#include <u.h>#include <libc.h>#include "String.h"  #define STRLEN 128#define STRALLOC 128 /* buffer pool for allocating String structures */typedef struct Stralloc{	String s[STRALLOC];	int o;} Stralloc;static Stralloc *freep=0; /* pool of freed Strings */static String *freed=0; extern voids_free(String *sp){	if (sp != 0) {		sp->ptr = (char *)freed;		freed = sp;	}} /* allocate a String head */extern String *s_alloc(void){	if (freep==0 || freep->o >= STRALLOC) {		freep = (Stralloc *)malloc(sizeof(Stralloc));		if (freep==0) {			perror("allocating String");			exits("malloc");		}		freep->o = 0;	}	return &(freep->s[freep->o++]);} /* create a new `short' String */extern String *s_new(void){	String *sp; 	if (freed!=0) {		sp = freed;		freed = (String *)(freed->ptr);		sp->ptr = sp->base;		return sp;	}	sp = s_alloc();	sp->base = sp->ptr = malloc(STRLEN);	if (sp->base == 0) {		perror("allocating String");		exits("malloc");	}	sp->end = sp->base + STRLEN;	s_terminate(sp);	return sp;} extern ints_isfree(String *sp){	String *s; 	for(s = freed; s; s = (String *)(s->ptr))		if(s == sp)			return 1;	return 0;}