libcoro/coro.h

/*
 * Copyright (c) 2001-2012 Marc Alexander Lehmann <schmorp@schmorp.de>
 *
 * Redistribution and use in source and binary forms, with or without modifica-
 * tion, are permitted provided that the following conditions are met:
 *
 *   1.  Redistributions of source code must retain the above copyright notice,
 *       this list of conditions and the following disclaimer.
 *
 *   2.  Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
 * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO
 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
 * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
 * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Alternatively, the contents of this file may be used under the terms of
 * the GNU General Public License ("GPL") version 2 or any later version,
 * in which case the provisions of the GPL are applicable instead of
 * the above. If you wish to allow the use of your version of this file
 * only under the terms of the GPL and not to allow others to use your
 * version of this file under the BSD license, indicate your decision
 * by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL. If you do not delete the
 * provisions above, a recipient may use your version of this file under
 * either the BSD or the GPL.
 *
 * This library is modelled strictly after Ralf S. Engelschalls article at
 * http://www.gnu.org/software/pth/rse-pmt.ps. So most of the credit must
 * go to Ralf S. Engelschall <rse@engelschall.com>.
 *
 * This coroutine library is very much stripped down. You should either
 * build your own process abstraction using it or - better - just use GNU
 * Portable Threads, http://www.gnu.org/software/pth/.
 *
 */

/*
 * 2006-10-26 Include stddef.h on OS X to work around one of its bugs.
 *            Reported by Michael_G_Schwern.
 * 2006-11-26 Use _setjmp instead of setjmp on GNU/Linux.
 * 2007-04-27 Set unwind frame info if gcc 3+ and ELF is detected.
 *            Use _setjmp instead of setjmp on _XOPEN_SOURCE >= 600.
 * 2007-05-02 Add assembly versions for x86 and amd64 (to avoid reliance
 *            on SIGUSR2 and sigaltstack in Crossfire).
 * 2008-01-21 Disable CFI usage on anything but GNU/Linux.
 * 2008-03-02 Switched to 2-clause BSD license with GPL exception.
 * 2008-04-04 New (but highly unrecommended) pthreads backend.
 * 2008-04-24 Reinstate CORO_LOSER (had wrong stack adjustments).
 * 2008-10-30 Support assembly method on x86 with and without frame pointer.
 * 2008-11-03 Use a global asm statement for CORO_ASM, idea by pippijn.
 * 2008-11-05 Hopefully fix misaligned stacks with CORO_ASM/SETJMP.
 * 2008-11-07 rbp wasn't saved in CORO_ASM on x86_64.
 *            introduce coro_destroy, which is a nop except for pthreads.
 *            speed up CORO_PTHREAD. Do no longer leak threads either.
 *            coro_create now allows one to create source coro_contexts.
 *            do not rely on makecontext passing a void * correctly.
 *            try harder to get _setjmp/_longjmp.
 *            major code cleanup/restructuring.
 * 2008-11-10 the .cfi hacks are no longer needed.
 * 2008-11-16 work around a freebsd pthread bug.
 * 2008-11-19 define coro_*jmp symbols for easier porting.
 * 2009-06-23 tentative win32-backend support for mingw32 (Yasuhiro Matsumoto).
 * 2010-12-03 tentative support for uclibc (which lacks all sorts of things).
 * 2011-05-30 set initial callee-saved-registers to zero with CORO_ASM.
 *            use .cfi_undefined rip on linux-amd64 for better backtraces.
 * 2011-06-08 maybe properly implement weird windows amd64 calling conventions.
 * 2011-07-03 rely on __GCC_HAVE_DWARF2_CFI_ASM for cfi detection.
 * 2011-08-08 cygwin trashes stacks, use pthreads with double stack on cygwin.
 * 2012-12-04 reduce misprediction penalty for x86/amd64 assembly switcher.
 * 2012-12-05 experimental fiber backend (allocates stack twice).
 */

#ifndef CORO_H
#define CORO_H

#if __cplusplus
extern "C" {
#endif

#define CORO_VERSION 2

/*
 * Changes since API version 1:
 * replaced bogus -DCORO_LOOSE with gramatically more correct -DCORO_LOSER
 */

