text: /*
   * Copyright (c) 2004-2007 Apple Inc. All rights reserved.
   *
   * @APPLE_LICENSE_HEADER_START@
   * 
   * This file contains Original Code and/or Modifications of Original Code
   * as defined in and that are subject to the Apple Public Source License
   * Version 2.0 (the 'License'). You may not use this file except in
   * compliance with the License. Please obtain a copy of the License at
   * http://www.opensource.apple.com/apsl/ and read it before using this
   * file.
   * 
   * The Original Code and all software distributed under the License are
   * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
   * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
   * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
   * Please see the License for the specific language governing rights and
   * limitations under the License.
   * 
   * @APPLE_LICENSE_HEADER_END@
   */
  
  #ifndef _OBJC_AUTO_H_
  #define _OBJC_AUTO_H_
  
  #include <objc/objc.h>
  #include <malloc/malloc.h>
  #include <stdint.h>
  #include <stddef.h>
  #include <string.h>
  #include <Availability.h>
  #include <AvailabilityMacros.h>
  #include <TargetConditionals.h>
  
  #if !TARGET_OS_WIN32
  #include <sys/types.h>
  #include <libkern/OSAtomic.h>
  #else
  #   define WINVER 0x0501		// target Windows XP and later
  #   define _WIN32_WINNT 0x0501	// target Windows XP and later
  #   define WIN32_LEAN_AND_MEAN
  // workaround: windef.h typedefs BOOL as int
  #   define BOOL WINBOOL
  #   include <windows.h>
  #   undef BOOL
  #endif
  
  
  /* GC is unsupported on some architectures. */
  
  #if TARGET_OS_EMBEDDED  ||  TARGET_OS_IPHONE  ||  TARGET_OS_WIN32
  #   define OBJC_NO_GC 1
  #endif
  
  
  /* objc_collect() options */
  enum {
      // choose one
      OBJC_RATIO_COLLECTION        = (0 << 0),  // run "ratio" generational collections, then a full
      OBJC_GENERATIONAL_COLLECTION = (1 << 0),  // run fast incremental collection
      OBJC_FULL_COLLECTION         = (2 << 0),  // run full collection.
      OBJC_EXHAUSTIVE_COLLECTION   = (3 << 0),  // run full collections until memory available stops improving
      
      OBJC_COLLECT_IF_NEEDED       = (1 << 3), // run collection only if needed (allocation threshold exceeded)
      OBJC_WAIT_UNTIL_DONE         = (1 << 4), // wait (when possible) for collection to end before returning (when collector is running on dedicated thread)
  };
  
  /* objc_clear_stack() options */
  enum {
      OBJC_CLEAR_RESIDENT_STACK = (1 << 0)
  };
  
  
  #ifndef OBJC_NO_GC
  
  
  /* GC declarations */
  
  /* Collection utilities */
  
  OBJC_EXPORT void objc_collect(unsigned long options)
      __OSX_AVAILABLE_STARTING(__MAC_10_6, __IPHONE_NA);
  OBJC_EXPORT BOOL objc_collectingEnabled(void)
      __OSX_AVAILABLE_STARTING(__MAC_10_5, __IPHONE_NA);
  OBJC_EXPORT malloc_zone_t *objc_collectableZone(void) 
      __OSX_AVAILABLE_STARTING(__MAC_10_7, __IPHONE_NA);
  
  /* GC configuration */
  
  /* Tells collector to wait until specified bytes have been allocated before trying to collect again. */
  OBJC_EXPORT void objc_setCollectionThreshold(size_t threshold)
      __OSX_AVAILABLE_STARTING(__MAC_10_5, __IPHONE_NA);
  
  /* Tells collector to run a full collection for every ratio generational collections. */
  OBJC_EXPORT void objc_setCollectionRatio(size_t ratio)
      __OSX_AVAILABLE_STARTING(__MAC_10_5, __IPHONE_NA);
  
