/*  Part of SWI-Prolog

    Author:        Jan Wielemaker
    E-mail:        J.Wielemaker@vu.nl
    WWW:           http://www.swi-prolog.org
    Copyright (c)  1985-2023, University of Amsterdam,
			      VU University Amsterdam
			      CWI, Amsterdam
			      SWI-Prolog Solutions b.v.
    All rights reserved.

    Redistribution and use in source and binary forms, with or without
    modification, 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 COPYRIGHT HOLDERS AND CONTRIBUTORS
    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
    INCIDENTAL, SPECIAL, 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 OTHERWISE) ARISING IN
    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
    POSSIBILITY OF SUCH DAMAGE.
*/

#ifndef _PL_INCLUDE_H
#define _PL_INCLUDE_H

#define PLNAME "swi"

#ifdef __WINDOWS__
#include "config/wincfg.h"
#else /*__WINDOWS__*/
#include <config.h>
#endif

#include <parms.h>			/* pick from the working dir */

/* gmp.h must be included PRIOR to SWI-Prolog.h to enable the API prototypes */
#if O_GMP || O_BF
#define O_BIGNUM			1
#endif

#if O_GMP
#include <gmp.h>
#elif O_BF
#include "libbf/bf_gmp_types.h"
#endif

#define PL_KERNEL		1

/* PL_SO_EXPORT is an optional declaration used by SWI-Prolog.h that
 * marks API symbols for being exported from libswipl.so.
 */
#ifdef HAVE_VISIBILITY_ATTRIBUTE
#define PL_SO_EXPORT __attribute__((visibility("default")))
#endif

/* The public API has references to a number of opaque types only
 * defined in internal library code. The PL_OPAQUE macro prefixes
 * the names with PL_ to avoid cluttering the type namespace, but
 * here we want the original names.
 */
#define PL_OPAQUE(type) type

/* Clang way to detect address_sanitizer */
#ifndef __has_feature
  #define __has_feature(x) 0
#endif
#ifndef __SANITIZE_ADDRESS__
#if __has_feature(address_sanitizer)
#define __SANITIZE_ADDRESS__
#endif
#endif

#ifdef __SANITIZE_ADDRESS__
#include <sanitizer/lsan_interface.h>
#endif

#if defined(O_PLMT) && !defined(O_ENGINES)
#define O_ENGINES		1
#endif

#include "SWI-Prolog.h"

/* Our definition of _PL_get_arg appears in pl-fli.h */
#undef _PL_get_arg

/* This is only here to assist static analysis; undefine this and
 * the LDFUNC functions will look like normal definitions, as though
 * this were a single-threaded build */
#define USE_LD_MACROS 1
#ifdef __INTELLISENSE__
# undef USE_LD_MACROS
#endif

/* COMMON() was a macro used to mark symbols to be global to the library
 * internals but not exported from the shared library. This is now the
 * default visibility for library symbols, so it is no longer necessary.
 */
#define COMMON(type) type

#if (defined(__GNUC__) || defined(__clang__)) && !defined(PEDANTIC)
#define O_EMPTY_STRUCTS 1
#endif

#include "pl-macros.h"

/* C11 gives us the _Static_assert operator, let's make it a little nicer.
 * Accept either static_assert(cond, "message") or static_assertion(cond). */
#ifndef _MSC_VER
#define static_assert(condition, message) _Static_assert(condition, message)
#endif
#define static_assertion(condition) _Static_assert(condition, "Assertion failed: ("#condition") [expansion: " A_STRINGIFY(condition) "]")

#include "pl-builtin.h"


/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
		      PROLOG SYSTEM OPTIONS

These are not really options normally.  They are there because I use  to
add  new  features  conditional  using  #if ... #endif.  In many cases I
leave them in for ducumentation purposes.   Notably  O_STRING  might  be
handy for it someone wants to add a data type to the system.

