Re: EXTERNAL: Re: [vhdl-200x] RE: Modular types

From: <whygee@f-cpu.org>
Date: Fri Aug 08 2014 - 07:04:35 PDT
Le 2014-08-08 15:42, jim@synthworks.com a écrit :
> Has anyone tested the performance of bit_vector?

Excellent question.

and then these numbers should be contrasted with
  - other types (std_logic_vector, integer)
  - different simulators and vendors (many forbid you this !)
  - different languages

I did a testbench some years ago for integer-intensive
computations, using Wikipedia's SHA pseudocode.
It's the archetypic example of integer-bound computations,
with a profile that looks like usual case for SoC/Computers.

http://ygdes.com/GHDL/int_bool/

it tests these types : integer, integer with range, std_ulogic_vector, 
bit_vector
but I only remember that I got a speedup of 400
by adding bool/shift to integers in GHDL.
I think that std_logic_vector was more or less as fast
as bit_vector, but this can not be generalised to other
simulators (VHPI implementation is certainly not portable).
GHDL does not "optimise" or "pack" bit ectors, AFAIK.

The script and all the files are available,
so i could just re-run it.

Is anybody willing to test it with other simulators ?
(if their NDA allows..........)

YG


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Received on Fri Aug 8 07:05:43 2014

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