Artifact 1f64e311ceb8d06468007d8525047e2ce81cda938419d35aa5587d60c6bcb36c:
- File
src/runtime/tagged-pointer.m
— part of check-in
[943cf97843]
at
2020-07-04 00:24:54
on branch tagged-pointers
— Only use 4 bits to classify tagged pointers
This leaves 28/60 bits for the value. (user: js, size: 1915) [annotate] [blame] [check-ins using]
/* * Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, * 2018, 2019, 2020 * 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 uint_fast8_t taggedPointerClassesCount; int_fast8_t objc_registerTaggedPointerClass(Class class) { uint_fast8_t 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; } Class object_getTaggedPointerClass(id object) { uintptr_t pointer = (uintptr_t)object; 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; pointer >>= TAGGED_POINTER_BITS; return pointer; } id objc_createTaggedPointer(uint_fast8_t class, uintptr_t value) { uintptr_t pointer; if (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; }