  O_STRING
      Include data type string.  This  feature  does  not  rely  on  any
      system  feature.   It  hardly has any consequences for the system.
      Because of its experimental nature it is optional.  The definition
      of the predicates operating on strings might change.
      (NOTE: Currently some of the boot files rely on strings. It is NOT
      suggested to leave them out).
  O_QUASIQUOTATIONS
      Support quasi quoted content in read_term/3 and friends.
  O_COMPILE_OR
      Compile ->/2, ;/2 and |/2 into WAM.  This  no  longer  is  a  real
      option.   the mechanism to handle cuts without compiling ;/2, etc.
      has been taken out.
  O_COMPILE_ARITH
      Include arithmetic compiler (compiles is/2, >/2, etc. into WAM).
  O_COMPILE_IS
      Compile Var = Value in the body.
  O_CALL_AT_MODULE
      Support the Goal@Module control-structure
  O_LABEL_ADDRESSES
      Means we can pick up the address of a label in  a function using
      the var  = `&&label' construct  and jump to  it using goto *var;
      This construct is known by the GNU-C compiler gcc version 2.  It
      is buggy in gcc-2.0, but seems to works properly in gcc-2.1.
  VMCODE_IS_ADDRESS
      Can only  be set when  O_LABEL_ADDRESSES is  set.  It causes the
      prolog  compiler  to put the  code  (=  label-) addresses in the
      compiled Prolog  code  rather than the  virtual-machine numbers.
      This speeds-up  the vm  instruction dispatching in  interpret().
      See also pl-comp.c
  O_LOGICAL_UPDATE
      Use `logical' update-view for dynamic predicates rather then the
      `immediate' update-view of older Prolog systems.
  O_PLMT
      Include support for multi-threading.
  O_ENGINES
      Include support for multiple engines.  This is implied by O_PLMT
  O_LARGEFILES
      Supports files >2GB on 32-bit systems (if the OS provides it).
  O_ATTVAR
      Include support for attributes variables.
      This option requires O_DESTRUCTIVE_ASSIGNMENT.
  O_GVAR
      Include support for backtrackable global variables.  This option
      requires O_DESTRUCTIVE_ASSIGNMENT.
  O_CYCLIC
      Provide support for cyclic terms.
  O_LOCALE
      Provide locale support on streams.
  O_GMP
      Use GNU gmp library for infinite precision arthmetic
  O_MITIGATE_SPECTRE
      Reduce spectre security risc.  Currently reduces timer resolution.
  O_PREFER_RATIONALS
      Default for the `prefer_rationals` flag.
  O_RATIONAL_SYNTAX
      Default support for rational syntax (RAT_NATURAL or RAT_COMPAT)
  O_SIGNALS
      Include OS-level signal-handling code. This does not affect any
      virtual Prolog "signals" defined above SIG_PROLOG_OFFSET, but
      PL_thread_raise loses its "interrupt a blocking system call"
      semantics when this is disabled.
  O_ROUND_UP_DOWN
      Force true values for floating point functions are between the
      downward and upward rounded values.  Works around the fact that
      most C runtime libraries do not correctly implement the float
      rouding modes for many of the trigonomy and expononential
      functions.
  O_COVERAGE
      Include low-level coverage analysis code.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#define O_COMPILE_OR		1
#define O_SOFTCUT		1
#define O_COMPILE_ARITH		1
#define O_COMPILE_IS		1
#define O_CALL_AT_MODULE	1
#define O_STRING		1
#define O_RESERVED_SYMBOLS	1
#define O_QUASIQUOTATIONS	1
#define O_CATCHTHROW		1
#define O_DEBUGGER		1
#define O_INTERRUPT		1
#define O_DESTRUCTIVE_ASSIGNMENT 1
#define O_TERMHASH		1
#define O_LIMIT_DEPTH		1
#define O_INFERENCE_LIMIT	1
#define O_SAFE_SIGNALS		1
#define O_LOGICAL_UPDATE	1
#define O_LOCALE		1
#define O_ATOMGC		1
#define O_CLAUSEGC		1
#define O_ATTVAR		1
#define O_CALL_RESIDUE		1
#define O_GVAR			1
#define O_CYCLIC		1
#define O_MITIGATE_SPECTRE	1
#define O_ROUND_UP_DOWN		1
#define O_COVERAGE		1
#ifndef O_PREFER_RATIONALS
#define O_PREFER_RATIONALS	FALSE
#endif
#ifndef O_RATIONAL_SYNTAX
#define O_RATIONAL_SYNTAX	RAT_COMPAT
#endif

/* Define either or none of O_DYNAMIC_EXTENSIONS and O_STATIC_EXTENSIONS */
#if (defined(HAVE_DLOPEN) || defined(HAVE_SHL_LOAD) || defined(EMULATE_DLOPEN)) \
    && !defined(O_STATIC_EXTENSIONS)
#define O_DYNAMIC_EXTENSIONS 1
#endif

#ifdef __WINDOWS__
#define NOTTYCONTROL           TRUE
#define O_DDE 1
#define O_DLL 1
#define O_HASDRIVES 1
#define O_HASSHARES 1
#define O_XOS 1
#define O_RLC 1
#endif

#ifdef __EMSCRIPTEN__
#define NOTTYCONTROL           TRUE
#define O_TIGHT_CSTACK 1
#endif

#ifdef __SANITIZE_ADDRESS__
#define O_TIGHT_CSTACK 1
#endif

#ifndef DOUBLE_TO_LONG_CAST_RAISES_SIGFPE
#ifdef __i386__
#define DOUBLE_TO_LONG_CAST_RAISES_SIGFPE 1
#endif
#endif

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
The ia64 says setjmp()/longjmp() buffer must be aligned at 128 bits
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#ifndef JMPBUF_ALIGNMENT
#ifdef __ia64__
#define JMPBUF_ALIGNMENT 128
#else
#if ALIGNOF_DOUBLE != ALIGNOF_VOIDP
#define JMPBUF_ALIGNMENT ALIGNOF_DOUBLE
#endif
#endif
#endif

#if defined(O_LABEL_ADDRESSES) && defined(PEDANTIC)
#undef O_LABEL_ADDRESSES
#endif

/* clang as of version 11 performs about 30% worse with this option */
#if O_LABEL_ADDRESSES && !defined(VMCODE_IS_ADDRESS) && !defined(__llvm__)
#define VMCODE_IS_ADDRESS	1
#endif

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Runtime version.  Uses somewhat less memory and has no tracer.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#ifdef O_RUNTIME
#undef O_PROFILE			/* no profiling */
#undef O_DEBUGGER			/* no debugging */
#undef O_INTERRUPT			/* no interrupts too */
#endif


/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
The macros below try to establish a common basis for various  compilers,
so  we  can  write  most  of the real code without having to worry about
compiler limits and differences.

