US 5,691,911 AGranted

Method for pre-processing a hardware independent description of a logic circuit

AssigneeSynopsys, Inc.

InventorsBrent L. Gregory, Russell B. Segal

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Abstract

A method and system are provided for generating a logic network using a hardware independent description means. A logic circuit synthesizer, in response to a user description specifying only signals and the circumstances under which the signals are produced, generates a logic network that generates the signals specified in the user description, e.g., a net list of logic elements, such as logic gates, high impedance drivers, level sensitive latches and edge sensitive flip-flops along with the interconnections of the logic elements. In one embodiment, the logic circuit synthesizer includes a preprocessor means and a logic circuit generator means. The preprocessor means, in response to the user description, converts signals and conditions in the user description into a structure having nodes interconnected by edges. The edges include an edge condition under which the edge is traversed. The logic circuit generator, using the structure and the edge conditions, creates a logic network that generates the signals specified in the user description.

Claims10

Dependent claims

A method for converting a user logic circuit description, that is hardware independent, and that includes (i) an IF statement controlled by a logic state of a condition signal C, and (ii) a directive statement that assigns a logical value to a signal E and a GOTO statement within said IF statement, into a structure in a computer memory representing said logic circuit, said method comprising:

generating a split node and a join node for said IF statement in said structure;
wherein said split node indicates a start of said IF statement and said join node indicates an end of said IF statement;
generating an operation node for said directive statement with a single edge entering said operation node and another single edge leaving said operation node in said structure;
wherein said single edge is coupled to said split node and said another single edge is coupled to said join node;
and
generating yet another single edge for said GOTO statement in said structure;
wherein said yet another single edge is connected to one of (i) said split node for said IF statement;
and (ii) a first node between said split node and said join node for said IF statement, and extends to yet another join node;
and
said yet another join node is positioned in any location in the group of location consisting of (i) a location in said structure between said operation node for said directive state and said join node for said IF statement;
(ii) a location coincident with said join node of said IF statement so that said yet another join node and said join node of said IF statement are the same node;
and (iii) a location in said structure after said join node for said IF statement.

9 more elements

Dependencies are inferred from the claim text.