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Showing posts with label SystemVerilog Net Type. Show all posts
Showing posts with label SystemVerilog Net Type. Show all posts

Monday, 26 January 2015

SystemVerilog Net Type

In Verilog, Net data types are used to model physical connections. They do not store values (there is only one exception - trireg, which stores a previously assigned value). The net data types have the value of their drivers. If a net variable has no driver, then it has a high-impedance value (z).

Verilog allows you to use nets without defining them, a feature called implicit nets. This shortcut helps net-listing tools and lazy designers, but is guaranteed to cause problems if you ever
misspell a net name in your SystemVerilog code. The solution is to disable this language feature with the Verilog-2001 compile directive: ‘default_nettype none. Put this (without a period) before the first module in your Verilog code. Any implicit net will cause a compilation error.

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