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).
 * 2012-12-07 API version 3 - add coro_stack_alloc/coro_stack_free.
 */

#ifndef CORO_H
#define CORO_H

#if __cplusplus
extern "C" {
#endif

/*
 * 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.
 *
 * All compiletime symbols must be defined both when including coro.h
 * (using libcoro) as well as when compiling coro.c (the implementation).
 *
 * You can manually specify which flavour you want. If you don't define
 * any of these, libcoro tries to choose a safe and fast default:
 *
 * -DCORO_UCONTEXT
 *
 *    This flavour uses SUSv2's get/set/swap/makecontext functions that
 *    unfortunately only some unices support, and is quite slow.
 *
 * -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 a bit cheaper. It should work on almost all unices.
 *
 * -DCORO_LINUX
 *
 *    CORO_SJLJ variant.
 *    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
 *
 *    CORO_SJLJ variant.
 *    Microsoft's highly proprietary platform doesn't support sigaltstack, and
 *    this selects a suitable workaround for this platform. It might not work
 *    with your compiler though - it has only been tested with MSVC 6.
 *
 * -DCORO_FIBER
 *
 *    Slower, but probably more portable variant for the Microsoft operating
 *    system, using fibers. Ignores the passed stack and allocates it internally.
 *    Also, due to bugs in cygwin, this does not work with cygwin.
 *
 * -DCORO_IRIX
 *
 *    CORO_SJLJ variant.
 *    For SGI's version of Microsoft's NT ;)
 *
 * -DCORO_ASM
 *
 *    Hand coded assembly, known to work only on a few architectures/ABI:
 *    GCC + x86/IA32 and amd64/x86_64 + GNU/Linux and a few BSDs. Fastest choice,
 *    if it works.
 *
 * -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 best/safest model. To help with the autodetection, you should check
 * (e.g. using autoconf) and define the following symbols: HAVE_UCONTEXT_H
 * / HAVE_SETJMP_H / HAVE_SIGALTSTACK.
 */

/*
 * Changes when the API changes incompatibly.
 * This is ONLY the API version - there is no ABI compatibility between releases.
 *
 * Changes in API version 2:
 * replaced bogus -DCORO_LOOSE with grammatically more correct -DCORO_LOSER
 * Changes in API version 3:
 * introduced stack management (CORO_STACKALLOC)
 */
#define CORO_VERSION 3

#include <stddef.h>

/*
 * 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 ssze 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 */
                  size_t ssze);      /* size of stack area in bytes */

/*
 * The following prototype defines the coroutine switching function. It is
 * sometimes 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 sometimes 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

/*****************************************************************************/
/* optional stack management                                                 */
/*****************************************************************************/
/*
 * You can disable all of the stack management functions by
 * defining CORO_STACKALLOC to 0. Otherwise, they are enabled by default.
 *
 * If stack management is enabled, you can influence the implementation via these
 * symbols:
 *
 * -DCORO_USE_VALGRIND
 *
 *    If defined, then libcoro will include valgrind/valgrind.h and register
 *    and unregister stacks with valgrind.
 *
 * -DCORO_GUARDPAGES=n
 *
 *    libcoro will try to use the specified number of guard pages to protect against
 *    stack overflow. If n is 0, then the feature will be disabled. If it isn't
 *    defined, then libcoro will choose a suitable default. If guardpages are not
 *    supported on the platform, then the feature will be silently disabled.
 */
#ifndef CORO_STACKALLOC
# define CORO_STACKALLOC 1
#endif

#if CORO_STACKALLOC

/*
 * The only allowed operations on these struct members is to read the
 * "sptr" and "ssze" members to pass it to coro_create, to read the "sptr"
 * member to see if it is false, in which case the stack isn't allocated,
 * and to set the "sptr" member to 0, to indicate to coro_stack_free to
 * not actually do anything.
 */

struct coro_stack
{
  void *sptr;
  size_t ssze;
#if CORO_USE_VALGRIND
  int valgrind_id;
#endif
};

