Fixed point math functions

Hello,

Thanks for the reply

for the case of signed bits:

If I have 2 inputs A(20,10) and B(20,10)

To make them signed. I should have A(21,10) and B(21,10) < number of bits is 31

multiplication of signed bits:

X(42,20)= A(21,10)*B(21,10) <<< should actually be X(41,20)? Do I remove the most significant bit or the one after the MSB?

Question 2:

for converting back to n bits

And to convert Y(21,10)<= {X[61],X[59:40],X[39:20]} or {X[60],X[59:40],X[39:20]} <because of the 2 sign bits

Addition: Nbits + Nbits = 2

X(22,10)=A(21,20) +B(21,20)

And to convert

Y(21,10)=X[41:0];?