how does a 8 bit SIGNED adder work?

[yuenkit]

signed adder

Hi, I am wondering, how does a 8-bit SIGNED adder work.

there are 3 inputs
a, b, cin

and 2 outputs
sum, cout


normally for unsigned operation, the msb is sent to cout, but for Signed operation, should the msb be sent to cout? how do we know which is carry bit? how do we propagate the sign (+ or -) to the next signed adder block?

Can someone show me with verilog code? thanks.

Edited **************
sorry, the msb i referred is msb of the summation.

 

[hr_rezaee]

verilog signed adder

Hi
i think
Cout is generated referred to MSB of inputs
therefor if inputs are positive we have carry and when inputs are negative and positive we have sign