[bpt/guile.git] / libguile / async.c

/*	Copyright (C) 1995,1996 Free Software Foundation, Inc.
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this software; see the file COPYING.  If not, write to
 * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 * As a special exception, the Free Software Foundation gives permission
 * for additional uses of the text contained in its release of GUILE.
 *
 * The exception is that, if you link the GUILE library with other files
 * to produce an executable, this does not by itself cause the
 * resulting executable to be covered by the GNU General Public License.
 * Your use of that executable is in no way restricted on account of
 * linking the GUILE library code into it.
 *
 * This exception does not however invalidate any other reasons why
 * the executable file might be covered by the GNU General Public License.
 *
 * This exception applies only to the code released by the
 * Free Software Foundation under the name GUILE.  If you copy
 * code from other Free Software Foundation releases into a copy of
 * GUILE, as the General Public License permits, the exception does
 * not apply to the code that you add in this way.  To avoid misleading
 * anyone as to the status of such modified files, you must delete
 * this exception notice from them.
 *
 * If you write modifications of your own for GUILE, it is your choice
 * whether to permit this exception to apply to your modifications.
 * If you do not wish that, delete this exception notice.  
 */
\f

#include <stdio.h>
#include <signal.h>
#include "_scm.h"

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif


\f
/* {Asynchronous Events}
 *
 *
 * Async == thunk + mark.
 *
 * Setting the mark guarantees future execution of the thunk.  More
 * than one set may be satisfied by a single execution.
 * 
 * scm_tick_clock decremented once per SCM_ALLOW_INTS.
 * Async execution triggered by SCM_ALLOW_INTS when scm_tick_clock drops to 0.
 * Async execution prevented by scm_mask_ints != 0.
 *
 * If the clock reaches 0 when scm_mask_ints != 0, then reset the clock
 * to 1.
 *
 * If the clock reaches 0 any other time, run marked asyncs.
 *
 * From a unix signal handler, mark a corresponding async and set the clock
 * to 1.   Do SCM_REDEFER_INTS;/SCM_REALLOW_INTS so that if the signal handler is not
 * called in the dynamic scope of a critical section, it is excecuted immediately.
 *
 * Overall, closely timed signals of a particular sort may be combined.  Pending signals
 * are delivered in a fixed priority order, regardless of arrival order.
 *
 */


#define min(A,B) ((A) < (B) ? (A) : (B))


unsigned int scm_async_clock = 20;
static unsigned int scm_async_rate = 20;
unsigned int scm_mask_ints = 1;

static unsigned int scm_tick_clock = 0;
static unsigned int scm_tick_rate = 0;
static unsigned int scm_desired_tick_rate = 0;
static unsigned int scm_switch_clock = 0;
static unsigned int scm_switch_rate = 0;
static unsigned int scm_desired_switch_rate = 0;

static SCM system_signal_asyncs[SCM_NUM_SIGS];
static SCM handler_var;
static SCM symbol_signal;


struct scm_async
{
  int got_it;			/* needs to be delivered? */
  SCM thunk;			/* the handler. */
};


static long scm_tc16_async;

#define SCM_ASYNCP(X) 	(scm_tc16_async == SCM_GCTYP16 (X))
#define SCM_ASYNC(X) 	((struct scm_async *)SCM_CDR (X))


\f

#ifdef __STDC__
static int
asyncs_pending (void)
#else
static int
asyncs_pending ()
#endif
{
  SCM pos;
  pos = scm_asyncs;
  while (pos != SCM_EOL)
    {
      SCM a;
      struct scm_async * it;
      a = SCM_CAR (pos);
      it = SCM_ASYNC (a);
      if (it->got_it)
	return 1;
      pos = SCM_CDR (pos);
    }
  return 0;
}


#ifdef __STDC__
void
scm_async_click (void)
#else
void
scm_async_click ()
#endif
{
  int owe_switch;
  int owe_tick;

  if (!scm_switch_rate)
    {
      owe_switch = 0;
      scm_switch_clock = scm_switch_rate = scm_desired_switch_rate;
      scm_desired_switch_rate = 0;
    }
  else
    {
      owe_switch = (scm_async_rate >= scm_switch_clock);
      if (owe_switch)
	{
	  if (scm_desired_switch_rate)
	    {
	      scm_switch_clock = scm_switch_rate = scm_desired_switch_rate;
	      scm_desired_switch_rate = 0;
	    }
	  else
	    scm_switch_clock = scm_switch_rate;
	}
      else
	{
	  if (scm_desired_switch_rate)
	    {
	      scm_switch_clock = scm_switch_rate = scm_desired_switch_rate;
	      scm_desired_switch_rate = 0;
	    }
	  else
	    scm_switch_clock -= scm_async_rate;
	}
    }

  if (scm_mask_ints)
    {
      if (owe_switch)
	scm_switch ();
      scm_async_clock = 1;
      return;;
    }
  
  if (!scm_tick_rate)
    {
      unsigned int r;
      owe_tick = 0;
      r = scm_desired_tick_rate;
      if (r)
	{
	  scm_desired_tick_rate = 0;
	  scm_tick_rate = r;
	  scm_tick_clock = r;
	}
    }
  else
    {
      owe_tick = (scm_async_rate >= scm_tick_clock);
      if (owe_tick)
	{
	  scm_tick_clock = scm_tick_rate = scm_desired_tick_rate;
	  scm_desired_tick_rate = 0;
	}
      else
	{
	  if (scm_desired_tick_rate)
	    {
	      scm_tick_clock = scm_tick_rate = scm_desired_tick_rate;
	      scm_desired_tick_rate = 0;
	    }
	  else
	    scm_tick_clock -= scm_async_rate;
	}
    }

  if (owe_tick)
    scm_async_mark (system_signal_asyncs[SCM_SIG_ORD(SCM_TICK_SIGNAL)]);

