YosysHQ/yosys
May 2025 – May 2026
5 Months active
Languages Used
C++SystemVerilogMakefileMarkdownTclYAMLYosys Script
Technical Skills
AIGER FormatC++Embedded systemsHardware Description Language (HDL)Regression TestingTcl scripting
Emil Jiří Tywoniak
PROFILE
Emil Jiří Tywoniak
Contributed to the YosysHQ/yosys open-source synthesis tool by developing and refining features that enhance design constraint management, clock gating, and build reliability. Leveraged C++, Verilog, and Tcl scripting to implement foundational SDC command support, refactor pin matching logic, and improve integration with build systems and CI/CD pipelines. Addressed stability by adding regression tests for AIGER I/O and fixing primitive semantics, ensuring consistent synthesis and simulation. Improved contributor experience through documentation updates and streamlined issue templates. The work emphasized maintainable code, robust test coverage, and clear abstractions, supporting both immediate tool reliability and future extensibility within digital design workflows.
Overall Statistics
Feature vs Bugs
70%Features
Repository Contributions
15Total
Bugs
3
Commits
15
Features
7
Lines of code
1,028,809
Activity Months5
Your Network
87 peopleWork History
May 2026
1 Commits • 1 Features
May 1, 2026May 2026 monthly summary: Delivered clock gating handling improvement in Yosys synthesis by rejecting the $sdffe primitive, improving priority handling for clock gating operations. Included updates to configuration files and addition of new issue templates to streamline bug reporting and feature requests. PR merged from YosysHQ/emil/clockgate-reject-sdffe (commit 1f023432681c159885f0b834a2e0717e67c4c115).
1 Commits • 1 Features
May 1, 2026May 2026 monthly summary: Delivered clock gating handling improvement in Yosys synthesis by rejecting the $sdffe primitive, improving priority handling for clock gating operations. Included updates to configuration files and addition of new issue templates to streamline bug reporting and feature requests. PR merged from YosysHQ/emil/clockgate-reject-sdffe (commit 1f023432681c159885f0b834a2e0717e67c4c115).
May 2026
April 2026
1 Commits
Apr 1, 2026April 2026 monthly summary for YosysHQ/yosys: Focused effort on stabilizing primitive semantics to improve tool reliability. Delivered a targeted bug fix for the DFFSR flip-flop by undefining its explicit set/reset behavior, thereby reducing undefined semantics and aligning synthesis with simulation. Change landed via a focused PR that merged commit 86448c0001e80240be1673827887ab2c7f9433b4 (PR #5655). This work reduces ambiguity in designs using DFFSR, improves predictability, and strengthens overall tool quality. Demonstrates solid collaboration, code-quality practices, and commitment to release-quality changes.
April 2026
1 Commits
Apr 1, 2026April 2026 monthly summary for YosysHQ/yosys: Focused effort on stabilizing primitive semantics to improve tool reliability. Delivered a targeted bug fix for the DFFSR flip-flop by undefining its explicit set/reset behavior, thereby reducing undefined semantics and aligning synthesis with simulation. Change landed via a focused PR that merged commit 86448c0001e80240be1673827887ab2c7f9433b4 (PR #5655). This work reduces ambiguity in designs using DFFSR, improves predictability, and strengthens overall tool quality. Demonstrates solid collaboration, code-quality practices, and commitment to release-quality changes.
September 2025
9 Commits • 3 Features
Sep 1, 20252025-09 Monthly Summary for YosysHQ/yosys focusing on delivering reliability, scalability, and contributor experience. Implemented build/runtime compatibility improvements for WebAssembly, extended liberty file handling via globbing across multiple components, fixed accuracy in Gowin test suite, and updated community guidelines to streamline collaboration. Demonstrated strong integration discipline, test coverage, and documentation improvements that translate to faster onboarding and more reliable builds.
9 Commits • 3 Features
Sep 1, 20252025-09 Monthly Summary for YosysHQ/yosys focusing on delivering reliability, scalability, and contributor experience. Implemented build/runtime compatibility improvements for WebAssembly, extended liberty file handling via globbing across multiple components, fixed accuracy in Gowin test suite, and updated community guidelines to streamline collaboration. Demonstrated strong integration discipline, test coverage, and documentation improvements that translate to faster onboarding and more reliable builds.
September 2025
August 2025
2 Commits • 2 Features
Aug 1, 2025August 2025: Core refactors in YosysHQ/yosys to improve reliability and maintainability of design-pin matching and SDC/Tcl workflows, reducing duplication and setting foundations for future enhancements.
August 2025
2 Commits • 2 Features
Aug 1, 2025August 2025: Core refactors in YosysHQ/yosys to improve reliability and maintainability of design-pin matching and SDC/Tcl workflows, reducing duplication and setting foundations for future enhancements.
May 2025
2 Commits • 1 Features
May 1, 2025May 2025: Delivered foundational SDC command support and reinforced I/O stability through regression testing. The work establishes groundwork for constraint-driven design features and improves the robustness of AIGER export paths. Focus areas include business value, technical achievements, and measurable outcomes for the Yosys verification and constraint-management roadmap.
2 Commits • 1 Features
May 1, 2025May 2025: Delivered foundational SDC command support and reinforced I/O stability through regression testing. The work establishes groundwork for constraint-driven design features and improves the robustness of AIGER export paths. Focus areas include business value, technical achievements, and measurable outcomes for the Yosys verification and constraint-management roadmap.
May 2025
Activity
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Quality Metrics
Correctness88.0%
Maintainability89.4%
Architecture88.0%
Performance81.4%
AI Usage24.0%
Skills & Technologies
Programming Languages
C++MakefileMarkdownSystemVerilogTclYAMLYosys Script
Technical Skills
AIGER FormatBuild AutomationBuild SystemBuild SystemsC++C++ DevelopmentC++ developmentCI/CDCommunity ManagementCompiler DevelopmentContinuous IntegrationDocumentationEmbedded systemsFile I/OGit
Repositories Contributed To
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