diff --git a/knhx.c b/knhx.c
index fd35a3f9..8dbd3b6e 100644
--- a/knhx.c
+++ b/knhx.c
@@ -91,17 +91,76 @@ knhx1_t *kn_parse(const char *nhx, int *_n, int *_error)
 	return ret;
 }
 
+#ifndef kroundup32
+#define kroundup32(x) (--(x), (x)|=(x)>>1, (x)|=(x)>>2, (x)|=(x)>>4, (x)|=(x)>>8, (x)|=(x)>>16, ++(x))
+#endif
+
+static inline int kputsn(const char *p, int l, kstring_t *s)
+{
+	if (s->l + l + 1 >= s->m) {
+		s->m = s->l + l + 2;
+		kroundup32(s->m);
+		s->s = (char*)realloc(s->s, s->m);
+	}
+	memcpy(s->s + s->l, p, l);
+	s->l += l; s->s[s->l] = 0;
+	return l;
+}
+
+static inline int kputc(int c, kstring_t *s)
+{
+	if (s->l + 1 >= s->m) {
+		s->m = s->l + 2;
+		kroundup32(s->m);
+		s->s = (char*)realloc(s->s, s->m);
+	}
+	s->s[s->l++] = c; s->s[s->l] = 0;
+	return c;
+}
+
+static void format_node_recur(const knhx1_t *node, const knhx1_t *p, kstring_t *s, char *numbuf)
+{
+	if (p->n) {
+		int i;
+		kputc('(', s);
+		for (i = 0; i < p->n; ++i) {
+			if (i) kputc(',', s);
+			format_node_recur(node, &node[p->child[i]], s, numbuf);
+		}
+		kputc(')', s);
+		if (p->name) kputsn(p->name, strlen(p->name), s);
+		if (p->d >= 0) {
+			sprintf(numbuf, ":%g", p->d);
+			kputsn(numbuf, strlen(numbuf), s);
+		}
+	} else kputsn(p->name, strlen(p->name), s);
+}
+
+void kn_format(const knhx1_t *node, int root, kstring_t *s) // TODO: get rid of recursion
+{
+	char numbuf[128];
+	format_node_recur(node, &node[root], s, numbuf);
+}
+
 #ifdef KNHX_MAIN
 int main(int argc, char *argv[])
 {
 	char *s = "((a[abc],d1)x:0.5,((b[&&NHX:S=MOUSE],h2)[&&NHX:S=HUMAN:B=99][blabla][&&NHX:K=foo],c))";
 	knhx1_t *node;
-	int i, n, error;
+	int i, j, n, error;
+	kstring_t str;
 	node = kn_parse(s, &n, &error);
 	for (i = 0; i < n; ++i) {
 		knhx1_t *p = node + i;
-		printf("%s[%d]: %d,%d,%lg\n", p->name, i, p->parent, p->n, p->d);
+		printf("[%d] %s\t%d\t%d\t%g", i, p->name, p->parent, p->n, p->d);
+		for (j = 0; j < p->n; ++j)
+			printf("\t%d", p->child[j]);
+		putchar('\n');
 	}
+	str.l = str.m = 0; str.s = 0;
+	kn_format(node, n-1, &str);
+	puts(str.s);
+	free(str.s);
 	return 0;
 }
 #endif
diff --git a/knhx.h b/knhx.h
index 3bb0f375..dbad7dd9 100644
--- a/knhx.h
+++ b/knhx.h
@@ -13,4 +13,23 @@ typedef struct {
 	double d;
 } knhx1_t;
 
+#ifndef KSTRING_T
+#define KSTRING_T kstring_t
+typedef struct __kstring_t {
+	size_t l, m;
+	char *s;
+} kstring_t;
+#endif
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+	knhx1_t *kn_parse(const char *nhx, int *_n, int *_error);
+	void kn_format(const knhx1_t *node, int root, kstring_t *s);
+
+#ifdef __cplusplus
+}
+#endif
+
 #endif