  SCM_DEFER_INTS;
  if (scm_tick_rate && scm_switch_rate)
    {
      scm_async_rate = min (scm_tick_clock,  scm_switch_clock);
      scm_async_clock = scm_async_rate;
    }
  else if (scm_tick_rate)
    {
      scm_async_clock = scm_async_rate = scm_tick_clock;
    }
  else if (scm_switch_rate)
    {
      scm_async_clock = scm_async_rate = scm_switch_clock;
    }
  else
    scm_async_clock = scm_async_rate = 1 << 16;
  SCM_ALLOW_INTS_ONLY;

 tail:
  scm_run_asyncs (scm_asyncs);

  SCM_DEFER_INTS;
  if (asyncs_pending ())
    {
      SCM_ALLOW_INTS_ONLY;
      goto tail;
    }
  SCM_ALLOW_INTS;

  if (owe_switch)
    scm_switch ();
}


\f

#ifdef __STDC__
void
scm_switch (void)
#else
void
scm_switch ()
#endif
{}


#ifdef __STDC__
static void
scm_deliver_signal (int num)
#else
static void
scm_deliver_signal (num)
     int num;
#endif
{
  SCM handler;
  handler = SCM_CDR (handler_var);
  if (handler != SCM_BOOL_F)
    scm_apply (handler, SCM_MAKINUM (num), scm_listofnull);
  else
    {
      scm_mask_ints = 0;
      scm_throw (symbol_signal,
			   scm_listify (SCM_MAKINUM (num), SCM_UNDEFINED));
    }
}


\f

#ifdef __STDC__
static int
print_async (SCM exp, SCM port, int writing)
#else
static int
print_async (exp, port, writing)
     SCM exp;
     SCM port;
     int writing;
#endif
{
  scm_gen_puts (scm_regular_string, "#<async ", port);
  scm_intprint(exp, 16, port);
  scm_gen_putc('>', port);
  return 1;
}

#ifdef __STDC__
static SCM
mark_async (SCM obj)
#else
static SCM
mark_async (obj)
     SCM obj;
#endif
{
  struct scm_async * it;
  if (SCM_GC8MARKP (obj))
    return SCM_BOOL_F;
  SCM_SETGC8MARK (obj);
  it = SCM_ASYNC (obj);
  return it->thunk;
}

#ifdef __STDC__
static scm_sizet
free_async (SCM obj)
#else
static scm_sizet
free_async (SCM obj)
     SCM obj;
#endif
{
  struct scm_async * it;
  it = SCM_ASYNC (obj);
  scm_must_free ((char *)it);
  return (sizeof (*it));
}


static scm_smobfuns  async_smob =
{
  mark_async,
  free_async,
  print_async,
  0
};


\f

SCM_PROC(s_async, "async", 1, 0, 0, scm_async);
#ifdef __STDC__
SCM
scm_async (SCM thunk)
#else
SCM
scm_async (thunk)
     SCM thunk;
#endif
{
  SCM it;
  struct scm_async * async;

  SCM_NEWCELL (it);
  SCM_DEFER_INTS;
  SCM_SETCDR (it, SCM_EOL);
  async = (struct scm_async *)scm_must_malloc (sizeof (*async), s_async);
  async->got_it = 0;
  async->thunk = thunk;
  SCM_SETCDR (it, (SCM)async);
  SCM_SETCAR (it, (SCM)scm_tc16_async);
  SCM_ALLOW_INTS;
  return it;
}

SCM_PROC(s_system_async, "system-async", 1, 0, 0, scm_system_async);
#ifdef __STDC__
SCM 
scm_system_async (SCM thunk)
#else
SCM 
scm_system_async (thunk)
     SCM thunk;
#endif
{
  SCM it;
  SCM list;

  it = scm_async (thunk);
  SCM_NEWCELL (list);
  SCM_DEFER_INTS;
  SCM_SETCAR (list, it);
  SCM_SETCDR (list, scm_asyncs);
  scm_asyncs = list;
  SCM_ALLOW_INTS;
  return it;
}

SCM_PROC(s_async_mark, "async-mark", 1, 0, 0, scm_async_mark);
#ifdef __STDC__
SCM
scm_async_mark (SCM a)
#else
SCM
scm_async_mark (a)
     SCM a;
#endif
{
  struct scm_async * it;
  SCM_ASSERT (SCM_NIMP (a) &&  SCM_ASYNCP (a), a, SCM_ARG1, s_async_mark);
  it = SCM_ASYNC (a);
  it->got_it = 1;
  return SCM_UNSPECIFIED;
}


SCM_PROC(s_system_async_mark, "system-async-mark", 1, 0, 0, scm_system_async_mark);
#ifdef __STDC__
SCM
scm_system_async_mark (SCM a)
#else
SCM
scm_system_async_mark (a)
     SCM a;
#endif
{
  struct scm_async * it;
  SCM_ASSERT (SCM_NIMP (a) &&  SCM_ASYNCP (a), a, SCM_ARG1, s_async_mark);
  it = SCM_ASYNC (a);
  SCM_REDEFER_INTS;
  it->got_it = 1;
  scm_async_rate = 1 + scm_async_rate - scm_async_clock;
  scm_async_clock = 1;
  SCM_REALLOW_INTS;
  return SCM_UNSPECIFIED;
}