The current version has prototypes  defined   for  all functions. If you
have a very old compiler, try  the   unprotoize  program that comes with
gcc.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#ifndef __unix__
#if defined(_AIX) || defined(__APPLE__) || defined(__unix) || defined(__BEOS__) || defined(__NetBSD__) || defined(__HAIKU__)
#define __unix__ 1
#endif
#endif

/* AIX requires this to be the first thing in the file.  */
#ifdef __GNUC__
# ifndef alloca
#  define alloca __builtin_alloca
# endif
#else
# if HAVE_ALLOCA_H
#  include <alloca.h>
# else
#  ifdef _AIX
 #pragma alloca
#  else
#   ifndef alloca /* predefined by HP cc +Olibcalls */
void *alloca ();
#   endif
#  endif
# endif
#endif

#if _FILE_OFFSET_BITS == 64 || defined(_LARGE_FILES)
#define O_LARGEFILES 1		/* use for conditional code in Prolog */
#else
#undef O_LARGEFILES
#endif

#include <sys/types.h>
#if __MINGW32__
typedef _sigset_t sigset_t;
#endif
#include <setjmp.h>
#ifdef ASSERT_H_REQUIRES_STDIO_H
#include <stdio.h>
#endif /*ASSERT_H_REQUIRES_STDIO_H*/
#ifdef NO_ASSERT_H		/* see pl-assert.c */
#define assert(c) (void)0
#else
#include <assert.h>
#endif
#include <stdlib.h>
#include <string.h>
#include <stddef.h>
#include <stdarg.h>
#include <limits.h>

#ifdef HAVE_SIGNAL_H
#include <signal.h>
#endif

/* We have two important feature test macros relating to signals. The first is
 * O_SIGNALS, which controls whether Prolog itself should perform OS-level
 * signal handling, and is set by the USE_SIGNALS config directive.
 *
 * The other macro is HAVE_OS_SIGNALS. This controls whether OS-level signal
 * handling is available at all, e.g. from the on_signal/3 predicate.
 */
#ifndef HAVE_OS_SIGNALS
# if defined(HAVE_SIGNAL) || defined(HAVE_SIGACTION)
/* if we have at least one of these functions, assume we have access to
 * OS-level signals, unless HAVE_OS_SIGNALS has been explicitly disabled. */
#  define HAVE_OS_SIGNALS 1
# endif
#elif !HAVE_OS_SIGNALS
/* If HAVE_OS_SIGNALS was explicitly defined to 0, turn that into an undef
 * so that we can use either #if or #ifdef with it in libswipl code. */
# undef HAVE_OS_SIGNALS
#endif

#if !HAVE_OS_SIGNALS
/* If we can't access OS signals, don't include code that uses them. */
# undef O_SIGNALS
#endif
#ifdef HAVE_MALLOC_H
#include <malloc.h>
#else
#ifdef HAVE_SYS_MALLOC_H
#include <sys/malloc.h>
#endif
#endif

#if defined(STDC_HEADERS) || defined(HAVE_STRING_H)
#include <string.h>
/* An ANSI string.h and pre-ANSI memory.h might conflict.  */
#if !defined(STDC_HEADERS) && defined(HAVE_MEMORY_H)
#include <memory.h>
#endif /* not STDC_HEADERS and HAVE_MEMORY_H */
#else /* not STDC_HEADERS and not HAVE_STRING_H */
#include <strings.h>
/* memory.h and strings.h conflict on some systems.  */
#endif /* not STDC_HEADERS and not HAVE_STRING_H */

#if OS2 && EMX
#include <process.h>
#include <io.h>
#endif /* OS2 */

/* prepare including BeOS types */
#ifdef __BEOS__
#define bool BOOL

#include <BeBuild.h>
#if (B_BEOS_VERSION <= B_BEOS_VERSION_5)
# include <socket.h>      /* include socket.h to get the fd_set structure */
#else
# include <SupportDefs.h> /* not needed for a BONE-based networking stack */
#endif
#include <OS.h>

#undef true
#undef false
#undef bool
#define EMULATE_DLOPEN 1		/* Emulated dlopen() in pl-beos.c */
#endif

/* PATH_MAX is an optional POSIX feature (Bug#63).  As SWI-Prolog has
   no length limits on text except for representing paths, we should
   rewrite all file handling code to avoid PATH_MAX.  For now we just
   define it.
*/

