Add original unix v6

source/m6/m63.c

@@ -0,0 +1,85 @@
+#
+
+#include "m6.h"
+
+char *
+finddef(n) {
+	char *p;
+	if((p = lookup(arg(n)))==0)
+		if((p = lookup(""))==0) diag("Software error");
+	return(p); 
+}
+
+char *
+lookup(s) {
+	char *dt;
+	dt = df;
+	while(dt>d0) {
+		if(dt->dswitch>=0 && comp(s,&dt->dident)) return(dt);
+		dt =+ dt->prev; 
+	}
+	return(0); 
+}
+
+comp(s,t) 
+char *s, *t; 
+{
+	for(;*s++ == *t;t++)
+		if(*t==0) return(1);
+	return(0); 
+}
+
+remove(n) {
+	char *p;
+	if(p = lookup(arg(n))) if(p>d0+2) {
+		trashflag++;
+		p->dswitch = -1; 
+	} 
+}
+
+trash() {
+	char *p,*q,*r;
+	if(lg>0) return;
+	while(df->dswitch<0) {
+		de = df;
+		df =+ df->prev;
+		trashflag--; 
+	}
+	if(trashflag<=0) return;
+	de = (de+1)&0177776;
+	revptr(de,df,&p,&q);
+	q = p;
+	for(;p->word!=0;p=+r->word) {
+		r = p;
+		if(p->dswitch>=0) {
+			r = q;
+			q = move(p,q,p->word); 
+		} 
+	}
+	q->word = 0;
+	revptr(d0,d0+2,&df,&de); 
+}
+
+
+revptr(p,q,np,nq) 
+char *p, *q, **np, **nq;
+{
+	int t;
+	p->word = 0;
+	while((t = q->word)!=0) {
+		q->word = p-q; 
+		p = q; 
+		q =+ t;
+		if(q<d0 || q>dmax) diag("Software error"); 
+	}
+	*np = p;
+	*nq = q; 
+}
+
+char *
+move(from,to,count) 
+char *from, *to;
+{
+	while(count-->0) *to++ = *from++;
+	return(to); 
+}