uRisc-V

uriscv - Another tiny RISC-V implementation

Github: https://github.com/ultraembedded/core_uriscv

Simple, small, multi-cycle 32-bit RISC-V CPU implementation.
Most instructions take 2 cycles, apart from load/stores which take 4+ cycles (depending on memory latency), and division which can take up-to 34 cycles.

Features

• 32-bit RISC-V ISA CPU core.
• Support RISC-V’s integer (I), multiplication and division (M), and CSR instructions (Z) extensions (RV32IMZicsr).
• Implements base ISA spec v2.1 and parts of the privileged ISA spec v1.11.
• Supports machine mode privilege level only.
• Configurable support for exceptions, interrupts, timers, multiplication, division and error traps.
• Verified using random instruction sequences using cosimulation against C++ ISA model.
• Synthesizable Verilog 2001, Verilator and FPGA friendly.
• Coremark: 1.48 CoreMark/MHz (with HW mul/div)
• Dhrystone: 0.58 DMIPS/MHz ('legal compile options' / 337 instructions per iteration / with HW mul/div)

For my higher performance pipelined cores, see here:

• Coremark: 2.94CM/MHZ - http://github.com/ultraembedded/riscv
• Coremark: 4.1CM/MHz - http://github.com/ultraembedded/biriscv

Getting Started

Cloning

To clone this project and its dependencies;

git clone https://github.com/ultraembedded/core_uriscv.git

Running Helloworld

To run a simple test image on the core RTL using Icarus Verilog;

# Install Icarus Verilog (Debian / Ubuntu / Linux Mint)
sudo apt-get install iverilog

# [or] Install Icarus Verilog (Redhat / Centos)
#sudo yum install iverilog

# Run a simple test image (test.elf)
cd tb/tb_core_icarus
make

The expected output is;

Starting bench
VCD info: dumpfile waveform.vcd opened for output.

Test:
1. Initialised data
2. Multiply
3. Divide
4. Shift left
5. Shift right
6. Shift right arithmetic
7. Signed comparision
8. Word access
9. Byte access
10. Comparision

Configuration