From: Stephan B. <boe...@ph...> - 2013-07-04 19:25:56
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Hi Martin, hi Itzok, thanks, ... Martin Whitaker <mai...@ma...> writes: > Yes, the simulator's behaviour is correct. The relevant sentence is in section > 12.3.8 of the 1364-2005 standard: > > "A port that is declared as input (output) but used as an output (input) or > inout may be coerced to inout. If not coerced to inout, a warning has to be > issued." A warning in not mandatory, because the port was coerced? Iztok Jeras <izt...@gm...> writes: > Before you declare this a bug please check with another simulator, > ModelSim Altera for example. I do not have access to other simulators. > - latch (not appropriate for most RTL) > - mismatch (code which could be interpreted incorrectly by the synthesis > tool, usually operator ===) > - feedback (usually a mix of registers with and without reset in the same > always block) This is a nice list of terms to add to my Makefile for parsing the logs, thanks. > Warnings should be also checked ... That's what I did to search for the bug. Eventually I found that a lot of logic was eliminated that should have been kept. I have a lot of logic that is optimized out by design, so that these messages were not sticking out. Quartus obviously does not coerce outputs to inputs. So it's not a bug report, but a feature request: Can iverilog emit a warning in cases like this? I have seen such warnings in other designs with input ports. There was no information going in the wrong direction, but there was a driver on the other end. Some pins of a status register were driven from inside the module, some from outside. The destination is inside, so I declared the bus as input. This gives a warning: ELABORATING DESIGN erena.v:75: warning: input port errors is coerced to inout. erena.v:75: warning: input port stats is coerced to inout. In the current case it is an output that should have been an input. And it was coerced without a warning. Stephan -- Stephan Böttcher Tel: +49-431-880-2508 Christian-Albrechts-Universität zu Kiel Inst. f. Exp. u. Angew. Physik, Abt. Extraterrestrische Physik Leibnizstr. 11, 24118 Kiel, Germany |