| Add Proposal | Add Analysis | Edit Class, Environment, or Release |
| Number | 247
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| Category | errata
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| Synopsis | 12.4 et al: hierarchical references to instance array
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| State | open
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| Class | errata-discuss
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| Arrival-Date | Jan 05 2003
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| Originator | Paul Graham
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| Release | 2001b: 7.1.5, 12.1.2, 12.4
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| Description |
There is no good discussion of a hierarchical reference to within an instance array. More specifically, 7.1.5 discusses arrays of primitives. It shows how to instantiate them. That is OK. But then it says, "An individual instance from an array of instances shall be referenced in the same manner as referencing an element of an array of regs." That is a very problematic statement. For one, you almost never reference an instance of a primitive except for its instantiation statement. For another, an array of regs may have many dimensions, whereas an array of instances of primitives may have only one dimension. And there are additional differences. 12.1.2 says, "The instantiations of modules can contain a range specification. This allows an array of instances to be created. The array of instances are described in 7.1. The syntax and semantics of arrays of instances defined for gates and primitives apply for modules as well." Again, not quite precise. Unlike with primitives, you can hierarchically reference a net or variable or instance within an element of a module instance array. There are no examples. There is almost no reference to the subject in 12.4. |
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| Audit-Trail |
From: Steven Sharp <sharp@cadence.com> To: etf-bugs@boyd.com Cc: Subject: Re: errata/247: 12.4 et al: hierarchical references from instance array Date: Mon, 6 Jan 2003 17:45:59 -0500 (EST) A very problematic statement indeed. You can't reference an instance from an array of instances in anything like the same manner as an element of an array of regs. In particular, you can't use non-constant indices for an instance in an array of instances. They aren't really arrays, since each instance can have different characteristics from the others. The standard does not document this. Steven Sharp sharp@cadence.com From: Shalom.Bresticker@motorola.com To: etf-bugs@boyd.com Cc: Subject: Re: errata/247: 12.4 et al: hierarchical references from instance array Date: Tue, 21 Oct 2003 14:04:39 +0200 (IST) Add also text that array indices in hierarchical references to instance array must be constant INTEGER expressions. -- Shalom Bresticker Shalom.Bresticker@motorola.com Design & Reuse Methodology Tel: +972 9 9522268 Motorola Semiconductor Israel, Ltd. Fax: +972 9 9522890 POB 2208, Herzlia 46120, ISRAEL Cell: +972 50 441478 |
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