  // 
  // GC-safe compare-and-swap
  //
  
  /* Atomic update, with write barrier. */
  OBJC_EXPORT BOOL objc_atomicCompareAndSwapPtr(id predicate, id replacement, volatile id *objectLocation) 
      __OSX_AVAILABLE_STARTING(__MAC_10_6, __IPHONE_NA);
  /* "Barrier" version also includes memory barrier. */
  OBJC_EXPORT BOOL objc_atomicCompareAndSwapPtrBarrier(id predicate, id replacement, volatile id *objectLocation) 
      __OSX_AVAILABLE_STARTING(__MAC_10_6, __IPHONE_NA);
  
  // atomic update of a global variable
  OBJC_EXPORT BOOL objc_atomicCompareAndSwapGlobal(id predicate, id replacement, volatile id *objectLocation)
      __OSX_AVAILABLE_STARTING(__MAC_10_6, __IPHONE_NA);
  OBJC_EXPORT BOOL objc_atomicCompareAndSwapGlobalBarrier(id predicate, id replacement, volatile id *objectLocation)
      __OSX_AVAILABLE_STARTING(__MAC_10_6, __IPHONE_NA);
  // atomic update of an instance variable
  OBJC_EXPORT BOOL objc_atomicCompareAndSwapInstanceVariable(id predicate, id replacement, volatile id *objectLocation)
      __OSX_AVAILABLE_STARTING(__MAC_10_6, __IPHONE_NA);
  OBJC_EXPORT BOOL objc_atomicCompareAndSwapInstanceVariableBarrier(id predicate, id replacement, volatile id *objectLocation)
      __OSX_AVAILABLE_STARTING(__MAC_10_6, __IPHONE_NA);
  
  
  // 
  // Read and write barriers
  // 
  
  OBJC_EXPORT id objc_assign_strongCast(id val, id *dest)
      __OSX_AVAILABLE_STARTING(__MAC_10_4, __IPHONE_NA);
  OBJC_EXPORT id objc_assign_global(id val, id *dest)
      __OSX_AVAILABLE_STARTING(__MAC_10_4, __IPHONE_NA);
  OBJC_EXPORT id objc_assign_threadlocal(id val, id *dest)
      __OSX_AVAILABLE_STARTING(__MAC_10_7, __IPHONE_NA);
  OBJC_EXPORT id objc_assign_ivar(id value, id dest, ptrdiff_t offset)
      __OSX_AVAILABLE_STARTING(__MAC_10_4, __IPHONE_NA);
  OBJC_EXPORT void *objc_memmove_collectable(void *dst, const void *src, size_t size)
      __OSX_AVAILABLE_STARTING(__MAC_10_4, __IPHONE_NA);
  
  OBJC_EXPORT id objc_read_weak(id *location)
      __OSX_AVAILABLE_STARTING(__MAC_10_5, __IPHONE_NA);
  OBJC_EXPORT id objc_assign_weak(id value, id *location)
      __OSX_AVAILABLE_STARTING(__MAC_10_5, __IPHONE_NA);
  
  OBJC_EXPORT id objc_read_strong(id *source)
      __OSX_AVAILABLE_STARTING(__MAC_10_7, __IPHONE_NA);
  
  
  //
  // Thread management
  // 
  
  /* Register the calling thread with the garbage collector. */
  OBJC_EXPORT void objc_registerThreadWithCollector(void)
      __OSX_AVAILABLE_STARTING(__MAC_10_6, __IPHONE_NA);
  
  /* Unregisters the calling thread with the garbage collector. 
     Unregistration also happens automatically at thread exit. */
  OBJC_EXPORT void objc_unregisterThreadWithCollector(void)
      __OSX_AVAILABLE_STARTING(__MAC_10_6, __IPHONE_NA);
  
  /* To be called from code which must only execute on a registered thread. */
  /* If the calling thread is unregistered then an error message is emitted and the thread is implicitly registered. */
  OBJC_EXPORT void objc_assertRegisteredThreadWithCollector(void)
      __OSX_AVAILABLE_STARTING(__MAC_10_6, __IPHONE_NA);
  
