Re: [Iverilog-devel] Update

[Maciej S. <mac...@ce...>]

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Excuse the lack of clarity. Steve got it right, I had problems with
regular (non-indexed) part selects, for example: local_data[ipn+8:ipn].

I have not used indexed part select before, therefore I am grateful to
Larry for his excellent suggestion. It is alread applied in the pull
request [1].

Regards,
Orson

1.
https://github.com/orsonmmz/iverilog/commit/d1dc98b7f73c21e4eae4bde91855ef5f41059dde

On 03/06/2015 11:14 PM, Stephen Williams wrote:
> 
> INDEXED part select can be non-constant. The width part of index
> part select must be strictly constant.
> 
> Regular part select indices must be strictly constant. I think if
> we don't use the work "indexed" then the part select is the regular
> kind. Is that really what you mean, Orson?
> 
> 
> On 03/06/2015 12:32 PM, Larry Doolittle wrote:
>> Orson -
> 
>> On Fri, Mar 06, 2015 at 08:57:35PM +0100, Maciej Sumiński wrote:
>>> I had to correct the previous implementation for accessing 
>>> constant arrays of vectors. I did not realize that ranges in
>>> part selection have to be constant, and variables are simply
>>> forbidden even if the difference between indices is constant.
>>> This makes the solution useless if one wants to implement e.g.
>>> a multiplexer.
> 
>> Maybe I don't fully understand the terminology, but I build 
>> multiplexers "all the time" using indexed part select, e.g.,
> 
>> module foo( input clk, input [3:0] ipn, output reg [7:0] ip1 );
>> reg [127:0] local_data; // stuff to set local_data not shown
>> always @(posedge clk) ip1 <= local_data[{ipn,3'b0}+:8];
>> endmodule
> 
>> - Larry
> 
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>
>> 
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> 
> 
> 
> ------------------------------------------------------------------------------
>
> 
Dive into the World of Parallel Programming The Go Parallel Website,
sponsored
> by Intel and developed in partnership with Slashdot Media, is your
> hub for all things parallel software development, from weekly
> thought leadership blogs to news, videos, case studies, tutorials
> and more. Take a look and join the conversation now.
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