>> Given a PARITY_MAGIC of 0x6996, this is even parity, not odd. > From "http://www.encyclopedia.com/doc/1O11-oddparity.html";, we can get > the definition of "odd parity": > odd parity A property that holds when a group of binary values contains > an odd number of 1s. That's correct, but the group of bits being discussed *includes the parity bit itself*. Let me be specific: Let x be a word, which is BITS bits long. Let parity(x) = popcount(x) & 1 Let y = x | parity(x) << BITS Let z = x | !parity(x) << BITS y is described as having even parity. z is described as having odd parity. x is not normally described using those terms The bits appended are usually referred to as an "even parity bit" and an "odd parity bit". You're right that your function returns "true" if the word fed to it has odd parity, but the bit it computes is an even parity bit. In the field of error-checking codes, an inverse convention is generally used: zero means no error and non-zero means error. When this convention is used, the same function can be used to both generate and check parity. (And the one you have is the even parity function.) I think the best solution is to just delete the word "odd". -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
