libcoro/coro.c

/*
 * Copyright (c) 2001-2008 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>.
 */

#include "coro.h"

#include <string.h>

/*****************************************************************************/
/* ucontext/setjmp/asm backends                                              */
/*****************************************************************************/
#if CORO_UCONTEXT || CORO_SJLJ || CORO_LOSER || CORO_LINUX || CORO_IRIX || CORO_ASM

# if CORO_UCONTEXT
#  include <stddef.h>
# endif

# if !defined(STACK_ADJUST_PTR)
#  if __sgi
/* IRIX is decidedly NON-unix */
#   define STACK_ADJUST_PTR(sp,ss) ((char *)(sp) + (ss) - 8)
#   define STACK_ADJUST_SIZE(sp,ss) ((ss) - 8)
#  elif (__i386__ && CORO_LINUX) || (_M_IX86 && CORO_LOSER)
#   define STACK_ADJUST_PTR(sp,ss) ((char *)(sp) + (ss))
#   define STACK_ADJUST_SIZE(sp,ss) (ss)
#  elif (__amd64__ && CORO_LINUX) || ((_M_AMD64 || _M_IA64) && CORO_LOSER)
#   define STACK_ADJUST_PTR(sp,ss) ((char *)(sp) + (ss) - 8)
#   define STACK_ADJUST_SIZE(sp,ss) (ss)
#  else
#   define STACK_ADJUST_PTR(sp,ss) (sp)
#   define STACK_ADJUST_SIZE(sp,ss) (ss)
#  endif
# endif

# include <stdlib.h>

# if CORO_SJLJ
#  include <stdio.h>
#  include <signal.h>
#  include <unistd.h>
# endif

static coro_func coro_init_func;
static void *coro_init_arg;
static coro_context *new_coro, *create_coro;

static void
coro_init (void)
{
  volatile coro_func func = coro_init_func;
  volatile void *arg = coro_init_arg;

  coro_transfer (new_coro, create_coro);

  func ((void *)arg);

  /* the new coro returned. bad. just abort() for now */
  abort ();
}

# if CORO_SJLJ

static volatile int trampoline_done;

/* trampoline signal handler */
static void
trampoline (int sig)
{
  if (
    #if _XOPEN_UNIX > 0
      _setjmp (new_coro->env)
    #else
      sigsetjmp (new_coro->env, 0)
    #endif
  ) {
      coro_init (); /* start it */
    }
  else
    trampoline_done = 1;
}

# endif

# if CORO_ASM

  asm (
       ".text\n"
       ".globl coro_transfer\n"
       ".type coro_transfer, @function\n"
       "coro_transfer:\n"
       #if __amd64
         #define NUM_SAVED 6
         "\tpush %rbp\n"
         "\tpush %rbx\n"
         "\tpush %r12\n"
         "\tpush %r13\n"
         "\tpush %r14\n"
         "\tpush %r15\n"
         "\tmov  %rsp, (%rdi)\n"
         "\tmov  (%rsi), %rsp\n"
         "\tpop  %r15\n"
         "\tpop  %r14\n"
         "\tpop  %r13\n"
         "\tpop  %r12\n"
         "\tpop  %rbx\n"
         "\tpop  %rbp\n"
       #elif __i386
         #define NUM_SAVED 4
         "\tpush %ebp\n"
         "\tpush %ebx\n"
         "\tpush %esi\n"
         "\tpush %edi\n"
         "\tmov  %esp, (%eax)\n"
         "\tmov  (%edx), %esp\n"
         "\tpop  %edi\n"
         "\tpop  %esi\n"
         "\tpop  %ebx\n"
         "\tpop  %ebp\n"
       #else
         #error unsupported architecture
       #endif
       "\tret\n"
  );

# endif

void
coro_create (coro_context *ctx, coro_func coro, void *arg, void *sptr, long ssize)
{
  coro_context nctx;
# if CORO_SJLJ
  stack_t ostk, nstk;
  struct sigaction osa, nsa;
  sigset_t nsig, osig;
# endif

  if (!coro)
    return;

  coro_init_func = coro;
  coro_init_arg  = arg;

  new_coro    = ctx;
  create_coro = &nctx;

