diff --git a/src/libregexp/regaux.c b/src/libregexp/regaux.c
new file mode 100644
index 0000000..956c1eb
--- /dev/null
+++ b/src/libregexp/regaux.c
@@ -0,0 +1,76 @@
+#include "lib9.h"
+#include "regexp9.h"
+#include "regcomp.h"
+
+
+/*
+ *  save a new match in mp
+ */
+extern void
+_renewmatch(Resub *mp, int ms, Resublist *sp)
+{
+	int i;
+
+	if(mp==0 || ms<=0)
+		return;
+	if(mp[0].s.sp==0 || sp->m[0].s.sp<mp[0].s.sp ||
+	   (sp->m[0].s.sp==mp[0].s.sp && sp->m[0].e.ep>mp[0].e.ep)){
+		for(i=0; i<ms && i<NSUBEXP; i++)
+			mp[i] = sp->m[i];
+		for(; i<ms; i++)
+			mp[i].s.sp = mp[i].e.ep = 0;
+	}
+}
+
+/*
+ * Note optimization in _renewthread:
+ * 	*lp must be pending when _renewthread called; if *l has been looked
+ *		at already, the optimization is a bug.
+ */
+extern Relist*
+_renewthread(Relist *lp,	/* _relist to add to */
+	Reinst *ip,		/* instruction to add */
+	Resublist *sep)		/* pointers to subexpressions */
+{
+	Relist *p;
+
+	for(p=lp; p->inst; p++){
+		if(p->inst == ip){
+			if((sep)->m[0].s.sp < p->se.m[0].s.sp)
+				p->se = *sep;
+			return 0;
+		}
+	}
+	p->inst = ip;
+	p->se = *sep;
+	(++p)->inst = 0;
+	return p;
+}
+
+/*
+ * same as renewthread, but called with
+ * initial empty start pointer.
+ */
+extern Relist*
+_renewemptythread(Relist *lp,	/* _relist to add to */
+	Reinst *ip,		/* instruction to add */
+	char *sp)		/* pointers to subexpressions */
+{
+	Relist *p;
+
+	for(p=lp; p->inst; p++){
+		if(p->inst == ip){
+			if(sp < p->se.m[0].s.sp) {
+				memset((void *)&p->se, 0, sizeof(p->se));
+				p->se.m[0].s.sp = sp;
+			}
+			return 0;
+		}
+	}
+	p->inst = ip;
+	memset((void *)&p->se, 0, sizeof(p->se));
+	p->se.m[0].s.sp = sp;
+	(++p)->inst = 0;
+	return p;
+}
+