| Add Proposal | Add Analysis | Edit Class, Environment, or Release |
| Number | 631
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| Category | errata
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| Synopsis | Issue: Genvar Clarification
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| State | open
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| Class | errata-simple
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| Arrival-Date | Nov 08 2004
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| Originator | Bineet SRIVASTAVA <bineet.srivastava@st.com>
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| Release | 2001b
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| Description |
Hello, according to section 12.1.3.1 on "genvar - generate statement index variable" "A genvar is an integer that is local to and shall only be used within a generate loop that uses it as an index variable." & "The value of a genvar can be referenced in any context where the value of a parameter could be referenced." Clarification is sought for, can we have genvar passed as the parameter value assignment for module instantiation?? bineet -----Original Message----- From: owner-etf@boyd.com [mailto:owner-etf@boyd.com] On Behalf Of Shalom.Bresticker@freescale.com Sent: Monday, November 08, 2004 1:50 PM To: etf-bugs@boyd.com Subject: Re: errata/288: PROPOSAL - 4.1.14: replication operator and function calls The following reply was made to PR errata/288; it has been noted by GNATS. From: Shalom.Bresticker@freescale.com To: brad.pierce@synopsys.com Cc: etf-bugs@boyd.com Subject: Re: errata/288: PROPOSAL - 4.1.14: replication operator and function calls Date: Mon, 8 Nov 2004 10:26:48 +0200 (IST) Brad, Without taking a position on your proposal, it should include closing 527 as well. Shalom -- Shalom Bresticker Shalom.Bresticker @freescale.com Design & Verification Methodology Tel: +972 9 9522268 Freescale Semiconductor Israel, Ltd. Fax: +972 9 9522890 POB 2208, Herzlia 46120, ISRAEL Cell: +972 50 5441478 |
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From: Shalom Bresticker <Shalom.Bresticker@freescale.com> To: Bineet SRIVASTAVA <bineet.srivastava@st.com> Cc: etf-bugs@boyd.com Subject: Re: errata/631: Genvar Clarification Date: Mon, 08 Nov 2004 14:09:56 +0200 Hi, There is a new version of the generate description. It says, "A loop generate construct permits a generate block to be instantiated multiple times using syntax that is similar to a for-loop statement. The loop index variable must be declared in a genvar declaration prior to its use in a loop generate scheme. The genvar is used as an integer during elaboration to evaluate the generate loop and create instances of the generate block, but it does not exist at simulation time. A genvar shall not be referenced anywhere other than in a loop generate scheme. Both the initialization and iteration assignments in the loop generate scheme shall assign to the same genvar. The initialization assignment shall not reference the loop index variable on the right hand side. Within the generate block of a loop generate construct, there is an implicit localparam declaration. This is an integer parameter that has the same name and type as the loop index variable, and its value within each instance of the generate block is the value of the index variable at the time the instance was elaborated. This parameter can be used anywhere within the generate block that a normal parameter with an integer value can be used. It can be referenced with a hierarchical name. Because this implicit localparam has the same name as the genvar, any reference to this name inside the loop generate block will be a reference to the localparam, not to the genvar. As a consequence, it is not possible to have two nested loop generate constructs that use the same genvar." So I believe the answer to your question is yes. However, if you will give an example of what you want to do, your question will be clearer. Thanks, Shalom > According to section 12.1.3.1 on "genvar - generate statement index > variable" > > "A genvar is an integer that is local to and shall only be used within a > generate loop that uses it as an index variable." > > "The value of a genvar can be referenced in any context where the value > of a parameter could be referenced." > > Clarification is sought for, can we have genvar passed as the parameter > value assignment for module instantiation?? -- Shalom Bresticker Shalom.Bresticker @freescale.com Design & Verification Methodology Tel: +972 9 9522268 Freescale Semiconductor Israel, Ltd. Fax: +972 9 9522890 POB 2208, Herzlia 46120, ISRAEL Cell: +972 50 5441478 [ ]Freescale Internal Use Only [ ]Freescale Confidential Proprietary From: Steven Sharp <sharp@cadence.com> To: etf-bugs@boyd.com, bineet.srivastava@st.com Cc: Subject: Re: errata/631: Issue: Genvar Clarification Date: Mon, 8 Nov 2004 14:46:33 -0500 (EST) >according to section 12.1.3.1 on "genvar - generate statement index >variable" > >"A genvar is an integer that is local to and shall only be used within a >generate loop that uses it as an index variable." > >& > >"The value of a genvar can be referenced in any context where the value >of a parameter could be referenced." > >Clarification is sought for, can we have genvar passed as the parameter >value assignment for module instantiation?? Yes. Assuming that the module instantiation is inside the generate loop, then the genvar is being used within the generate loop, as required. The parameter being overridden with the value of the genvar is not inside the generate loop, but the use of the genvar is. As Shalom has said, there has been some rewording to resolve the potential confusion between the genvar, which takes on different values as controlled by the for-loop, and a reference to the genvar inside the loop scope, which is a constant for any given instance of the loop scope. But the answer to your question is still "Yes". The only difference is that now you aren't technically using the genvar in the parameter value override, you are using the implicitly declared localparam that has the same name as the genvar. It is declared in the scope associated with the generate-loop, and can be used like any localparam declared in that scope. Steven Sharp sharp@cadence.com |
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