#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][nbbarena];static ulong	*bbcur[narena] = {&bbarena[0][0], &bbarena[1][0]};static ulong	*bblast[narena] = {0, 0}; #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;	splx(s);	bblast[a] = ans;	return ans;} 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;}