# if CORO_SJLJ
  /* we use SIGUSR2. first block it, then fiddle with it. */

  sigemptyset (&nsig);
  sigaddset (&nsig, SIGUSR2);
  sigprocmask (SIG_BLOCK, &nsig, &osig);

  nsa.sa_handler = trampoline;
  sigemptyset (&nsa.sa_mask);
  nsa.sa_flags = SA_ONSTACK;

  if (sigaction (SIGUSR2, &nsa, &osa))
    {
      perror ("sigaction");
      abort ();
    }

  /* set the new stack */
  nstk.ss_sp    = STACK_ADJUST_PTR (sptr,ssize); /* yes, some platforms (IRIX) get this wrong. */
  nstk.ss_size  = STACK_ADJUST_SIZE (sptr,ssize);
  nstk.ss_flags = 0;

  if (sigaltstack (&nstk, &ostk) < 0)
    {
      perror ("sigaltstack");
      abort ();
    }

  trampoline_done = 0;
  kill (getpid (), SIGUSR2);
  sigfillset (&nsig); sigdelset (&nsig, SIGUSR2);

  while (!trampoline_done)
    sigsuspend (&nsig);

  sigaltstack (0, &nstk);
  nstk.ss_flags = SS_DISABLE;
  if (sigaltstack (&nstk, 0) < 0)
    perror ("sigaltstack");

  sigaltstack (0, &nstk);
  if (~nstk.ss_flags & SS_DISABLE)
    abort ();

  if (~ostk.ss_flags & SS_DISABLE)
    sigaltstack (&ostk, 0);

  sigaction (SIGUSR2, &osa, 0);
  sigprocmask (SIG_SETMASK, &osig, 0);

# elif CORO_LOSER

  setjmp (ctx->env);
  #if __CYGWIN__
    ctx->env[7] = (long)((char *)sptr + ssize) - sizeof (long);
    ctx->env[8] = (long)coro_init;
  #elif defined(_M_IX86)
    ((_JUMP_BUFFER *)&ctx->env)->Eip   = (long)coro_init;
    ((_JUMP_BUFFER *)&ctx->env)->Esp   = (long)STACK_ADJUST_PTR (sptr, ssize) - sizeof (long);
  #elif defined(_M_AMD64)
    ((_JUMP_BUFFER *)&ctx->env)->Rip   = (__int64)coro_init;
    ((_JUMP_BUFFER *)&ctx->env)->Rsp   = (__int64)STACK_ADJUST_PTR (sptr, ssize) - sizeof (long);
  #elif defined(_M_IA64)
    ((_JUMP_BUFFER *)&ctx->env)->StIIP = (__int64)coro_init;
    ((_JUMP_BUFFER *)&ctx->env)->IntSp = (__int64)STACK_ADJUST_PTR (sptr, ssize) - sizeof (long);
  #else
    #error "microsoft libc or architecture not supported"
  #endif

# elif CORO_LINUX

  _setjmp (ctx->env);
  #if __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 0 && defined (JB_PC) && defined (JB_SP)
    ctx->env[0].__jmpbuf[JB_PC] = (long)coro_init;
    ctx->env[0].__jmpbuf[JB_SP] = (long)STACK_ADJUST_PTR (sptr, ssize) - sizeof (long);
  #elif __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 0 && defined (__mc68000__)
    ctx->env[0].__jmpbuf[0].__aregs[0] = (long int)coro_init;
    ctx->env[0].__jmpbuf[0].__sp = (int *)((char *)sptr + ssize) - sizeof (long);
  #elif defined (__GNU_LIBRARY__) && defined (__i386__)
    ctx->env[0].__jmpbuf[0].__pc = (char *)coro_init;
    ctx->env[0].__jmpbuf[0].__sp = (void *)((char *)sptr + ssize) - sizeof (long);
  #elif defined (__GNU_LIBRARY__) && defined (__amd64__)
    ctx->env[0].__jmpbuf[JB_PC]  = (long)coro_init;
    ctx->env[0].__jmpbuf[0].__sp = (void *)((char *)sptr + ssize) - sizeof (long);
  #else
    #error "linux libc or architecture not supported"
  #endif

# elif CORO_IRIX

  sigsetjmp (ctx->env, 0);
  ctx->env[JB_PC] = (__uint64_t)coro_init;
  ctx->env[JB_SP] = (__uint64_t)STACK_ADJUST_PTR (sptr, ssize) - sizeof (long);

