> The algorithm for signing a 7bit 2's complement value is cool, but i am > confused as to select which approach from the 2 given below. > > let me consider an example, say byte x = 3; -> 00000011 > now x = -3 will be -> > 11111101 (as per the usual representation of negative values) > > Ist approach: > if we find the 7 bit value as -> > 0000011 > then check the 7th bit (Hi bit), its 0 so its a positive 3 > > if we find the 7 bit value as -> > 1000011 > then check the 7th bit (Hi bit), its 1 so its a negative 3
1000011 does not equal -3, it equals -61. A negative twos complement is the binary inverse of the positive number plus 1. The msb will always be 1 for a negative number. By looking for the sign bit and simply filling the the 8th bit with a 1 is the same as filling it with a zero for a positive number. If you still don't understand why my algorithm will work, do a google search on "twos complement". Trust me... Ryan --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] Mailing List: http://jakarta.apache.org/site/mail2.html#poi The Apache Jakarta POI Project: http://jakarta.apache.org/poi/
