Xor Sum

I need to understand how to work out a checksum for this A0 00 00 04 20 00 AF, the answer is 2B but I dont understand how to work out an XOR sum. According to the website I got this from, its says 2B is an XOR sum of Bytes 1-7.

Sphere.....

Just start with byte 1 and XOR each of the following bytes.
The sequence works like this...

A0
XOR 00 = A0
XOR 00 = A0
XOR 04 = A4
XOR 20 = 84
XOR 00 = 84
XOR AF = 2B

Quote:

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Originally Posted by Sphere

I need to understand how to work out a checksum for this A0 00 00 04 20 00 AF, the answer is 2B but I dont understand how to work out an XOR sum. According to the website I got this from, its says 2B is an XOR sum of Bytes 1-7.

Sphere.....

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Here is a simple demo of how to accomplish this in PBP:

Code:

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DataPacket var byte[7]
XORsum var byte

DataPacket[0] = A0
DataPacket[1] = 00
DataPacket[2] = 00
DataPacket[3] = 04
DataPacket[4] = 20
DataPacket[5] = 00
DataPacket[6] = AF

XORsum = DataPacket[0] ^ DataPacket[1]
XORsum = XORsum  ^ DataPacket[2]
XORsum = XORsum  ^ DataPacket[3]
XORsum = XORsum  ^ DataPacket[4]
XORsum = XORsum  ^ DataPacket[5]
XORsum = XORsum  ^ DataPacket[6]

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HTH,
Steve

EDIT: Corrected the DataPacket array declaration to 7 bytes

Thanks alot keithdoxey and SteveB it worked first time, it will save me alot of code space.

Thanks again Sphere.