# elif CORO_ASM

  ctx->sp = (void **)(ssize + (char *)sptr);
  *--ctx->sp = (void *)abort; /* needed for alignment only */
  *--ctx->sp = (void *)coro_init;
  ctx->sp -= NUM_SAVED;

# elif CORO_UCONTEXT

  getcontext (&(ctx->uc));

  ctx->uc.uc_link           =  0;
  ctx->uc.uc_stack.ss_sp    = sptr;
  ctx->uc.uc_stack.ss_size  = (size_t)ssize;
  ctx->uc.uc_stack.ss_flags = 0;

  makecontext (&(ctx->uc), (void (*)())coro_init, 0);

# endif

  coro_transfer (create_coro, new_coro);
}

/*****************************************************************************/
/* pthread backend                                                           */
/*****************************************************************************/
#elif CORO_PTHREAD

/* this mutex will be locked by the running coroutine */
pthread_mutex_t coro_mutex = PTHREAD_MUTEX_INITIALIZER;

struct coro_init_args
{
  coro_func func;
  void *arg;
  coro_context *self, *main;
};

static pthread_t null_tid;

/* I'd so love to cast pthread_mutex_unlock to void (*)(void *)... */
static void
mutex_unlock_wrapper (void *arg)
{
  pthread_mutex_unlock ((pthread_mutex_t *)arg);
}

static void *
coro_init (void *args_)
{
  struct coro_init_args *args = (struct coro_init_args *)args_;
  coro_func func = args->func;
  void *arg = args->arg;

  pthread_mutex_lock (&coro_mutex);

  /* we try to be good citizens and use deferred cancellation and cleanup handlers */
  pthread_cleanup_push (mutex_unlock_wrapper, &coro_mutex);
    coro_transfer (args->self, args->main);
    func (arg);
  pthread_cleanup_pop (1);

  return 0;
}

void
coro_transfer (coro_context *prev, coro_context *next)
{
  pthread_cond_signal (&next->cv);
  pthread_cond_wait (&prev->cv, &coro_mutex);
#if __FreeBSD__ /* freebsd is of course broken and needs manual testcancel calls... yay... */
  pthread_testcancel ();
#endif
}

void
coro_create (coro_context *ctx, coro_func coro, void *arg, void *sptr, long ssize)
{
  static coro_context nctx;
  static int once;

  if (!once)
    {
      once = 1;

      pthread_mutex_lock (&coro_mutex);
      pthread_cond_init (&nctx.cv, 0);
      null_tid = pthread_self ();
    }

  pthread_cond_init (&ctx->cv, 0);

  if (coro)
    {
      pthread_attr_t attr;
      struct coro_init_args args;

      args.func = coro;
      args.arg  = arg;
      args.self = ctx;
      args.main = &nctx;

      pthread_attr_init (&attr);
      pthread_attr_setstack (&attr, sptr, (size_t)ssize);
      pthread_attr_setscope (&attr, PTHREAD_SCOPE_PROCESS);
      pthread_create (&ctx->id, &attr, coro_init, &args);

      coro_transfer (args.main, args.self);
    }
  else
    ctx->id = null_tid;
}

void
coro_destroy (coro_context *ctx)
{
  if (!pthread_equal (ctx->id, null_tid))
    {
      pthread_cancel (ctx->id);
      pthread_mutex_unlock (&coro_mutex);
      pthread_join (ctx->id, 0);
      pthread_mutex_lock (&coro_mutex);
    }