/*
 * Try to allocate a stack of at least the given size and return true if
 * successful, or false otherwise.
 *
 * The size is *NOT* specified in bytes, but in units of sizeof (void *),
 * i.e. the stack is typically 4(8) times larger on 32 bit(64 bit) platforms
 * then the size passed in.
 *
 * If size is 0, then a "suitable" stack size is chosen (usually 1-2MB).
 */
int coro_stack_alloc (struct coro_stack *stack, unsigned int size);

/*
 * Free the stack allocated by coro_stack_alloc again. It is safe to
 * call this function on the coro_stack structure even if coro_stack_alloc
 * failed.
 */
void coro_stack_free (struct coro_stack *stack);

#endif

/*
 * That was it. No other user-serviceable parts below 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 __i386 || (__x86_64 || 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 __linux && (__i386 || (__x86_64 && !__ILP32))
#  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 glibc */
# 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;
};

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

#endif

#if __cplusplus
}
#endif

#endif

Revision:	1.53
Committed:	Wed Dec 19 23:49:10 2012 UTC (11 years, 5 months ago) by root
Content type:	text/plain
Branch:	MAIN
Changes since 1.52:	+2 -2 lines
Log Message:	* empty log message *
#	User	Rev	Content
1	root	1.1	/*
2	root	1.51	* Copyright (c) 2001-2012 Marc Alexander Lehmann <schmorp@schmorp.de>
3			*
4	root	1.1	* Redistribution and use in source and binary forms, with or without modifica-
5			* tion, are permitted provided that the following conditions are met:
6	root	1.51	*
7	root	1.1	* 1. Redistributions of source code must retain the above copyright notice,
8			* this list of conditions and the following disclaimer.
9	root	1.51	*
10	root	1.1	* 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	root	1.51	*
14	root	1.1	* 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	root	1.24	* 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	root	1.1	* This library is modelled strictly after Ralf S. Engelschalls article at
37	root	1.24	* http://www.gnu.org/software/pth/rse-pmt.ps. So most of the credit must
38	root	1.1	* go to Ralf S. Engelschall <rse@engelschall.com>.
39			*
40			* This coroutine library is very much stripped down. You should either
41	pcg	1.7	* build your own process abstraction using it or - better - just use GNU
42	root	1.1	* Portable Threads, http://www.gnu.org/software/pth/.
43	root	1.4	*
44	root	1.1	*/
45
46	root	1.14	/*
47			* 2006-10-26 Include stddef.h on OS X to work around one of its bugs.
48			* Reported by Michael_G_Schwern.
49	root	1.17	* 2006-11-26 Use _setjmp instead of setjmp on GNU/Linux.
50	root	1.20	* 2007-04-27 Set unwind frame info if gcc 3+ and ELF is detected.
51	root	1.21	* Use _setjmp instead of setjmp on _XOPEN_SOURCE >= 600.
52	root	1.22	* 2007-05-02 Add assembly versions for x86 and amd64 (to avoid reliance
53			* on SIGUSR2 and sigaltstack in Crossfire).
54	root	1.23	* 2008-01-21 Disable CFI usage on anything but GNU/Linux.
55	root	1.24	* 2008-03-02 Switched to 2-clause BSD license with GPL exception.
56	root	1.25	* 2008-04-04 New (but highly unrecommended) pthreads backend.
57	root	1.26	* 2008-04-24 Reinstate CORO_LOSER (had wrong stack adjustments).
58	root	1.28	* 2008-10-30 Support assembly method on x86 with and without frame pointer.
59	root	1.29	* 2008-11-03 Use a global asm statement for CORO_ASM, idea by pippijn.
