tcam memory parity bit generation for parameter extractor

[mahalakshmi r]

please any tell me, whether parity bit calculation possible in tcam memory parameter extraction..
i.e., xor operation can perform unknown x(either 0 or 1) value.
another one is,
if binary word has unknown term we can say that word is even or odd parity?

 

[ads-ee]

please any tell me, whether parity bit calculation possible in tcam memory parameter extraction..
i.e., xor operation can perform unknown x(either 0 or 1) value.
another one is,
if binary word has unknown term we can say that word is even or odd parity?

XOR with an unknown (i.e. X) will be X.

e.g.
0 ^ X => X
1 ^ X => X
X ^ X => X

 

[mahalakshmi r]

XOR with an unknown (i.e. X) will be X.

e.g.
0 ^ X => X
1 ^ X => X
X ^ X => X

thank you for reply....
but i have doubt that binary word with this unknown term can defined by even or odd parity?

 

[ads-ee]

thank you for reply....
but i have doubt that binary word with this unknown term can defined by even or odd parity?

It can't be defined at all. To compute a parity value for any bit sequence you have to know what ALL the bits are in the sequence. Any bit that is X results in a parity value that can not be computed. As by it's very nature X means "We don't know if the bit is a 1 or a 0".

And for whether or not the parity is even or odd, that is defined by the parity scheme that was specified for the data, it has nothing to do with the bit sequence you are computing the parity for.

e.g.
Compute odd parity for...
10010001x0010000 = X
1001000100010000 = 1 (4, 1's plus 1 parity = 5, 1's)
1001000110010000 = 0 (5, 1's)

Compute even parity for...
10010001x0010000 = X
1001000100010000 = 0 (4, 1's)
1001000110010000 = 1 (5, 1's plus 1 parity = 6, 1's)