/* Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997 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.  
 */

/* "continue.h" Scheme Continuations for C.
   Author: Aubrey Jaffer. */

#ifdef vax
# ifndef CHEAP_CONTINUATIONS

   typedef int jump_buf[17];
   extern int setjump(jump_buf env);
   extern int longjump(jump_buf env, int ret);

# else
#  include <setjmp.h>
#  define jump_buf jmp_buf
#  define setjump setjmp
#  define longjump longjmp
# endif
#else				/* ndef vax */
# ifdef _CRAY1

    typedef int jump_buf[112];
    extern int setjump(jump_buf env);
    extern int longjump(jump_buf env, int ret);

# else				/* ndef _CRAY1 */
#  include <setjmp.h>
#  include <signal.h>
#  ifdef SIG_UNBLOCK
#   define jump_buf sigjmp_buf
#   define setjump(buf) sigsetjmp((buf), !0)
#   define longjump siglongjmp
#  else
#   define jump_buf jmp_buf
#   define setjump setjmp
#   define longjump longjmp
#  endif                        /* ndef HAVE_SIGSETJMP */
# endif				/* ndef _CRAY1 */
#endif				/* ndef vax */

/* `other' is a CONTINUATION slot for miscellaneous data of type
   CONTINUATION_OTHER.  */

#ifndef CONTINUATION_OTHER
# define CONTINUATION_OTHER int
#endif

/* If stack is not longword aligned then */

/* #define SHORT_ALIGN */
#ifdef THINK_C
# define SHORT_ALIGN
#endif
#ifdef __MWERKS__
# define SHORT_ALIGN
#endif
#ifdef MSDOS
# define SHORT_ALIGN
#endif
#ifdef atarist
# define SHORT_ALIGN
#endif

#ifdef SHORT_ALIGN
typedef short STACKITEM;
#else
typedef long STACKITEM;
#endif

struct Continuation {jump_buf jmpbuf;
		     long thrwval;
		     long length;
		     STACKITEM *stkbse;
		     CONTINUATION_OTHER other;
		     struct Continuation *parent;
		   };
typedef struct Continuation CONTINUATION;

#ifndef P
# ifdef USE_ANSI_PROTOTYPES
#  define P(s) s
# else
#  define P(s) ()
# endif
#endif

extern long thrown_value;
long stack_size P((STACKITEM *start));
CONTINUATION *make_root_continuation P((STACKITEM *stack_base));
CONTINUATION *make_continuation P((CONTINUATION *parent_cont));
void free_continuation P((CONTINUATION *cont));
void dynthrow P((long *a));
void grow_throw P((long *a));
void throw_to_continuation P((CONTINUATION *cont, long val,
			      CONTINUATION *root_cont));

/* how to get the local definition for malloc */

#ifndef STDC_HEADERS
# ifndef malloc
	char *malloc P((sizet size));
# endif
	char *realloc P((char *ptr, sizet size));
#endif

/* PTR_LT defines how to compare two addresses (which may not be in
   the same array).  */

#if defined(__TURBOC__) && !defined(__TOS__)
# ifdef PROT386
#  define PTR_LT(x, y) (((long)(x)) < ((long)(y)))
# else
#  define PTR_LT(x, y) ((x) < (y))
# endif
#else /* not __TURBOC__ */
# ifdef nosve
#  define PTR_MASK 0xffffffffffff
#  define PTR_LT(x, y) (((int)(x)&PTR_MASK) < ((int)(y)&PTR_MASK))
# else
#  define PTR_LT(x, y) ((x) < (y))
# endif
#endif

#define PTR_GT(x, y) PTR_LT(y, x)
#define PTR_LE(x, y) (!PTR_GT(x, y))
#define PTR_GE(x, y) (!PTR_LT(x, y))

/* James Clark came up with this neat one instruction fix for
   continuations on the SPARC.  It flushes the register windows so
   that all the state of the process is contained in the stack. */

#ifdef sparc
# define FLUSH_REGISTER_WINDOWS asm("ta 3")
#else
# define FLUSH_REGISTER_WINDOWS /* empty */
#endif

/* If stacks grow up then */

/* #define STACK_GROWS_UP */
#ifdef hp9000s800
# define STACK_GROWS_UP
#endif
#ifdef pyr
# define STACK_GROWS_UP
#endif
#ifdef nosve
# define STACK_GROWS_UP
#endif
#ifdef _UNICOS
# define STACK_GROWS_UP
#endif
