fill a paragraph by just breaking the newlines

Hello On one hand when using auto-fill long lines get wrapped according to *set-fill-column*, on the other hand using fill-paragraph and the alike, not only wraps lines which are too long but formats the whole buffer such that all lines have equal length. I am looking for a function which would in a given buffer or region just wrap lines which are too long, the way auto-fill does it, but which does not touch the rest of the region or paragraph. Anybody has an idea about such a function[1] Thanks Uwe Brauer Footnotes: [1] I know of packages like long lines or wrap lines but they look to complicate and besides when I tried them they did not work well with Xemacs.