On Tue, Oct 17, 2006 at 02:51:09PM -0700, Greg KH wrote: > From: Grant Grundler <[EMAIL PROTECTED]> > > extract() and implement() have brain damaged attempts to handle 32-bit wide > "fields".
Brain-damaged though they may be, they sure work with my devices a whole lot better than your "new and improved" version. > The problem is the index math in the original code didn't clear all the > relevant bits. (offset >> 5) only compensated for 32-bit index. We need > (offset >> 6) if we want to use 64-bit loads. > > But it was also wrong in that it tried to use quasi-aligned loads. Ie > "report" was only incremented in multiples of 4 bytes and then the offset > was masked off for values greater than 4 bytes. The right way is to > pretend "report" points at a byte array. And offset is then only minor > adjustment for < 8 bits of offset. "n" (field width) can then be as big as > 24 (assuming 32-bit loads) since "offset" will never be bigger than 7. > > If someone needs either function to handle more than 24-bits, please > document why - point at a specification or specific USB hid device - in > comments in the code. Ummm. Ok. How many pages of the HID 1.11 spec shall I paste in? I'm not sure what makes you think there's some magic 24 bit limit. I see no limit specified, although in practice I've never seen anything larger than 32 bits. The size of a report field (in bits) is set by the Report Size global item, the data portion of which can be at most a 32 bit integer, thus giving a maximum field width of 4 Gbits. Clearly taking it that far would be insane, but limiting it to 24 bits arbitrarily is equally nuts. I can send report descriptors of devices in my possession which have 32 bit wide fields. I'm the guy who patched the original extract() from "& ((1 << n)" to "& ((1ULL << n)" precisely because it didn't work on such devices, a bug which you've kindly recreated. Please, revert this patch or fix it to handle 32 bit fields. --Adam ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
