#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. * The allocated memory must have a flushed instruction * cache, and the data cache must be flushed by bbdflush(). * To avoid the need for frequent cache flushes, the memory * is allocated out of an arena, and the i-cache is only * flushed when it has to be reused.  By returning an * address in non-cached space, the need for flushing the * d-cache is avoided. * * 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 INTLEVEL(v)	((v)&0x700)void *bbmalloc(int nbytes){	int nw, a;	int s;	ulong *ans; 	nw = nbytes/sizeof(long);	s = splhi();	a = INTLEVEL(s)? 1 : 0;	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 = INTLEVEL(s)? 1 : 0;	if(p == bblast[a])		bbcur[a] = (ulong *)(((char *)bblast[a]) + n);	splx(s);} voidflushvirtpage(void *p){	USED(p);	flushcpucache();} voidbbdflush(void *p, int n){	USED(p, n);	flushcpucache();} intbbonstack(void){	if(u)		return 1;	return 0;} voidbbexec(void (*memstart)(void), int len, int onstack){	if(onstack) {		icflush(memstart, len);		memstart();		return;	}	memstart();	bbfree(memstart, len);}