CONS_BLOCK       2824 src/alloc.c      GETMARKBIT (CONS_BLOCK (fptr), CONS_INDEX ((fptr)))
CONS_BLOCK       2827 src/alloc.c      SETMARKBIT (CONS_BLOCK (fptr), CONS_INDEX ((fptr)))
CONS_BLOCK       2830 src/alloc.c      UNSETMARKBIT (CONS_BLOCK (fptr), CONS_INDEX ((fptr)))