SCM_PROC(s_run_asyncs, "run-asyncs", 1, 0, 0, scm_run_asyncs);
#ifdef __STDC__
SCM
scm_run_asyncs (SCM list_of_a)
#else
SCM
scm_run_asyncs (list_of_a)
     SCM list_of_a;
#endif
{
  SCM pos;

  if (scm_mask_ints)
    return SCM_BOOL_F;
  pos = list_of_a;
  while (pos != SCM_EOL)
    {
      SCM a;
      struct scm_async * it;
      SCM_ASSERT (SCM_NIMP (pos) && SCM_CONSP (pos), pos, SCM_ARG1, s_run_asyncs);
      a = SCM_CAR (pos);
      SCM_ASSERT (SCM_NIMP (a) &&  SCM_ASYNCP (a), a, SCM_ARG1, s_run_asyncs);
      it = SCM_ASYNC (a);
      scm_mask_ints = 1;
      if (it->got_it)
	{
	  it->got_it = 0;
	  scm_apply (it->thunk, SCM_EOL, SCM_EOL);
	}
      scm_mask_ints = 0;
      pos = SCM_CDR (pos);
    }
  return SCM_BOOL_T;
}

\f


SCM_PROC(s_noop, "noop", 0, 0, 1, scm_noop);
#ifdef __STDC__
SCM
scm_noop (SCM args)
#else
SCM
scm_noop (args)
     SCM args;
#endif
{
  return (SCM_NULLP (args)
	  ? SCM_BOOL_F
	  : SCM_CAR (args));
}


\f

SCM_PROC(s_set_tick_rate, "set-tick-rate", 1, 0, 0, scm_set_tick_rate);
#ifdef __STDC__
SCM
scm_set_tick_rate (SCM n)
#else
SCM
scm_set_tick_rate (n)
     SCM n;
#endif
{
  unsigned int old_n;
  SCM_ASSERT (SCM_INUMP (n), n, SCM_ARG1, s_set_tick_rate);
  old_n = scm_tick_rate;
  scm_desired_tick_rate = SCM_INUM (n);
  scm_async_rate = 1 + scm_async_rate - scm_async_clock;
  scm_async_clock = 1;
  return SCM_MAKINUM (old_n);
}

\f


SCM_PROC(s_set_switch_rate, "set-switch-rate", 1, 0, 0, scm_set_switch_rate);
#ifdef __STDC__
SCM
scm_set_switch_rate (SCM n)
#else
SCM
scm_set_switch_rate (n)
     SCM n;
#endif
{
  unsigned int old_n;
  SCM_ASSERT (SCM_INUMP (n), n, SCM_ARG1, s_set_switch_rate);
  old_n = scm_switch_rate;
  scm_desired_switch_rate = SCM_INUM (n);
  scm_async_rate = 1 + scm_async_rate - scm_async_clock;
  scm_async_clock = 1;
  return SCM_MAKINUM (old_n);
}

\f

#ifdef __STDC__
static SCM
scm_sys_hup_async_thunk (void)
#else
static SCM
scm_sys_hup_async_thunk ()
#endif
{
  scm_deliver_signal (SCM_HUP_SIGNAL);
  return SCM_BOOL_F;
}

#ifdef __STDC__
static SCM
scm_sys_int_async_thunk (void)
#else
static SCM
scm_sys_int_async_thunk ()
#endif
{
  scm_deliver_signal (SCM_INT_SIGNAL);
  return SCM_BOOL_F;
}

#ifdef __STDC__
static SCM
scm_sys_fpe_async_thunk (void)
#else
static SCM
scm_sys_fpe_async_thunk ()
#endif
{
  scm_deliver_signal (SCM_FPE_SIGNAL);
  return SCM_BOOL_F;
}

#ifdef __STDC__
static SCM
scm_sys_bus_async_thunk (void)
#else
static SCM
scm_sys_bus_async_thunk ()
#endif
{
  scm_deliver_signal (SCM_BUS_SIGNAL);
  return SCM_BOOL_F;
}

#ifdef __STDC__
static SCM
scm_sys_segv_async_thunk (void)
#else
static SCM
scm_sys_segv_async_thunk ()
#endif
{
  scm_deliver_signal (SCM_SEGV_SIGNAL);
  return SCM_BOOL_F;
}

#ifdef __STDC__
static SCM
scm_sys_alrm_async_thunk (void)
#else
static SCM
scm_sys_alrm_async_thunk ()
#endif
{
  scm_deliver_signal (SCM_ALRM_SIGNAL);
  return SCM_BOOL_F;
}

#ifdef __STDC__
static SCM
scm_sys_gc_async_thunk (void)
#else
static SCM
scm_sys_gc_async_thunk ()
#endif
{
  scm_deliver_signal (SCM_GC_SIGNAL);
  return SCM_BOOL_F;
}

#ifdef __STDC__
static SCM
scm_sys_tick_async_thunk (void)
#else
static SCM
scm_sys_tick_async_thunk ()
#endif
{
  scm_deliver_signal (SCM_TICK_SIGNAL);
  return SCM_BOOL_F;
}


