Date: Sun, 11 Feb 2007 10:32:24 +0100 From: Hans Petter Selasky <hselasky@c2i.net> To: freebsd-hackers@freebsd.org Cc: "Eugene M. Kim" <freebsd.org@ab.ote.we.lv> Subject: Re: sin()/cos()/tan() for kernel code? '_ 'a Message-ID: <200702111032.24080.hselasky@c2i.net> In-Reply-To: <45CED641.7020608@ab.ote.we.lv> References: <45CED641.7020608@ab.ote.we.lv>
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On Sunday 11 February 2007 09:39, Eugene M. Kim wrote: > Hello all, > > I am writing a mouse device driver for my Wacom tablet (Intuos 2 9x12). > The tablet comes with a mouse and I managed to get valid coordinate data > from the device. However, unlike usual mice, the coordinate system is > tied not to the orientation of the mouse itself, but to the tablet, > which acts much like a "mouse pad". So, for example, if I rotate the > mouse 30 degrees to the left and move it left and right, the mouse > cursor would move not horizontally, but to 2- or 8-o'clock. > > Fortunately the mouse also provides orientation data along with > coordinate data, so the correct cursor movement could be calculated from > it. The problem: The calculation needs trigonometry, but there seems to > be no math library support in the kernel (I ran "grep -w cos" on the > -CURRENT source tree, which turned nothing up). > > Does anyone have an idea on how to do this? > Is it possible to use a small integer table to do the conversion ? --HPS
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