$ perl -MData::Dumper -wle '
  $s = 5;
  @a = (1,5,7,9,32,197,8,4,5); $e=int $#a/$s;
  @b = map {$_*=$s; [@a[$_..($_+$s>$#a?$#a:$_+$s-1)]]} 0..$e;
  print Dumper \@b
'