diff --git a/src/cmd/sam/rasp.c b/src/cmd/sam/rasp.c
new file mode 100644
index 0000000..45ac820
--- /dev/null
+++ b/src/cmd/sam/rasp.c
@@ -0,0 +1,325 @@
+#include "sam.h"
+/*
+ * GROWDATASIZE must be big enough that all errors go out as Hgrowdata's,
+ * so they will be scrolled into visibility in the ~~sam~~ window (yuck!).
+ */
+#define	GROWDATASIZE	50	/* if size is > this, send data with grow */
+
+void	rcut(List*, Posn, Posn);
+int	rterm(List*, Posn);
+void	rgrow(List*, Posn, Posn);
+
+static	Posn	growpos;
+static	Posn	grown;
+static	Posn	shrinkpos;
+static	Posn	shrunk;
+
+/*
+ * rasp routines inform the terminal of changes to the file.
+ *
+ * a rasp is a list of spans within the file, and an indication
+ * of whether the terminal knows about the span.
+ *
+ * optimize by coalescing multiple updates to the same span
+ * if it is not known by the terminal.
+ *
+ * other possible optimizations: flush terminal's rasp by cut everything,
+ * insert everything if rasp gets too large.
+ */
+
+/*
+ * only called for initial load of file
+ */
+void
+raspload(File *f)
+{
+	if(f->rasp == nil)
+		return;
+	grown = f->_.nc;
+	growpos = 0;
+	if(f->_.nc)
+		rgrow(f->rasp, 0, f->_.nc);
+	raspdone(f, 1);
+}
+
+void
+raspstart(File *f)
+{
+	if(f->rasp == nil)
+		return;
+	grown = 0;
+	shrunk = 0;
+	noflush = 1;
+}
+
+void
+raspdone(File *f, int toterm)
+{
+	if(f->dot.r.p1 > f->_.nc)
+		f->dot.r.p1 = f->_.nc;
+	if(f->dot.r.p2 > f->_.nc)
+		f->dot.r.p2 = f->_.nc;
+	if(f->mark.p1 > f->_.nc)
+		f->mark.p1 = f->_.nc;
+	if(f->mark.p2 > f->_.nc)
+		f->mark.p2 = f->_.nc;
+	if(f->rasp == nil)
+		return;
+	if(grown)
+		outTsll(Hgrow, f->tag, growpos, grown);
+	else if(shrunk)
+		outTsll(Hcut, f->tag, shrinkpos, shrunk);
+	if(toterm)
+		outTs(Hcheck0, f->tag);
+	outflush();
+	noflush = 0;
+	if(f == cmd){
+		cmdpt += cmdptadv;
+		cmdptadv = 0;
+	}
+}
+
+void
+raspdelete(File *f, uint p1, uint p2, int toterm)
+{
+	long n;
+
+	n = p2 - p1;
+	if(n == 0)
+		return;
+
+	if(p2 <= f->dot.r.p1){
+		f->dot.r.p1 -= n;
+		f->dot.r.p2 -= n;
+	}
+	if(p2 <= f->mark.p1){
+		f->mark.p1 -= n;
+		f->mark.p2 -= n;
+	}
+
+	if(f->rasp == nil)
+		return;
+
+	if(f==cmd && p1<cmdpt){
+		if(p2 <= cmdpt)
+			cmdpt -= n;
+		else
+			cmdpt = p1;
+	}
+	if(toterm){
+		if(grown){
+			outTsll(Hgrow, f->tag, growpos, grown);
+			grown = 0;
+		}else if(shrunk && shrinkpos!=p1 && shrinkpos!=p2){
+			outTsll(Hcut, f->tag, shrinkpos, shrunk);
+			shrunk = 0;
+		}
+		if(!shrunk || shrinkpos==p2)
+			shrinkpos = p1;
+		shrunk += n;
+	}
+	rcut(f->rasp, p1, p2);
+}
+
+void
+raspinsert(File *f, uint p1, Rune *buf, uint n, int toterm)
+{
+	Range r;
+
+	if(n == 0)
+		return;
+
+	if(p1 < f->dot.r.p1){
+		f->dot.r.p1 += n;
+		f->dot.r.p2 += n;
+	}
+	if(p1 < f->mark.p1){
+		f->mark.p1 += n;
+		f->mark.p2 += n;
+	}
+
+
+	if(f->rasp == nil)
+		return;
+	if(f==cmd && p1<cmdpt)
+		cmdpt += n;
+	if(toterm){
+		if(shrunk){
+			outTsll(Hcut, f->tag, shrinkpos, shrunk);
+			shrunk = 0;
+		}
+		if(n>GROWDATASIZE || !rterm(f->rasp, p1)){
+			rgrow(f->rasp, p1, n);
