#include <u.h>#include <libc.h>#include <lock.h> /* *  mutex malloc */ enum{	MAGIC		= 0xbada110c,	MAX2SIZE	= 20}; typedef struct Bucket Bucket;struct Bucket{	int	size;	int	magic;	Bucket	*next;	char	data[1];}; typedef struct Arena Arena;struct Arena{	Bucket	*btab[MAX2SIZE];	};static Arena arena; static Lock mlock; #define datoff		((int)((Bucket*)0)->data)#define nil		((void*)0) void*malloc(long size){	int pow;	Bucket *bp; 	lock(&mlock);	for(pow = 1; pow < MAX2SIZE; pow++) {		if(size <= (1<<pow))			goto good;	}	unlock(&mlock); 	return nil;good:	/* Allocate off this list */	bp = arena.btab[pow];	if(bp) {		arena.btab[pow] = bp->next;		unlock(&mlock); 		if(bp->magic != 0)			abort(); 		bp->magic = MAGIC; 		memset(bp->data, 0,  size);		return  bp->data;	}	size = sizeof(Bucket)+(1<<pow);	bp = sbrk(size);	unlock(&mlock);	if((int)bp < 0)		return nil; 	bp->size = pow;	bp->magic = MAGIC; 	return bp->data;} voidfree(void *ptr){	Bucket *bp, **l; 	if(ptr == nil)		return; 	/* Find the start of the structure */	bp = (Bucket*)((uint)ptr - datoff); 	if(bp->magic != MAGIC)		abort(); 	bp->magic = 0;	lock(&mlock);	l = &arena.btab[bp->size];	bp->next = *l;	*l = bp;	unlock(&mlock);} void*realloc(void *ptr, long n){	void *new;	uint osize;	Bucket *bp; 	if(ptr == nil)		return malloc(n); 	/* Find the start of the structure */	bp = (Bucket*)((uint)ptr - datoff); 	if(bp->magic != MAGIC)		abort(); 	/* enough space in this bucket */	osize = 1<<bp->size;	if(osize >= n)		return ptr; 	new = malloc(n);	if(new == nil)		return nil; 	memmove(new, ptr, osize);	free(ptr); 	return new;}