#ifndef PATH_MAX
#define PATH_MAX 1024
#endif

/* If we have a threads-supporting C11 environment, we can use C11 thread
 * primitives (as a fallback, if we don't have a system-specific impl).
 * We do not need this stuff on Windows as it is used for internal signal
 * handling if no true signals are available.
 */
#if __STDC_VERSION__ >= 201112L && !defined(__STDC_NO_THREADS__) && defined(HAVE_THREADS_H)
# include <threads.h>
# undef thread_local /* we use this as an identifier, it's not in the C11 spec anyway */
# define HAVE_STDC_THREADS	1
#endif

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
A common basis for C keywords.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#if __GNUC__ && !__STRICT_ANSI__
#define HAVE_INLINE 1
#define HAVE_VOLATILE 1
#define HAVE___BUILTIN_EXPECT 1
#endif

#if !defined(HAVE_INLINE) && !defined(inline)
#define inline
#endif

#if defined(__GNUC__) && !defined(__OPTIMIZE__)
#define _DEBUG 1
#endif

#ifndef HAVE_VOLATILE
#define volatile
#endif

#if defined(__GNUC__) && !defined(NORETURN)
#define NORETURN __attribute__ ((noreturn))
#else
#define NORETURN
#endif

#if defined(__GNUC__) && !defined(MAY_ALIAS)
#define MAY_ALIAS __attribute__ ((__may_alias__))
#else
#define MAY_ALIAS
#endif

#if defined(__GNUC__) && !defined(MAYBE_UNUSED)
#define MAYBE_UNUSED __attribute__ ((unused))
#else
#define MAYBE_UNUSED
#endif

#ifdef HAVE___BUILTIN_EXPECT
#define likely(x)       __builtin_expect((x), 1)
#define unlikely(x)     __builtin_expect((x), 0)
#else
#define likely(x)	(x)
#define unlikely(x)	(x)
#endif

#ifdef DMALLOC
#include <dmalloc.h>			/* Use www.dmalloc.com debugger */

#define PL_ALLOC_DONE 1
#define DMALLOC_FUNC_CHECK 1
#define allocHeap(n)		malloc(n)
#define allocHeapOrHalt(n)	xmalloc(n)
#define freeHeap(ptr, n)	do { (void)(n); xfree(ptr); } while(0)
#endif /*DMALLOC*/

#define forwards static		/* forwards function declarations */

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Booleans,  addresses,  strings  and other   goodies.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

typedef int			bool;

#if __GNUC__ && !__STRICT_ANSI__
#define LocalArray(t, n, s)	t n[s]
#else
#define LocalArray(t, n, s)	t *n = (t *) alloca((s)*sizeof(t))
#endif

#define TermVector(name, s)	LocalArray(Word, name, s)

#ifndef TRUE
#define TRUE			1
#define FALSE			0
#endif
#define succeed			return TRUE
#define fail			return FALSE
#define TRY(goal)		do { if (!(goal)) return FALSE; } while(0)

#define CL_START		((ClauseRef)1)	/* asserta */
#define CL_END			((ClauseRef)2)	/* assertz */

typedef void *			caddress;

#define EOS			('\0')
#define ESC			((char) 27)
#define streq(s, q)		((strcmp((s), (q)) == 0))

				/* n is 2^m !!! */
#define ROUND(p, n)		((((p) + (n) - 1) & ~((n) - 1)))
#define addPointer(p, n)	((void *) ((intptr_t)(p) + (intptr_t)(n)))
#define diffPointers(p1, p2)	((intptr_t)(p1) - (intptr_t)(p2))

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
			     LIMITS

Below are some arbitrary limits on object sizes.  Feel free  to  enlarge
them.  Descriptions:

	* LINESIZ
	Buffer used to store textual info.  It is not concerned with
	critical things, just things like building an error message,
	reading a command for the tracer, etc.

	* MAXARITY
	Maximum arity of a predicate.  May be enarged further, but
	wastes stack (4 bytes for each argument) on machines that
	use malloc() for allocating the stack as the local and global
	stack need to be apart by this amount.  Also, an interrupt
	skips this amount of stack.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#define LINESIZ			1024	/* size of a data line */
#define MAXARITY		1024	/* arity of predicate */
#define MINFOREIGNSIZE		32	/* Minimum term_t in foreign frame */
#define MAXSYMBOLLEN		256	/* max size of foreign symbols */
#define OP_MAXPRIORITY		1200	/* maximum operator priority */
#define SMALLSTACK		32 * 1024 /* GC policy */
#define MAX_PORTRAY_NESTING	100	/* Max recursion in portray */

#define LOCAL_MARGIN (sizeof(struct localFrame) + MAXARITY*sizeof(word) + \
		      sizeof(struct choice))

#define WORDBITSIZE		(8 * sizeof(word))
#define LONGBITSIZE		(8 * sizeof(long))
#define INTBITSIZE		(8 * sizeof(int))
#define INT64BITSIZE		(8 * sizeof(int64_t))
#define WORDS_PER_DOUBLE        ((sizeof(double)+sizeof(word)-1)/sizeof(word))
#define WORDS_PER_INT64		(sizeof(int64_t)/sizeof(word))