\f

#ifdef __STDC__
SCM
scm_take_signal (int n)
#else
SCM
scm_take_signal (n)
     int n;
#endif
{
  SCM ignored;
  if (!scm_ints_disabled)
    {
      SCM_NEWCELL (ignored);		/* In case we interrupted SCM_NEWCELL,
					 * throw out the possibly already allocated
					 * free cell.
					 */
    }
  scm_system_async_mark (system_signal_asyncs[SCM_SIG_ORD(n)]);
  return SCM_BOOL_F;
}

\f

SCM_PROC(s_unmask_signals, "unmask-signals", 0, 0, 0, scm_unmask_signals);
#ifdef __STDC__
SCM
scm_unmask_signals (void)
#else
SCM
scm_unmask_signals ()
#endif
{
  scm_mask_ints = 0;
  return SCM_UNSPECIFIED;
}


SCM_PROC(s_mask_signals, "mask-signals", 0, 0, 0, scm_mask_signals);
#ifdef __STDC__
SCM
scm_mask_signals (void)
#else
SCM
scm_mask_signals ()
#endif
{
  scm_mask_ints = 1;
  return SCM_UNSPECIFIED;
}

\f

#ifdef __STDC__
void
scm_init_async (void)
#else
void
scm_init_async ()
#endif
{
  SCM a_thunk;
  scm_tc16_async = scm_newsmob (&async_smob);
  symbol_signal = SCM_CAR (scm_sysintern ("signal", strlen ("signal")));
  scm_permanent_object (symbol_signal);

  /* These are in the opposite order of delivery priortity. 
   *
   * Error conditions are given low priority:
   */
  a_thunk = scm_make_gsubr ("%hup-thunk", 0, 0, 0, scm_sys_hup_async_thunk);
  system_signal_asyncs[SCM_SIG_ORD(SCM_HUP_SIGNAL)] = scm_system_async (a_thunk);
  a_thunk = scm_make_gsubr ("%int-thunk", 0, 0, 0, scm_sys_int_async_thunk);
  system_signal_asyncs[SCM_SIG_ORD(SCM_INT_SIGNAL)] = scm_system_async (a_thunk);
  a_thunk = scm_make_gsubr ("%fpe-thunk", 0, 0, 0, scm_sys_fpe_async_thunk);
  system_signal_asyncs[SCM_SIG_ORD(SCM_FPE_SIGNAL)] = scm_system_async (a_thunk);
  a_thunk = scm_make_gsubr ("%bus-thunk", 0, 0, 0, scm_sys_bus_async_thunk);
  system_signal_asyncs[SCM_SIG_ORD(SCM_BUS_SIGNAL)] = scm_system_async (a_thunk);
  a_thunk = scm_make_gsubr ("%segv-thunk", 0, 0, 0, scm_sys_segv_async_thunk);
  system_signal_asyncs[SCM_SIG_ORD(SCM_SEGV_SIGNAL)] = scm_system_async (a_thunk);


  a_thunk = scm_make_gsubr ("%gc-thunk", 0, 0, 0, scm_sys_gc_async_thunk);
  system_signal_asyncs[SCM_SIG_ORD(SCM_GC_SIGNAL)] = scm_system_async (a_thunk);

  /* Clock and PC driven conditions are given highest priority. */
  a_thunk = scm_make_gsubr ("%tick-thunk", 0, 0, 0, scm_sys_tick_async_thunk);
  system_signal_asyncs[SCM_SIG_ORD(SCM_TICK_SIGNAL)] = scm_system_async (a_thunk);
  a_thunk = scm_make_gsubr ("%alrm-thunk", 0, 0, 0, scm_sys_alrm_async_thunk);
  system_signal_asyncs[SCM_SIG_ORD(SCM_ALRM_SIGNAL)] = scm_system_async (a_thunk);