  pthread_cond_destroy (&ctx->cv);
}

#else
# error unsupported backend
#endif

Revision:	1.43
Committed:	Sun Nov 16 00:55:41 2008 UTC (15 years, 6 months ago) by root
Content type:	text/plain
Branch:	MAIN
Changes since 1.42:	+3 -0 lines
Log Message:	* empty log message *
#	Content
1	/*
2	* Copyright (c) 2001-2008 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
41	#include "coro.h"
42
43	#include <string.h>
44
45	/*****************************************************************************/
46	/* ucontext/setjmp/asm backends */
47	/*****************************************************************************/
48	#if CORO_UCONTEXT \|\| CORO_SJLJ \|\| CORO_LOSER \|\| CORO_LINUX \|\| CORO_IRIX \|\| CORO_ASM
49
50	# if CORO_UCONTEXT
51	# include <stddef.h>
52	# endif
53
54	# if !defined(STACK_ADJUST_PTR)
55	# if __sgi
56	/* IRIX is decidedly NON-unix */
57	# define STACK_ADJUST_PTR(sp,ss) ((char *)(sp) + (ss) - 8)
58	# define STACK_ADJUST_SIZE(sp,ss) ((ss) - 8)
59	# elif (__i386__ && CORO_LINUX) \|\| (_M_IX86 && CORO_LOSER)
60	# define STACK_ADJUST_PTR(sp,ss) ((char *)(sp) + (ss))
61	# define STACK_ADJUST_SIZE(sp,ss) (ss)
62	# elif (__amd64__ && CORO_LINUX) \|\| ((_M_AMD64 \|\| _M_IA64) && CORO_LOSER)
63	# define STACK_ADJUST_PTR(sp,ss) ((char *)(sp) + (ss) - 8)
64	# define STACK_ADJUST_SIZE(sp,ss) (ss)
65	# else
66	# define STACK_ADJUST_PTR(sp,ss) (sp)
67	# define STACK_ADJUST_SIZE(sp,ss) (ss)
68	# endif
69	# endif
70
71	# include <stdlib.h>
72
73	# if CORO_SJLJ
74	# include <stdio.h>
75	# include <signal.h>
76	# include <unistd.h>
77	# endif
78
79	static coro_func coro_init_func;
80	static void *coro_init_arg;
81	static coro_context new_coro, create_coro;
82
83	static void
84	coro_init (void)
85	{
86	volatile coro_func func = coro_init_func;
87	volatile void *arg = coro_init_arg;
88
89	coro_transfer (new_coro, create_coro);
90
91	func ((void *)arg);
92
93	/* the new coro returned. bad. just abort() for now */
94	abort ();
95	}
96
97	# if CORO_SJLJ
98
99	static volatile int trampoline_done;
100
101	/* trampoline signal handler */
102	static void
103	trampoline (int sig)
104	{
105	if (
106	#if _XOPEN_UNIX > 0
107	_setjmp (new_coro->env)
108	#else
109	sigsetjmp (new_coro->env, 0)
110	#endif
111	) {
112	coro_init (); /* start it */
113	}
114	else
115	trampoline_done = 1;
116	}
117
118	# endif
119
120	# if CORO_ASM
121
122	asm (
123	".text\n"
124	".globl coro_transfer\n"
125	".type coro_transfer, @function\n"
126	"coro_transfer:\n"
127	#if __amd64
128	#define NUM_SAVED 6
129	"\tpush %rbp\n"
130	"\tpush %rbx\n"
131	"\tpush %r12\n"
132	"\tpush %r13\n"
133	"\tpush %r14\n"
134	"\tpush %r15\n"
135	"\tmov %rsp, (%rdi)\n"
136	"\tmov (%rsi), %rsp\n"
137	"\tpop %r15\n"
138	"\tpop %r14\n"
139	"\tpop %r13\n"
140	"\tpop %r12\n"
141	"\tpop %rbx\n"
142	"\tpop %rbp\n"
143	#elif __i386
144	#define NUM_SAVED 4
145	"\tpush %ebp\n"
146	"\tpush %ebx\n"
147	"\tpush %esi\n"
148	"\tpush %edi\n"
149	"\tmov %esp, (%eax)\n"
150	"\tmov (%edx), %esp\n"
151	"\tpop %edi\n"
152	"\tpop %esi\n"
153	"\tpop %ebx\n"
154	"\tpop %ebp\n"
155	#else
156	#error unsupported architecture
157	#endif
158	"\tret\n"
159	);
160
161	# endif
162
163	void
164	coro_create (coro_context ctx, coro_func coro, void arg, void *sptr, long ssize)
165	{
166	coro_context nctx;
167	# if CORO_SJLJ
