## 'desc' assembly directives.# Desc: adt {	id:	int;		# Dis type identifier	ln:	int;		# length, in bytes, of mapped object	map:	array of byte;	# bit map of pointers	nmap:	int;		# number of bytes in map	next:	cyclic ref Desc;}; dlist:	ref Desc;dtail:	ref Desc;id:	int = 0;  # reserve id == 0 for Module Data type descriptor ## Allocate a Desc adt.# newDesc(id: int, ln: int, nmap: int, map: array of byte): ref Desc{	return ref Desc(id, ln, map, nmap, nil);} mapeq(a, b: array of byte, n: int): int{	while(n-- > 0) {		if(a[n] != b[n])			return 0;	}	return 1;} ## Save a type descriptor; reuse existing descriptor if identical.# descid(ln: int, nmap: int, map: array of byte): int{	d: ref Desc; 	for(d = dlist; d != nil; d = d.next) {		if(d.ln == ln && d.nmap == nmap && mapeq(d.map, map, nmap))			return d.id;	} 	id += 1;	d = newDesc(id, ln, nmap, map);	if(dlist == nil)		dlist = d;	else		dtail.next = d;	dtail = d; 	return d.id;} ## Save type descriptor for module data.# mpdescid(ln: int, nmap: int, map: array of byte){	d: ref Desc; 	d = newDesc(0, ln, nmap, map);	d.next = dlist;	dlist = d;} ## Emit assembly 'desc' directives.# asmdesc(){	d: ref Desc;	i: int; 	for(d = dlist; d != nil; d = d.next) {		bout.puts("\tdesc\t$" + string d.id + "," + string d.ln + ",\"");		for(i = 0; i < d.nmap; i++)			bout.puts(hex(int d.map[i], 2));		bout.puts("\"\n");	}} disndesc(){	discon(id+1);} disdesc(){	d: ref Desc; 	for(d = dlist; d != nil; d = d.next) {		discon(d.id);		discon(d.ln);		discon(d.nmap);		bout.write(d.map, d.nmap);	}}