  handler_var = scm_sysintern ("signal-handler", strlen ("signal"));
  SCM_SETCDR (handler_var, SCM_BOOL_F);
  scm_permanent_object (handler_var);
#include "async.x"
}
Commit	Line	Data
0f2d19dd JB	1	/* Copyright (C) 1995,1996 Free Software Foundation, Inc.
	2	*
	3	* This program is free software; you can redistribute it and/or modify
	4	* it under the terms of the GNU General Public License as published by
	5	* the Free Software Foundation; either version 2, or (at your option)
	6	* any later version.
	7	*
	8	* This program is distributed in the hope that it will be useful,
	9	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	10	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	11	* GNU General Public License for more details.
	12	*
	13	* You should have received a copy of the GNU General Public License
	14	* along with this software; see the file COPYING. If not, write to
	15	* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
	16	*
	17	* As a special exception, the Free Software Foundation gives permission
	18	* for additional uses of the text contained in its release of GUILE.
	19	*
	20	* The exception is that, if you link the GUILE library with other files
	21	* to produce an executable, this does not by itself cause the
	22	* resulting executable to be covered by the GNU General Public License.
	23	* Your use of that executable is in no way restricted on account of
	24	* linking the GUILE library code into it.
	25	*
	26	* This exception does not however invalidate any other reasons why
	27	* the executable file might be covered by the GNU General Public License.
	28	*
	29	* This exception applies only to the code released by the
	30	* Free Software Foundation under the name GUILE. If you copy
	31	* code from other Free Software Foundation releases into a copy of
	32	* GUILE, as the General Public License permits, the exception does
	33	* not apply to the code that you add in this way. To avoid misleading
	34	* anyone as to the status of such modified files, you must delete
	35	* this exception notice from them.
	36	*
	37	* If you write modifications of your own for GUILE, it is your choice
	38	* whether to permit this exception to apply to your modifications.
	39	* If you do not wish that, delete this exception notice.
	40	*/
	41	\f
	42
	43	#include <stdio.h>
	44	#include <signal.h>
	45	#include "_scm.h"
	46
	47	#ifdef HAVE_UNISTD_H
	48	#include <unistd.h>
	49	#endif
	50
	51
	52	\f
	53	/* {Asynchronous Events}
	54	*
	55	*
	56	* Async == thunk + mark.
	57	*
	58	* Setting the mark guarantees future execution of the thunk. More
	59	* than one set may be satisfied by a single execution.
	60	*
	61	* scm_tick_clock decremented once per SCM_ALLOW_INTS.
	62	* Async execution triggered by SCM_ALLOW_INTS when scm_tick_clock drops to 0.
	63	* Async execution prevented by scm_mask_ints != 0.
	64	*
65	* If the clock reaches 0 when scm_mask_ints != 0, then reset the clock
66	* to 1.
67	*
68	* If the clock reaches 0 any other time, run marked asyncs.
69	*
70	* From a unix signal handler, mark a corresponding async and set the clock
71	* to 1. Do SCM_REDEFER_INTS;/SCM_REALLOW_INTS so that if the signal handler is not
72	* called in the dynamic scope of a critical section, it is excecuted immediately.
73	*
74	* Overall, closely timed signals of a particular sort may be combined. Pending signals
75	* are delivered in a fixed priority order, regardless of arrival order.
76	*
77	*/
78
79
80	#define min(A,B) ((A) < (B) ? (A) : (B))
81
82
83	unsigned int scm_async_clock = 20;
84	static unsigned int scm_async_rate = 20;
85	unsigned int scm_mask_ints = 1;
86
87	static unsigned int scm_tick_clock = 0;
88	static unsigned int scm_tick_rate = 0;
89	static unsigned int scm_desired_tick_rate = 0;
90	static unsigned int scm_switch_clock = 0;
91	static unsigned int scm_switch_rate = 0;
92	static unsigned int scm_desired_switch_rate = 0;
93
94	static SCM system_signal_asyncs[SCM_NUM_SIGS];
95	static SCM handler_var;
96	static SCM symbol_signal;
97
98
99	struct scm_async
100	{
101	int got_it; /* needs to be delivered? */
102	SCM thunk; /* the handler. */
103	};
104
105
106	static long scm_tc16_async;
107
108	#define SCM_ASYNCP(X) (scm_tc16_async == SCM_GCTYP16 (X))
109	#define SCM_ASYNC(X) ((struct scm_async *)SCM_CDR (X))
110
111
112
113
114	\f
115
116	#ifdef __STDC__
