/*
* Copyright (c) 2008-2021 Jonathan Schleifer <js@nil.im>
*
* All rights reserved.
*
* This file is part of ObjFW. It may be distributed under the terms of the
* Q Public License 1.0, which can be found in the file LICENSE.QPL included in
* the packaging of this file.
*
* Alternatively, it may be distributed under the terms of the GNU General
* Public License, either version 2 or 3, which can be found in the file
* LICENSE.GPLv2 or LICENSE.GPLv3 respectively included in the packaging of this
* file.
*/
#import "ObjFWRT.h"
#import "private.h"
#define TAGGED_POINTER_BITS 4
#define NUM_TAGGED_POINTER_CLASSES (1 << (TAGGED_POINTER_BITS - 1))
Class objc_tagged_pointer_classes[NUM_TAGGED_POINTER_CLASSES];
static int taggedPointerClassesCount;
uintptr_t objc_tagged_pointer_secret;
void
objc_setTaggedPointerSecret(uintptr_t secret)
{
objc_tagged_pointer_secret = secret & ~(uintptr_t)1;
}
int
objc_registerTaggedPointerClass(Class class)
{
int i;
objc_global_mutex_lock();
if (taggedPointerClassesCount == NUM_TAGGED_POINTER_CLASSES) {
objc_global_mutex_unlock();
return -1;
}
i = taggedPointerClassesCount++;
objc_tagged_pointer_classes[i] = class;
objc_global_mutex_unlock();
return i;
}
bool
object_isTaggedPointer(id object)
{
uintptr_t pointer = (uintptr_t)object;
return pointer & 1;
}
Class
object_getTaggedPointerClass(id object)
{
uintptr_t pointer = (uintptr_t)object ^ objc_tagged_pointer_secret;
pointer &= (1 << TAGGED_POINTER_BITS) - 1;
pointer >>= 1;
if (pointer >= NUM_TAGGED_POINTER_CLASSES)
return Nil;
return objc_tagged_pointer_classes[pointer];
}
uintptr_t
object_getTaggedPointerValue(id object)
{
uintptr_t pointer = (uintptr_t)object ^ objc_tagged_pointer_secret;
pointer >>= TAGGED_POINTER_BITS;
return pointer;
}
id
objc_createTaggedPointer(int class, uintptr_t value)
{
uintptr_t pointer;
if (class < 0 || class >= NUM_TAGGED_POINTER_CLASSES)
return nil;
if (value > (UINTPTR_MAX >> TAGGED_POINTER_BITS))
return nil;
pointer = (class << 1) | 1;
pointer |= (value << TAGGED_POINTER_BITS);
return (id)(pointer ^ objc_tagged_pointer_secret);
}