Bash code:

break_chars()
{
  BINMODE=3 awk '
    BEGIN { FS="" }
    {
      $0 = $0 RT
      for(i = 1; i <= NF; i = i + 1)
      {
        printf "%s\n", ($i == "\r" ? "\\r" :
                        $i == "\n" ? "\\n" :
                        $i);
      }
    }'
}

char_vals()
{
  sed -e "s/.*/'&'/" |
  sed -e "/'\\\\.'/ s/^/\$/" |
  sed -e "s/'''/\\\\'/" |
  sed -e "s/^/printf %d\\\\\\\n \\\\'/" |
  bash |
  sed -e '/^-/ s/.*/$((256&))/; s/^/printf %02x\\\\n /' |
  bash
}

hexdump()
{
  break_chars | char_vals
}