117	static int
118	asyncs_pending (void)
119	#else
120	static int
121	asyncs_pending ()
122	#endif
123	{
124	SCM pos;
125	pos = scm_asyncs;
126	while (pos != SCM_EOL)
127	{
128	SCM a;
129	struct scm_async * it;
130	a = SCM_CAR (pos);
131	it = SCM_ASYNC (a);
132	if (it->got_it)
133	return 1;
134	pos = SCM_CDR (pos);
135	}
136	return 0;
137	}
138
139
140	#ifdef __STDC__
141	void
142	scm_async_click (void)
143	#else
144	void
145	scm_async_click ()
146	#endif
147	{
148	int owe_switch;
149	int owe_tick;
150
151	if (!scm_switch_rate)
152	{
153	owe_switch = 0;
154	scm_switch_clock = scm_switch_rate = scm_desired_switch_rate;
155	scm_desired_switch_rate = 0;
156	}
157	else
158	{
159	owe_switch = (scm_async_rate >= scm_switch_clock);
160	if (owe_switch)
161	{
162	if (scm_desired_switch_rate)
163	{
164	scm_switch_clock = scm_switch_rate = scm_desired_switch_rate;
165	scm_desired_switch_rate = 0;
166	}
167	else
168	scm_switch_clock = scm_switch_rate;
169	}
170	else
171	{
172	if (scm_desired_switch_rate)
173	{
174	scm_switch_clock = scm_switch_rate = scm_desired_switch_rate;
175	scm_desired_switch_rate = 0;
176	}
177	else
178	scm_switch_clock -= scm_async_rate;
179	}
180	}
181
182	if (scm_mask_ints)
183	{
184	if (owe_switch)
185	scm_switch ();
186	scm_async_clock = 1;
187	return;;
188	}
189
190	if (!scm_tick_rate)
191	{
192	unsigned int r;
193	owe_tick = 0;
194	r = scm_desired_tick_rate;
195	if (r)
196	{
197	scm_desired_tick_rate = 0;
198	scm_tick_rate = r;
199	scm_tick_clock = r;
200	}
201	}
202	else
203	{
204	owe_tick = (scm_async_rate >= scm_tick_clock);
205	if (owe_tick)
206	{
207	scm_tick_clock = scm_tick_rate = scm_desired_tick_rate;
208	scm_desired_tick_rate = 0;
209	}
210	else
211	{
212	if (scm_desired_tick_rate)
213	{
214	scm_tick_clock = scm_tick_rate = scm_desired_tick_rate;
215	scm_desired_tick_rate = 0;
216	}
217	else
218	scm_tick_clock -= scm_async_rate;
219	}
220	}
221
222	if (owe_tick)
223	scm_async_mark (system_signal_asyncs[SCM_SIG_ORD(SCM_TICK_SIGNAL)]);
224
225	SCM_DEFER_INTS;
226	if (scm_tick_rate && scm_switch_rate)
227	{
228	scm_async_rate = min (scm_tick_clock, scm_switch_clock);
229	scm_async_clock = scm_async_rate;
230	}
231	else if (scm_tick_rate)
232	{
233	scm_async_clock = scm_async_rate = scm_tick_clock;
234	}
235	else if (scm_switch_rate)
236	{
237	scm_async_clock = scm_async_rate = scm_switch_clock;
238	}
239	else
240	scm_async_clock = scm_async_rate = 1 << 16;
241	SCM_ALLOW_INTS_ONLY;
242
243	tail:
244	scm_run_asyncs (scm_asyncs);
245
246	SCM_DEFER_INTS;
247	if (asyncs_pending ())
248	{
249	SCM_ALLOW_INTS_ONLY;
250	goto tail;
251	}
252	SCM_ALLOW_INTS;
253
254	if (owe_switch)
255	scm_switch ();
256	}
257
258
259	\f
260
261	#ifdef __STDC__
262	void
263	scm_switch (void)
264	#else
265	void
266	scm_switch ()
267	#endif
268	{}
269
270
271	#ifdef __STDC__
272	static void
273	scm_deliver_signal (int num)
274	#else
275	static void
276	scm_deliver_signal (num)
277	int num;
278	#endif
279	{
280	SCM handler;
281	handler = SCM_CDR (handler_var);
282	if (handler != SCM_BOOL_F)
283	scm_apply (handler, SCM_MAKINUM (num), scm_listofnull);
284	else
285	{
286	scm_mask_ints = 0;
287	scm_throw (symbol_signal,
288	scm_listify (SCM_MAKINUM (num), SCM_UNDEFINED));
289	}
290	}
291
292
293	\f
294
295	#ifdef __STDC__
296	static int
297	print_async (SCM exp, SCM port, int writing)
298	#else
299	static int
300	print_async (exp, port, writing)
301	SCM exp;
302	SCM port;
303	int writing;
304	#endif
305	{
306	scm_gen_puts (scm_regular_string, "#<async ", port);
307	scm_intprint(exp, 16, port);
308	scm_gen_putc('>', port);
309	return 1;
310	}
311
312	#ifdef __STDC__
313	static SCM
314	mark_async (SCM obj)
315	#else
316	static SCM
317	mark_async (obj)
318	SCM obj;
319	#endif
320	{
321	struct scm_async * it;
322	if (SCM_GC8MARKP (obj))
323	return SCM_BOOL_F;
324	SCM_SETGC8MARK (obj);
325	it = SCM_ASYNC (obj);
326	return it->thunk;
327	}
328
329	#ifdef __STDC__
330	static scm_sizet
331	free_async (SCM obj)
332	#else
333	static scm_sizet
334	free_async (SCM obj)
335	SCM obj;
336	#endif
337	{
338	struct scm_async * it;
339	it = SCM_ASYNC (obj);
340	scm_must_free ((char *)it);
341	return (sizeof (*it));
342	}
343
344
345	static scm_smobfuns async_smob =
346	{
347	mark_async,
348	free_async,
349	print_async,
350	0
351	};
352
353
354	\f
355
356	SCM_PROC(s_async, "async", 1, 0, 0, scm_async);
