#include	"u.h"#include	"../port/lib.h"#include	"mem.h"#include	"dat.h"#include	"fns.h"#include	"io.h" /* * Allocate memory for use in kernel bitblts. * * This code will have to be interlocked if we ever get * a multiprocessor with a bitmapped display. */ /* a 0->3 bitblt can take 800 longs */enum {	narena=2,	/* put interrupt time stuff in separate arena */	nbbarena=4096	/* number of words in an arena */}; static ulong	*bbarena[narena];static ulong	*bbcur[narena];static ulong	*bblast[narena]; #define INTENABLED(v)	((v)&(1<<9))void *bbmalloc(int nbytes){	int nw, a;	int s;	ulong *ans; 	nw = nbytes/sizeof(long);	s = splhi();	a = INTENABLED(s) ? 0 : 1;	if(bbcur[a] + nw > bbarena[a] + nbbarena)		ans = bbarena[a];	else		ans = bbcur[a];	bbcur[a] = ans + nw;	bblast[a] = ans;	splx(s);	return ans;} voidbbinit(void){	int i; 	if(bbarena[0])		return;	for(i = 0; i < narena; i++){		bbarena[i] = xalloc(nbbarena * sizeof(long));		bbcur[i] = bbarena[i];		bblast[i] = 0;	}}  voidbbfree(void *p, int n){	int a, s; 	s = splhi();	a = INTENABLED(s) ? 0 : 1;	if(p == bblast[a])		bbcur[a] = (ulong *)(((char *)bblast[a]) + n);	splx(s);} voidbbdflush(void *p, int n){	USED(p, n);} intbbonstack(void){	return 0;} voidbbexec(void (*memstart)(void), int len, int onstack){	USED(len, onstack);	memstart();}