AsFigo - enabling opensource chip design and verification.

Ensuring Correctness and Observability in SPI Signal Assertions In SPI verification, a fundamental requirement is that all active signals— SCLK , MOSI , and MISO —must be fully defined whenever chip-select is asserted . Any unknown or high-impedance state ( X or Z ) can compromise data integrity and lead to subtle bugs. SystemVerilog Assertions (SVA) offer a natural mechanism to codify this requirement. When applied thoughtfully, they enforce correctness and enhance diagnostic clarity. Clear, modular assertions make failures immediately understandable, particularly in larger testbenches, which aligns well with style-aware analysis tools. Issue 1: Functional Correctness A common misstep is to combine multiple signals in a single $isunknown call with a logical AND: // INCORRECT $isunknown(spiclk && mosi && miso) The problem: logical AND short-circuits evaluation, potentially masking unknown states. Example: spiclk = X, mosi = 0, miso = 1 spiclk ...

A solution‑first guide to preventing the classic dangling else error caused by UVM reporting macros. UVMLint Rule: No Trailing Semicolon After UVM Reporting Macros Define a lint rule that flags any UVM reporting macro invocation immediately followed by a semicolon. Implementation detail: This rule should be parser‑aware . Avoid pure regex; require an AST/token stream so comments, strings, and macro line breaks are handled correctly. Why This Rule Exists Consider a simple user code as below:  // Buggy code if (debug_on) `uvm_info("DEBUG", "state info", UVM_LOW); // semicolon here else $display("Doing something else"); The UVM BCL defines  `uvm_info  as a  complete  begin...end  block . Adding a semicolon after the macro turns into a null statement that terminates the  if  prematurely, leaving the  else  orphaned. // UVM BCL (abridged) `define uvm_info(I...

Linting SystemVerilog and UVM testbench code is crucial to maintain quality and compatibility. Many teams start by writing quick regex or string-search scripts to catch problematic patterns—like deprecated variables, disallowed constructs, or outdated API usage. While regex-based linting can be tempting due to its simplicity, it often leads to false failures and missed issues because SystemVerilog’s syntax and preprocessing are too complex for simple text matching. In this series, we will explore common linting scenarios, we introduced this in an earlier post here:   https://asfigo.blogspot.com/2025/02/linting-systemverilog-testbench-code.html  Below is the next one in this series with a concrete example - detecting deprecated UVM constructs like uvm_top , and demonstrate why a proper parser-based approach using tools like Google’s Verible is superior. A Quick, regex style lint example When maintaining UVM code for compatibility, one common check is to detect the use of u...

Following the positive reception and thoughtful engagement at our recent technical meetups in Reading and Cambridge , AsFigo is pleased to invite you to our next UVMLint Technical Meetup , taking place in Newbury — a region with a strong footprint in semiconductor design and verification. This free, hybrid event offers a focused technical forum for engineers seeking to enhance the quality and maintainability of their UVM environments through structured linting , metrics analysis , and practical methodology insights . 📍 Event Details Date: Friday, 18th July 2025 Time: 14:00 – 16:00 BST Venue: Oxford House, 12–20 Oxford Street, Newbury, Berkshire, RG14 1JB Meeting Room: Donnington Register at:   https://forms.gle/VCiVEiKgzKJgPiAD8  Remote Access:   Join the meeting now: https://teams.microsoft.com/l/meetup-join/19%3ameeting_OGNiY2RjYzEtNGI0OC00MDg3LTk2OGYtZGZiZWMzNTQyMGQ1%40thread.v2/0?context=%7b%22Tid%22%3a%22ce8c6d03-7521-4120-aa04-...

We're inviting all SystemVerilog developers to share their testbench code using #UVM and/or #SVA for a free lint-check as part of our upcoming technical meetup. ✅ Submit your repo path or URL ✅ We’ll run our lint tools on it ✅ Get a detailed report ✅ Your code might be featured in a live demo! 🗓️ Event: #UVMLint and #SVALint Meetup 📍 Location: Cambridge, UK (remote attendance available) 👥 113+ engineers already registered , and counting! Don’t miss the chance to get valuable insights into your testbench quality — from syntax to assertions to methodology compliance. Register now: https://lnkd.in/dW3nX_KC Join via:  UVMLint meetup - Cambridge, June 27 | Meeting-Join | Microsoft Teams   Special thanks to our collaborators: Ajeetha Kumari, Ben Cohen, Hemamalini Sundaram and the #AsFigo team. #SystemVerilog #UVM #SVA #Lint #EDA #Verification #OpenSource #Meetup