/*
 * This library consists of only three files
 * coro.h, coro.c and LICENSE (and optionally README)
 *
 * It implements what is known as coroutines, in a hopefully
 * portable way. At the moment you have to define which kind
 * of implementation flavour you want:
 *
 * -DCORO_UCONTEXT
 *
 *    This flavour uses SUSv2's get/set/swap/makecontext functions that
 *    unfortunately only newer unices support.
 *
 * -DCORO_SJLJ
 *
 *    This flavour uses SUSv2's setjmp/longjmp and sigaltstack functions to
 *    do it's job. Coroutine creation is much slower than UCONTEXT, but
 *    context switching is often a bit cheaper. It should work on almost
 *    all unices.
 *
 * -DCORO_LINUX
 *
 *    Old GNU/Linux systems (<= glibc-2.1) only work with this implementation
 *    (it is very fast and therefore recommended over other methods, but
 *    doesn't work with anything newer).
 *
 * -DCORO_LOSER
 *
 *    Microsoft's highly proprietary platform doesn't support sigaltstack, and
 *    this automatically selects a suitable workaround for this platform.
 *    (untested)
 *
 * -DCORO_FIBER
 *
 *    slower, but probably more portable variant for the Microsoft operating
 *    system, using fibers. ignores your stack.
 *
 * -DCORO_IRIX
 *
 *    SGI's version of Microsoft's NT ;)
 *
 * -DCORO_ASM
 *
 *    Handcoded assembly, known to work only on a few architectures/ABI:
 *    GCC + x86/IA32 and amd64/x86_64 + GNU/Linux and a few BSDs.
 *
 * -DCORO_PTHREAD
 *
 *    Use the pthread API. You have to provide <pthread.h> and -lpthread.
 *    This is likely the slowest backend, and it also does not support fork(),
 *    so avoid it at all costs.
 *
 * If you define neither of these symbols, coro.h will try to autodetect
 * the model. This currently works for CORO_LOSER only. For the other
 * alternatives you should check (e.g. using autoconf) and define the
 * following symbols: HAVE_UCONTEXT_H / HAVE_SETJMP_H / HAVE_SIGALTSTACK.
 */

/*
 * This is the type for the initialization function of a new coroutine.
 */
typedef void (*coro_func)(void *);

/*
 * A coroutine state is saved in the following structure. Treat it as an
 * opaque type. errno and sigmask might be saved, but don't rely on it,
 * implement your own switching primitive if you need that.
 */
typedef struct coro_context coro_context;

/*
 * This function creates a new coroutine. Apart from a pointer to an
 * uninitialised coro_context, it expects a pointer to the entry function
 * and the single pointer value that is given to it as argument.
 *
 * Allocating/deallocating the stack is your own responsibility.
 *
 * As a special case, if coro, arg, sptr and ssize are all zero,
 * then an "empty" coro_context will be created that is suitable
 * as an initial source for coro_transfer.
 *
 * This function is not reentrant, but putting a mutex around it
 * will work.
 */
void coro_create (coro_context *ctx, /* an uninitialised coro_context */
                  coro_func coro,    /* the coroutine code to be executed */
                  void *arg,         /* a single pointer passed to the coro */
                  void *sptr,        /* start of stack area */
                  long ssize);       /* size of stack area */

/*
 * The following prototype defines the coroutine switching function. It is
 * usually implemented as a macro, so watch out.
 *
 * This function is thread-safe and reentrant.
 */
#if 0
void coro_transfer (coro_context *prev, coro_context *next);
#endif

/*
 * The following prototype defines the coroutine destroy function. It is
 * usually implemented as a macro, so watch out. It also serves
 * no purpose unless you want to use the CORO_PTHREAD backend,
 * where it is used to clean up the thread. You are responsible
 * for freeing the stack and the context itself.
 *
 * This function is thread-safe and reentrant.
 */
#if 0
void coro_destroy (coro_context *ctx);
#endif

