Calculate Checksum VB 6

[fabianuat]

Could I have some help calculating a checksum for receive data from a Video server?

The data is in Hex and the values and here is an example:
20 24 49 4C 30 31 37 38 37 39 CS
CS=Checksum

the cheksum is the 2's complement of the sum of the values.

If anyone have an algoritm or knows how to do it, please help me, thanks

 

[stevexff]

How to do it - break the data down into bytes, and treat each byte as an int. Add them all together (total).

Checksum = 256 - (total % 256), which you will need to reduce to 1 byte.

Alternative - flip all the bits in total by a bitwise AND with xFF, then add 1.

That's the theory. How to do it in VB6, over to one of the experts...

Steve

[small]"Every program can be reduced by one instruction, and every program has at least one bug. Therefore, any program can be reduced to one instruction which doesn't work." (Object:erlDesignPatterns)[/small]

 

[fabianuat]

all right thanks stevexff