OpenHW Group CORE-V CV32E41P RISC-V IP

CV32E41P is a small and efficient, 32-bit, in-order RISC-V core with a 4-stage pipeline that implements the RV32IM[F,Zfinx]C[Zce] instruction set architecture, and the Xpulp custom extensions for achieving higher code density, performance, and energy efficiency [1], [2]. It started its life as a fork of the CV32E40P core to implement the official RISC-V Zfinx and Zce ISA extensions.

A first implementation of the Zce ISA extensions has been explored in [3] to investigate code reduction benefits.

Documentation

The CV32E41P user manual can be found in the docs folder and it is captured in reStructuredText, rendered to html using Sphinx. These documents are viewable using readthedocs and can be viewed here.

Verification

The verification environment for the CV32E41P is not in this Repository. There is a small, simple testbench here which is useful for experimentation only and should not be used to validate any changes to the RTL prior to pushing to the master branch of this repo.

The verification environment for this core as well as other cores in the OpenHW Group CORE-V family is at the core-v-verif repository on GitHub.

The Makefiles supported in the core-v-verif project automatically clone the appropriate version of the cv32e41p RTL sources.

Constraints

Example synthesis constraints for the CV32E41P are provided.

Contributing

We highly appreciate community contributions. We are currently using the lowRISC contribution guide. To ease our work of reviewing your contributions, please:

• Create your own fork to commit your changes and then open a Pull Request.
• Split large contributions into smaller commits addressing individual changes or bug fixes. Do not mix unrelated changes into the same commit!
• Write meaningful commit messages. For more information, please check out the the Ibex contribution guide.
• If asked to modify your changes, do fixup your commits and rebase your branch to maintain a clean history.

When contributing SystemVerilog source code, please try to be consistent and adhere to the lowRISC Verilog coding style guide.

To get started, please check out the "Good First Issue" list.

The RTL code has been formatted with "Verible" v0.0-1149-g7eae750.

Issues and Troubleshooting

If you find any problems or issues with CV32E41P or the documentation, please check out the issue tracker and create a new issue if your problem is not yet tracked.

References

1. Gautschi, Michael, et al. "Near-Threshold RISC-V Core With DSP Extensions for Scalable IoT Endpoint Devices." in IEEE Transactions on Very Large Scale Integration (VLSI) Systems, vol. 25, no. 10, pp. 2700-2713, Oct. 2017

2. Schiavone, Pasquale Davide, et al. "Slow and steady wins the race? A comparison of ultra-low-power RISC-V cores for Internet-of-Things applications." 27th International Symposium on Power and Timing Modeling, Optimization and Simulation (PATMOS 2017)

3. Perotti, Matteo, et al. "HW/SW approaches for RISC-V code size reduction." Workshop on Computer Architecture Research with RISC-V (CARRV 2020). 2020.