  /* Erases any stale references in unused parts of the stack. */
  OBJC_EXPORT void objc_clear_stack(unsigned long options)
      __OSX_AVAILABLE_STARTING(__MAC_10_5, __IPHONE_NA);
  
  
  //
  // Finalization
  // 
  
  /* Returns true if object has been scheduled for finalization.  Can be used to avoid operations that may lead to resurrection, which are fatal. */
  OBJC_EXPORT BOOL objc_is_finalized(void *ptr)
      __OSX_AVAILABLE_STARTING(__MAC_10_4, __IPHONE_NA);
  
  // Deprcated. Tells runtime to issue finalize calls on the main thread only.
  OBJC_EXPORT void objc_finalizeOnMainThread(Class cls)
      AVAILABLE_MAC_OS_X_VERSION_10_5_AND_LATER_BUT_DEPRECATED;
  
  
  //
  // Deprecated names. 
  //
  
  /* Deprecated. Use objc_collectingEnabled() instead. */
  OBJC_EXPORT BOOL objc_collecting_enabled(void)
      __OSX_AVAILABLE_BUT_DEPRECATED(__MAC_10_4,__MAC_10_5, __IPHONE_NA,__IPHONE_NA);
  /* Deprecated. Use objc_setCollectionThreshold() instead. */
  OBJC_EXPORT void objc_set_collection_threshold(size_t threshold)
      __OSX_AVAILABLE_BUT_DEPRECATED(__MAC_10_4,__MAC_10_5, __IPHONE_NA,__IPHONE_NA);
  /* Deprecated. Use objc_setCollectionRatio() instead. */
  OBJC_EXPORT void objc_set_collection_ratio(size_t ratio)
      __OSX_AVAILABLE_BUT_DEPRECATED(__MAC_10_4,__MAC_10_5, __IPHONE_NA,__IPHONE_NA);
  /* Deprecated. Use objc_startCollectorThread() instead. */
  OBJC_EXPORT void objc_start_collector_thread(void)
      __OSX_AVAILABLE_BUT_DEPRECATED(__MAC_10_4,__MAC_10_5, __IPHONE_NA,__IPHONE_NA);
  /* Deprecated. No replacement. Formerly told the collector to run using a dedicated background thread. */
  OBJC_EXPORT void objc_startCollectorThread(void)
  __OSX_AVAILABLE_BUT_DEPRECATED(__MAC_10_5,__MAC_10_7, __IPHONE_NA,__IPHONE_NA);
  
  
  /* Deprecated. Use class_createInstance() instead. */
  OBJC_EXPORT id objc_allocate_object(Class cls, int extra)
      AVAILABLE_MAC_OS_X_VERSION_10_4_AND_LATER_BUT_DEPRECATED;
  
  
  /* !defined(OBJC_NO_GC) */
  #else
  /* defined(OBJC_NO_GC) */
  
  
  /* Non-GC declarations */
  
  static OBJC_INLINE void objc_collect(unsigned long options __unused) { }
  static OBJC_INLINE BOOL objc_collectingEnabled(void) { return NO; }
  static OBJC_INLINE void objc_setCollectionThreshold(size_t threshold __unused) { }
  static OBJC_INLINE void objc_setCollectionRatio(size_t ratio __unused) { }
  static OBJC_INLINE void objc_startCollectorThread(void) { }
  
  #if TARGET_OS_WIN32
  static OBJC_INLINE BOOL objc_atomicCompareAndSwapPtr(id predicate, id replacement, volatile id *objectLocation) 
      { void *original = InterlockedCompareExchangePointer((void * volatile *)objectLocation, (void *)replacement, (void *)predicate); return (original == predicate); }
  
  static OBJC_INLINE BOOL objc_atomicCompareAndSwapPtrBarrier(id predicate, id replacement, volatile id *objectLocation) 
      { void *original = InterlockedCompareExchangePointer((void * volatile *)objectLocation, (void *)replacement, (void *)predicate); return (original == predicate); }
  #else
  static OBJC_INLINE BOOL objc_atomicCompareAndSwapPtr(id predicate, id replacement, volatile id *objectLocation) 
      { return OSAtomicCompareAndSwapPtr((void *)predicate, (void *)replacement, (void * volatile *)objectLocation); }
  
