Field Name             Bits   Default Description
VERTEX_FIFO            2:0    0x0     Number of words remaining in input vertex fifo before
                                      asserting nearly full
INDEX_FIFO             5:3    0x0     Number of words remaining in input primitive fifo
                                      before asserting nearly full
REG_FIFO               13:6   0x0     Number of words remaining in input register fifo before
                                      asserting nearly full
