pipelines

• ld_read_ringbuf — Read a portion from a ringbuffer
• ld_relread_ringbuf — Read a portion from a ringbuffer relative to the currently set marker position
• ld_ringbuf — inittialise a new ringbuffer
• ld_setmarkerW_ringbuf — Set the current marker position to the lastly written element
• ld_write_ringbuf — Write a portion to a ringbuffer