357	#ifdef __STDC__
358	SCM
359	scm_async (SCM thunk)
360	#else
361	SCM
362	scm_async (thunk)
363	SCM thunk;
364	#endif
365	{
366	SCM it;
367	struct scm_async * async;
368
369	SCM_NEWCELL (it);
370	SCM_DEFER_INTS;
371	SCM_SETCDR (it, SCM_EOL);
372	async = (struct scm_async )scm_must_malloc (sizeof (async), s_async);
373	async->got_it = 0;
374	async->thunk = thunk;
375	SCM_SETCDR (it, (SCM)async);
376	SCM_SETCAR (it, (SCM)scm_tc16_async);
377	SCM_ALLOW_INTS;
378	return it;
379	}
380
381	SCM_PROC(s_system_async, "system-async", 1, 0, 0, scm_system_async);
382	#ifdef __STDC__
383	SCM
384	scm_system_async (SCM thunk)
385	#else
386	SCM
387	scm_system_async (thunk)
388	SCM thunk;
389	#endif
390	{
391	SCM it;
392	SCM list;
393
394	it = scm_async (thunk);
395	SCM_NEWCELL (list);
396	SCM_DEFER_INTS;
397	SCM_SETCAR (list, it);
398	SCM_SETCDR (list, scm_asyncs);
399	scm_asyncs = list;
400	SCM_ALLOW_INTS;
401	return it;
402	}
403
404	SCM_PROC(s_async_mark, "async-mark", 1, 0, 0, scm_async_mark);
405	#ifdef __STDC__
406	SCM
407	scm_async_mark (SCM a)
408	#else
409	SCM
410	scm_async_mark (a)
411	SCM a;
412	#endif
413	{
414	struct scm_async * it;
415	SCM_ASSERT (SCM_NIMP (a) && SCM_ASYNCP (a), a, SCM_ARG1, s_async_mark);
416	it = SCM_ASYNC (a);
417	it->got_it = 1;
418	return SCM_UNSPECIFIED;
419	}
420
421
422	SCM_PROC(s_system_async_mark, "system-async-mark", 1, 0, 0, scm_system_async_mark);
423	#ifdef __STDC__
424	SCM
425	scm_system_async_mark (SCM a)
426	#else
427	SCM
428	scm_system_async_mark (a)
429	SCM a;
430	#endif
431	{
432	struct scm_async * it;
433	SCM_ASSERT (SCM_NIMP (a) && SCM_ASYNCP (a), a, SCM_ARG1, s_async_mark);
434	it = SCM_ASYNC (a);
435	SCM_REDEFER_INTS;
436	it->got_it = 1;
437	scm_async_rate = 1 + scm_async_rate - scm_async_clock;
438	scm_async_clock = 1;
439	SCM_REALLOW_INTS;
440	return SCM_UNSPECIFIED;
441	}
442
443
444	SCM_PROC(s_run_asyncs, "run-asyncs", 1, 0, 0, scm_run_asyncs);
445	#ifdef __STDC__
446	SCM
447	scm_run_asyncs (SCM list_of_a)
448	#else
449	SCM
450	scm_run_asyncs (list_of_a)
451	SCM list_of_a;
452	#endif
453	{
454	SCM pos;
455
456	if (scm_mask_ints)
457	return SCM_BOOL_F;
458	pos = list_of_a;
459	while (pos != SCM_EOL)
460	{
461	SCM a;
462	struct scm_async * it;
463	SCM_ASSERT (SCM_NIMP (pos) && SCM_CONSP (pos), pos, SCM_ARG1, s_run_asyncs);
464	a = SCM_CAR (pos);
465	SCM_ASSERT (SCM_NIMP (a) && SCM_ASYNCP (a), a, SCM_ARG1, s_run_asyncs);
466	it = SCM_ASYNC (a);
467	scm_mask_ints = 1;
468	if (it->got_it)
469	{
470	it->got_it = 0;
471	scm_apply (it->thunk, SCM_EOL, SCM_EOL);
472	}
473	scm_mask_ints = 0;
474	pos = SCM_CDR (pos);
475	}
476	return SCM_BOOL_T;
477	}
478
479	\f
480
481
482	SCM_PROC(s_noop, "noop", 0, 0, 1, scm_noop);
483	#ifdef __STDC__
484	SCM
485	scm_noop (SCM args)
486	#else
487	SCM
488	scm_noop (args)
489	SCM args;
490	#endif
491	{
492	return (SCM_NULLP (args)
493	? SCM_BOOL_F
494	: SCM_CAR (args));
495	}
496
497
498	\f
499
500	SCM_PROC(s_set_tick_rate, "set-tick-rate", 1, 0, 0, scm_set_tick_rate);
501	#ifdef __STDC__
502	SCM
503	scm_set_tick_rate (SCM n)
504	#else
505	SCM
506	scm_set_tick_rate (n)
507	SCM n;
508	#endif
509	{
510	unsigned int old_n;
511	SCM_ASSERT (SCM_INUMP (n), n, SCM_ARG1, s_set_tick_rate);
512	old_n = scm_tick_rate;
513	scm_desired_tick_rate = SCM_INUM (n);
514	scm_async_rate = 1 + scm_async_rate - scm_async_clock;
515	scm_async_clock = 1;
516	return SCM_MAKINUM (old_n);
517	}
518
519	\f
520
521
522	SCM_PROC(s_set_switch_rate, "set-switch-rate", 1, 0, 0, scm_set_switch_rate);
523	#ifdef __STDC__
524	SCM
525	scm_set_switch_rate (SCM n)
526	#else
527	SCM
528	scm_set_switch_rate (n)
529	SCM n;
530	#endif
531	{
532	unsigned int old_n;
533	SCM_ASSERT (SCM_INUMP (n), n, SCM_ARG1, s_set_switch_rate);
534	old_n = scm_switch_rate;
535	scm_desired_switch_rate = SCM_INUM (n);
536	scm_async_rate = 1 + scm_async_rate - scm_async_clock;
537	scm_async_clock = 1;
538	return SCM_MAKINUM (old_n);
539	}
540
541	\f
542
543	#ifdef __STDC__
544	static SCM
545	scm_sys_hup_async_thunk (void)
546	#else
547	static SCM
548	scm_sys_hup_async_thunk ()
549	#endif
550	{
551	scm_deliver_signal (SCM_HUP_SIGNAL);
552	return SCM_BOOL_F;
553	}
554
555	#ifdef __STDC__
556	static SCM
557	scm_sys_int_async_thunk (void)
558	#else
559	static SCM
560	scm_sys_int_async_thunk ()
561	#endif
562	{
