Subject: Re: TBV2: Associative arrays proposal submitted
From: Stephen Bailey (stephen@srbailey.com)
Date: Sun Apr 27 2003 - 20:30:37 PDT
> Is an associative array the same as the sparse array (TBV12)?
> I think a sparse array was intended for creating space
> on demand for modeling something like a RAM. Sounds
> like associative array is the same thing.
Associative arrays could be used to model sparse arrays. However, sparse arrays are more specific. They are used specifically for
modeling large memories efficiently when only a small percentage of the memory addresses are used in any given simulation.
To easily model sparse memories, associative arrays would need to support:
1. A bit (std_logic) vector as an index expression. (The memory address.)
2. Support constraining the index according to the memory size.
I had requested that the proposal ensure that both of these be covered (permitted).
There may also be efficiency of implementation considerations that might determine that sparse arrays should either have their own
syntax or that a standard "generic" associative array subtype be defined to be used for sparse array/memory modeling. Either of
these would then be what implementations key on to kick in any relevant optimizations.
BTW, it would also be good to define load and dump operations for associative/sparse arrays.
-Steve Bailey
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