function join_by() {
  # Join array elements with character $1
  #
  # arg $1: A single-character delimiter, e.g. ','
  # arg $2: Name of source array
  # arg $3: Variable name to store result
  validate_args 3 "$@" || return $?
  local delimiter="${1}"
  local -n source_array_ptr=$2
  local -n joined_ptr=$3

  # https://stackoverflow.com/a/2317171
  joined_ptr=$(printf "${delimiter}%s" "${source_array_ptr[@]}") || return $?
  joined_ptr=${joined_ptr:1} || return $?
}

function newline_to_space() {
  # Replaces all newlines with spaces
  #
  # arg $1: Name of variable
  validate_args 1 "$@" || return $?
  local -n ptr=$1

  # Replace newlines with spaces.
  # See bash string substitution: https://gist.github.com/JPvRiel/b279524d3e56229a896477cb8082a72b
  ptr="${ptr//$'\n'/' '}"
}

function newline_separated_to_array() {
  # Watch out for tailing newlines as these result in additional elements "" at the end of the array.
  # $1 and $2 can be equal (if the result shall be written to the input variable).
  #
  # arg $1: Name of variable with newline separated list
  # arg $2: Name of array to store values into
  validate_args 2 "$@" || return $?
  local -n source_ptr=$1
  local -n array1_ptr=$2

  # source_ptr is a newline separated list.
  # Store this as array array1_ptr.
  # shellcheck disable=SC2034
  readarray -t array1_ptr <<<"${source_ptr}"
}

function space_separated_to_array() {
  # arg $1: Name of variable with space separated list
  # arg $2: Name of array to store values into
  validate_args 2 "$@" || return $?
  local -n source_ptr=$1
  # shellcheck disable=SC2178
  local -n array2_ptr=$2

  # source_ptr space separated list.
  # Store this as array array2_ptr.
  # Without newline at last array element: https://unix.stackexchange.com/a/519917/315162
  # shellcheck disable=SC2034
  readarray -d ' ' -t array2_ptr < <(printf '%s' "${source_ptr}")
}

function get_cpu_vendor() {
  # If $1 does already contain a known CPU vendor, nothing is done.
  #
  # Otherwise, we try to detect the CPU vendor and save it into $1.
  #
  # arg $1: Name of variable to store CPU vendor into.
  #
  # @pre
  #   $1 ("amd", "intel", "none", *)
  # @post
  #   $1 ("amd", "intel", "none")
  validate_args 1 "$@" || return $?
  local -n cpu_vendor_ptr=$1

  # Check if variable does already contain known CPU vendor.
  case "${cpu_vendor_ptr}" in
    amd|intel|none)
      return 0
      ;;
    *)
      :
      ;;
  esac

  # If in virtual environment (e.g. VirtualBox), then no CPU microcode is required.
  if grep --quiet '^flags.*hypervisor' /proc/cpuinfo; then
    echo 'Detected virtual environment.'
    cpu_vendor_ptr='none'
    return 0
  fi

  local vendor_id
  vendor_id="$(grep vendor_id /proc/cpuinfo | head -1 | sed 's|vendor_id\s*:\s*||')"

  if [ "${vendor_id}" = 'AuthenticAMD' ]; then
    cpu_vendor_ptr='amd'
    return 0
  elif [ "${vendor_id}" = 'GenuineIntel' ]; then
    cpu_vendor_ptr='intel'
    return 0
  else
    echo 'Unknown CPU vendor'
    return 1
  fi
}