CCITT-CRC Feature

This group of constants, macros, variables and functions implement the CRC support. More...

Collaboration diagram for CCITT-CRC Feature:

Functions
static int8	cgmCtlPntMsgFindCRC (cgmCtlPntMsg_t *pMsg)
	This function checks the presence of the CRC field in the CGMCP command. More...
static int8	cgmRACPMsgFindCRC (cgmRACPMsg_t *pMsg)
	This function checks the presence of the CRC field in the RACP command. More...
unsigned short	ccitt_crc16 (unsigned char *message, short length)
	CRC-CCITT calculation using the tabular form. More...
char	ccitt_crc16_test (unsigned char *message, short length)
	Test the input message against its attached CRC16 code. More...

Detailed Description

This group of constants, macros, variables and functions implement the CRC support.

Function Documentation

unsigned short ccitt_crc16	(	unsigned char *	message,
		short	length
	)

CRC-CCITT calculation using the tabular form.

Parameters

[in]	message	- the pointer to the message array.
[in]	length	- the length of the message.

Returns

the 16-bit CRC value.

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char ccitt_crc16_test	(	unsigned char *	message,
		short	length
	)

Test the input message against its attached CRC16 code.

Note

Here we assume that the CRC is attached as the last two bytes of the message.

Parameters

[in]	message	- pointer to the message character array
[in]	length	- the length of the message array

Returns

the result of the test.

Value	Meaning
0	The CRC test is failed
1	The CRC test is passed

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static int8 cgmCtlPntMsgFindCRC ( cgmCtlPntMsg_t *  pMsg )

static

This function checks the presence of the CRC field in the CGMCP command.

The function checks the presence of CRC by checking the command length corresponding to each of the possible CGMCP operation.

Parameters

[in]

pMsg

- the pointer to the CGMCP command message

Returns

The result

Value	Meaning
0	The CRC is missing
1	The CRC is present

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static int8 cgmRACPMsgFindCRC ( cgmRACPMsg_t *  pMsg )

static

This function checks the presence of the CRC field in the RACP command.

The function checks the presence of CRC by checking the command length corresponding to each of the possible RACP operation.

Parameters

[in]

pMsg

- the pointer to the RACP command message

Returns

The result

Value	Meaning
0	The CRC is missing
1	The CRC is present