Daniel > 14.16 Synchronous drives. > There is: > "The second form of the synchronous drive uses the intra-assignment > syntax. An intra-assignment event_count specification also delays > execution of the assignment. In this case, the process does not > block, and the right-hand expression is evaluated when the statementexecutes." > > There is no 2nd form as in 1800-2009 it was removed. This paragraph > need to be rewriten. Oh dear, this is definitely a problem. I can't believe this slipped through all the 890 discussions, but obviously it did. I suspect it is caused by BNF and text getting out-of-sync. The following examples clearly and correctly capture the result of the Mantis 890 discussions: ##N in any procedural context, even if used to delay a synchronous (clocking) drive, means delay by N cycles of the DEFAULT clocking. But ##N as an intra-assignment delay, which is legal only on the RHS of a synchronous drive, means postpone the drive by N cycles of the TARGET CLOCKVAR's clocking. Not only the paragraph you mention, but also the immediately previous paragraph, is misleading. The italicised "event_count" does not appear anywhere else in the LRM. I've raised Mantis 2596 to address this, and will post a proposed text change shortly. > There is also lack of illegal drive example given : data[3:0] <= 4?h5; Sorry, I don't really understand what you're asking here; I agree that there are no illegal examples, but I'm not sure what value they would bring. -- Jonathan Bromley Consultant DOULOS - Developing Design Know-how VHDL * Verilog * SystemC * e * Perl * Tcl/Tk * Project Services Doulos Ltd. Church Hatch, 22 Market Place, Ringwood, Hampshire, BH24 1AW, UK Tel: +44 (0)1425 471223 Email: jonathan.bromley@doulos.com Fax: +44 (0)1425 471573 Web: http://www.doulos.com This message may contain personal views which are not the views of Doulos Ltd., unless specifically stated. -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean.Received on Fri Mar 13 07:08:17 2009
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