EmbDev.net

Forum: FPGA, VHDL & Verilog FLoating point multiplier Logicore


von Misbah F. (Company: fast) (mis6358)


Rate this post
useful
not useful
Does any one know the function of floating point multiplier in logicore? 
its not giving me accurate answers i want to know how it works and how 
it gives the answer and in what form

von Lothar M. (Company: Titel) (lkmiller) (Moderator)


Rate this post
useful
not useful
What manual do you use as reference? What information are you missing 
there? What results do you expect and what results do you get?

von Rolf S. (audiorolf)


Rate this post
useful
not useful
"Logicore" is Xilinx, right? You will have to provide code and an 
example to make people be able to help you.

von Misbah F. (Company: fast) (mis6358)


Rate this post
useful
not useful
I am using the manual which is provided on the xilinx site. A want a 
answer of a simple multiplier like 1.2 x 1.2 should give me 2.4 in 
binary at the output but it is giving me some dummy values.

von Misbah F. (Company: fast) (mis6358)


Rate this post
useful
not useful
There is no code. I am using schematics. A simple floating point 
multiplier in the schematics.

von Klaus Falser (Guest)


Rate this post
useful
not useful
Misbah Faiz wrote:
> I am using the manual which is provided on the xilinx site. A want
> a
> answer of a simple multiplier like 1.2 x 1.2 should give me 2.4 in
> binary at the output but it is giving me some dummy values.

I'm not surprised.
1.2 x 1.2 gives 1.44 in my understanding.

von AHED (Guest)


Rate this post
useful
not useful
I suppose

"1.2" means a signed fractional format with 1 integer bit and 2 
fractional bits.
When multiplying two such numbers using a 3-bit signed integer 
multiplier the result has to be interpreted as "2.4".

However, when dealing with floating point ( normalized mantissa, || < 
1.0 )
the multiplication result is usually modified by dropping the unused 
MSbits
so that "1.4" is left. Now, the new additional LSbits ( in this case 2 ) 
that cannot be represented in the destination format which is usually 
the same as the input format "1.2" are dropped as well ( possibly after 
rounding )

This might explain the confusion

Please log in before posting. Registration is free and takes only a minute.
Existing account
Do you have a Google/GoogleMail account? No registration required!
Log in with Google account
No account? Register here.