Adapted from a hat pattern that Bronislava posted to her blog.

I cast on 80 with alternate cable cast-on, then worked K1P1 rib for about 12 cm.

Transition from brim is 2 purled rounds, 2 knit rounds. Then decrease 5 times per round until flat, circular crown is complete.

This could be easily reversed, knitting a flat circle out from the center, then finishing with brim; easier to adjust fit that way.