byucc.jhdl.base
Interface UndrivenInputsAllowable

All Known Implementing Classes:

ClockDriver, cy4, fmap, fmap, fmap, fmap, hmap, opad, opad, opad, opad

public interface UndrivenInputsAllowable

This interface marks a primitive Cell which ignores certain input ports based on decisions made at construction (for example, the cy4 block of the Xilinx XC4000 library operates in a number of modes, and not all inputs are used in each mode). When implementing this interface, the cell guarantees that returning true for a particular port means that the wire attached to that port will never be ready by get(). This means that the library-writer can attach nc() to the input port(s), so that all ports are connected; while avoiding the normal error of having an undriven input. This interface should only be used by library writers, and then only on primitive cells that have the possibility of undriven inputs.

Author:

Eric Blake

Method Summary

boolean

portMayBeUndriven(java.lang.String portname) This method will be called when JHDL detects an undriven input port.

Method Detail

portMayBeUndriven

public boolean portMayBeUndriven(java.lang.String portname)

This method will be called when JHDL detects an undriven input port. If the return value is true, the typical error will be avoided. If the return value is false, JHDL will treat the port like any other, and throw an exception that an undriven input was detected.

Parameters:

portname - the name of the port, from the cell_interface

Returns:

true if this port may be undriven based on the primitive's mode of operation.