60	root	1.30	* 2008-11-05 Hopefully fix misaligned stacks with CORO_ASM/SETJMP.
61	root	1.31	* 2008-11-07 rbp wasn't saved in CORO_ASM on x86_64.
62	root	1.32	* 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	root	1.33	* do not rely on makecontext passing a void * correctly.
66			* try harder to get _setjmp/_longjmp.
67			* major code cleanup/restructuring.
68	root	1.37	* 2008-11-10 the .cfi hacks are no longer needed.
69	root	1.39	* 2008-11-16 work around a freebsd pthread bug.
70	root	1.40	* 2008-11-19 define coro_*jmp symbols for easier porting.
71	root	1.41	* 2009-06-23 tentative win32-backend support for mingw32 (Yasuhiro Matsumoto).
72	root	1.44	* 2010-12-03 tentative support for uclibc (which lacks all sorts of things).
73	root	1.45	* 2011-05-30 set initial callee-saved-registers to zero with CORO_ASM.
74	root	1.47	* use .cfi_undefined rip on linux-amd64 for better backtraces.
75	root	1.48	* 2011-06-08 maybe properly implement weird windows amd64 calling conventions.
76	root	1.49	* 2011-07-03 rely on __GCC_HAVE_DWARF2_CFI_ASM for cfi detection.
77	root	1.50	* 2011-08-08 cygwin trashes stacks, use pthreads with double stack on cygwin.
78	root	1.51	* 2012-12-04 reduce misprediction penalty for x86/amd64 assembly switcher.
79			* 2012-12-05 experimental fiber backend (allocates stack twice).
80	root	1.52	* 2012-12-07 API version 3 - add coro_stack_alloc/coro_stack_free.
81	root	1.14	*/
82
83	root	1.1	#ifndef CORO_H
84			#define CORO_H
85
86	root	1.43	#if __cplusplus
87			extern "C" {
88			#endif
89
90	root	1.2	/*
91			* This library consists of only three files
92	root	1.9	* coro.h, coro.c and LICENSE (and optionally README)
93	root	1.2	*
94			* It implements what is known as coroutines, in a hopefully
95	root	1.52	* portable way.
96			*
97			* All compiletime symbols must be defined both when including coro.h
98			* (using libcoro) as well as when compiling coro.c (the implementation).
99			*
100			* You can manually specify which flavour you want. If you don't define
101			* any of these, libcoro tries to choose a safe and fast default:
102	root	1.2	*
103			* -DCORO_UCONTEXT
104			*
105			* This flavour uses SUSv2's get/set/swap/makecontext functions that
106	root	1.52	* unfortunately only some unices support, and is quite slow.
107	root	1.2	*
108			* -DCORO_SJLJ
109			*
110	root	1.13	* This flavour uses SUSv2's setjmp/longjmp and sigaltstack functions to
111	root	1.2	* do it's job. Coroutine creation is much slower than UCONTEXT, but
112	root	1.52	* context switching is a bit cheaper. It should work on almost all unices.
113	root	1.3	*
114			* -DCORO_LINUX
115			*
116	root	1.52	* CORO_SJLJ variant.
117	root	1.24	* Old GNU/Linux systems (<= glibc-2.1) only work with this implementation
118			* (it is very fast and therefore recommended over other methods, but
119			* doesn't work with anything newer).
120	root	1.2	*
121	root	1.11	* -DCORO_LOSER
122	root	1.2	*
123	root	1.52	* CORO_SJLJ variant.
124	root	1.2	* Microsoft's highly proprietary platform doesn't support sigaltstack, and
125	root	1.52	* this selects a suitable workaround for this platform. It might not work
126			* with your compiler though - it has only been tested with MSVC 6.
127	root	1.2	*
128	root	1.51	* -DCORO_FIBER
129			*
130	root	1.52	* Slower, but probably more portable variant for the Microsoft operating
131			* system, using fibers. Ignores the passed stack and allocates it internally.
