On Mon, Mar 2, 2009 at 10:12 PM, Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > > You should do the ~ before the cast, or use - if you just want to reverse > things. It probably doesn't much matter (the difference between ~ and - i > just one), but still.. > > Also, quite frankly, it looks like your 'coords[]' array should just be of > type 's16' (rather than 'int') to begin with. You seem to really never use > it as an int anyway. That would get rid of the cast. > >> Is there a cleaner way to accomplish the transition from 16-bit >> unsigned little endian to 16-bit signed host endian? > > I think the code is fine, but I think you'd be better off if the "data" > pointer was perhaps of type "le16 *" to begin with. > > That obviously means that your "offset" addition should now be in 16-bit > words rather than in bytes, so you'd need to divide the offsets by two to > do that, but those are just numbers anyway. And quite frankly, it looks > like the actual data is just offset differently - but with the same fixed > offset between values - for the two cases, so you could just have _one_ > offset (and even just add that into the 'data' pointer). > > That would get rid of the second cast. You'd end up with just > > s16 coords[4]; > > /* In words - so this is 12 vs 6 bytes into the data */ > data += (xpad->xtype == XTYPE_XBOX) ? 6 : 3; > > coords[0] = le16_to_cpup(data); > coords[1] = ~le16_to_cpup(data + 1); > coords[2] = le16_to_cpup(data + 2); > coords[3] = ~le16_to_cpup(data + 3); > .. > > which looks a bit shorter and avoids those casts. I dunno. > > Linus > Thanks Linus... that solution worked, and it did make the code shorter. To get a clean compile, I had to cast the actual argument data pointer to (__le16 *), but that only adds 2 casts. I will send the revision shortly. Thanks, Mike -- Mike Murphy Ph.D. Candidate and NSF Graduate Research Fellow Clemson University School of Computing 120 McAdams Hall Clemson, SC 29634-0974 USA Tel: +1 864.656.2838 Fax: +1 864.656.0145 http://cirg.cs.clemson.edu/~mamurph -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
