#include <u.h>#include <libc.h>#include <libg.h>#include <frame.h>#include "dat.h"#include "fns.h" struct proc	proc; Proc*newproc(void (*f)(void), void *arg){	Proc *p; 	p = malloc(sizeof(Proc));	if(p == 0)		error("newproc");	p->label[JMPBUFPC] = ((ulong)f+JMPBUFDPC);	p->label[JMPBUFSP] = (ulong)(&p->stack[NSTACK-2]);	/* old pc, new pc */	p->arg = arg;	p->next = 0;	p->nextrun = 0;	p->dead = 0;	return p;} voidsched(void){	while(proc.head == 0)		io();	if(setjmp(proc.p->label) == 0){    again:		proc.p = proc.head;		if(proc.tail == proc.head)			proc.tail = 0;		proc.head = proc.head->nextrun;		if(proc.p->dead){			free(proc.p);			goto again;		}		longjmp(proc.p->label, 1);	}} voidrun(Proc *p){	Proc *q; 	/*	 * First check not already there; there are rare cases when this could happen	 */	if(proc.head){		q = proc.head;		do			if(p == q)				return;		while(q = q->next);	/* assign = */	}	p->nextrun = 0;	if(proc.tail)		proc.tail->nextrun = p;	if(proc.head == 0)		proc.head = p;	proc.tail = p;}