				/* Prolog's integer range */
#define PLMINTAGGEDINT		(-(intptr_t)((word)1<<(WORDBITSIZE-LMASK_BITS-1)))
#define PLMAXTAGGEDINT		(-PLMINTAGGEDINT - 1)
#define PLMINTAGGEDINT32	(-(intptr_t)((word)1<<(32-LMASK_BITS-1)))
#define PLMAXTAGGEDINT32	(-PLMINTAGGEDINT32 - 1)
#define inTaggedNumRange(n)	(valInt(consInt(n)) == (n))
#define PLMININT		(-PLMAXINT - 1)
#define PLMAXINT		((int64_t)(((uint64_t)1<<(INT64BITSIZE-1)) - 1))

#if vax
#define MAXREAL			(1.701411834604692293e+38)
#else					/* IEEE double */
#define MAXREAL			(1.79769313486231470e+308)
#endif

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Macros to handle hash tables.  See pl-table.c for  details.   First  the
sizes  of  the  hash  tables are defined.  Note that these should all be
2^N.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#define ATOMHASHSIZE		4096	/* global atom table */
#define FUNCTORHASHSIZE		512	/* global functor table */
#define PROCEDUREHASHSIZE	1024	/* predicates in module user */
#define MODULEPROCEDUREHASHSIZE 16	/* predicates in other modules */
#define MODULEHASHSIZE		128	/* global module table */
#define PUBLICHASHSIZE		8	/* Module export table */
#define FLAGHASHSIZE		16	/* global flag/3 table */

#include "os/pl-table.h"
#include "pl-vmi.h"

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Arithmetic comparison
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#define LT 1
#define GT 2
#define LE 3
#define GE 4
#define NE 5
#define EQ 6

#define LT_C <
#define GT_C >
#define LE_C <=
#define GE_C >=
#define NE_C !=
#define EQ_C ==

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Operator types.  NOTE: if you change OP_*, check operatorTypeToAtom()!
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#define OP_PREFIX  0
#define OP_INFIX   1
#define OP_POSTFIX 2
#define OP_MASK    0xf

#define	OP_FX	(0x10|OP_PREFIX)
#define OP_FY	(0x20|OP_PREFIX)
#define OP_XF	(0x30|OP_POSTFIX)
#define OP_YF	(0x40|OP_POSTFIX)
#define OP_XFX	(0x50|OP_INFIX)
#define OP_XFY	(0x60|OP_INFIX)
#define OP_YFX	(0x70|OP_INFIX)

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Magic for assertions.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#define StackMagic(n)	((n) | 0x98765000)
#define QID_MAGIC	StackMagic(1)	/* Query frame */
#define QID_CMAGIC	StackMagic(2)	/* Closed Query frame */

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
			  PROLOG DATA REPRESENTATION

Prolog data objects live on various places:

	- In the variable and argument slots of environment frames.
	- As arguments to complex terms on the global stack.
	- In records (recorda/recorded database) in the heap.
	- In variables in foreign language functions.

All Prolog data is packed into a `word'.  A word is  a  32  bit  entity.
The top 3 bits are used to indicate the type; the bottom 2 bits are used
for  the  garbage  collector.   The  bits  for the garbage collector are
always 0 during normal execution.  This implies we do not have  to  care
about  them  for  pointers  and  as  pointers  always  point  to 4 bytes
entities, the range is not harmed by the garbage collection bits.

The remaining 27 bits can hold a  unique  representation  of  the  value
itself  or  can be a pointer to the global stack where the real value is
stored.  We call the latter type of data `indirect'.

Below is a description of the  representation  used  for  each  type  of
Prolog data:

***TBD*** This is totally out of date.  The datatypes are accessed using
macros defined in pl-data.h.

INTEGER
    Integers are stored in the  27  remaining  bits  of  a  word.   This
    implies they are limited to +- 2^26.
FLOAT
    For a real, the 27 bits are a pointer to a 8 byte unit on the global
    stack.  For both words of the 8 byte unit, the top 3  and  bottom  2
    bits  are  reserved  for identification and garbage collection.  The
    remaining bits hold the exponent and mantisse.  See pack_real()  and
    unpack_real() in pl-alloc.c for details.
ATOM
    For atoms, the 27 bits represent a pointer  to  an  atom  structure.
    Atom  structures are cells of a hash table.  Equality of the pointer
    implies equality of the atoms and visa versa.  Atom  structures  are
    not  collected by the garbage collector and thus live for the entire
    Prolog session.
STRING
    For a string, the 27 bits are a pointer to the  global  stack.   The
    first  word  of  the  string  again reserves  the top 3 and bottom 2
    bits.  The remaining bits indicate the length of the  string.   Next
    follows a 0 terminated character string.  Finally a word exactly the
    same  as the header word, to allow the garbage collector to traverse
    the stack downwards and identify the string.
TERM
    For a compound term, the 27 bits are a pointer to the global  stack.
    the  first  word there is a pointer to a functordef structure, which
    determines the name and arity of the  term.   functordef  structures
    are  cells  of  a hash table like atom structures.  They to live for
    the entire Prolog session.  Next, there are just as  many  words  as
    the  arity  of the term, each word representing a normal Prolog data
    object.
VARIABLES
    An unbound variable is represented by NULL.
REFERENCES
    References are the result of sharing variables.   If  two  variables
    must  share,  the one with the shortest livetime is made a reference
    pointer to the other.  This way a tree of reference pointers can  be
    constructed.   The root of the tree is the variable with the longest
    livetime.  To bind the entire tree of variables this root is  bound.
    The  others remain reference pointers.  This implies that ANY prolog
    data object might be a reference  pointer  to  another  Prolog  data
    object,  holding  the  real  value.  To find the real value, a macro
    called deRef() is available.

