )
   {
     val <<= 1;
     val |= (inwords[i/32]>>(31-i%32))&1;
     if ((val>>order)&1)
       val ^= poly;
   }
   for ( int i = 0 ; i < order ; ++i )
   {
     val <<= 1;
     if ((val>>order)&1)
       val ^= poly;
   }
   return val;
 }

◆ crc9fibre()

uint32_t GenericCrc::crc9fibre	(	const std::vector< uint32_t > &	inwords,
		size_t	num_bits
	)		const

Functions calculating CRC over input data.

CRC9 with polynomial 1011111011 over num_bits bits

Uses a more succinct CRC calculation and flexible in terms of digits, checked versus old code but only supports bit reversal = true

Definition at line 5 of file GenericCrc.cxx.

 {
     size_t num_words = inwords.size();
     if ( (num_bits+31)/32 > num_words )
     {
       std::cout << "ERROR: not enough words (" << num_words << ") for " << num_bits << "-bit CRC calculation." << std::endl;
       return 0;
     }
     uint32_t val = 0x1ff;
     for ( size_t i = 0 ; i < num_bits ; ++i )
     {
       if ( (inwords.at(i/32)>>(i%32)) & 1 )
         val ^= 1;
       if ( val&1 )
         val ^= 0x37d;     // 1101111101 = polynomial reversed
       val >>= 1;
     }
     return val;
 } 

The documentation for this class was generated from the following files: