Four-State Semantic X-Propagation in Digital Emulation
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Solution Overview
Problem
Conventional emulation methods for identifying unpredictable behavior in digital systems, particularly in complex integrated circuits, are inefficient due to the need for extensive digital logic operations to detect unknown states, which can take millions of emulation cycles, especially in advanced processes like 22 nanometers and below.
Innovation Solution
The system converts digital signals from a two-state semantic to a four-state semantic to represent unknown states, allowing for the propagation of uncertainties through digital logic circuits, thereby enabling prompt identification of improper operations in the DUT by using a host system and an emulator that configures FPGAs to perform digital logic operations based on the converted signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional two-state binary emulation is used to identify unknown operations in complex integrated circuits, then emulation can be performed with simple binary representation, but the process requires millions of emulation cycles and is time consuming
Solution Approach 1:
The patent transitions from a two-state binary representation (0 and 1) to a four-state representation by adding uncertainty dimension. Each signal is represented by two binary signals: one for the value state and another for the uncertainty state. This dimensional expansion allows the system to track and propagate unknown states through the circuit, enabling identification of improper operations in thousands of cycles instead of millions.
Solution Approach 2:
The patent introduces an intermediary uncertainty representation layer between the binary signal values and the emulation results. By adding uncertainty indicator signals that mediate the propagation of unknown states through logic circuits, the system can efficiently identify sources of improper operations without requiring exhaustive simulation of all possible binary state combinations.
2Reliability
If extensive digital logic operations are performed to propagate unknown states through billions of logic circuits, then complete coverage of the DUT is achieved, but the debugging process becomes inefficient and resource intensive
Solution Approach 1:
The patent performs preliminary action by initializing uncertainty states at the beginning of emulation and propagating them forward through the circuit. By pre-establishing the uncertainty tracking mechanism and propagating unknown states as they originate, the system identifies improper operations much earlier in the emulation process, achieving both complete coverage and high debugging efficiency.
Solution Approach 2:
The patent implements feedback by continuously monitoring uncertainty propagation through the circuit and using this information to identify sources of improper operations. The uncertainty states provide feedback signals that indicate when and where unknown operations occur, allowing the emulation system to efficiently locate and report debugging issues without exhaustive simulation.
Data Source
AI summary
Embodiments relate to the emulation of circuits, and representation of unknown states of signals. A disclosed system (and method and computer program product) includes an emulation environment to convert a digital signal of a DUT in a form capable of representing an unknown state. In addition, the disclosed system converts digital logic circuits such as Boolean logic, flip flops, latches, and memory circuits to be operable with signals having unknown states. Thus, an unknown state of a signal is indicated and propagated through digital logic circuits represented in a disclosed semantic to enable prompt detection of improper operation of the DUT, for example, due to power shut down or inadequate initialization.