| Number | 480
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| Category | errata
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| Synopsis | /471 Re: udp scheduling semantics
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| State | closed
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| Class | mistaken
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| Arrival-Date | Sep 16 2003
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| Originator | Stephen Williams <steve@icarus.com>
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| Release | 2001b
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| Environment |
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| Description |
Shalom.Bresticker@motorola.com wrote: > Precedence: bulk > > In my opinion, the erratum is that the standard does not specify the > scheduling of UDPs. The standard also does not say that they are scheduled > on the active events queue, even though I agree that that is what the > simulators do. In principle. by IEEE rules, another simulator could schedule > them differently and still claim compliance to the standard. And in any case, > one should not have to guess or to experiment in order to discover it. Exactly my original point. I was left guessing, so I made a guess. I guessed right, then reasoned it out differently, and changed my guess. Even some people who should have known better supported my "improved" reasoning, as did some frustrated users. We were all wrong, apparently. Strictly speaking even ordinary primitive gates are left for the implementer to guess about, although putting propagation events in the active queue seems obvious. The *only* constructs that have their output scheduling explicitly stated are the assignments and the tran devices. So for errata/471 the solution I proposed is apparently wrong, but the fault it tries to fix is valid. The correct (I hope) answer is to explicitly state that the outputs of all primitives, including user defined conbinational and sequential primitives, are propagated through the _active_ events queue. -- Steve Williams "The woods are lovely, dark and deep. steve at icarus.com But I have promises to keep, http://www.icarus.com and lines to code before I sleep, http://www.picturel.com And lines to code before I sleep." |
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