how to map joomla users to moodle ones?

Hi, i'm trying to obtain the list of all moodle users by a script in joomla... i was trying using the Moodle WS but it seems not work (another topic)... so i wish to know how to obtain, from the list of joomla users, the corresponding moodle records.... using the Moodle WS exist the function which gets the users by id, but i know just the 'username' (unique).
thanks for all responses!

You can check functions:
getMoodleUsers
getAllUsers
in administrator/components/com_joomdle/helpers/content.php

thanks Antonio... but i'm trying to make these functions works in a component without results... the following code fails at the require:once... i'm pretty confuse about the way to use the JoomdleHelperContent class.

require_once(JURI::root()."administrator/components/com_joomdle/helpers/content.php");
$joomdleHelper = new JoomdleHelperContent();
$res = $joomdleHelper->getMoodleUsers (0, 20, "firstname", "desc", "");

JURI:root returns a URL.
You need this:
require_once(JPATH_ADMINISTRATOR.'/components/com_joomdle/helpers/content.php');

thanks... it works but the result is not what i need...
if i call getMoodleUsers(0, 2, "name", "desc", "rts"); or if i call getAllUsers(0, 2, "name", "desc", "rts"); in the result for both cases i have the id (758) of joomla account.. instead i need the id of correspondent moodle one..

Moreover if i call getJoomdleUsers(0, 2, "name", "desc", "rts"); the result is an SQL error because it tries to run an sql query with "rts" as column (but the query seems to be correct)..

There is no Joomdle function to return Moodle ids for all users.

And there is any function to return moodle ids using a search query?... For example if i had a joomla user with joomla id 758 and i know his username in moodle, how can i get its moodle id?

You can use user_id joomdle function.

and where is defined?

All functions code is in moodle/auth/joomdle/auth.php