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Forum: FPGA, VHDL & Verilog Fixed point operations


Author: dhootha adhi (Company: Student) (gollum)
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I have to deal with real type numbers in my code(synthesisable) so I am 
using     fixed point packages. I have a few doubts in this.
1.I want to define all variables in my function as ufixed(7 downto -6). 
I believe that all the values i get here dont need more than these 
number of bits.  When i am supposed to find  a+b or a/b or a*b , I would 
type it as resize(a/b , a'high, a'low). Would I get any problems with 
this format of representation ??
2. How do i find square root and exponent function of a fixed point 
number here? I can't use ** in fixed operations as per fixed point 
package rules.

Author: Andreas (Guest)
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1. That should work, the result will be rounded/truncated. See 
http://www.vhdl.org/fphdl/Fixed_ug.pdf.
2. Implement it yourself, or find a core that does it. It's an operation 
that is too expensive/application-dependent that it would make sense to 
define it as a VHDL operator.

Author: dhootha adhi (Company: Student) (gollum)
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Okay.Thanks for replying :)

Author: dhootha adhi (Company: Student) (gollum)
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How do i find b^a when i want to write as a synthesisable code??? Please 
give me an Idea.

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