scrambleBytes.cpp File Reference

#include "scrambleBytes.hh"

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Functions
static u_int64_t	crc64 (u_int8_t seed, u_int8_t const *buffer, unsigned bufferSize)
void	getScrambleBytes (u_int8_t recordType, u_int8_t keyByte, u_int8_t *resultScrambleBytes)

Variables
static u_int64_t	crc64Table [256]

Function Documentation

crc64()

static u_int64_t crc64 ( u_int8_t  seed, u_int8_t const *  buffer, unsigned  bufferSize  )

static

Definition at line 116 of file scrambleBytes.cpp.

                                                                                   {
  u_int64_t crc = seed;

  for (unsigned i = 0; i < bufferSize; ++i) {
    u_int8_t tabIndex = buffer[i] ^ crc;
    crc = crc64Table[tabIndex] ^ (crc >> 8);
  }

  return crc;
}

References crc64Table.

Referenced by getScrambleBytes().

getScrambleBytes()

void getScrambleBytes	(	u_int8_t	recordType,
		u_int8_t	keyByte,
		u_int8_t *	resultScrambleBytes
	)

Definition at line 127 of file scrambleBytes.cpp.

                                                     {
  // Set up the (8-byte) buffer to compute the CRC over:
  u_int64_t dataForBuffer = 0x123456789ABCDEF0*keyByte;
  u_int8_t bufferToCRC[8];
  // Fill in the buffer in little-endian order:
  for (unsigned i = 0; i < sizeof bufferToCRC; ++i) {
    bufferToCRC[i] = dataForBuffer; // low 8 bits
    dataForBuffer >>= 8;
  }

  // Compute a CRC over this buffer, using our "recordType" and "keyByte" parameters as salt:
  u_int64_t crcResult = crc64(recordType + keyByte, bufferToCRC, sizeof bufferToCRC);

  // Unpack this into "resultScrambleBytes", in little-endian order:
  for (unsigned i = 0; i < 8; ++i) {
    resultScrambleBytes[i] = crcResult; // low 8 bits
    crcResult >>= 8;
  }
}

References crc64().

Referenced by RecordAndDetailsParser::parseRecord().

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Variable Documentation

crc64Table

u_int64_t crc64Table[256]

static

Definition at line 28 of file scrambleBytes.cpp.

Referenced by crc64().