#include <u.h>#include <libc.h>#include <thread.h>#include "threadimpl.h" /* first argument goes in a register; simplest just to ignore it */static voidlauncheramd64(int, void (*f)(void *arg), void *arg){	(*f)(arg);	threadexits(nil);} void_threadinitstack(Thread *t, void (*f)(void*), void *arg){	uvlong *tos; 	tos = (uvlong*)&t->stk[t->stksize&~7];	*--tos = (uvlong)arg;	*--tos = (uvlong)f;	*--tos = 0;	/* first arg to launcheramd64 */	t->sched[JMPBUFPC] = (uvlong)launcheramd64+JMPBUFDPC;	t->sched[JMPBUFSP] = (uvlong)tos - 2*8;		/* old PC and new PC */}