[dmd-internals] __tls_callbacks_a

[Walter Bright]

Here's the source code for it. If you can propose a change to it, I can merge it in.
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/*_ tlsdata.c   Tue Jan 24 1995 */
/* Copyright (C) 1995 by Digital Mars */
/* All Rights Reserved                          */
/* $Revision: 1.1.1.1 $ */

#if defined(_WIN32)

/************************************************************************
  * This file contains the necessary declartions for __declspec(thread)
  * support.  The main work is done by the linker.  The values in tls_used
  * are fixed up into a special segment by the linker that NT will then
  * fix up to FS:__tls_array for each thread.
  *   See file tlsseg.asm for other declarations.
  */

  extern long _tlsstart;
  extern long _tlsend;

  unsigned _tls_index = 0;  /* index referred to by compiler */
  void *_tls_callbacks_a[1] = { 0 };

  struct {
     void *tlsstart;   /* contains address of start of tls segment (Raw Data 
Start VA) */
     void *tlsend;     /* contains address of end of tls segment */
     void *tlsindex;   /* contains address of index into tls segment */
     void *tlscallbacks;  /* Pointer to an array of TLS callback functions
                             The array is null-terminated, so if there
                             is no callback function support, this field
                             points to four bytes set to 0.  The prototype
                             for these functions is the same as DLL-Entry.
                             These are most useful for declspec(thread) tagged
                             objects which need to be constructed and destructed
                             for each thread that attaches.
                           */
     long  zerofill;   /* The size in bytes of hte template beyond the
                          initialized data defined by tlsstart
                          and tlsend.  The total template
                          size should be the same as the total size of TLS
                          data in the image file.  The zero fill is the amount
                          of data that comes after the initialized non-zero data
                          The linker fills this in at link time.
                        */
     long  characteristics;  /* Reserved, currently not used */

  } _tls_used = {
&_tlsstart,
&_tlsend,
&_tls_index,
&_tls_callbacks_a[0],
     0,
     0
  };

#endif