-static int decode_nul(bitstr_t * bs, field_t * f, char *base, int level);
-static int decode_bool(bitstr_t * bs, field_t * f, char *base, int level);
-static int decode_oid(bitstr_t * bs, field_t * f, char *base, int level);
-static int decode_int(bitstr_t * bs, field_t * f, char *base, int level);
-static int decode_enum(bitstr_t * bs, field_t * f, char *base, int level);
-static int decode_bitstr(bitstr_t * bs, field_t * f, char *base, int level);
-static int decode_numstr(bitstr_t * bs, field_t * f, char *base, int level);
-static int decode_octstr(bitstr_t * bs, field_t * f, char *base, int level);
-static int decode_bmpstr(bitstr_t * bs, field_t * f, char *base, int level);
-static int decode_seq(bitstr_t * bs, field_t * f, char *base, int level);
-static int decode_seqof(bitstr_t * bs, field_t * f, char *base, int level);
-static int decode_choice(bitstr_t * bs, field_t * f, char *base, int level);
+static int decode_nul(bitstr_t *bs, const struct field_t *f, char *base, int level);
+static int decode_bool(bitstr_t *bs, const struct field_t *f, char *base, int level);
+static int decode_oid(bitstr_t *bs, const struct field_t *f, char *base, int level);
+static int decode_int(bitstr_t *bs, const struct field_t *f, char *base, int level);
+static int decode_enum(bitstr_t *bs, const struct field_t *f, char *base, int level);
+static int decode_bitstr(bitstr_t *bs, const struct field_t *f, char *base, int level);
+static int decode_numstr(bitstr_t *bs, const struct field_t *f, char *base, int level);
+static int decode_octstr(bitstr_t *bs, const struct field_t *f, char *base, int level);
+static int decode_bmpstr(bitstr_t *bs, const struct field_t *f, char *base, int level);
+static int decode_seq(bitstr_t *bs, const struct field_t *f, char *base, int level);
+static int decode_seqof(bitstr_t *bs, const struct field_t *f, char *base, int level);
+static int decode_choice(bitstr_t *bs, const struct field_t *f, char *base, int level);