132			* Also, due to bugs in cygwin, this does not work with cygwin.
133	root	1.51	*
134	root	1.5	* -DCORO_IRIX
135			*
136	root	1.52	* CORO_SJLJ variant.
137			* For SGI's version of Microsoft's NT ;)
138	root	1.5	*
139	root	1.22	* -DCORO_ASM
140			*
141	root	1.52	* Hand coded assembly, known to work only on a few architectures/ABI:
142			* GCC + x86/IA32 and amd64/x86_64 + GNU/Linux and a few BSDs. Fastest choice,
143			* if it works.
144	root	1.22	*
145	root	1.25	* -DCORO_PTHREAD
146			*
147			* Use the pthread API. You have to provide <pthread.h> and -lpthread.
148	root	1.39	* This is likely the slowest backend, and it also does not support fork(),
149			* so avoid it at all costs.
150	root	1.25	*
151	root	1.2	* If you define neither of these symbols, coro.h will try to autodetect
152	root	1.52	* the best/safest model. To help with the autodetection, you should check
153			* (e.g. using autoconf) and define the following symbols: HAVE_UCONTEXT_H
154			* / HAVE_SETJMP_H / HAVE_SIGALTSTACK.
155	root	1.2	*/
156
157			/*
158	root	1.52	* Changes when the API changes incompatibly.
159			* This is ONLY the API version - there is no ABI compatibility between releases.
160			*
161			* Changes in API version 2:
162			* replaced bogus -DCORO_LOOSE with grammatically more correct -DCORO_LOSER
163			* Changes in API version 3:
164			* introduced stack management (CORO_STACKALLOC)
165			*/
166			#define CORO_VERSION 3
167
168			#include <stddef.h>
169
170			/*
171	root	1.6	* This is the type for the initialization function of a new coroutine.
172	root	1.2	*/
173	root	1.1	typedef void (coro_func)(void );
174	root	1.2
175			/*
176	root	1.19	* A coroutine state is saved in the following structure. Treat it as an
177	root	1.2	* opaque type. errno and sigmask might be saved, but don't rely on it,
178	root	1.19	* implement your own switching primitive if you need that.
179	root	1.2	*/
180			typedef struct coro_context coro_context;
181
182			/*
183			* This function creates a new coroutine. Apart from a pointer to an
184	root	1.13	* uninitialised coro_context, it expects a pointer to the entry function
185	root	1.2	* and the single pointer value that is given to it as argument.
186			*
187	root	1.32	* Allocating/deallocating the stack is your own responsibility.
188			*
189	root	1.52	* As a special case, if coro, arg, sptr and ssze are all zero,
190	root	1.38	* then an "empty" coro_context will be created that is suitable
191	root	1.32	* as an initial source for coro_transfer.
192			*
193			* This function is not reentrant, but putting a mutex around it
194			* will work.
195	root	1.2	*/
196	root	1.19	void coro_create (coro_context ctx, / an uninitialised coro_context */
197			coro_func coro, /* the coroutine code to be executed */
198			void arg, / a single pointer passed to the coro */
199			void sptr, / start of stack area */
200	root	1.52	size_t ssze); /* size of stack area in bytes */
201	root	1.2
202			/*
203			* The following prototype defines the coroutine switching function. It is
204	root	1.52	* sometimes implemented as a macro, so watch out.
205	root	1.2	*
206	root	1.32	* This function is thread-safe and reentrant.
207	root	1.2	*/
208	root	1.32	#if 0
209			void coro_transfer (coro_context prev, coro_context next);
210			#endif
211
212			/*
213	root	1.52	* The following prototype defines the coroutine destroy function. It