    The direction of reference pointers is critical.  It MUST  point  in
    the direction of the longest living variable.  If not, the reference
    pointer  will  point  into  the  dark  if  the other end dies.  This
    implies that if both cells are part of an environment frame, the one
    in the child function (closest to the top of the stack)  must  point
    to  the  one in the parent function.  If one is on the local and one
    on the global stack, the  pointer  must  point  towards  the  global
    stack.   Inside  the global stack it is irrelevant.  If backtracking
    destroys a variable, it also will reset the reference towards it  if
    there is one.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Common Prolog objects typedefs. Note that   code is word-aligned for two
reasons. First of all, we want to get   the maximum speed and second, we
must ensure that sizeof(struct clause) is  a multiple of sizeof(word) to
place them on the stack (see I_USERCALL).
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#ifdef __GNUC__
#define WORD_ALIGNED __attribute__ ((aligned (sizeof(word))))
#else
#define WORD_ALIGNED
#endif

#if 0
/* The following have all been defined in SWI-Prolog.h, included above,
 * and are repeated here only for programmer reference and convenience.
 */

typedef uintptr_t		word;		/* Anonymous ptr-sized object*/
typedef	word			atom_t;		/* encoded atom */
typedef word			functor_t;	/* encoded functor */
typedef struct module *		module_t;	/* a module */
typedef struct procedure *	predicate_t;	/* a predicate handle */
typedef struct record *		record_t;	/* handle to a recorded term */
typedef uintptr_t		term_t;		/* external term-reference */
typedef uintptr_t		qid_t;		/* external query-id */
typedef uintptr_t		PL_fid_t;	/* external foreign context-id */
typedef struct foreign_context *control_t;	/* non-deterministic control arg */
typedef struct PL_local_data *	PL_engine_t;	/* handle to an engine */
typedef uintptr_t		PL_atomic_t;	/* same a word */
typedef uintptr_t		foreign_t;	/* return type of foreign functions */
typedef wchar_t			pl_wchar_t;	/* Prolog wide character */
typedef foreign_t		(*pl_function_t)(); /* foreign language functions */
typedef uintptr_t		buf_mark_t;	/* buffer mark handle */

#define				fid_t \
	PL_fid_t				/* avoid AIX name-clash */
#endif

typedef uintptr_t		word;		/* Anonymous ptr-sized object*/
typedef word *			Word;		/* a pointer to anything */
typedef word			atom_t;		/* encoded atom */
typedef word			functor_t;	/* encoded functor */
typedef uintptr_t		code WORD_ALIGNED; /* bytes codes */
typedef code *			Code;		/* pointer to byte codes */
typedef int			Char;		/* char that can pass EOF */
typedef foreign_t		(*Func)();	/* foreign functions */
typedef int			(*ArithF)();	/* arithmetic function */

typedef struct atom *		Atom;		/* atom */
typedef struct functor *	Functor;	/* complex term */
typedef struct functorDef *	FunctorDef;	/* name/arity pair */
typedef struct procedure *	Procedure;	/* predicate */
typedef struct definition *	Definition;	/* predicate definition */
typedef struct definition_chain *DefinitionChain; /* linked list of defs */
typedef struct clause *		Clause;		/* compiled clause */
typedef struct clause_ref *	ClauseRef;      /* reference to a clause */
typedef struct clause_index *	ClauseIndex;    /* Clause indexing table */
typedef struct clause_bucket *	ClauseBucket;   /* Bucked in clause-index table */
typedef struct operator *	Operator;	/* see pl-op.c, pl-read.c */
typedef struct record *		Record;		/* recorda/3, etc. */
typedef struct recordRef *	RecordRef;      /* reference to a record */
typedef struct recordList *	RecordList;	/* list of these */
typedef struct module *		Module;		/* predicate modules */
typedef struct sourceFile *	SourceFile;	/* file adminitration */
typedef struct list_cell *	ListCell;	/* Anonymous list */
typedef struct localFrame *	LocalFrame;	/* environment frame */
typedef struct local_definitions *LocalDefinitions; /* thread-local preds */
typedef struct choice *		Choice;		/* Choice-point */
typedef struct clause_choice *  ClauseChoice;   /* firstClause()/nextClause() */
typedef struct queryFrame *	QueryFrame;     /* toplevel query frame */
typedef struct fliFrame *	FliFrame;	/* FLI interface frame */
typedef struct trail_entry *	TrailEntry;	/* Entry of trail stack */
typedef struct gc_trail_entry *	GCTrailEntry;	/* Entry of trail stack (GC) */
typedef struct mark		mark;		/* backtrack mark */
typedef struct stack *		Stack;		/* machine stack */
typedef struct _varDef *	VarDef;		/* pl-comp.c */
typedef struct extension_cell *	ExtensionCell;  /* pl-ext.c */
typedef struct abort_handle *	AbortHandle;	/* PL_abort_hook() */
typedef struct initialise_handle * InitialiseHandle;
typedef struct canonical_dir *	CanonicalDir;	/* pl-os.c */
typedef struct on_halt *	OnHalt;		/* pl-os.c */
typedef struct find_data_tag *	FindData;	/* pl-trace.c */
typedef struct feature *	Feature;	/* pl-prims.c */
typedef struct dirty_def_info * DirtyDefInfo;
typedef struct counting_mutex	counting_mutex;
typedef struct pl_mutex		pl_mutex;

