#define SCM_BIGSIZEFIELD 17
#define SCM_BIGSIGN(x) (SCM_CELL_WORD_0 (x) & SCM_BIGSIGNFLAG)
#define SCM_BDIGITS(x) ((SCM_BIGDIG *) (SCM_CELL_WORD_1 (x)))
+#define SCM_SET_BIGNUM_BASE(n, b) (SCM_SET_CELL_WORD_1 ((n), (b)))
#define SCM_NUMDIGS(x) ((scm_sizet) (SCM_CELL_WORD_0 (x) >> SCM_BIGSIZEFIELD))
#define SCM_SETNUMDIGS(x, v, sign) \
SCM_SET_CELL_WORD_0 (x, \