168	stack_t ostk, nstk;
169	struct sigaction osa, nsa;
170	sigset_t nsig, osig;
171	# endif
172
173	if (!coro)
174	return;
175
176	coro_init_func = coro;
177	coro_init_arg = arg;
178
179	new_coro = ctx;
180	create_coro = &nctx;
181
182	# if CORO_SJLJ
183	/* we use SIGUSR2. first block it, then fiddle with it. */
184
185	sigemptyset (&nsig);
186	sigaddset (&nsig, SIGUSR2);
187	sigprocmask (SIG_BLOCK, &nsig, &osig);
188
189	nsa.sa_handler = trampoline;
190	sigemptyset (&nsa.sa_mask);
191	nsa.sa_flags = SA_ONSTACK;
192
193	if (sigaction (SIGUSR2, &nsa, &osa))
194	{
195	perror ("sigaction");
196	abort ();
197	}
198
199	/* set the new stack */
200	nstk.ss_sp = STACK_ADJUST_PTR (sptr,ssize); /* yes, some platforms (IRIX) get this wrong. */
201	nstk.ss_size = STACK_ADJUST_SIZE (sptr,ssize);
202	nstk.ss_flags = 0;
203
204	if (sigaltstack (&nstk, &ostk) < 0)
205	{
206	perror ("sigaltstack");
207	abort ();
208	}
209
210	trampoline_done = 0;
211	kill (getpid (), SIGUSR2);
212	sigfillset (&nsig); sigdelset (&nsig, SIGUSR2);
213
214	while (!trampoline_done)
215	sigsuspend (&nsig);
216
217	sigaltstack (0, &nstk);
218	nstk.ss_flags = SS_DISABLE;
219	if (sigaltstack (&nstk, 0) < 0)
220	perror ("sigaltstack");
221
222	sigaltstack (0, &nstk);
223	if (~nstk.ss_flags & SS_DISABLE)
224	abort ();
225
226	if (~ostk.ss_flags & SS_DISABLE)
227	sigaltstack (&ostk, 0);
228
229	sigaction (SIGUSR2, &osa, 0);
230	sigprocmask (SIG_SETMASK, &osig, 0);
231
232	# elif CORO_LOSER
233
234	setjmp (ctx->env);
235	#if __CYGWIN__
236	ctx->env[7] = (long)((char *)sptr + ssize) - sizeof (long);
237	ctx->env[8] = (long)coro_init;
238	#elif defined(_M_IX86)
239	((_JUMP_BUFFER *)&ctx->env)->Eip = (long)coro_init;
240	((_JUMP_BUFFER *)&ctx->env)->Esp = (long)STACK_ADJUST_PTR (sptr, ssize) - sizeof (long);
241	#elif defined(_M_AMD64)
242	((_JUMP_BUFFER *)&ctx->env)->Rip = (__int64)coro_init;
243	((_JUMP_BUFFER *)&ctx->env)->Rsp = (__int64)STACK_ADJUST_PTR (sptr, ssize) - sizeof (long);
244	#elif defined(_M_IA64)
245	((_JUMP_BUFFER *)&ctx->env)->StIIP = (__int64)coro_init;
246	((_JUMP_BUFFER *)&ctx->env)->IntSp = (__int64)STACK_ADJUST_PTR (sptr, ssize) - sizeof (long);
247	#else
248	#error "microsoft libc or architecture not supported"
249	#endif
250
251	# elif CORO_LINUX
252
253	_setjmp (ctx->env);
254	#if __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 0 && defined (JB_PC) && defined (JB_SP)
255	ctx->env[0].__jmpbuf[JB_PC] = (long)coro_init;
256	ctx->env[0].__jmpbuf[JB_SP] = (long)STACK_ADJUST_PTR (sptr, ssize) - sizeof (long);
257	#elif __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 0 && defined (__mc68000__)
258	ctx->env[0].__jmpbuf[0].__aregs[0] = (long int)coro_init;
259	ctx->env[0].__jmpbuf[0].__sp = (int )((char )sptr + ssize) - sizeof (long);
260	#elif defined (__GNU_LIBRARY__) && defined (__i386__)
261	ctx->env[0].__jmpbuf[0].__pc = (char *)coro_init;
262	ctx->env[0].__jmpbuf[0].__sp = (void )((char )sptr + ssize) - sizeof (long);
263	#elif defined (__GNU_LIBRARY__) && defined (__amd64__)
264	ctx->env[0].__jmpbuf[JB_PC] = (long)coro_init;
265	ctx->env[0].__jmpbuf[0].__sp = (void )((char )sptr + ssize) - sizeof (long);
266	#else
267	#error "linux libc or architecture not supported"
268	#endif
269
270	# elif CORO_IRIX
271
272	sigsetjmp (ctx->env, 0);
