196 lines
3.4 KiB
C
196 lines
3.4 KiB
C
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/* crc.h
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*
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* Copyright (c) 1994-1995 by DataBeam Corporation, Lexington, KY
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*
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* Abstract:
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* This file contains the CRC class definition. This class can use either
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* the table-driven or bit-shifting approach to generate its CRC.
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*
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* Public Instance Variable:
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* None
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*
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* Caveats:
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* None.
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*
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* Authors:
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* Marvin Nicholson
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*/
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#ifndef _CRC_
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#define _CRC_
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#include "databeam.h"
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#define CRC_TABLE_SIZE 256
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class CRC
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{
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public:
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CRC ();
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~CRC ();
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ULong OldCRCGenerator(
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PUChar block_adr,
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ULong block_len);
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ULong CRCGenerator(
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PUChar block_adr,
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ULong block_len);
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DBBoolean CheckCRC(
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PUChar block_adr,
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ULong block_len);
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Void GetOverhead(
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UShort maximum_packet,
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PUShort new_maximum_packet);
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private:
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UShort CRCTableValue(
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Int Index,
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ULong poly);
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Void CRCTableGenerator(
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ULong poly);
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UShort CRC_Table[CRC_TABLE_SIZE];
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Int CRC_Width;
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ULong CRC_Poly;
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ULong CRC_Init;
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UShort CRC_Check_Value;
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DBBoolean Invert;
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UShort CRC_Register;
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};
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typedef CRC * PCRC;
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#endif
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/*
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* CRC::CRC ();
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*
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* Functional Description
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* This is the constructor for this class.
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*
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* Formal Parameters
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* None.
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*
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* Return Value
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* None
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*
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* Side Effects
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* None
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*
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* Caveats
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* None
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*/
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/*
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* CRC::~CRC ();
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*
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* Functional Description
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* This is the destructor for this class.
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*
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* Formal Parameters
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* None.
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*
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* Return Value
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* None
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*
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* Side Effects
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* None
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*
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* Caveats
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* None
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*/
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/*
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* ULong CRC::OldCRCGenerator(
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* PUChar block_adr,
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* ULong block_len);
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*
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* Functional Description
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* This function generates the crc using bit-shifting methods. This method
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* is slower than the table-driven approach.
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*
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* Formal Parameters
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* block_adr (i) - Address of buffer to generate CRC on.
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* block_lengh (i) - Length of buffer
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*
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* Return Value
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* CRC value
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*
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* Side Effects
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* None
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*
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* Caveats
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* None
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*/
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/*
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* ULong CRC::CRCGenerator(
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* PUChar block_adr,
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* ULong block_len);
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*
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* Functional Description
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* This function generates the crc using the table-driven method.
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*
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* Formal Parameters
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* block_adr (i) - Address of buffer to generate CRC on.
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* block_lengh (i) - Length of buffer
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*
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* Return Value
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* CRC value
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*
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* Side Effects
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* None
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*
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* Caveats
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* None
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*/
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/*
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* DBBoolean CRC::CheckCRC(
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* PUChar block_adr,
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* ULong block_len);
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*
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* Functional Description
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* This function generates a CRC based on the block passed in. It assumes
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* that the CRC is attached to the end of the block. It compares the
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* CRC generated to the CRC at the end of the block and returns TRUE if
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* the CRC is correct.
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*
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* Formal Parameters
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* block_adr (i) - Address of buffer to generate CRC on.
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* block_lengh (i) - Length of buffer
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*
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* Return Value
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* TRUE - CRC in the block is correct
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* FALSE - CRC in the block is NOT correct
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*
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* Side Effects
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* None
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*
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* Caveats
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* None
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*/
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/*
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* Void CRC::GetOverhead(
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* UShort maximum_packet,
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* PUShort new_maximum_packet);
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*
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* Functional Description
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* This function is called to determine the overhead that will be added
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* to the packet by the CRC.
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*
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* Formal Parameters
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* maximum_packet (i) - Current max. packet size
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* new_maximum_packet (o) - Maximum length of packet including CRC.
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*
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* Return Value
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* None
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*
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* Side Effects
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* None
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*
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* Caveats
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* None
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*/
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