source: rtems-libbsd/freebsd/sys/sys/kobj.h @ 66659ff

/*-
 * Copyright (c) 2000,2003 Doug Rabson
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      $FreeBSD$
 */

#ifndef _SYS_KOBJ_H_
#define _SYS_KOBJ_H_

/*
 * Forward declarations
 */
typedef struct kobj             *kobj_t;
typedef struct kobj_class       *kobj_class_t;
typedef struct kobj_method      kobj_method_t;
typedef int                     (*kobjop_t)(void);
typedef struct kobj_ops         *kobj_ops_t;
typedef struct kobjop_desc      *kobjop_desc_t;
struct malloc_type;

struct kobj_method {
        kobjop_desc_t   desc;
        kobjop_t        func;
};

/*
 * A class is simply a method table and a sizeof value. When the first
 * instance of the class is created, the method table will be compiled 
 * into a form more suited to efficient method dispatch. This compiled 
 * method table is always the first field of the object.
 */
#define KOBJ_CLASS_FIELDS                                               \
        const char      *name;          /* class name */                \
        kobj_method_t   *methods;       /* method table */              \
        size_t          size;           /* object size */               \
        kobj_class_t    *baseclasses;   /* base classes */              \
        u_int           refs;           /* reference count */           \
        kobj_ops_t      ops             /* compiled method table */

struct kobj_class {
        KOBJ_CLASS_FIELDS;
};

/*
 * Implementation of kobj.
 */
#define KOBJ_FIELDS                             \
        kobj_ops_t      ops

struct kobj {
        KOBJ_FIELDS;
};

/*
 * The ops table is used as a cache of results from kobj_lookup_method().
 */

#define KOBJ_CACHE_SIZE 256

struct kobj_ops {
        kobj_method_t   *cache[KOBJ_CACHE_SIZE];
        kobj_class_t    cls;
};

struct kobjop_desc {
        unsigned int    id;             /* unique ID */
        kobj_method_t   *deflt;         /* default implementation */
};

/*
 * Shorthand for constructing method tables.
 * The ternary operator is (ab)used to provoke a warning when FUNC
 * has a signature that is not compatible with kobj method signature.
 */
#define KOBJMETHOD(NAME, FUNC) \
        { &NAME##_desc, (kobjop_t) (1 ? FUNC : (NAME##_t *)NULL) }

/*
 *
 */
#define KOBJMETHOD_END  { NULL, NULL }

/*
 * Declare a class (which should be defined in another file.
 */
#define DECLARE_CLASS(name) extern struct kobj_class name

/*
 * Define a class with no base classes (api backward-compatible. with
 * FreeBSD-5.1 and earlier).
 */
#define DEFINE_CLASS(name, methods, size)               \
DEFINE_CLASS_0(name, name ## _class, methods, size)

/*
 * Define a class with no base classes. Use like this:
 *
 * DEFINE_CLASS_0(foo, foo_class, foo_methods, sizeof(foo_softc));
 */
#define DEFINE_CLASS_0(name, classvar, methods, size)   \
                                                        \
struct kobj_class classvar = {                          \
        #name, methods, size, NULL                      \
}

/*
 * Define a class inheriting a single base class. Use like this:
 *
 * DEFINE_CLASS_1(foo, foo_class, foo_methods, sizeof(foo_softc),
 *                        bar);
 */
#define DEFINE_CLASS_1(name, classvar, methods, size,   \
                       base1)                           \
                                                        \
static kobj_class_t name ## _baseclasses[] =            \
        { &base1, NULL };                               \
struct kobj_class classvar = {                          \
        #name, methods, size, name ## _baseclasses      \
}

/*
 * Define a class inheriting two base classes. Use like this:
 *
 * DEFINE_CLASS_2(foo, foo_class, foo_methods, sizeof(foo_softc),
 *                        bar, baz);
 */
#define DEFINE_CLASS_2(name, methods, size,             \
                       base1, base2)                    \
                                                        \
static kobj_class_t name ## _baseclasses[] =            \
        { &base1,                                       \
          &base2, NULL };                               \
struct kobj_class name ## _class = {                    \
        #name, methods, size, name ## _baseclasses      \
}

/*
 * Define a class inheriting three base classes. Use like this:
 *
 * DEFINE_CLASS_3(foo, foo_class, foo_methods, sizeof(foo_softc),
 *                        bar, baz, foobar);
 */
#define DEFINE_CLASS_3(name, methods, size,             \
                       base1, base2, base3)             \
                                                        \
static kobj_class_t name ## _baseclasses[] =            \
        { &base1,                                       \
          &base2,                                       \
          &base3, NULL };                               \
struct kobj_class name ## _class = {                    \
        #name, methods, size, name ## _baseclasses      \
}


/*
 * Compile the method table in a class.
 */
void            kobj_class_compile(kobj_class_t cls);

/*
 * Compile the method table, with the caller providing the space for
 * the ops table.(for use before malloc is initialised).
 */
void            kobj_class_compile_static(kobj_class_t cls, kobj_ops_t ops);

/*
 * Free the compiled method table in a class.
 */
void            kobj_class_free(kobj_class_t cls);

/*
 * Allocate memory for and initialise a new object.
 */
kobj_t          kobj_create(kobj_class_t cls,
                            struct malloc_type *mtype,
                            int mflags);

/*
 * Initialise a pre-allocated object.
 */
void            kobj_init(kobj_t obj, kobj_class_t cls);
void            kobj_init_static(kobj_t obj, kobj_class_t cls);

/*
 * Delete an object. If mtype is non-zero, free the memory.
 */
void            kobj_delete(kobj_t obj, struct malloc_type *mtype);

/*
 * Maintain stats on hits/misses in lookup caches.
 */
#ifdef KOBJ_STATS
extern u_int kobj_lookup_hits;
extern u_int kobj_lookup_misses;
#endif

/*
 * Lookup the method in the cache and if it isn't there look it up the
 * slow way.
 */
#ifdef KOBJ_STATS
#define KOBJOPLOOKUP(OPS,OP) do {                               \
        kobjop_desc_t _desc = &OP##_##desc;                     \
        kobj_method_t **_cep =                                  \
            &OPS->cache[_desc->id & (KOBJ_CACHE_SIZE-1)];       \
        kobj_method_t *_ce = *_cep;                             \
        kobj_lookup_hits++; /* assume hit */                    \
        if (_ce->desc != _desc)                                 \
                _ce = kobj_lookup_method(OPS->cls,              \
                                         _cep, _desc);          \
        _m = _ce->func;                                         \
} while(0)
#else
#define KOBJOPLOOKUP(OPS,OP) do {                               \
        kobjop_desc_t _desc = &OP##_##desc;                     \
        kobj_method_t **_cep =                                  \
            &OPS->cache[_desc->id & (KOBJ_CACHE_SIZE-1)];       \
        kobj_method_t *_ce = *_cep;                             \
        if (_ce->desc != _desc)                                 \
                _ce = kobj_lookup_method(OPS->cls,              \
                                         _cep, _desc);          \
        _m = _ce->func;                                         \
} while(0)
#endif

kobj_method_t* kobj_lookup_method(kobj_class_t cls,
                                  kobj_method_t **cep,
                                  kobjop_desc_t desc);


/*
 * Default method implementation. Returns ENXIO.
 */
int kobj_error_method(void);

#endif /* !_SYS_KOBJ_H_ */