Coprosit

Posit and quire arithmetic coprocessor compliant with the RISC-V eXtension interface core-v-xif. It uses the PRAU as an execution unit. Coprosit is integrated into the X-HEEP platform in PHEE.

If you use Coprosit in your academic work, you can cite our preprint:

@misc{mallasen2025Increasing,
      title={Increasing the Energy-Efficiency of Wearables Using Low-Precision Posit Arithmetic with PHEE}, 
      author={David Mallasén and Pasquale Davide Schiavone and Alberto A. Del Barrio and Manuel Prieto-Matias and David Atienza},
      year={2025},
      eprint={2501.18253},
      archivePrefix={arXiv},
      primaryClass={cs.AR},
      url={https://arxiv.org/abs/2501.18253}, 
}

Posit configuration

To configure the posit size, specify the appropiate flag when running make sim or make synth-pynq-z2, i.e. FUSESOC_FLAGS="--flag=use_posit32".

In any case, only values of POSLEN smaller or equal to XLEN are supported (for now). E.g. you can only use posit32 or smaller in a 32-bit CPU.

You can also set flags to include log-approximate multiplication, division and square root units or to include quire operations.

The available flags are the following:

• Posit size: use_posit8, use_posit16, use_posit32, use_posit64
• Posit log-approximate units: use_pos_log_mult, use_pos_log_div, use_pos_log_sqrt
• Quire operations: use_quire

Example

source venv/bin/activate
make sim FUSESOC_FLAGS="--flag=use_posit32 --flag=use_quire"
cd build/esl-epfl_ip_coprosit_0.0.1/sim-modelsim
make run-gui