/*
 * That was it. No other user-visible functions are implemented here.
 */

/*****************************************************************************/

#if !defined CORO_LOSER      && !defined CORO_UCONTEXT \
    && !defined CORO_SJLJ    && !defined CORO_LINUX \
    && !defined CORO_IRIX    && !defined CORO_ASM \
    && !defined CORO_PTHREAD && !defined CORO_FIBER
# if defined WINDOWS && (defined __x86 || defined __amd64 || defined _M_IX86 || defined _M_AMD64)
#  define CORO_ASM 1
# elif defined WINDOWS || defined _WIN32
#  define CORO_LOSER 1 /* you don't win with windoze */
# elif defined __linux && (defined __x86 || defined __amd64)
#  define CORO_ASM 1
# elif defined HAVE_UCONTEXT_H
#  define CORO_UCONTEXT 1
# elif defined HAVE_SETJMP_H && defined HAVE_SIGALTSTACK
#  define CORO_SJLJ 1
# else
error unknown or unsupported architecture
# endif
#endif

/*****************************************************************************/

#if CORO_UCONTEXT

# include <ucontext.h>

struct coro_context {
  ucontext_t uc;
};

# define coro_transfer(p,n) swapcontext (&((p)->uc), &((n)->uc))
# define coro_destroy(ctx) (void *)(ctx)

#elif CORO_SJLJ || CORO_LOSER || CORO_LINUX || CORO_IRIX

# if defined(CORO_LINUX) && !defined(_GNU_SOURCE)
#  define _GNU_SOURCE /* for linux libc */
# endif

# if !CORO_LOSER
#  include <unistd.h>
# endif

/* solaris is hopelessly borked, it expands _XOPEN_UNIX to nothing */
# if __sun
#  undef _XOPEN_UNIX
#  define _XOPEN_UNIX 1
# endif

# include <setjmp.h>

# if _XOPEN_UNIX > 0 || defined (_setjmp)
#  define coro_jmp_buf      jmp_buf
#  define coro_setjmp(env)  _setjmp (env)
#  define coro_longjmp(env) _longjmp ((env), 1)
# elif CORO_LOSER
#  define coro_jmp_buf      jmp_buf
#  define coro_setjmp(env)  setjmp (env)
#  define coro_longjmp(env) longjmp ((env), 1)
# else
#  define coro_jmp_buf      sigjmp_buf
#  define coro_setjmp(env)  sigsetjmp (env, 0)
#  define coro_longjmp(env) siglongjmp ((env), 1)
# endif

struct coro_context {
  coro_jmp_buf env;
};

# define coro_transfer(p,n) do { if (!coro_setjmp ((p)->env)) coro_longjmp ((n)->env); } while (0)
# define coro_destroy(ctx) (void *)(ctx)

#elif CORO_ASM

struct coro_context {
  void **sp; /* must be at offset 0 */
};

void __attribute__ ((__noinline__, __regparm__(2)))
coro_transfer (coro_context *prev, coro_context *next);

# define coro_destroy(ctx) (void *)(ctx)

#elif CORO_PTHREAD

# include <pthread.h>

extern pthread_mutex_t coro_mutex;

struct coro_context {
  pthread_cond_t cv;
  pthread_t id;
};

void coro_transfer (coro_context *prev, coro_context *next);
void coro_destroy (coro_context *ctx);

#elif CORO_FIBER

struct coro_context {
  void *fiber;
  /* only used for initialisation */
  coro_func coro;
  void *arg;
};