  static OBJC_INLINE BOOL objc_atomicCompareAndSwapPtrBarrier(id predicate, id replacement, volatile id *objectLocation) 
      { return OSAtomicCompareAndSwapPtrBarrier((void *)predicate, (void *)replacement, (void * volatile *)objectLocation); }
  #endif
  
  static OBJC_INLINE BOOL objc_atomicCompareAndSwapGlobal(id predicate, id replacement, volatile id *objectLocation) 
      { return objc_atomicCompareAndSwapPtr(predicate, replacement, objectLocation); }
  
  static OBJC_INLINE BOOL objc_atomicCompareAndSwapGlobalBarrier(id predicate, id replacement, volatile id *objectLocation) 
      { return objc_atomicCompareAndSwapPtrBarrier(predicate, replacement, objectLocation); }
  
  static OBJC_INLINE BOOL objc_atomicCompareAndSwapInstanceVariable(id predicate, id replacement, volatile id *objectLocation) 
      { return objc_atomicCompareAndSwapPtr(predicate, replacement, objectLocation); }
  
  static OBJC_INLINE BOOL objc_atomicCompareAndSwapInstanceVariableBarrier(id predicate, id replacement, volatile id *objectLocation) 
      { return objc_atomicCompareAndSwapPtrBarrier(predicate, replacement, objectLocation); }
  
  
  static OBJC_INLINE id objc_assign_strongCast(id val, id *dest) 
      { return (*dest = val); }
  
  static OBJC_INLINE id objc_assign_global(id val, id *dest) 
      { return (*dest = val); }
  
  static OBJC_INLINE id objc_assign_ivar(id val, id dest, ptrdiff_t offset) 
      { return (*(id*)((char *)dest+offset) = val); }
  
  static OBJC_INLINE void *objc_memmove_collectable(void *dst, const void *src, size_t size) 
      { return memmove(dst, src, size); }
  
  static OBJC_INLINE id objc_read_weak(id *location) 
      { return *location; }
  
  static OBJC_INLINE id objc_assign_weak(id value, id *location) 
      { return (*location = value); }
  
  static OBJC_INLINE id objc_read_strong(id *location) 
      { return *location; }
  
  static OBJC_INLINE void objc_finalizeOnMainThread(Class cls __unused) { }
  static OBJC_INLINE BOOL objc_is_finalized(void *ptr __unused) { return NO; }
  static OBJC_INLINE void objc_clear_stack(unsigned long options __unused) { }
  
  static OBJC_INLINE BOOL objc_collecting_enabled(void) { return NO; }
  static OBJC_INLINE void objc_set_collection_threshold(size_t threshold __unused) { } 
  static OBJC_INLINE void objc_set_collection_ratio(size_t ratio __unused) { } 
  static OBJC_INLINE void objc_start_collector_thread(void) { }
  
  OBJC_EXPORT id class_createInstance(Class cls, size_t extraBytes)
      __OSX_AVAILABLE_STARTING(__MAC_10_0, __IPHONE_2_0);
  static OBJC_INLINE id objc_allocate_object(Class cls, int extra) 
      { return class_createInstance(cls, extra); }
  
  static OBJC_INLINE void objc_registerThreadWithCollector() { }
  static OBJC_INLINE void objc_unregisterThreadWithCollector() { }
  static OBJC_INLINE void objc_assertRegisteredThreadWithCollector() { }
  
  /* defined(OBJC_NO_GC) */
  #endif
  
  
  #if TARGET_OS_EMBEDDED
  enum {
      OBJC_GENERATIONAL = (1 << 0)
  };
  static OBJC_INLINE void objc_collect_if_needed(unsigned long options) __attribute__((deprecated));
  static OBJC_INLINE void objc_collect_if_needed(unsigned long options __unused) { }
  #endif
  
  #endif
  