ebitmap.h

xen虚拟机源代码安装包

/*
 * An extensible bitmap is a bitmap that supports an
 * arbitrary number of bits.  Extensible bitmaps are
 * used to represent sets of values, such as types,
 * roles, categories, and classes.
 *
 * Each extensible bitmap is implemented as a linked
 * list of bitmap nodes, where each bitmap node has
 * an explicitly specified starting bit position within
 * the total bitmap.
 *
 * Author : Stephen Smalley, <[e-mail]>
 */
#ifndef _SS_EBITMAP_H_
#define _SS_EBITMAP_H_

#define MAPTYPE u64            /* portion of bitmap in each node */
#define MAPSIZE (sizeof(MAPTYPE) * 8)    /* number of bits in node bitmap */
#define MAPBIT  1ULL            /* a bit in the node bitmap */

struct ebitmap_node {
    u32 startbit;        /* starting position in the total bitmap */
    MAPTYPE map;        /* this node's portion of the bitmap */
    struct ebitmap_node *next;
};

struct ebitmap {
    struct ebitmap_node *node;    /* first node in the bitmap */
    u32 highbit;    /* highest position in the total bitmap */
};

#define ebitmap_length(e) ((e)->highbit)
#define ebitmap_startbit(e) ((e)->node ? (e)->node->startbit : 0)

static inline unsigned int ebitmap_start(struct ebitmap *e,
                                                 struct ebitmap_node **n)
{
    *n = e->node;
    return ebitmap_startbit(e);
}

static inline void ebitmap_init(struct ebitmap *e)
{
    memset(e, 0, sizeof(*e));
}

static inline unsigned int ebitmap_next(struct ebitmap_node **n,
                                                        unsigned int bit)
{
    if ( (bit == ((*n)->startbit + MAPSIZE - 1)) && (*n)->next )
    {
        *n = (*n)->next;
        return (*n)->startbit;
    }

    return (bit+1);
}

static inline int ebitmap_node_get_bit(struct ebitmap_node * n,
                                                        unsigned int bit)
{
    if ( n->map & (MAPBIT << (bit - n->startbit)) )
        return 1;
    return 0;
}

#define ebitmap_for_each_bit(e, n, bit) \
    for ( bit = ebitmap_start(e, &n); bit < ebitmap_length(e); \
                                    bit = ebitmap_next(&n, bit) ) \

int ebitmap_cmp(struct ebitmap *e1, struct ebitmap *e2);
int ebitmap_cpy(struct ebitmap *dst, struct ebitmap *src);
int ebitmap_contains(struct ebitmap *e1, struct ebitmap *e2);
int ebitmap_get_bit(struct ebitmap *e, unsigned long bit);
int ebitmap_set_bit(struct ebitmap *e, unsigned long bit, int value);
void ebitmap_destroy(struct ebitmap *e);
int ebitmap_read(struct ebitmap *e, void *fp);

#endif    /* _SS_EBITMAP_H_ */