		 /*******************************
		 *	    ARITHMETIC		*
		 *******************************/

/* the numtype enum requires total ordering.
*/

typedef enum
{ V_INTEGER,				/* integer (64-bit) value */
#ifdef O_BIGNUM
  V_MPZ,				/* mpz_t */
  V_MPQ,				/* mpq_t */
#endif
  V_FLOAT				/* Floating point number (double) */
} numtype;

typedef struct
{ numtype type;				/* type of number */
  union { double f;			/* value as a floating point number */
	  int64_t i;			/* value as integer */
	  word  w[WORDS_PER_DOUBLE];	/* for packing/unpacking the double */
#ifdef O_BIGNUM
	  mpz_t mpz;			/* GMP integer */
	  mpq_t mpq;			/* GMP rational */
#endif
	} value;
} number, *Number;

#define TOINT_CONVERT_FLOAT	0x1	/* toIntegerNumber() */
#define TOINT_TRUNCATE		0x2

#ifdef O_BIGNUM
#define intNumber(n)	((n)->type <=  V_MPZ)
#define ratNumber(n)	((n)->type <=  V_MPQ)
#else
#define intNumber(n)	((n)->type <  V_FLOAT)
#define ratNumber(n)	((n)->type <  V_FLOAT)
#endif
#define floatNumber(n)	((n)->type >= V_FLOAT)

typedef enum
{ NUM_ERROR = FALSE,			/* Syntax error */
  NUM_OK    = TRUE,			/* Ok */
  NUM_FUNDERFLOW = -1,			/* Float underflow */
  NUM_FOVERFLOW = -2,			/* Float overflow */
  NUM_IOVERFLOW = -3,			/* Integer overflow */
  NUM_CONSTRANGE = -4			/* numeric constant out of range */
} strnumstat;



		 /*******************************
		 *	   GET-PROCEDURE	*
		 *******************************/

#define GP_FIND		0		/* find anywhere */
#define GP_FINDHERE	1		/* find in this module */
#define GP_CREATE	2		/* create (in this module) */
#define GP_DEFINE	4		/* define a procedure */
#define GP_RESOLVE	5		/* find defenition */

#define GP_HOW_MASK	0x0ff
#define GP_NAMEARITY	0x100		/* or'ed mask */
#define GP_HIDESYSTEM	0x200		/* hide system module */
#define GP_TYPE_QUIET	0x400		/* don't throw errors on wrong types */
#define GP_EXISTENCE_ERROR 0x800	/* throw error if proc is not found */
#define GP_QUALIFY	0x1000		/* Always module-qualify */
#define GP_NOT_QUALIFIED 0x2000		/* Demand unqualified name/arity */

					/* get_functor() */
#define GF_EXISTING	0x1
#define GF_PROCEDURE	0x2		/* check for max arity */
#define GF_NAMEARITY	0x4		/* only accept name/arity */

#define SM_NOCREATE	0x1		/* stripModule(): do not create modules */

		 /*******************************
		 *	       ALERT		*
		 *******************************/

/* See updateAlerted()
*/

#define	ALERT_SIGNAL	     0x001
#define	ALERT_GCREQ	     0x002
#define	ALERT_PROFILE	     0x004
#define	ALERT_EXITREQ	     0x008
#define	ALERT_DEPTHLIMIT     0x010
#define	ALERT_INFERENCELIMIT 0x020
#define	ALERT_WAKEUP	     0x040
#define	ALERT_DEBUG	     0x080
#define	ALERT_BUFFER	     0x100
#define	ALERT_UNDO	     0x200
#define ALERT_COVERAGE	     0x400


		 /*******************************
		 *	     CLEANUP		*
		 *******************************/

typedef enum
{ CLN_NORMAL = 0,			/* Normal mode */
  CLN_PROLOG,				/* Prolog hooks */
  CLN_FOREIGN,				/* Foreign hooks */
  CLN_IO,				/* Cleaning I/O */
  CLN_SHARED,				/* Unload shared objects */
  CLN_DATA				/* Remaining data */
} cleanup_status;


