RISC-V Assembly First Steps

The following procedure should get you started with a clean running RISC-V Assembly project.

Prerequisites

Please Download & Read:

• RISC-V Book cap 1 to 3.
• RISC-V Green Card

Please Install:

• RISC-V GNU Compiler Toolchain from here, with --enable-multilib option

  • Add to your ~/.bashrc file:

  # assume RISC-V is installed to /opt/riscv/
  export RISCV_PATH=/opt/riscv
  export PATH=$PATH:$RISCV_PATH/bin

• Icarus Verilog from here, compile from source

• Download this repository and execeute the following commands to add execution permissions:

  chmod +x doasm.sh

  chmod +x compile.sh

  chmod +x reset.sh

Test Tools Before Proceeding

• RISC-V GNU Compiler Toolchain

  riscv64-unknown-elf-gcc --version

  riscv64-unknown-elf-objcopy --version

• Iverilog
  • Follow the guide

Fibonacci Sequence in RISC-V Assembly by Cristian Miranda

Such that each number is the sum of the two preceding ones, starting from 0 and 1. Ref

• 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, ...

_start:
 li t0, 255; //Final
 li t1, 1;   //ultimo
 li t2, 0;   //penultimo
 li t3, 0;   //suma
 .inicio:
		
  add t1, zero, 1;  //Inicializamos el ultimo en uno
		
  add t2, zero ,0;  //Limpiamos el penultimo en cero para comenzar nuevamente la serie
		
   .sigueSumando:  //Bucle para calcular la serie
		
    add t3, t2, t1; //sumamos ultimo y penultimo

    bge t3, t0, .inicio;  //Verificamos que la suma no se pase de la variable final=255.
                          //Salto a .inicio si suma >= final

    add t2, t1, 0;  //penultimo = ultimo
    add t1, t3, 0;  //ultimo = suma

    jal x1, .sigueSumando //Saltamos a .sigueSumando
			
j _start

Run The Compiler

doasm.sh script will:

• Compile the asm program
• Assemble your program
• Get the binary mahine code
• Get the HEX file for Verilog techbench
• Print the dumped file
• Print the number of instructions

./doasm.sh assembly/projects/fibonacci.S

Run the Simulator

cd verilog

iverilog -o test *.v

vvp test

Check the Waveform

gtkwave test.vcd

PWM C program to RISC-V Assembly by Cristian Miranda

Run The Compiler

compile.sh script will:

• Compile the Start.S program
• Compile the C program
• Assemble your program with the Start.S
• Get the binary mahine code
• Get the HEX file for Verilog techbench
• Print the dumped file
• Print the number of instructions

./compile.sh c_program/PWM.c

Then Repet Run the Simulator & Check the Waveform