On 04/20/2011 08:28 AM, Peter Hutterer wrote: > Use enums for the direction bits, not hardcoded bitfield values that are > added up. > > Signed-off-by: Peter Hutterer <peter.hutte...@who-t.net> > --- > dix/ptrveloc.c | 37 +++++++++++++++++++++++++------------ > 1 files changed, 25 insertions(+), 12 deletions(-) > > diff --git a/dix/ptrveloc.c b/dix/ptrveloc.c > index a913666..e95ccbe 100644 > --- a/dix/ptrveloc.c > +++ b/dix/ptrveloc.c > @@ -429,14 +429,27 @@ InitTrackers(DeviceVelocityPtr vel, int ntracker) > vel->num_tracker = ntracker; > } > > +enum directions { > + N = (1 << 0), > + NE = (1 << 1), > + E = (1 << 2), > + SE = (1 << 3), > + S = (1 << 4), > + SW = (1 << 5), > + W = (1 << 6), > + NW = (1 << 7), > + UNDEFINED = 0xFF > +}; > /** > * return a bit field of possible directions. > - * 0 = N, 2 = E, 4 = S, 6 = W, in-between is as you guess. > * There's no reason against widening to more precise directions (<45 > degrees), > * should it not perform well. All this is needed for is sort out non-linear > * motion, so precision isn't paramount. However, one should not flag > direction > * too narrow, since it would then cut the linear segment to zero size way > too > * often. > + * > + * @return A bitmask for N, NE, S, SE, etc. indicating the directions for > + * this movement. > */ > static int > DoGetDirection(int dx, int dy){ > @@ -446,23 +459,23 @@ DoGetDirection(int dx, int dy){ > if(abs(dx) < 2 && abs(dy) < 2){ > /* first check diagonal cases */ > if(dx > 0 && dy > 0) > - return 4+8+16; > + return E | SE | S; > if(dx > 0 && dy < 0) > - return 1+2+4; > + return N | NE | E; > if(dx < 0 && dy < 0) > - return 1+128+64; > + return W | NW | N; > if(dx < 0 && dy > 0) > - return 16+32+64; > + return W | SW | S; > /* check axis-aligned directions */ > if(dx > 0) > - return 2+4+8; /*E*/ > + return NE | E | SE; > if(dx < 0) > - return 128+64+32; /*W*/ > + return NW | W | SW; > if(dy > 0) > - return 32+16+8; /*S*/ > + return SE | S | SW; > if(dy < 0) > - return 128+1+2; /*N*/ > - return 255; /* shouldn't happen */ > + return NE | N | NW; > + return UNDEFINED; /* shouldn't happen */ > } > /* else, compute angle and set appropriate flags */ > #ifdef _ISOC99_SOURCE > @@ -478,7 +491,7 @@ DoGetDirection(int dx, int dy){ > i1 = (int)(r+0.1) % 8; > i2 = (int)(r+0.9) % 8; > if(i1 < 0 || i1 > 7 || i2 < 0 || i2 > 7) > - return 255; /* shouldn't happen */ > + return UNDEFINED; /* shouldn't happen */ > return 1 << i1 | 1 << i2; > } > > @@ -558,7 +571,7 @@ CalcTracker(DeviceVelocityPtr vel, int offset, int cur_t){ > */ > static float > QueryTrackers(DeviceVelocityPtr vel, int cur_t){ > - int n, offset, dir = 255, i = -1, age_ms; > + int n, offset, dir = UNDEFINED, i = -1, age_ms; > /* initial velocity: a low-offset, valid velocity */ > float iveloc = 0, res = 0, tmp, vdiff; > float vfac = vel->corr_mul * vel->const_acceleration; /* premultiply */ Reviewed-by: Simon Thum <simon.t...@gmx.de>
That's a big improvement in readability. Cheers, Simon _______________________________________________ xorg-devel@lists.x.org: X.Org development Archives: http://lists.x.org/archives/xorg-devel Info: http://lists.x.org/mailman/listinfo/xorg-devel