function check_rustup {
    if type rustup >/dev/null; then
        rustup --version
        echo "rustup is installed!"
        return 0
    else
        echo "rustup not found"
        echo "starting to install rustup.."
        curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
        return 4
    fi
}

check_rustup
echo "updateing rustup.."
rustup update
echo "installing llvm-tools.."
rustup component add llvm-tools
rustup component add rustfmt
rustup default stable
rustup update stable
echo "adding some popular toolchains.."
rustup target add thumbv6m-none-eabi           # Cortex-M0 and Cortex-M0+
rustup target add thumbv7m-none-eabi           # Cortex-M3
rustup target add thumbv7em-none-eabi          # Cortex-M4 and Cortex-M7 (no FPU)
rustup target add thumbv7em-none-eabihf        # Cortex-M4F and Cortex-M7F (with FPU)
rustup target add thumbv8m.main-none-eabi       # Cortex-M33 and M55 (no FPU)
rustup target add thumbv8m.main-none-eabihf     # Cortex-M33 and M55 (with FPU)
rustup target add riscv32imac-unknown-none-elf # RISC-V 32-bit
echo "rustup rustc and cargo is ready to go!"
echo "rustc version"
rustc --version
rustup show