Re: Data Object Kinds

From: Shalom.Bresticker@motorola.com
Date: Thu Mar 18 2004 - 02:28:06 PST

  • Next message: Tom Fitzpatrick: "SystemVerilog Data Types"

    Specifically regarding PLI calls that change the value of a net,
    section 27.32 (vpi_put_value) says,

    "When vpi_put_value() is called for an object of type vpiNet or vpiNetBit, and with modes of vpiInertialDelay, vpiTransportDelay, vpiPureTransportDelay, or vpiNoDelay, the value supplied overrides the resolved value of the net. This value shall remain in effect until one of the drivers of the net changes value. When this occurs, the net shall be re-evaluated using the normal resolution algorithms."

    > Similarly, $deposit (a nonstandard system task) and some PLI calls can
    > change the value of a net without continuously driving it. The behavior
    > of this is unpredictable and nonportable. Since nets are conceptually
    > viewed as being continuously driven, not updated under defined
    > circumstances, the standard does not specify when this value will
    > get overwritten with the driven value. It should clearly be overwritten
    > if the driven value changes, but might or might not be overwritten in
    > other situations. This makes the behavior implementation-dependent. It
    > is probably best to just ignore this questionable capability.

    Shalom 

    -- 
Shalom Bresticker                           Shalom.Bresticker@motorola.com
Design & Reuse Methodology                             Tel: +972 9 9522268
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