#endif

#if __cplusplus
}
#endif

#endif

Revision:	1.51
Committed:	Wed Dec 5 01:09:12 2012 UTC (11 years, 6 months ago) by root
Content type:	text/plain
Branch:	MAIN
Changes since 1.50:	+31 -13 lines
Log Message:	fiber
#	Content
1	/*
2	* Copyright (c) 2001-2012 Marc Alexander Lehmann <schmorp@schmorp.de>
3	*
4	* Redistribution and use in source and binary forms, with or without modifica-
5	* tion, are permitted provided that the following conditions are met:
6	*
7	* 1. Redistributions of source code must retain the above copyright notice,
8	* this list of conditions and the following disclaimer.
9	*
10	* 2. Redistributions in binary form must reproduce the above copyright
11	* notice, this list of conditions and the following disclaimer in the
12	* documentation and/or other materials provided with the distribution.
13	*
14	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
15	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
16	* CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
17	* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
18	* CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19	* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
20	* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
21	* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
22	* ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
23	* OF THE POSSIBILITY OF SUCH DAMAGE.
24	*
25	* Alternatively, the contents of this file may be used under the terms of
26	* the GNU General Public License ("GPL") version 2 or any later version,
27	* in which case the provisions of the GPL are applicable instead of
28	* the above. If you wish to allow the use of your version of this file
29	* only under the terms of the GPL and not to allow others to use your
30	* version of this file under the BSD license, indicate your decision
31	* by deleting the provisions above and replace them with the notice
32	* and other provisions required by the GPL. If you do not delete the
33	* provisions above, a recipient may use your version of this file under
34	* either the BSD or the GPL.
35	*
36	* This library is modelled strictly after Ralf S. Engelschalls article at
37	* http://www.gnu.org/software/pth/rse-pmt.ps. So most of the credit must
38	* go to Ralf S. Engelschall <rse@engelschall.com>.
39	*
40	* This coroutine library is very much stripped down. You should either
41	* build your own process abstraction using it or - better - just use GNU
42	* Portable Threads, http://www.gnu.org/software/pth/.
43	*
44	*/
45
46	/*
47	* 2006-10-26 Include stddef.h on OS X to work around one of its bugs.
48	* Reported by Michael_G_Schwern.
49	* 2006-11-26 Use _setjmp instead of setjmp on GNU/Linux.
50	* 2007-04-27 Set unwind frame info if gcc 3+ and ELF is detected.
51	* Use _setjmp instead of setjmp on _XOPEN_SOURCE >= 600.
52	* 2007-05-02 Add assembly versions for x86 and amd64 (to avoid reliance
53	* on SIGUSR2 and sigaltstack in Crossfire).
54	* 2008-01-21 Disable CFI usage on anything but GNU/Linux.
55	* 2008-03-02 Switched to 2-clause BSD license with GPL exception.
56	* 2008-04-04 New (but highly unrecommended) pthreads backend.
57	* 2008-04-24 Reinstate CORO_LOSER (had wrong stack adjustments).
58	* 2008-10-30 Support assembly method on x86 with and without frame pointer.
59	* 2008-11-03 Use a global asm statement for CORO_ASM, idea by pippijn.
60	* 2008-11-05 Hopefully fix misaligned stacks with CORO_ASM/SETJMP.
61	* 2008-11-07 rbp wasn't saved in CORO_ASM on x86_64.
62	* introduce coro_destroy, which is a nop except for pthreads.
63	* speed up CORO_PTHREAD. Do no longer leak threads either.
64	* coro_create now allows one to create source coro_contexts.
65	* do not rely on makecontext passing a void * correctly.
66	* try harder to get _setjmp/_longjmp.
67	* major code cleanup/restructuring.
68	* 2008-11-10 the .cfi hacks are no longer needed.
69	* 2008-11-16 work around a freebsd pthread bug.
70	* 2008-11-19 define coro_*jmp symbols for easier porting.
71	* 2009-06-23 tentative win32-backend support for mingw32 (Yasuhiro Matsumoto).