273	ctx->env[JB_PC] = (__uint64_t)coro_init;
274	ctx->env[JB_SP] = (__uint64_t)STACK_ADJUST_PTR (sptr, ssize) - sizeof (long);
275
276	# elif CORO_ASM
277
278	ctx->sp = (void *)(ssize + (char )sptr);
279	--ctx->sp = (void )abort; /* needed for alignment only */
280	--ctx->sp = (void )coro_init;
281	ctx->sp -= NUM_SAVED;
282
283	# elif CORO_UCONTEXT
284
285	getcontext (&(ctx->uc));
286
287	ctx->uc.uc_link = 0;
288	ctx->uc.uc_stack.ss_sp = sptr;
289	ctx->uc.uc_stack.ss_size = (size_t)ssize;
290	ctx->uc.uc_stack.ss_flags = 0;
291
292	makecontext (&(ctx->uc), (void (*)())coro_init, 0);
293
294	# endif
295
296	coro_transfer (create_coro, new_coro);
297	}
298
299	/*****************************************************************************/
300	/* pthread backend */
301	/*****************************************************************************/
302	#elif CORO_PTHREAD
303
304	/* this mutex will be locked by the running coroutine */
305	pthread_mutex_t coro_mutex = PTHREAD_MUTEX_INITIALIZER;
306
307	struct coro_init_args
308	{
309	coro_func func;
310	void *arg;
311	coro_context self, main;
312	};
313
314	static pthread_t null_tid;
315
316	/* I'd so love to cast pthread_mutex_unlock to void ()(void )... */
317	static void
318	mutex_unlock_wrapper (void *arg)
319	{
320	pthread_mutex_unlock ((pthread_mutex_t *)arg);
321	}
322
323	static void *
324	coro_init (void *args_)
325	{
326	struct coro_init_args args = (struct coro_init_args )args_;
327	coro_func func = args->func;
328	void *arg = args->arg;
329
330	pthread_mutex_lock (&coro_mutex);
331
332	/* we try to be good citizens and use deferred cancellation and cleanup handlers */
333	pthread_cleanup_push (mutex_unlock_wrapper, &coro_mutex);
334	coro_transfer (args->self, args->main);
335	func (arg);
336	pthread_cleanup_pop (1);
337
338	return 0;
339	}
340
341	void
342	coro_transfer (coro_context prev, coro_context next)
343	{
344	pthread_cond_signal (&next->cv);
345	pthread_cond_wait (&prev->cv, &coro_mutex);
346	#if __FreeBSD__ /* freebsd is of course broken and needs manual testcancel calls... yay... */
347	pthread_testcancel ();
348	#endif
349	}
350
351	void
352	coro_create (coro_context ctx, coro_func coro, void arg, void *sptr, long ssize)
353	{
354	static coro_context nctx;
355	static int once;
356
357	if (!once)
358	{
359	once = 1;
360
361	pthread_mutex_lock (&coro_mutex);
362	pthread_cond_init (&nctx.cv, 0);
363	null_tid = pthread_self ();
364	}
365
366	pthread_cond_init (&ctx->cv, 0);
367
368	if (coro)
369	{
370	pthread_attr_t attr;
371	struct coro_init_args args;
372
373	args.func = coro;
374	args.arg = arg;
375	args.self = ctx;
376	args.main = &nctx;
377
378	pthread_attr_init (&attr);
379	pthread_attr_setstack (&attr, sptr, (size_t)ssize);
380	pthread_attr_setscope (&attr, PTHREAD_SCOPE_PROCESS);
381	pthread_create (&ctx->id, &attr, coro_init, &args);
382
383	coro_transfer (args.main, args.self);
384	}
385	else
386	ctx->id = null_tid;
387	}
388
389	void
390	coro_destroy (coro_context *ctx)
391	{
392	if (!pthread_equal (ctx->id, null_tid))
393	{
394	pthread_cancel (ctx->id);
395	pthread_mutex_unlock (&coro_mutex);
396	pthread_join (ctx->id, 0);
397	pthread_mutex_lock (&coro_mutex);
398	}
399
400	pthread_cond_destroy (&ctx->cv);
401	}
402
403	#else
404	# error unsupported backend
405	#endif
406