Fork of https://github.com/riscv-non-isa/riscv-nexus-trace/tree/main/refcode/c

Nexus Trace TG reference code - for CEDARtools.TraceEncoder

Reference code for RISC-V Nexus Trace TG recommendations.

Updated 2026/06/01 - CEDARtools.TraceEncoder fork

This fork adds decoding capabilities related to the open CEDARtools.TraceEncoder RTL implementation.

• Add CTXP trace export
• Add data message decoding
• Add optional SRC field decoding/encoding
• Pass timestamps (absolut and relative mode)
• Helper script to compare against upstream at scripts/diff-upstream.sh
• Treat call-stack decoding as validation check
• The third-party benchmark inputs for examples/all (RISC-V ELF binaries and Spike PC traces) are not committed, for licensing reasons. Run examples/all/from_etrace/fetch.sh to reconstruct them from upstream, then point RV_OBJDUMP in the makefile at your own toolchain objdump. See examples/all/from_etrace/README.md for sources and licenses.
• Code is licensed under ISC (per the source headers); the reference PDF remains CC-BY-4.0 as upstream.

Tests

Run the regression suite with tests/run_tests.sh (needs only the built NexRv.exe):

• Assembler round-trip — a tiny hand-written RISC-V program (tests/apps/roundtrip/roundtrip.S) is converted to a trace by the encoder, decoded again, and the decoded PC stream is checked byte-for-byte against the original execution. Repeated for several encoder compression levels.
• CEDARtools.TraceEncoder capture regression — real Nexus traces captured from the open CEDARtools.TraceEncoder testbenches (combined and csr_cap) are decoded to CTXP and compared against golden references cross-checked against the testbenches' own expected output.

Acknowledgment - TRISTAN EU project

This fork was developed as part of the TRISTAN project, a European Union research initiative involving 46 partners to advance the RISC-V ecosystem. The TRISTAN project, nr. 101095947 is supported by Chips Joint Undertaking (CHIPS-JU) and its members Austria, Belgium, Bulgaria, Croatia, Cyprus, Czechia, Germany, Denmark, Estonia, Greece, Spain, Finland, France, Hungary, Ireland, Iceland, Italy, Lithuania, Luxembourg, Latvia, Malta, Netherlands, Norway, Poland, Portugal, Romania, Sweden, Slovenia, Slovakia, Turkey. See https://tristan-project.eu/ for more information.

Updated 2025/01/02 - upstream

• Support for -cs and -rpt added (to control callstack mode and repeat messages).
• Support for 64-bit.
• Scripts to run all examples added.
• Make other enhancements.

Top level overview is provided here: NexusTraceTG-RefCode.pdf.

• Source (DOC) for above PDF is lost and this PDF does not exactly correspon to current version.
• Newest usage can be seen by running NexRv.exe.
• Also ./examples/t1/makefile and ./examples/all/makefile show different usage examples.

Example with additional instructions and usage details is here.