diff options
Diffstat (limited to 'src/gallium/include/pipe')
| -rw-r--r-- | src/gallium/include/pipe/p_winsys.h | 31 |
1 files changed, 27 insertions, 4 deletions
diff --git a/src/gallium/include/pipe/p_winsys.h b/src/gallium/include/pipe/p_winsys.h index e784c92491..1383bd0544 100644 --- a/src/gallium/include/pipe/p_winsys.h +++ b/src/gallium/include/pipe/p_winsys.h @@ -104,13 +104,36 @@ struct pipe_winsys * usage is a bitmask of PIPE_BUFFER_USAGE_PIXEL/VERTEX/INDEX/CONSTANT. This * usage argument is only an optimization hint, not a guarantee, therefore * proper behavior must be observed in all circumstances. + * + * alignment indicates the client's alignment requirements, eg for + * SSE instructions. */ struct pipe_buffer *(*buffer_create)( struct pipe_winsys *sws, - unsigned alignment, - unsigned usage, - unsigned size ); + unsigned alignment, + unsigned usage, + unsigned size ); - /** Create a buffer that wraps user-space data */ + /** + * Create a buffer that wraps user-space data. + * + * Effectively this schedules a delayed call to buffer_create + * followed by an upload of the data at *some point in the future*, + * or perhaps never. Basically the allocate/upload is delayed + * until the buffer is actually passed to hardware. + * + * The intention is to provide a quick way to turn regular data + * into a buffer, and secondly to avoid a copy operation if that + * data subsequently turns out to be only accessed by the CPU. + * + * Common example is OpenGL vertex buffers that are subsequently + * processed either by software TNL in the driver or by passing to + * hardware. + * + * XXX: What happens if the delayed call to buffer_create() fails? + * + * Note that ptr may be accessed at any time upto the time when the + * buffer is destroyed, so the data must not be freed before then. + */ struct pipe_buffer *(*user_buffer_create)(struct pipe_winsys *sws, void *ptr, unsigned bytes); |