Precomputed tables and constants for the CRC calculation. More...

Collaboration diagram for CxxUtils::CRCTable:

Public Member Functions
	CRCTable (uint64_t p, uint64_t initial=0xffffffffffffffff)
	Initialize the CRC tables and constants. More...

Public Attributes
uint64_t	m_initial
	Initial CRC value. More...

uint64_t	m_table [256]
	Lookup table for bytewise CRC calculation. More...

Detailed Description

Precomputed tables and constants for the CRC calculation.

Definition at line 464 of file crc64.cxx.

Constructor & Destructor Documentation

◆ CRCTable()

CxxUtils::CRCTable::CRCTable	(	uint64_t	p,
		uint64_t	initial = `0xffffffffffffffff`
	)

Initialize the CRC tables and constants.

Parameters

p	Polynomial for the CRC. A 1 in the 2^64 bit is implied.

Definition at line 495 of file crc64.cxx.

 {
   m_initial = initial;
  
   uint64_t prev = bit_reflect (p);
   for (int i = 0; i < 256; i++)
   {
     uint64_t r = i;
     for (int j = 0; j < 8; j++)
     {
       if (r & 1)
         r = (r >> 1) ^ prev;
       else
         r >>= 1;
     }
     m_table[i] = r;
   }
  
 #if ATH_CRC64_VEC
   const uint64_t k1 = bit_reflect (exp_mod (128+64, p)) << 1;
   const uint64_t k2 = bit_reflect (exp_mod (128, p)) << 1;
   const uint64_t mu = (bit_reflect (exp129_div (p)) << 1) | 1;
   const uint64_t prev65 =  (bit_reflect (p) << 1) | 1;
   v2du a = {k1, k2};
   m_fold_constants = reinterpret_cast<v2di>(a);
   v2du b = { mu, prev65 };
   m_barrett_constants = reinterpret_cast<v2di>(b);
 #endif
 }

Member Data Documentation

◆ m_initial

uint64_t CxxUtils::CRCTable::m_initial

Initial CRC value.

Definition at line 475 of file crc64.cxx.

◆ m_table

uint64_t CxxUtils::CRCTable::m_table[256]

Lookup table for bytewise CRC calculation.

Definition at line 478 of file crc64.cxx.

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

crc64.cxx