+			if(grown && growpos+grown!=p1 && growpos!=p1){
+				outTsll(Hgrow, f->tag, growpos, grown);
+				grown = 0;
+			}
+			if(!grown)
+				growpos = p1;
+			grown += n;
+		}else{
+			if(grown){
+				outTsll(Hgrow, f->tag, growpos, grown);
+				grown = 0;
+			}
+			rgrow(f->rasp, p1, n);
+			r = rdata(f->rasp, p1, n);
+			if(r.p1!=p1 || r.p2!=p1+n)
+				panic("rdata in toterminal");
+			outTsllS(Hgrowdata, f->tag, p1, n, tmprstr(buf, n));
+		}
+	}else{
+		rgrow(f->rasp, p1, n);
+		r = rdata(f->rasp, p1, n);
+		if(r.p1!=p1 || r.p2!=p1+n)
+			panic("rdata in toterminal");
+	}
+}
+
+#define	M	0x80000000L
+#define	P(i)	r->longptr[i]
+#define	T(i)	(P(i)&M)	/* in terminal */
+#define	L(i)	(P(i)&~M)	/* length of this piece */
+
+void
+rcut(List *r, Posn p1, Posn p2)
+{
+	Posn p, x;
+	int i;
+
+	if(p1 == p2)
+		panic("rcut 0");
+	for(p=0,i=0; i<r->nused && p+L(i)<=p1; p+=L(i++))
+		;
+	if(i == r->nused)
+		panic("rcut 1");
+	if(p < p1){	/* chop this piece */
+		if(p+L(i) < p2){
+			x = p1-p;
+			p += L(i);
+		}else{
+			x = L(i)-(p2-p1);
+			p = p2;
+		}
+		if(T(i))
+			P(i) = x|M;
+		else
+			P(i) = x;
+		i++;
+	}
+	while(i<r->nused && p+L(i)<=p2){
+		p += L(i);
+		dellist(r, i);
+	}
+	if(p < p2){
+		if(i == r->nused)
+			panic("rcut 2");
+		x = L(i)-(p2-p);
+		if(T(i))
+			P(i) = x|M;
+		else
+			P(i) = x;
+	}
+	/* can we merge i and i-1 ? */
+	if(i>0 && i<r->nused && T(i-1)==T(i)){
+		x = L(i-1)+L(i);
+		dellist(r, i--);
+		if(T(i))
+			P(i)=x|M;
+		else
+			P(i)=x;
+	}
+}
+
+void
+rgrow(List *r, Posn p1, Posn n)
+{
+	Posn p;
+	int i;
+
+	if(n == 0)
+		panic("rgrow 0");
+	for(p=0,i=0; i<r->nused && p+L(i)<=p1; p+=L(i++))
+		;
+	if(i == r->nused){	/* stick on end of file */
+		if(p!=p1)
+			panic("rgrow 1");
+		if(i>0 && !T(i-1))
+			P(i-1)+=n;
+		else
+			inslist(r, i, n);
+	}else if(!T(i))		/* goes in this empty piece */
+		P(i)+=n;
+	else if(p==p1 && i>0 && !T(i-1))	/* special case; simplifies life */
+		P(i-1)+=n;
+	else if(p==p1)
+		inslist(r, i, n);
+	else{			/* must break piece in terminal */
+		inslist(r, i+1, (L(i)-(p1-p))|M);
+		inslist(r, i+1, n);
+		P(i) = (p1-p)|M;
+	}
+}
+
+int
+rterm(List *r, Posn p1)
+{
+	Posn p;
+	int i;
+
+	for(p = 0,i = 0; i<r->nused && p+L(i)<=p1; p+=L(i++))
+		;
+	if(i==r->nused && (i==0 || !T(i-1)))
+		return 0;
+	return T(i);
+}
+
+Range
+rdata(List *r, Posn p1, Posn n)
+{
+	Posn p;
+	int i;
+	Range rg;
+
+	if(n==0)
+		panic("rdata 0");
+	for(p = 0,i = 0; i<r->nused && p+L(i)<=p1; p+=L(i++))
+		;
+	if(i==r->nused)
+		panic("rdata 1");
+	if(T(i)){
+		n-=L(i)-(p1-p);
+		if(n<=0){
+			rg.p1 = rg.p2 = p1;
+			return rg;
+		}
+		p+=L(i++);
+		p1 = p;
+	}
+	if(T(i) || i==r->nused)
+		panic("rdata 2");
+	if(p+L(i)<p1+n)
+		n = L(i)-(p1-p);
+	rg.p1 = p1;
+	rg.p2 = p1+n;
+	if(p!=p1){
+		inslist(r, i+1, L(i)-(p1-p));
+		P(i)=p1-p;
+		i++;
+	}
+	if(L(i)!=n){
+		inslist(r, i+1, L(i)-n);
+		P(i)=n;
+	}
+	P(i)|=M;
+	/* now i is set; can we merge? */
+	if(i<r->nused-1 && T(i+1)){
+		P(i)=(n+=L(i+1))|M;
+		dellist(r, i+1);
+	}
+	if(i>0 && T(i-1)){
+		P(i)=(n+L(i-1))|M;
+		dellist(r, i-1);
+	}
+	return rg;
+}