ComparingVariablesVsSignals

ComparingVariablesVsSignals - Comparing Signals and...

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(From: http://www.xilinx.com/itp/xilinx4/data/docs/sim/coding4.html ) Comparing Signals and Variables (VHDL only) You can use signals and variables in your designs. Signals are similar to hardware and are not updated until the end of a process. Variables are immediately updated and, as a result, can affect the functionality of your design. Xilinx recommends using signals for hardware descriptions; however, variables allow quick simulation. The following VHDL examples show a synthesized design that uses signals and variables, respectively. These examples are shown implemented with gates in the "Gate Implementation of XOR_VAR" and "Gate Implementation of XOR_SIG" figures. Note If you assign several values to a signal in one process, only the final value is used. When you assign a value to a variable, the assignment takes place immediately. A variable maintains its value until you specify a new value. Using Signals (VHDL)
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This document was uploaded on 03/05/2012.

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ComparingVariablesVsSignals - Comparing Signals and...

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