fixed point multiplication using verilog

[siva_7517]

verilog fixed point

Hi,

In fixed-point multiplication, we should add an extended sign bit in the multiplication process . Example below:

1.110 -0.25 B
X 0.110 0.75 C
-------------------------
0000
111110
11110
0000
-----------------------------
11110100 -0.1875 A


I have try to do a verilog as below:

assign A = B * C

But i dont have an idea on how to do a extended bit in verilog. Hope can help me on this.
Thank in advance.

 

[jcss]

fixed point multiplication

You can use the concatenation operator.

assign A = {4{B[3]}, B} * {4{C[3]}, C};

 

[siva_7517]

verilog multiplication

Hi,

Is this equation is include with the extra sign bit while doing the multiplication?

assign A = {4{B[3]}, B} * {4{C[3]}, C};Hi,

 

[jcss]

signed multiplication verilog

Yes, it is 4-bit signed times 4-bit signed and result is 8-bit signed.

 

[siva_7517]

fixed point verilog

Hi,



-----------------1.110 @@@@@@@ -0.25 B
--------------X 0.110 @@@@@@ 0.75 C
-------------------------
---------------- 0000
------------111110------------------->extended sign bit
------------11110--------------------->extended sign bit
----------+0000
-----------------------------
----------11110100 @@@@@@@@-0.1875 A



i understand with concept of increase the output bit........but when we do a fixed point multiplication there is extra sign bit in inserted before the adding is done. I have difficulty on how to intepret this in verilog.thanx