CRC-CCITT Checksum

[Tom Hanlin]

Have you tried a Forum search? Seems like I may have seen this in the Source Code Forum.

It shouldn't be hard to translate this to PowerBASIC, though. I gather it's from 16-bit
C code, so the "unsigned short" translates as WORD, and "unsigned char" as BYTE. The ">>"
operator means "SHIFT RIGHT", "^" is XOR, and "&" is AND. "*" is still *.

(those spots that say "unsigned sort" are surely typos for "unsigned short").

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Tom Hanlin
PowerBASIC Staff

[Matthias Kuhn]

Hi,

has anyone a sample in PB how to program a 16-Bit CRC-CCITT
Checksum.

I´ve only a sample in c:

unsigned sort crc;
crc = 0;
calc_crc( ID_H );
calc_crc( ID_L );
.
.
.
calc_crc( <last databyte> );

CRC_H = (unsigned char)(crc>>8);
CRC_L = (unsigned char)crc;
.
.
void calc_crc( unsigned char character )
{
unsigned sort crc_tmp;
crc_tmp=(crc^character) & 0x0F;
crc=(crc>>4)^(crc_tmp*4225);
crc_tmp=(crc^(charcter>>4))& 0x0F;
crc=(crc>>4)^(crc_tmp*4225)
}

Thanks for any help.

Regards

Matthias Kuhn

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