Is there un-wp_autop function?

I have a problem with WP that need your help. Some of my posts have content that was applied “wp_autop” filters already. This filter turned all double break lines into <p> tag. I want to the opposite thing: turn all <p> tag into double break lines.

Do you have any suggestions? Thank you.

I just ran into this situation. Here is a function I used to undo wpautop. I might be missing something, but this is a good start:

function reverse_wpautop($s)
{
    //remove any new lines already in there
    $s = str_replace("\n", "", $s);

    //remove all <p>
    $s = str_replace("<p>", "", $s);

    //replace <br /> with \n
    $s = str_replace(array("<br />", "<br>", "<br/>"), "\n", $s);

    //replace </p> with \n\n
    $s = str_replace("</p>", "\n\n", $s);       

    return $s;      
}