214			* is sometimes implemented as a macro, so watch out. It also serves no
215			* purpose unless you want to use the CORO_PTHREAD backend, where it is
216			* used to clean up the thread. You are responsible for freeing the stack
217			* and the context itself.
218	root	1.32	*
219			* This function is thread-safe and reentrant.
220			*/
221			#if 0
222			void coro_destroy (coro_context *ctx);
223			#endif
224	root	1.2
225	root	1.52	/*****************************************************************************/
226			/* optional stack management */
227			/*****************************************************************************/
228			/*
229			* You can disable all of the stack management functions by
230			* defining CORO_STACKALLOC to 0. Otherwise, they are enabled by default.
231			*
232			* If stack management is enabled, you can influence the implementation via these
233			* symbols:
234			*
235			* -DCORO_USE_VALGRIND
236			*
237			* If defined, then libcoro will include valgrind/valgrind.h and register
238			* and unregister stacks with valgrind.
239			*
240			* -DCORO_GUARDPAGES=n
241			*
242			* libcoro will try to use the specified number of guard pages to protect against
243			* stack overflow. If n is 0, then the feature will be disabled. If it isn't
244			* defined, then libcoro will choose a suitable default. If guardpages are not
245			* supported on the platform, then the feature will be silently disabled.
246			*/
247			#ifndef CORO_STACKALLOC
248			# define CORO_STACKALLOC 1
249			#endif
250
251			#if CORO_STACKALLOC
252
253	root	1.2	/*
254	root	1.52	* The only allowed operations on these struct members is to read the
255			* "sptr" and "ssze" members to pass it to coro_create, to read the "sptr"
256			* member to see if it is false, in which case the stack isn't allocated,
257			* and to set the "sptr" member to 0, to indicate to coro_stack_free to
258			* not actually do anything.
259			*/
260
261			struct coro_stack
262			{
263			void *sptr;
264			size_t ssze;
265			#if CORO_USE_VALGRIND
266			int valgrind_id;
267			#endif
268			};
269
270			/*
271			* Try to allocate a stack of at least the given size and return true if
272			* successful, or false otherwise.
273			*
274			* The size is NOT specified in bytes, but in units of sizeof (void *),
275			* i.e. the stack is typically 4(8) times larger on 32 bit(64 bit) platforms
276			* then the size passed in.
277			*
278			* If size is 0, then a "suitable" stack size is chosen (usually 1-2MB).
279			*/
280			int coro_stack_alloc (struct coro_stack *stack, unsigned int size);
281
282			/*
283			* Free the stack allocated by coro_stack_alloc again. It is safe to
284			* call this function on the coro_stack structure even if coro_stack_alloc
285			* failed.
286			*/
287			void coro_stack_free (struct coro_stack *stack);
288
289			#endif
290
291			/*
292			* That was it. No other user-serviceable parts below here.
293	root	1.2	*/
294
295	root	1.5	/*****************************************************************************/
296
297	root	1.51	#if !defined CORO_LOSER && !defined CORO_UCONTEXT \
298			&& !defined CORO_SJLJ && !defined CORO_LINUX \
299			&& !defined CORO_IRIX && !defined CORO_ASM \
300			&& !defined CORO_PTHREAD && !defined CORO_FIBER
301	root	1.53	# if defined WINDOWS && (defined __i386 \|\| (__x86_64 \|\| defined _M_IX86 \|\| defined _M_AMD64)
302	root	1.51	# define CORO_ASM 1
303			# elif defined WINDOWS \|\| defined _WIN32
