zptr.h

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/*
 * Copyright (C) 2017 Kaspar Schleiser <kaspar@schleiser.de>
 *
 * This file is subject to the terms and conditions of the GNU Lesser
 * General Public License v2.1. See the file LICENSE in the top level
 * directory for more details.
 */
 
#ifndef ZPTR_H
#define ZPTR_H
 
#include <assert.h>
#include <stdint.h>
#include <inttypes.h>
 
#ifdef __cplusplus
extern "C" {
#endif
 
#if ZPTR_BASE || defined(DOXYGEN)
 
typedef uint16_t zptr_t;
 
#define PRIzptr PRIu16
 
#define ZPTR_MAX_ADDR   ((uintptr_t)ZPTR_BASE + (1 << 18))
 
static inline int zptr_check(void *pointer)
{
    uintptr_t int_ptr = (uintptr_t)pointer;
    return ((!(int_ptr & 0x3)) \
            && (int_ptr >= (uintptr_t)ZPTR_BASE) \
            && (int_ptr < ZPTR_MAX_ADDR));
}
 
static inline zptr_t zptrc(void *pointer)
{
    assert(zptr_check(pointer));
    return (uint16_t)(((uint32_t)pointer - (uint32_t)ZPTR_BASE) >> 2);
}
 
static inline void *zptrd(zptr_t zptr)
{
    return (void *)(ZPTR_BASE + ((uint32_t)zptr << 2));
}
 
#else /* ZPTR_BASE */
/* fallback implementation */
typedef void *zptr_t;
#define PRIzptr "p"
static inline int zptr_check(void *pointer) { (void)pointer; return 0; }
static inline zptr_t zptrc(void *pointer) { return (zptr_t)pointer; }
static inline void *zptrd(zptr_t zptr) { return (void *)zptr; }
#endif
 
#ifdef __cplusplus
}
#endif
 
#endif /* ZPTR_H */