CxxUtils::CRCTable Class Reference

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.

Public Attributes
uint64_t	m_initial
	Initial CRC value.
uint64_t	m_table [256]
	Lookup table for bytewise CRC calculation.

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.

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

• crc64.cxx