72	* 2010-12-03 tentative support for uclibc (which lacks all sorts of things).
73	* 2011-05-30 set initial callee-saved-registers to zero with CORO_ASM.
74	* use .cfi_undefined rip on linux-amd64 for better backtraces.
75	* 2011-06-08 maybe properly implement weird windows amd64 calling conventions.
76	* 2011-07-03 rely on __GCC_HAVE_DWARF2_CFI_ASM for cfi detection.
77	* 2011-08-08 cygwin trashes stacks, use pthreads with double stack on cygwin.
78	* 2012-12-04 reduce misprediction penalty for x86/amd64 assembly switcher.
79	* 2012-12-05 experimental fiber backend (allocates stack twice).
80	*/
81
82	#ifndef CORO_H
83	#define CORO_H
84
85	#if __cplusplus
86	extern "C" {
87	#endif
88
89	#define CORO_VERSION 2
90
91	/*
92	* Changes since API version 1:
93	* replaced bogus -DCORO_LOOSE with gramatically more correct -DCORO_LOSER
94	*/
95
96	/*
97	* This library consists of only three files
98	* coro.h, coro.c and LICENSE (and optionally README)
99	*
100	* It implements what is known as coroutines, in a hopefully
101	* portable way. At the moment you have to define which kind
102	* of implementation flavour you want:
103	*
104	* -DCORO_UCONTEXT
105	*
106	* This flavour uses SUSv2's get/set/swap/makecontext functions that
107	* unfortunately only newer unices support.
108	*
109	* -DCORO_SJLJ
110	*
111	* This flavour uses SUSv2's setjmp/longjmp and sigaltstack functions to
112	* do it's job. Coroutine creation is much slower than UCONTEXT, but
113	* context switching is often a bit cheaper. It should work on almost
114	* all unices.
115	*
116	* -DCORO_LINUX
117	*
118	* Old GNU/Linux systems (<= glibc-2.1) only work with this implementation
119	* (it is very fast and therefore recommended over other methods, but
120	* doesn't work with anything newer).
121	*
122	* -DCORO_LOSER
123	*
124	* Microsoft's highly proprietary platform doesn't support sigaltstack, and
125	* this automatically selects a suitable workaround for this platform.
126	* (untested)
127	*
128	* -DCORO_FIBER
129	*
130	* slower, but probably more portable variant for the Microsoft operating
131	* system, using fibers. ignores your stack.
132	*
133	* -DCORO_IRIX
134	*
135	* SGI's version of Microsoft's NT ;)
136	*
137	* -DCORO_ASM
138	*
139	* Handcoded assembly, known to work only on a few architectures/ABI:
140	* GCC + x86/IA32 and amd64/x86_64 + GNU/Linux and a few BSDs.
141	*
142	* -DCORO_PTHREAD
143	*
144	* Use the pthread API. You have to provide <pthread.h> and -lpthread.
145	* This is likely the slowest backend, and it also does not support fork(),
146	* so avoid it at all costs.
147	*
148	* If you define neither of these symbols, coro.h will try to autodetect
149	* the model. This currently works for CORO_LOSER only. For the other
150	* alternatives you should check (e.g. using autoconf) and define the
151	* following symbols: HAVE_UCONTEXT_H / HAVE_SETJMP_H / HAVE_SIGALTSTACK.
152	*/
153
154	/*
155	* This is the type for the initialization function of a new coroutine.
156	*/
157	typedef void (coro_func)(void );
158
159	/*
160	* A coroutine state is saved in the following structure. Treat it as an
161	* opaque type. errno and sigmask might be saved, but don't rely on it,
162	* implement your own switching primitive if you need that.
163	*/
164	typedef struct coro_context coro_context;
165
166	/*
167	* This function creates a new coroutine. Apart from a pointer to an
168	* uninitialised coro_context, it expects a pointer to the entry function
169	* and the single pointer value that is given to it as argument.
170	*
171	* Allocating/deallocating the stack is your own responsibility.
172	*
173	* As a special case, if coro, arg, sptr and ssize are all zero,
174	* then an "empty" coro_context will be created that is suitable
175	* as an initial source for coro_transfer.
176	*
177	* This function is not reentrant, but putting a mutex around it
178	* will work.
179	*/
180	void coro_create (coro_context ctx, / an uninitialised coro_context */
181	coro_func coro, /* the coroutine code to be executed */
182	void arg, / a single pointer passed to the coro */
183	void sptr, / start of stack area */
184	long ssize); /* size of stack area */
185
186	/*
187	* The following prototype defines the coroutine switching function. It is
188	* usually implemented as a macro, so watch out.
189	*
190	* This function is thread-safe and reentrant.
191	*/
192	#if 0
193	void coro_transfer (coro_context prev, coro_context next);
194	#endif
195
196	/*
197	* The following prototype defines the coroutine destroy function. It is
198	* usually implemented as a macro, so watch out. It also serves
199	* no purpose unless you want to use the CORO_PTHREAD backend,
200	* where it is used to clean up the thread. You are responsible
201	* for freeing the stack and the context itself.
202	*
203	* This function is thread-safe and reentrant.
204	*/
205	#if 0
206	void coro_destroy (coro_context *ctx);
207	#endif
208
209	/*
210	* That was it. No other user-visible functions are implemented here.
211	*/
212
213	/*****************************************************************************/
214
215	#if !defined CORO_LOSER && !defined CORO_UCONTEXT \
216	&& !defined CORO_SJLJ && !defined CORO_LINUX \
217	&& !defined CORO_IRIX && !defined CORO_ASM \
218	&& !defined CORO_PTHREAD && !defined CORO_FIBER
219	# if defined WINDOWS && (defined __x86 \|\| defined __amd64 \|\| defined _M_IX86 \|\| defined _M_AMD64)
220	# define CORO_ASM 1
221	# elif defined WINDOWS \|\| defined _WIN32
222	# define CORO_LOSER 1 /* you don't win with windoze */
223	# elif defined __linux && (defined __x86 \|\| defined __amd64)
224	# define CORO_ASM 1
225	# elif defined HAVE_UCONTEXT_H
226	# define CORO_UCONTEXT 1
227	# elif defined HAVE_SETJMP_H && defined HAVE_SIGALTSTACK
228	# define CORO_SJLJ 1
229	# else
230	error unknown or unsupported architecture
231	# endif
232	#endif
233
234	/*****************************************************************************/
235
236	#if CORO_UCONTEXT
237
238	# include <ucontext.h>
239
240	struct coro_context {
241	ucontext_t uc;
242	};
243
244	# define coro_transfer(p,n) swapcontext (&((p)->uc), &((n)->uc))
245	# define coro_destroy(ctx) (void *)(ctx)
246
247	#elif CORO_SJLJ \|\| CORO_LOSER \|\| CORO_LINUX \|\| CORO_IRIX
248
249	# if defined(CORO_LINUX) && !defined(_GNU_SOURCE)
250	# define _GNU_SOURCE /* for linux libc */
251	# endif
252
253	# if !CORO_LOSER
254	# include <unistd.h>
255	# endif
256
257	/* solaris is hopelessly borked, it expands _XOPEN_UNIX to nothing */
258	# if __sun
259	# undef _XOPEN_UNIX
260	# define _XOPEN_UNIX 1
261	# endif
262
263	# include <setjmp.h>
264
265	# if _XOPEN_UNIX > 0 \|\| defined (_setjmp)
266	# define coro_jmp_buf jmp_buf
267	# define coro_setjmp(env) _setjmp (env)
268	# define coro_longjmp(env) _longjmp ((env), 1)
269	# elif CORO_LOSER
270	# define coro_jmp_buf jmp_buf
271	# define coro_setjmp(env) setjmp (env)
272	# define coro_longjmp(env) longjmp ((env), 1)
273	# else
274	# define coro_jmp_buf sigjmp_buf
275	# define coro_setjmp(env) sigsetjmp (env, 0)
276	# define coro_longjmp(env) siglongjmp ((env), 1)
277	# endif
278
279	struct coro_context {
280	coro_jmp_buf env;
281	};
282
283	# define coro_transfer(p,n) do { if (!coro_setjmp ((p)->env)) coro_longjmp ((n)->env); } while (0)
284	# define coro_destroy(ctx) (void *)(ctx)
285
286	#elif CORO_ASM
287
288	struct coro_context {
289	void *sp; / must be at offset 0 */
290	};
291
292	void __attribute__ ((__noinline__, __regparm__(2)))
293	coro_transfer (coro_context prev, coro_context next);
294
295	# define coro_destroy(ctx) (void *)(ctx)
296
297	#elif CORO_PTHREAD
298
299	# include <pthread.h>
300
301	extern pthread_mutex_t coro_mutex;
302
303	struct coro_context {
304	pthread_cond_t cv;
305	pthread_t id;
306	};
307
308	void coro_transfer (coro_context prev, coro_context next);
309	void coro_destroy (coro_context *ctx);
310
311	#elif CORO_FIBER
312
313	struct coro_context {
314	void *fiber;
315	/* only used for initialisation */
316	coro_func coro;
317	void *arg;
318	};
319
320	#endif
321
322	#if __cplusplus
323	}
324	#endif
325
326	#endif
327