reference.h

/*
 * Copyright (C) 2010 Philippe Gerum <rpm@xenomai.org>.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
 */
#ifndef _COPPERPLATE_REFERENCE_H
#define _COPPERPLATE_REFERENCE_H
 
#include <boilerplate/limits.h>
#include <boilerplate/scope.h>
#include <boilerplate/setup.h>
 
#define libcopperplate_tag  0   /* Library tag - unique and constant. */
#define libcopperplate_cbi  1   /* Callback binary interface level. */
 
#ifdef CONFIG_XENO_PSHARED
/*
 * Layout of a function reference handle in shared memory (32-bit
 * value):
 *
 * xxHHHHHHHHHHHHHHHHHHHHLLLLLPPPPP
 *
 * where: 'P' => function index in the per-library array
 *        'L' => library tag
 *        'H' => symbol hash value (symname + cbi)
 *        'x' => unassigned
 *
 * NOTE: handle value -1 is kept for representing a NULL function
 * pointer; bit #31 should remain unassigned and cleared for this
 * purpose.
 */
 
struct __fnref {
        void (*fn)(void);
        unsigned int hash;
};
 
#define __refvar(l, s)          __ ## l ## __ref__ ## s
#define __refmangle(l, h, p)    (((h & 0xfffff) << 10)|((l & 0x1f) << 5)|(p & 0x1f))
#define __refhash(r)            (((r) >> 10) & 0xfffffU)
#define __reftag(r)             (((r) >> 5) & 0x1f)
#define __refpos(r)             ((r) & 0x1f)
#define __refchk(v, r)                                                  \
        ({                                                              \
                int __tag = __reftag(r), __pos = __refpos(r);           \
                typeof(v) __p = (typeof(v))__fnrefs[__tag][__pos].fn;   \
                assert(__fnrefs[__tag][__pos].hash == __refhash(r));    \
                assert(__p != NULL);                                    \
                __p;                                                    \
        })
#define fnref_type(t)           int
#define fnref_null              -1
static inline int __fnref_nofn(void *fnaddr)
{
        return fnaddr == NULL;
}
#define fnref_put(l, s)         (__fnref_nofn((void *)(s)) ? fnref_null : __refvar(l, s))
#define fnref_get(v, r)         ((v) = (r) < 0 ? NULL : __refchk(v, r))
#define fnref_register(l, s)                                            \
        int __refvar(l, s);                                             \
        static void __early_ctor __ifnref_ ## s(void)                   \
        {                                                               \
                __refvar(l, s) = __fnref_register(#l, l ## _tag,        \
                                                  l ## _cbi,            \
                                                  #s, (void (*)(void))s); \
        }
#define fnref_declare(l, s)     extern int __refvar(l, s)
 
#define MAX_FNLIBS  16          /* max=32 */
#define MAX_FNREFS  16          /* max=32 */
 
extern struct __fnref __fnrefs[MAX_FNLIBS][MAX_FNREFS];
 
int __fnref_register(const char *libname,
                     int libtag, int cbirev,
                     const char *symname, void (*fn)(void));
 
#else /* !CONFIG_XENO_PSHARED */
 
#define fnref_type(t)           __typeof__(t)
#define fnref_null              NULL
#define fnref_put(l, s)         (s)
#define fnref_get(v, r)         ((v) = (r))
#define fnref_register(l, s)
#define fnref_declare(l, s)
 
#endif /* !CONFIG_XENO_PSHARED */
 
#endif /* _COPPERPLATE_REFERENCE_H */