563	scm_deliver_signal (SCM_INT_SIGNAL);
564	return SCM_BOOL_F;
565	}
566
567	#ifdef __STDC__
568	static SCM
569	scm_sys_fpe_async_thunk (void)
570	#else
571	static SCM
572	scm_sys_fpe_async_thunk ()
573	#endif
574	{
575	scm_deliver_signal (SCM_FPE_SIGNAL);
576	return SCM_BOOL_F;
577	}
578
579	#ifdef __STDC__
580	static SCM
581	scm_sys_bus_async_thunk (void)
582	#else
583	static SCM
584	scm_sys_bus_async_thunk ()
585	#endif
586	{
587	scm_deliver_signal (SCM_BUS_SIGNAL);
588	return SCM_BOOL_F;
589	}
590
591	#ifdef __STDC__
592	static SCM
593	scm_sys_segv_async_thunk (void)
594	#else
595	static SCM
596	scm_sys_segv_async_thunk ()
597	#endif
598	{
599	scm_deliver_signal (SCM_SEGV_SIGNAL);
600	return SCM_BOOL_F;
601	}
602
603	#ifdef __STDC__
604	static SCM
605	scm_sys_alrm_async_thunk (void)
606	#else
607	static SCM
608	scm_sys_alrm_async_thunk ()
609	#endif
610	{
611	scm_deliver_signal (SCM_ALRM_SIGNAL);
612	return SCM_BOOL_F;
613	}
614
615	#ifdef __STDC__
616	static SCM
617	scm_sys_gc_async_thunk (void)
618	#else
619	static SCM
620	scm_sys_gc_async_thunk ()
621	#endif
622	{
623	scm_deliver_signal (SCM_GC_SIGNAL);
624	return SCM_BOOL_F;
625	}
626
627	#ifdef __STDC__
628	static SCM
629	scm_sys_tick_async_thunk (void)
630	#else
631	static SCM
632	scm_sys_tick_async_thunk ()
633	#endif
634	{
635	scm_deliver_signal (SCM_TICK_SIGNAL);
636	return SCM_BOOL_F;
637	}
638
639
640
641	\f
642
643	#ifdef __STDC__
644	SCM
645	scm_take_signal (int n)
646	#else
647	SCM
648	scm_take_signal (n)
649	int n;
650	#endif
651	{
652	SCM ignored;
653	if (!scm_ints_disabled)
654	{
655	SCM_NEWCELL (ignored); /* In case we interrupted SCM_NEWCELL,
656	* throw out the possibly already allocated
657	* free cell.
658	*/
659	}
660	scm_system_async_mark (system_signal_asyncs[SCM_SIG_ORD(n)]);
661	return SCM_BOOL_F;
662	}
663
664	\f
665
666	SCM_PROC(s_unmask_signals, "unmask-signals", 0, 0, 0, scm_unmask_signals);
667	#ifdef __STDC__
668	SCM
669	scm_unmask_signals (void)
670	#else
671	SCM
672	scm_unmask_signals ()
673	#endif
674	{
675	scm_mask_ints = 0;
676	return SCM_UNSPECIFIED;
677	}
678
679
680	SCM_PROC(s_mask_signals, "mask-signals", 0, 0, 0, scm_mask_signals);
681	#ifdef __STDC__
682	SCM
683	scm_mask_signals (void)
684	#else
685	SCM
686	scm_mask_signals ()
687	#endif
688	{
689	scm_mask_ints = 1;
690	return SCM_UNSPECIFIED;
691	}
692
693	\f
694
695	#ifdef __STDC__
696	void
697	scm_init_async (void)
698	#else
699	void
700	scm_init_async ()
701	#endif
702	{
703	SCM a_thunk;
704	scm_tc16_async = scm_newsmob (&async_smob);
705	symbol_signal = SCM_CAR (scm_sysintern ("signal", strlen ("signal")));
706	scm_permanent_object (symbol_signal);
707
708	/* These are in the opposite order of delivery priortity.
709	*
710	* Error conditions are given low priority:
711	*/
712	a_thunk = scm_make_gsubr ("%hup-thunk", 0, 0, 0, scm_sys_hup_async_thunk);
713	system_signal_asyncs[SCM_SIG_ORD(SCM_HUP_SIGNAL)] = scm_system_async (a_thunk);
714	a_thunk = scm_make_gsubr ("%int-thunk", 0, 0, 0, scm_sys_int_async_thunk);
715	system_signal_asyncs[SCM_SIG_ORD(SCM_INT_SIGNAL)] = scm_system_async (a_thunk);
716	a_thunk = scm_make_gsubr ("%fpe-thunk", 0, 0, 0, scm_sys_fpe_async_thunk);
717	system_signal_asyncs[SCM_SIG_ORD(SCM_FPE_SIGNAL)] = scm_system_async (a_thunk);
718	a_thunk = scm_make_gsubr ("%bus-thunk", 0, 0, 0, scm_sys_bus_async_thunk);
719	system_signal_asyncs[SCM_SIG_ORD(SCM_BUS_SIGNAL)] = scm_system_async (a_thunk);
720	a_thunk = scm_make_gsubr ("%segv-thunk", 0, 0, 0, scm_sys_segv_async_thunk);
721	system_signal_asyncs[SCM_SIG_ORD(SCM_SEGV_SIGNAL)] = scm_system_async (a_thunk);
722
723
724	a_thunk = scm_make_gsubr ("%gc-thunk", 0, 0, 0, scm_sys_gc_async_thunk);
725	system_signal_asyncs[SCM_SIG_ORD(SCM_GC_SIGNAL)] = scm_system_async (a_thunk);
726
727	/* Clock and PC driven conditions are given highest priority. */
728	a_thunk = scm_make_gsubr ("%tick-thunk", 0, 0, 0, scm_sys_tick_async_thunk);
729	system_signal_asyncs[SCM_SIG_ORD(SCM_TICK_SIGNAL)] = scm_system_async (a_thunk);
730	a_thunk = scm_make_gsubr ("%alrm-thunk", 0, 0, 0, scm_sys_alrm_async_thunk);
731	system_signal_asyncs[SCM_SIG_ORD(SCM_ALRM_SIGNAL)] = scm_system_async (a_thunk);
732
733	handler_var = scm_sysintern ("signal-handler", strlen ("signal"));
734	SCM_SETCDR (handler_var, SCM_BOOL_F);
735	scm_permanent_object (handler_var);
736	#include "async.x"
737	}