csi_crc.h File Reference

CRC calculation for Common Serial Interface (CSI) protocol. More...

#include "csi_const.h"
#include "csi_plfabstr.h"

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Functions
CSI_API uint16_t	CsiCrcCalc (const uint16_t *pDataArray, uint16_t NumberOfWords)
	Calculate CRC-field for CSI protocol. More...
CSI_API uint16_t	CsiCrcCalcIncremental (const uint16_t *pWordArray, uint16_t NumberOfWords, uint16_t CRC)
	Calculate CRC-field for CSI protocol. More...

Detailed Description

CRC calculation for Common Serial Interface (CSI) protocol.

Author

Uwe Kindler (UK)

Date

2009/08/27

Function Documentation

CSI_API uint16_t CsiCrcCalc	(	const uint16_t *	pDataArray,
		uint16_t	NumberOfWords
	)

Calculate CRC-field for CSI protocol.

Parameters

[in]	pDataArray	Points to array of data words to calculate checksum
[in]	NumberOfWords	The number of words in pDataArray

Returns

CRC checksum for CRC field

{
    return CsiCrcCalcIncremental(pWordArray, NumberOfWords, 0);
}

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CSI_API uint16_t CsiCrcCalcIncremental	(	const uint16_t *	pWordArray,
		uint16_t	NumberOfWords,
		uint16_t	CRC
	)

Calculate CRC-field for CSI protocol.

Parameters

[in]	pWordArray	Points to array of data words to calculate checksum
[in]	NumberOfWords	The number of words in pDataArray
[in]	CRC	The current CRC sum

Returns

CRC checksum for CRC field

Referenced by CsiBusWriteLargeData(), and CsiCrcCalc().

{
    uint16_t shifter;
    uint16_t DataWord;
    uint16_t carry;

    //
    // Calculate pDataArray Word by Word
    //
    while(NumberOfWords--)
    {
        shifter = 0x8000;
        DataWord = *pWordArray++;
        do
        {
            carry = CRC & 0x8000;
            CRC <<= 1;
            if(DataWord & shifter)
            {
                CRC++;
            }

            if(carry)
            {
                CRC ^= 0x1021;
            }
            shifter >>= 1;
        }
        while(shifter);
    } // while(wNumberOfWords--)
    return CRC;
}