Re: [vhdl-200x] Fwd: Proposal for the next version of the IEEE 1076 standard

My reply to Lars:
[clip .. stuff on joining working group]

WRT your request, note currently you can use configuration declarations
to do this.  In the following, CfgUart is a testbench level configuration
that reaches down through the FPGA design to select the
architecture uart_arch_1 of the subblock Uart.  Note that currently
you must use component declarations and component instances (
vs entity instances) to be able to select architectures in a configuration.


Library LIB_MemIO ;
configuration CfgUart of testbench is
   for Structural

     for U_FPGA : FPGA
       use entity Lib_FPGA.FPGA (fpga_arch) ;

       for fpga_arch

         for U_Uart : Uart
           use entity Lib_FPGA.Uart(uart_arch_1) ;
         end for ;

       end for ;
     end for ;
   end for ;
end CfgUart ;


This should at least help out for the time being.
One reason people don't use configurations much is
that the synthesis tools don't like them.  However,
for synthesis we can manage the problem by
using the most recently compiled architecture.

If this does not meet your needs entirely, we would
need a use model that elaborates how you intend to
use the new feature.

Note you can emulate your request using if-generate
to instantiate a specific architecture and a generic
makes a specific if-generate true.  With a VHDL-2008
tool you will also have elsif and else with if-generate
and also have case generate.

Best Regards,
Jim

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