diff --git a/src/libregexp/rregexec.c b/src/libregexp/rregexec.c
new file mode 100644
index 0000000..e96c972
--- /dev/null
+++ b/src/libregexp/rregexec.c
@@ -0,0 +1,213 @@
+#include "lib9.h"
+#include "regexp9.h"
+#include "regcomp.h"
+
+/*
+ *  return	0 if no match
+ *		>0 if a match
+ *		<0 if we ran out of _relist space
+ */
+static int
+rregexec1(Reprog *progp,	/* program to run */
+	Rune *bol,		/* string to run machine on */
+	Resub *mp,		/* subexpression elements */
+	int ms,			/* number of elements at mp */
+	Reljunk *j)
+{
+	int flag=0;
+	Reinst *inst;
+	Relist *tlp;
+	Rune *s;
+	int i, checkstart;
+	Rune r, *rp, *ep;
+	Relist* tl;		/* This list, next list */
+	Relist* nl;
+	Relist* tle;		/* ends of this and next list */
+	Relist* nle;
+	int match;
+
+	match = 0;
+	checkstart = j->startchar;
+	if(mp)
+		for(i=0; i<ms; i++) {
+			mp[i].s.rsp = 0;
+			mp[i].e.rep = 0;
+		}
+	j->relist[0][0].inst = 0;
+	j->relist[1][0].inst = 0;
+
+	/* Execute machine once for each character, including terminal NUL */
+	s = j->rstarts;
+	do{
+
+		/* fast check for first char */
+		if(checkstart) {
+			switch(j->starttype) {
+			case RUNE:
+				while(*s != j->startchar) {
+					if(*s == 0)
+						return match;
+					s++;
+				}
+				break;
+			case BOL:
+				if(s == bol)
+					break;
+				while(*s != '\n') {
+					if(*s == 0)
+						return match;
+					s++;
+				}
+				break;
+			}
+		}
+
+		r = *s;
+
+		/* switch run lists */
+		tl = j->relist[flag];
+		tle = j->reliste[flag];
+		nl = j->relist[flag^=1];
+		nle = j->reliste[flag];
+		nl->inst = 0;
+
+		/* Add first instruction to current list */
+		_rrenewemptythread(tl, progp->startinst, s);
+
+		/* Execute machine until current list is empty */
+		for(tlp=tl; tlp->inst; tlp++){
+			for(inst=tlp->inst; ; inst = inst->u2.next){
+				switch(inst->type){
+				case RUNE:	/* regular character */
+					if(inst->u1.r == r)
+						if(_renewthread(nl, inst->u2.next, &tlp->se)==nle)
+							return -1;
+					break;
+				case LBRA:
+					tlp->se.m[inst->u1.subid].s.rsp = s;
+					continue;
+				case RBRA:
+					tlp->se.m[inst->u1.subid].e.rep = s;
+					continue;
+				case ANY:
+					if(r != '\n')
+						if(_renewthread(nl, inst->u2.next, &tlp->se)==nle)
+							return -1;
+					break;
+				case ANYNL:
+					if(_renewthread(nl, inst->u2.next, &tlp->se)==nle)
+							return -1;
+					break;
+				case BOL:
+					if(s == bol || *(s-1) == '\n')
+						continue;
+					break;
+				case EOL:
+					if(s == j->reol || r == 0 || r == '\n')
+						continue;
+					break;
+				case CCLASS:
+					ep = inst->u1.cp->end;
+					for(rp = inst->u1.cp->spans; rp < ep; rp += 2)
+						if(r >= rp[0] && r <= rp[1]){
+							if(_renewthread(nl, inst->u2.next, &tlp->se)==nle)
+								return -1;
+							break;
+						}
+					break;
+				case NCCLASS:
+					ep = inst->u1.cp->end;
+					for(rp = inst->u1.cp->spans; rp < ep; rp += 2)
+						if(r >= rp[0] && r <= rp[1])
+							break;
+					if(rp == ep)
+						if(_renewthread(nl, inst->u2.next, &tlp->se)==nle)
+							return -1;
+					break;
+				case OR:
+					/* evaluate right choice later */
+					if(_renewthread(tlp, inst->u1.right, &tlp->se) == tle)
+						return -1;
+					/* efficiency: advance and re-evaluate */
+					continue;
+				case END:	/* Match! */
+					match = 1;
+					tlp->se.m[0].e.rep = s;
+					if(mp != 0)
+						_renewmatch(mp, ms, &tlp->se);
+					break;
+				}
+				break;
+			}
+		}
+		if(s == j->reol)
+			break;
+		checkstart = j->startchar && nl->inst==0;
+		s++;
+	}while(r);
+	return match;
+}
+
+static int
+rregexec2(Reprog *progp,	/* program to run */
+	Rune *bol,	/* string to run machine on */
+	Resub *mp,	/* subexpression elements */
+	int ms,		/* number of elements at mp */
+	Reljunk *j
+)
+{
+	Relist relist0[5*LISTSIZE], relist1[5*LISTSIZE];
+
+	/* mark space */
+	j->relist[0] = relist0;
+	j->relist[1] = relist1;
+	j->reliste[0] = relist0 + nelem(relist0) - 2;
+	j->reliste[1] = relist1 + nelem(relist1) - 2;
+
+	return rregexec1(progp, bol, mp, ms, j);
+}
+
+extern int
+rregexec(Reprog *progp,	/* program to run */
+	Rune *bol,	/* string to run machine on */
+	Resub *mp,	/* subexpression elements */
+	int ms)		/* number of elements at mp */
+{
+	Reljunk j;
+	Relist relist0[LISTSIZE], relist1[LISTSIZE];
+	int rv;
+
+	/*
+ 	 *  use user-specified starting/ending location if specified
+	 */
+	j.rstarts = bol;
+	j.reol = 0;
+	if(mp && ms>0){
+		if(mp->s.sp)
+			j.rstarts = mp->s.rsp;
+		if(mp->e.ep)
+			j.reol = mp->e.rep;
+	}
+	j.starttype = 0;
+	j.startchar = 0;
+	if(progp->startinst->type == RUNE && progp->startinst->u1.r < (Rune)Runeself) {
+		j.starttype = RUNE;
+		j.startchar = progp->startinst->u1.r;
+	}
+	if(progp->startinst->type == BOL)
+		j.starttype = BOL;
+
+	/* mark space */
+	j.relist[0] = relist0;
+	j.relist[1] = relist1;
+	j.reliste[0] = relist0 + nelem(relist0) - 2;
+	j.reliste[1] = relist1 + nelem(relist1) - 2;
+
+	rv = rregexec1(progp, bol, mp, ms, &j);
+	if(rv >= 0)
+		return rv;
+	rv = rregexec2(progp, bol, mp, ms, &j);
+	if(rv >= 0)
+		return rv;
+	return -1;
+}