Re: [Iverilog-devel] Update

[Stephen W. <st...@ic...>]

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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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