pvr2_stream_get_ready_buffer
bp = pvr2_stream_get_ready_buffer(stream);
while ((bp = pvr2_stream_get_ready_buffer(sp)) != NULL) {
struct pvr2_buffer *pvr2_stream_get_ready_buffer(struct pvr2_stream *);
cp->c_buf = pvr2_stream_get_ready_buffer(cp->stream);