################################################################################
##
##  $Revision: 10 $
##  $Author: mhx $
##  $Date: 2005/01/31 08:10:52 +0100 $
##
################################################################################
##
##  Version 3.x, Copyright (C) 2004-2005, Marcus Holland-Moritz.
##  Version 2.x, Copyright (C) 2001, Paul Marquess.
##  Version 1.x, Copyright (C) 1999, Kenneth Albanowski.
##
##  This program is free software; you can redistribute it and/or
##  modify it under the same terms as Perl itself.
##
################################################################################

=provides

START_MY_CXT
dMY_CXT_SV
dMY_CXT
MY_CXT_INIT
MY_CXT_CLONE
MY_CXT
pMY_CXT
pMY_CXT_
_pMY_CXT
aMY_CXT
aMY_CXT_
_aMY_CXT

=implementation

/*
 * Boilerplate macros for initializing and accessing interpreter-local
 * data from C.  All statics in extensions should be reworked to use
 * this, if you want to make the extension thread-safe.  See ext/re/re.xs
 * for an example of the use of these macros.
 *
 * Code that uses these macros is responsible for the following:
 * 1. #define MY_CXT_KEY to a unique string, e.g. "DynaLoader_guts"
 * 2. Declare a typedef named my_cxt_t that is a structure that contains
 *    all the data that needs to be interpreter-local.
 * 3. Use the START_MY_CXT macro after the declaration of my_cxt_t.
 * 4. Use the MY_CXT_INIT macro such that it is called exactly once
 *    (typically put in the BOOT: section).
 * 5. Use the members of the my_cxt_t structure everywhere as
 *    MY_CXT.member.
 * 6. Use the dMY_CXT macro (a declaration) in all the functions that
 *    access MY_CXT.
 */

#if defined(MULTIPLICITY) || defined(PERL_OBJECT) || \
    defined(PERL_CAPI)    || defined(PERL_IMPLICIT_CONTEXT)

#ifndef START_MY_CXT

/* This must appear in all extensions that define a my_cxt_t structure,
 * right after the definition (i.e. at file scope).  The non-threads
 * case below uses it to declare the data as static. */
#define START_MY_CXT

#if (PERL_VERSION < 4 || (PERL_VERSION == 4 && PERL_SUBVERSION < 68 ))
/* Fetches the SV that keeps the per-interpreter data. */
#define dMY_CXT_SV \
	SV *my_cxt_sv = get_sv(MY_CXT_KEY, FALSE)
#else /* >= perl5.004_68 */
#define dMY_CXT_SV \
	SV *my_cxt_sv = *hv_fetch(PL_modglobal, MY_CXT_KEY,		\
				  sizeof(MY_CXT_KEY)-1, TRUE)
#endif /* < perl5.004_68 */

/* This declaration should be used within all functions that use the
 * interpreter-local data. */
#define dMY_CXT	\
	dMY_CXT_SV;							\
	my_cxt_t *my_cxtp = INT2PTR(my_cxt_t*,SvUV(my_cxt_sv))

/* Creates and zeroes the per-interpreter data.
 * (We allocate my_cxtp in a Perl SV so that it will be released when
 * the interpreter goes away.) */
#define MY_CXT_INIT \
	dMY_CXT_SV;							\
	/* newSV() allocates one more than needed */			\
	my_cxt_t *my_cxtp = (my_cxt_t*)SvPVX(newSV(sizeof(my_cxt_t)-1));\
	Zero(my_cxtp, 1, my_cxt_t);					\
	sv_setuv(my_cxt_sv, PTR2UV(my_cxtp))

/* This macro must be used to access members of the my_cxt_t structure.
 * e.g. MYCXT.some_data */
#define MY_CXT		(*my_cxtp)

/* Judicious use of these macros can reduce the number of times dMY_CXT
 * is used.  Use is similar to pTHX, aTHX etc. */
#define pMY_CXT		my_cxt_t *my_cxtp
#define pMY_CXT_	pMY_CXT,
#define _pMY_CXT	,pMY_CXT
#define aMY_CXT		my_cxtp
#define aMY_CXT_	aMY_CXT,
#define _aMY_CXT	,aMY_CXT

#endif /* START_MY_CXT */

#ifndef MY_CXT_CLONE
/* Clones the per-interpreter data. */
#define MY_CXT_CLONE \
	dMY_CXT_SV;							\
	my_cxt_t *my_cxtp = (my_cxt_t*)SvPVX(newSV(sizeof(my_cxt_t)-1));\
	Copy(INT2PTR(my_cxt_t*, SvUV(my_cxt_sv)), my_cxtp, 1, my_cxt_t);\
	sv_setuv(my_cxt_sv, PTR2UV(my_cxtp))
#endif

#else /* single interpreter */

#ifndef START_MY_CXT

#define START_MY_CXT	static my_cxt_t my_cxt;
#define dMY_CXT_SV	dNOOP
#define dMY_CXT		dNOOP
#define MY_CXT_INIT	NOOP
#define MY_CXT		my_cxt

#define pMY_CXT		void
#define pMY_CXT_
#define _pMY_CXT
#define aMY_CXT
#define aMY_CXT_
#define _aMY_CXT

#endif /* START_MY_CXT */

#ifndef MY_CXT_CLONE
#define MY_CXT_CLONE	NOOP
#endif

#endif

=xsmisc

#define MY_CXT_KEY "Devel::PPPort::_guts" XS_VERSION
 
typedef struct {
  /* Put Global Data in here */
  int dummy;          
} my_cxt_t;
 
START_MY_CXT     

=xsboot

{
  MY_CXT_INIT;
  /* If any of the fields in the my_cxt_t struct need
   * to be initialised, do it here.
   */
  MY_CXT.dummy = 42;
}

=xsubs

int
MY_CXT_1()
	CODE:
		dMY_CXT;
		RETVAL = MY_CXT.dummy == 42;
		++MY_CXT.dummy;
	OUTPUT:
		RETVAL

int
MY_CXT_2()
	CODE:
		dMY_CXT;
		RETVAL = MY_CXT.dummy == 43;
	OUTPUT:
		RETVAL

int
MY_CXT_CLONE()
	CODE:
		MY_CXT_CLONE;
		RETVAL = 42;
	OUTPUT:
		RETVAL

=tests plan => 3

ok(&Devel::PPPort::MY_CXT_1());
ok(&Devel::PPPort::MY_CXT_2());
ok(&Devel::PPPort::MY_CXT_CLONE());

