http://bugs.winehq.org/show_bug.cgi?id=7284
--- Comment #44 from Tobias Jakobi liquid.acid@gmx.net 2009-04-11 08:05:08 --- It's in the regular DX8 docs. I uploaded them here: http://www.math.uni-bielefeld.de/~tjakobi/wine/DirectX-8.chm
They provide some pseudocode for the rcp instruction. According to that code (and the remark that follows later) a w-component of zero generates +infty as result.