Q: puzzle about the index of PrepareAccess

Michel Dänzer michel at daenzer.net
Fri Dec 3 00:03:21 PST 2010

On Fre, 2010-12-03 at 10:04 +0800, fancy fang wrote:
> So, according to your explaination, the driver PrepareAccess can not
> know exactly whether the pixmap is used to read or write. Well, what's
> the usage of the index passed to driver PrepareAccess? 

From exa.h:

     * The index is one of #EXA_PREPARE_DEST, #EXA_PREPARE_SRC,
     * #EXA_PREPARE_AUX_MASK. Since only up to #EXA_NUM_PREPARE_INDICES pixmaps
     * will have PrepareAccess() called on them per operation, drivers can have
     * a small, statically-allocated space to maintain state for PrepareAccess()
     * and FinishAccess() in.  Note that PrepareAccess() is only called once per
     * pixmap and operation, regardless of whether the pixmap is used as a
     * destination and/or source, and the index may not reflect the usage.

Earthling Michel Dänzer           |                http://www.vmware.com
Libre software enthusiast         |          Debian, X and DRI developer

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