AsFigo invites you to our next technical session, focused on enabling semiconductor design teams to adopt open-source EDA tools—especially for testbench linting workflows. Remote-dial-in link:  UVMLint meetup - Cambridge, June 27 | Meeting-Join | Microsoft Teams 📍 Event: UVMLint & SVALint – Enablers to Move Your Chip Design Ahead 📅 Date: Friday, June 27, 2025 🕙 Time: 10:00 AM to 12:00 Noon (UK Time) 📌 Location: Wellington House, East Road, Cambridge, CB1 1BH, United Kingdom ☎ Phone: +44 1223 451000 🌐 Format: Hybrid (in-person & remote via Microsoft Teams) 💡 Cost: Free (registration required - https://forms.gle/upzLGyWJbRnbgRzU7 ) After a successful SVALint session in Reading, UK, we’re bringing this discussion to Cambridge—one of the UK’s most active semiconductor hubs. This event is geared toward engineers working in UVM based verification, formal verification, and testbench architecture using UVM and SVA. Ag...

SVALint Technical Meetup – Hybrid Event in Reading, UK AsFigo invites engineers and verification professionals to a focused technical meetup on SVALint —an open-source static verification abstraction linting framework. The event takes place on Sunday, 8 June 2025 , from 15:00 to 18:00 BST , hosted in a hybrid format (face-to-face and online). Register via:  https://forms.gle/qo8TBczXjNk62yAP6   Venue (In-Person) Meeting Room-5, First floor,  Novotel Reading Centre 25B Friar Street – RG1 1DP, Reading – United Kingdom T +44 (0) 1189 522 610 novotel.com/5432 Virtual Attendance Join via Microsoft Teams Why SVA Linting? SystemVerilog Assertions (SVA) play a critical role in ensuring correctness in complex verification environments. However, poorly structured assertions can hurt simulation performance, complicate debugging, or lead to ambiguous semantics. Linting SVAs helps catch such issues early—enforci...

The AsFigo Instance Extraction Utility ( $afPrHier ) is a Verilog Procedural Interface (VPI) app designed to automate the extraction of instance hierarchy data in Verilog simulations. It provides an efficient solution for analyzing and documenting the structural organization of Verilog designs, particularly in complex simulations. Purpose and Benefits Objective $afPrHier simplifies the process of collecting and documenting hierarchical relationships among modules and their instances in a Verilog simulation. It automates this task to reduce manual effort and potential errors. Features Automated Hierarchy Extraction: Gathers all module-instance relationships in a design and organizes them in a structured format. CSV-Based Reporting: Outputs hierarchy details in output_hier_info.csv with two essential columns: Module Name Instance Name ...

As open-source electronic design automation (EDA) tools continue to grow in popularity, events like WOSET (Workshop on Open-Source EDA Technology) have become essential for showcasing community-driven advancements. The 2024 edition of WOSET features an exciting lineup, including yoYoLint—a new open-source SystemVerilog RTL linter designed for Yosys. Built on AsFigo’s innovative "Build Your Own Linter" (BYOL) model, yoYoLint adds a much-needed layer of quality control to open-source HDL flows, addressing the often-overlooked process of HDL linting. Understanding the Role of HDL Linting in EDA Linting is a critical phase in hardware description language (HDL) design flows, helping enforce design rules, style guides, and best practices to ensure code quality. A robust HDL linter for SystemVerilog helps identify errors early, such as unused variables, unsupported constructs, potential race conditions, or missing sensitivity list items, enabling teams to produce clean, consist...

Our Director of Verification, Ajeetha Kumari took part in offering her review comments based on her decades of AMS design verification experience to Accellera's UVM-MS standard.  Overall, our focus is on  clarity, correctness, good coding practices, and ensuring UVM-MS follows standard verification methodologies .    Clarifications and Expansions Suggested explicitly stating IEEE 1800.2 UVM version to avoid ambiguity. Asked whether VHDL should also be considered in addition to SystemVerilog. Recommended good coding guidelines for UVM-MS lint rules . Pointed out grammatical issues , such as removing unnecessary "s" in certain words. Suggested formatting improvements, such as italicizing specific terms . Code and Implementation Improvements Recommended ensuring all UVM components/agents are in separate packages for better reuse. Questioned the lack of UVM factory registration for some proxy classes. Suggested adding function prototypes (like ne...

Introduction to MSIE Multi-Snapshot Incremental Elaboration (MSIE, Copyright Cadence Design Systems) is a powerful feature of Cadence Xcelium that optimizes the verification process for digital designs by enabling incremental changes to be elaborated without needing to re-elaborate the entire design. This approach significantly reduces the time required for compiling and elaborating designs, making verification faster and more efficient. Typical simulation flow (without MSIE)  The below figure depicts a traditional approach to running test scenarios in a design and verification environment.   Each scenario involves three stages:  Compilation of the environment (testbench + DUT),  Elaboration of the compiled environment,  and Simulation of the elaborated environment.  This sequential process is repeated for each test scenario. How MSIE Works Primary and Incremental Snapshots: MSIE works by creating pre-elaborated snapshots of the d...