staging: comedi: add new comedi_buf_write_n_available()
Add a new function `comedi_buf_write_n_available()` to return the amount of buffer space available for writing, including space already allocated by `comedi_buf_write_alloc()` plus any unallocated space available. This is currently just for internal use by the comedi core, so is not exported. Signed-off-by: Ian Abbott <abbotti@mev.co.uk> Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -253,6 +253,14 @@ static unsigned int comedi_buf_write_n_unalloc(struct comedi_subdevice *s)
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return free_end - async->buf_write_alloc_count;
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}
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unsigned int comedi_buf_write_n_available(struct comedi_subdevice *s)
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{
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struct comedi_async *async = s->async;
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unsigned int free_end = async->buf_read_count + async->prealloc_bufsz;
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return free_end - async->buf_write_count;
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}
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/**
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* comedi_buf_write_alloc() - Reserve buffer space for writing
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* @s: COMEDI subdevice.
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@ -31,6 +31,7 @@ void comedi_buf_map_get(struct comedi_buf_map *bm);
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int comedi_buf_map_put(struct comedi_buf_map *bm);
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struct comedi_buf_map *comedi_buf_map_from_subdev_get(
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struct comedi_subdevice *s);
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unsigned int comedi_buf_write_n_available(struct comedi_subdevice *s);
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unsigned int comedi_buf_write_n_allocated(struct comedi_subdevice *s);
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void comedi_device_cancel_all(struct comedi_device *dev);
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bool comedi_can_auto_free_spriv(struct comedi_subdevice *s);
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