checksum correction

[Imran]

Hello all

I am trying to calculate a checksum correction for 16 byte checksum
calculation.

I have 1 lines of data

xxxxxxxxyyyyyyyy80804C0400004204UUUUUUUU

What I am trying to achive is to find a right UUUUUUUU
value so that when I reclaculate the checksum of whole
line, it should be yyyyyyyy.

My tried / failed algoritham is as follows

int final_cks(UUUUUUUU) = xxxxxxxx + 8080+4C04+0000+4204 - yyyyyyyy

i will patch this final_cks to UUUUUUUU, then i re-calculate the checksum
again,

int final_cks= xxxxxxxx + 8080+4C04+0000+4204 +UUUU+UUUU

it should be equal to yyyyyyyy
Any sugg?

Thank you

[Johannes Bauer]

Imran schrieb:

i will patch this final_cks to UUUUUUUU, then i re-calculate the checksum
again,

int final_cks= xxxxxxxx + 8080+4C04+0000+4204 +UUUU+UUUU

it should be equal to yyyyyyyy

UUUUUUUU needs to be 42.

Seriously, nobody will be able to help you without telling which
algorithm you use. There is no such thing as "the" 16-bit checksum
function. But anyways, it doesn't have anything to do with C.

Greetings,
Johannes

--
"Viele der Theorien der Mathematiker sind falsch und klar
Gotteslästerlich. Ich vermute, dass diese falschen Theorien genau
deshalb so geliebt werden." -- Prophet und Visionär Hans Joss aka
HJP in de.sci.mathematik <47**********************@news.sunrise.ch>