Block_private.h   [plain text]

/*
 * Block_private.h
 * Blaine Garst
 * 2/13/2008
 *
 * SPI for Blocks
 *
 * Copyright 2008 Appple.  All rights reserved
 *
 */

#ifndef _BLOCK_PRIVATE_H_
#define _BLOCK_PRIVATE_H_

#if !defined(BLOCK_EXPORT)
#   if defined(__cplusplus)
#       define BLOCK_EXPORT extern "C" 
#   else
#       define BLOCK_EXPORT extern
#   endif
#endif

#include <AvailabilityMacros.h>
#include <TargetConditionals.h>

#include <stdbool.h>

#if __cplusplus
extern "C" {
#endif



enum {
    BLOCK_REFCOUNT_MASK =     (0xffff),
    BLOCK_NEEDS_FREE =        (1 << 24),
    BLOCK_HAS_COPY_DISPOSE =  (1 << 25),
    BLOCK_HAS_CTOR =          (1 << 26), // helpers have C++ code
    BLOCK_IS_GC =             (1 << 27),
    BLOCK_IS_GLOBAL =         (1 << 28),
    BLOCK_HAS_DESCRIPTOR =    (1 << 29),
};

// revised new layout
struct Block_descriptor {
    unsigned long int reserved;
    unsigned long int size;
    void (*copy)(void *dst, void *src);
    void (*dispose)(void *);
};

struct Block_layout {
    void *isa;
    int flags;
    int reserved; 
    void (*invoke)(void *, ...);
    struct Block_descriptor *descriptor;
    // imported variables
};



struct Block_byref {
    void *isa;
    struct Block_byref *forwarding;
    int flags;//refcount;
    int size;
    void (*byref_keep)(struct Block_byref *dst, struct Block_byref *src);
    void (*byref_destroy)(struct Block_byref *);
    // long shared[0];
};

struct Block_byref_header {
    void *isa;
    struct Block_byref *forwarding;
    int flags;
    int size;
};


// Runtime support functions used by compiler when generating copy/dispose helpers

enum {
    // see function implementation for a more complete description of these fields and combinations
    BLOCK_FIELD_IS_OBJECT   =  3,  // id, NSObject, __attribute__((NSObject)), block, ...
    BLOCK_FIELD_IS_BLOCK    =  7,  // a block variable
    BLOCK_FIELD_IS_BYREF    =  8,  // the on stack structure holding the __block variable
    BLOCK_FIELD_IS_WEAK     = 16,  // declared __weak, only used in byref copy helpers
    BLOCK_BYREF_CALLER      = 128, // called from __block (byref) copy/dispose support routines.
};

// Runtime entry point called by compiler when assigning objects inside copy helper routines
BLOCK_EXPORT void _Block_object_assign(void *destAddr, const void *object, const int flags);
    // BLOCK_FIELD_IS_BYREF is only used from within block copy helpers


// runtime entry point called by the compiler when disposing of objects inside dispose helper routine
BLOCK_EXPORT void _Block_object_dispose(const void *object, const int flags);



// Other support functions

// runtime entry to get total size of a closure
BLOCK_EXPORT unsigned long int Block_size(void *block_basic);



// the raw data space for runtime classes for blocks
// class+meta used for stack, malloc, and collectable based blocks
BLOCK_EXPORT void * _NSConcreteStackBlock[32];
BLOCK_EXPORT void * _NSConcreteMallocBlock[32];
BLOCK_EXPORT void * _NSConcreteAutoBlock[32];
BLOCK_EXPORT void * _NSConcreteFinalizingBlock[32];
BLOCK_EXPORT void * _NSConcreteGlobalBlock[32];
BLOCK_EXPORT void * _NSConcreteWeakBlockVariable[32];


// the intercept routines that must be used under GC
BLOCK_EXPORT void _Block_use_GC( void *(*alloc)(const unsigned long, const bool isOne, const bool isObject),
                                  void (*setHasRefcount)(const void *, const bool),
                                  void (*gc_assign_strong)(void *, void **),
                                  void (*gc_assign_weak)(const void *, void *),
                                  void (*gc_memmove)(void *, void *, unsigned long));

// earlier version, now simply transitional
BLOCK_EXPORT void _Block_use_GC5( void *(*alloc)(const unsigned long, const bool isOne, const bool isObject),
                                  void (*setHasRefcount)(const void *, const bool),
                                  void (*gc_assign_strong)(void *, void **),
                                  void (*gc_assign_weak)(const void *, void *));

BLOCK_EXPORT void _Block_use_RR( void (*retain)(const void *),
                                 void (*release)(const void *));

// make a collectable GC heap based Block.  Not useful under non-GC.
BLOCK_EXPORT void *_Block_copy_collectable(const void *aBlock);

// thread-unsafe diagnostic
BLOCK_EXPORT const char *_Block_dump(const void *block);


// Obsolete

// first layout
struct Block_basic {
    void *isa;
    int Block_flags;  // int32_t
    int Block_size; // XXX should be packed into Block_flags
    void (*Block_invoke)(void *);
    void (*Block_copy)(void *dst, void *src);  // iff BLOCK_HAS_COPY_DISPOSE
    void (*Block_dispose)(void *);             // iff BLOCK_HAS_COPY_DISPOSE
    //long params[0];  // where const imports, __block storage references, etc. get laid down
};


#if __cplusplus
}
#endif


#endif