diff --git a/route.c b/route.c
new file mode 100644
index 0000000..db368aa
--- /dev/null
+++ b/route.c
@@ -0,0 +1,109 @@
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <errno.h>
+#include <assert.h>
+
+#include "treetrie.h"
+#include "critbit.h"
+#include "route.h"
+
+static inline tt_node_ptr_t rseq(tt_arena_t *a, tt_atom_t s, tt_node_ptr_t r) {
+  if (TT_EMPTY_P(r)) {
+    return TT_EMPTY;
+  }
+  assert(s != TT_WILD);
+  return tt_cons_branch(a, TT_EMPTY, RET_IF_NO_PTR(tt_dict_singleton(a, s, r)));
+}
+
+static inline tt_node_ptr_t rwild(tt_arena_t *a, tt_node_ptr_t r) {
+  if (TT_EMPTY_P(r)) {
+    return TT_EMPTY;
+  }
+  return tt_cons_branch(a, r, TT_EMPTY_DICT);
+}
+
+static inline tt_node_ptr_t rbranch(tt_arena_t *a,
+				    tt_node_ptr_t wild, /* trie */
+				    tt_node_ptr_t others) /* dict */
+{
+  if (TT_EMPTY_P(wild) && TT_EMPTY_DICT_P(others)) {
+    return TT_EMPTY;
+  }
+  return tt_cons_branch(a, wild, others);
+}
+
+static inline tt_node_ptr_t rwildseq(tt_arena_t *a, tt_node_ptr_t r) {
+  if (TT_EMPTY_P(r)) {
+    return TT_EMPTY;
+  }
+  return tt_cons_tail(a, r);
+}
+
+static inline tt_node_ptr_t runwildseq(tt_arena_t *a, tt_node_ptr_t r) {
+  if (tt_ptr_tag(r) == TT_TAG_TAIL) {
+    return TT_TAIL_TRIE(a,r);
+  } else {
+    return TT_EMPTY;
+  }
+}
+
+static inline tt_node_ptr_t rlookup(tt_arena_t *a,
+				    tt_node_ptr_t r,
+				    tt_atom_t key)
+{
+  tt_node_ptr_t result;
+  assert(tt_ptr_tag(r) == TT_TAG_BRANCH);
+  result = tt_dict_get(a, TT_BRANCH_OTHERS(a,r), key);
+  if (!TT_NO_PTR_P(result)) {
+    return result;
+  }
+  result = TT_BRANCH_WILDCARD(a,r);
+  switch (key) {
+    case TT_BOS: return rwildseq(a, result);
+    case TT_EOS: return runwildseq(a, result);
+    default:     return result;
+  }
+}
+
+static inline tt_node_ptr_t rupdate(tt_arena_t *a,
+				    tt_node_ptr_t r0, /* branch */
+				    tt_atom_t key,
+				    tt_node_ptr_t k) /* trie */
+{
+  assert(key != TT_WILD);
+  if (TT_EMPTY_P(r0)) {
+    return rseq(a, key, k);
+  } else {
+    tt_node_ptr_t old_wild;
+    tt_node_ptr_t old_others;
+    assert(tt_ptr_tag(r0) == TT_TAG_BRANCH);
+    old_wild = TT_BRANCH_WILDCARD(a,r0);
+    old_others = TT_BRANCH_OTHERS(a,r0);
+
+#define R0_SANS_KEY() (rbranch(a, old_wild, RET_IF_NO_PTR(tt_dict_remove(a, old_others, key))))
+#define R0_WITH_KEY() (rbranch(a, old_wild, RET_IF_NO_PTR(tt_dict_set(a, old_others, key, k))))
+
+    switch (key) {
+      case TT_BOS:
+	if (tt_ptr_tag(k) == TT_TAG_TAIL) {
+	  return (TT_TAIL_TRIE(a,k) == old_wild) ? R0_SANS_KEY() : R0_WITH_KEY();
+	} else {
+	  return TT_EMPTY_P(k) ? R0_SANS_KEY() : R0_WITH_KEY();
+	}
+      case TT_EOS:
+	if (tt_ptr_tag(old_wild) == TT_TAG_TAIL) {
+	  return (TT_TAIL_TRIE(a,old_wild) == k) ? R0_SANS_KEY() : R0_WITH_KEY();
+	} else {
+	  return TT_EMPTY_P(k) ? R0_SANS_KEY() : R0_WITH_KEY();
+	}
+      default:
+	return (k == old_wild) ? R0_SANS_KEY() : R0_WITH_KEY();
+    }
+
+#undef R0_SANS_KEY
+#undef R0_WITH_KEY
+
+  }
+}
diff --git a/route.h b/route.h
new file mode 100644
index 0000000..6491319
--- /dev/null
+++ b/route.h
@@ -0,0 +1,23 @@
+#ifndef ROUTE_H_c2d88c54_f18d_4b71_9fce_5d43c0723360
+#define ROUTE_H_c2d88c54_f18d_4b71_9fce_5d43c0723360
+
+/* Sticking to odd-numbered constants, since the plan is for most
+   bindings to use odd-numbered atoms for immediates and even-numbered
+   atoms for heap-allocated complex values. TODO: make this a proper
+   part of the interface? */
+#define TT_WILD ((tt_atom_t) -1)	/* Wildcard */
+#define TT_BOS ((tt_atom_t) -3)		/* Beginning of sequence */
+#define TT_EOS ((tt_atom_t) -5)		/* End of sequence */
+#define TT_BOC ((tt_atom_t) -7)		/* Beginning of capture */
+#define TT_EOC ((tt_atom_t) -9)		/* End of capture */
+
+// TODO move to the right place
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif