Question

No use perl, python, and similar.

Answer 1

Use printf, a bash builtin: http://mywiki.wooledge.org/BashFAQ/071

If you want the ASCII code of a character in hex:

function ord {
  printf %x "'$1"
}

ord A # 41
ord 0 # 30

The use of the single leading quote is explained here:
http://pubs.opengroup.org/onlinepubs/009695399/utilities/printf.html

If the leading character is a single-quote or double-quote, the value shall be
the numeric value in the underlying codeset of the character following the
single-quote or double-quote.