Hi Johan, I have expressed my opinions below. Lisa -----Original Message----- From: owner-sv-ac@eda.org [mailto:owner-sv-ac@eda.org] On Behalf Of Johan Mårtensson Sent: Friday, October 19, 2007 10:36 AM To: sv-ac@eda.org Subject: [sv-ac] ended, matched only in sequence_expression. All, In section 16.13.6 Sequence methods, at the end of the fourth paragraph it is stated that "Like ended, matched can only be used in sequence expressions.". What is excluded by this? [Lisa Piper >>>] HDL is excluded by this. For example, the sequence method "triggered" is intended for HDL usage. The usage is governed by the scheduling semantics. Ended is only valid in the observed region. Triggered is valid until the end of the timeslot. It is explicitly stated in the second paragraph that S.ended cannot be used in disable iff boolean expression for properties. My interpretation that sequence_method_calls like ended and matched can be used in "boolean positions" in expressions as long as these expressions are part of sequence expressions. Is that correct? [Lisa Piper >>>] This is due to a scheduling issue. "disable iff" uses current value, not the sampled value. Ended is not available in the preponed region so the sampled value is undefined. Matched is tricky because it synchronizes between clocks. Form 16.5 of draft4 titled "Boolean Expressions" The expression in the disable iff clause is evaluated using the current values of variables (not sampled) and can contain the sequence boolean method triggered. It must not contain any reference to local variables and the sequence methods ended and matched. If a sampled value function (see 16.8.3) is used in the expression, the sampling clock must be explicitly specified in the actual argument list. For example: Best Regards, Johan M -- ------------------------------------------------------------ Johan Mårtensson, Office: +46 31 7451913, Mobile: +46 703749681, Skype ID: johanmartensson, PGP key ID: A8857A60 ------------------------------------------------------------ -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean.Received on Fri Oct 19 07:58:41 2007
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