304	root	1.11	# define CORO_LOSER 1 /* you don't win with windoze */
305	root	1.53	# elif __linux && (__i386 \|\| (__x86_64 && !__ILP32))
306	root	1.22	# define CORO_ASM 1
307	root	1.51	# elif defined HAVE_UCONTEXT_H
308	root	1.2	# define CORO_UCONTEXT 1
309	root	1.51	# elif defined HAVE_SETJMP_H && defined HAVE_SIGALTSTACK
310	root	1.2	# define CORO_SJLJ 1
311			# else
312	root	1.1	error unknown or unsupported architecture
313	root	1.2	# endif
314	root	1.1	#endif
315
316	root	1.5	/*****************************************************************************/
317
318	root	1.1	#if CORO_UCONTEXT
319
320	root	1.22	# include <ucontext.h>
321	root	1.1
322	root	1.52	struct coro_context
323			{
324	root	1.1	ucontext_t uc;
325	root	1.2	};
326	root	1.1
327	root	1.22	# define coro_transfer(p,n) swapcontext (&((p)->uc), &((n)->uc))
328	root	1.32	# define coro_destroy(ctx) (void *)(ctx)
329	root	1.1
330	root	1.11	#elif CORO_SJLJ \|\| CORO_LOSER \|\| CORO_LINUX \|\| CORO_IRIX
331	root	1.1
332	root	1.22	# if defined(CORO_LINUX) && !defined(_GNU_SOURCE)
333	root	1.52	# define _GNU_SOURCE /* for glibc */
334	root	1.22	# endif
335	root	1.8
336	root	1.33	# if !CORO_LOSER
337			# include <unistd.h>
338			# endif
339
340	root	1.36	/* solaris is hopelessly borked, it expands _XOPEN_UNIX to nothing */
341			# if __sun
342			# undef _XOPEN_UNIX
343			# define _XOPEN_UNIX 1
344			# endif
345
346	root	1.22	# include <setjmp.h>
347	root	1.1
348	root	1.40	# if _XOPEN_UNIX > 0 \|\| defined (_setjmp)
349			# define coro_jmp_buf jmp_buf
350			# define coro_setjmp(env) _setjmp (env)
351			# define coro_longjmp(env) _longjmp ((env), 1)
352	root	1.34	# elif CORO_LOSER
353	root	1.40	# define coro_jmp_buf jmp_buf
354			# define coro_setjmp(env) setjmp (env)
355			# define coro_longjmp(env) longjmp ((env), 1)
356	root	1.22	# else
357	root	1.40	# define coro_jmp_buf sigjmp_buf
358			# define coro_setjmp(env) sigsetjmp (env, 0)
359			# define coro_longjmp(env) siglongjmp ((env), 1)
360	root	1.22	# endif
361
362	root	1.52	struct coro_context
363			{
364	root	1.40	coro_jmp_buf env;
365			};
366
367			# define coro_transfer(p,n) do { if (!coro_setjmp ((p)->env)) coro_longjmp ((n)->env); } while (0)
368	root	1.32	# define coro_destroy(ctx) (void *)(ctx)
369
370	root	1.22	#elif CORO_ASM
371
372	root	1.52	struct coro_context
373			{
374	root	1.34	void *sp; / must be at offset 0 */
375	root	1.22	};
376
377	root	1.27	void __attribute__ ((__noinline__, __regparm__(2)))
378	root	1.29	coro_transfer (coro_context prev, coro_context next);
379	root	1.25
380	root	1.32	# define coro_destroy(ctx) (void *)(ctx)
381
382	root	1.25	#elif CORO_PTHREAD
383
384	root	1.32	# include <pthread.h>
385	root	1.25
386			extern pthread_mutex_t coro_mutex;
387
388	root	1.52	struct coro_context
389			{
390	root	1.32	pthread_cond_t cv;
391			pthread_t id;
392	root	1.25	};
393
394			void coro_transfer (coro_context prev, coro_context next);
395	root	1.32	void coro_destroy (coro_context *ctx);
396	root	1.1
397	root	1.51	#elif CORO_FIBER
398
399	root	1.52	struct coro_context
400			{
401	root	1.51	void *fiber;
402			/* only used for initialisation */
403			coro_func coro;
404			void *arg;
405			};
406
407	root	1.52	void coro_transfer (coro_context prev, coro_context next);
408			void coro_destroy (coro_context *ctx);
409
410	root	1.1	#endif
411
412	root	1.43	#if __cplusplus
413			}
414			#endif
415
416	root	1.1	#endif
417