		 /*******************************
		 *	      FLAGS		*
		 *******************************/

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Many of the structures have a large number of booleans  associated  with
them.   Early  versions defined these using `unsigned <name> : 1' in the
structure definition.  When I ported SWI-Prolog to a  machine  that  did
not  understand  this  construct  I  decided  to pack all the flags in a
short.  As this allows us to set, clear and test combinations  of  flags
with one operation, it turns out to be faster as well.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#define true(s, a)		((s)->flags & (a))
#define alltrue(s, a)		(((s)->flags & (a)) == (a))
#define false(s, a)		(!true((s), (a)))
#define set(s, a)		ATOMIC_OR(&(s)->flags, (a))
#define clear(s, a)		ATOMIC_AND(&(s)->flags, ~(a))
#define clearFlags(s)		((s)->flags = 0)

/* Flags on predicates (packed in uint64_t) */

#define P_SSU_DET		(0x00000001LL) /* Single Sided Unification: det */
#define P_CLAUSABLE		(0x00000002LL) /* Clause/2 always works */
#define P_QUASI_QUOTATION_SYNTAX (0x00000004LL) /* {|Type||Quasi Quote|} */
#define P_NON_TERMINAL		(0x00000008LL) /* Grammar rule (Name//ArityLL) */
#define P_SHRUNKPOW2		(0x00000010LL) /* See reconsider_index(LL) */
#define P_FOREIGN		(0x00000020LL) /* Implemented in C */
#define P_NONDET		(0x00000040LL) /* Foreign: nondet */
#define P_VARARG		(0x00000080LL) /* Foreign: use alt calling API */
#define P_FOREIGN_CREF		(0x00000100LL) /* Foreign: ndet ctx is clause */
#define P_DYNAMIC		(0x00000200LL) /* Dynamic predicate */
#define P_THREAD_LOCAL		(0x00000400LL) /* Thread local predicate */
#define P_VOLATILE		(0x00000800LL) /* Clauses are not saved */
#define P_DISCONTIGUOUS		(0x00001000LL) /* Clauses are not together */
#define P_MULTIFILE		(0x00002000LL) /* Clauses are in multiple files */
#define P_PUBLIC		(0x00004000LL) /* Called from somewhere */
#define P_ISO			(0x00008000LL) /* Part of the ISO standard */
#define P_LOCKED		(0x00010000LL) /* Locked as system predicate */
#define P_NOPROFILE		(0x00020000LL) /* Profile children, not me */
#define P_TRANSPARENT		(0x00040000LL) /* Inherit calling module */
#define P_META			(0x00080000LL) /* Has meta_predicate decl */
#define P_MFCONTEXT		(0x00100000LL) /* Used for Goal@Module */
#define P_DIRTYREG		(0x00200000LL) /* Part of GD->procedures.dirty */
#define P_ERASED		(0x00400000LL) /* Predicate has been destroyed */
#define HIDE_CHILDS		(0x00800000LL) /* Hide children from tracer */
#define SPY_ME			(0x01000000LL) /* Spy point placed */
#define TRACE_ME		(0x02000000LL) /* Can be debugged */
#define P_DET			(0x04000000LL) /* Predicate is deterministic */
#define P_AUTOLOAD		(0x08000000LL) /* autoload/2 explicit import */
#define P_WAITED_FOR		(0x10000000LL) /* Someone is waiting for me */
#define	P_LOCKED_SUPERVISOR	(0x20000000LL) /* Fixed supervisor */
#define FILE_ASSIGNED		(0x40000000LL) /* Is assigned to a file */
#define P_REDEFINED		(0x80000000LL) /* Overrules a definition */
#define P_SIG_ATOMIC	      (0x0100000000LL) /* Do not call handleSignals */
#define P_TRANSACT	      (0x0200000000LL) /* Subject to transactions */
#define PROC_DEFINED		(P_DYNAMIC|P_FOREIGN|P_MULTIFILE|\
				 P_DISCONTIGUOUS|P_LOCKED_SUPERVISOR)
/* flags for p_reload data (reconsult) */
#define P_MODIFIED	      (0x1000000000LL) /* Clause list as modified */
#define P_NEW		      (0x2000000000LL) /* New predicate */
#define P_NO_CLAUSES	      (0x4000000000LL) /* Foreign or thread local */
#define P_CHECK_SSU	      (0x8000000000LL) /* Check mixed => and :- */

/* Flags on clauses (unsigned int) */

#define CL_ERASED		(0x0001) /* clause was erased */
#define UNIT_CLAUSE		(0x0002) /* Clause has no body */
#define HAS_BREAKPOINTS		(0x0004) /* Clause has breakpoints */
#define GOAL_CLAUSE		(0x0008) /* Dummy for meta-calling */
#define COMMIT_CLAUSE		(0x0010) /* This clause will commit */
#define DBREF_CLAUSE		(0x0020) /* Clause has db-reference */
#define DBREF_ERASED_CLAUSE	(0x0040) /* Deleted while referenced */
#define CL_BODY_CONTEXT		(0x0080) /* Module context of body is different */
					 /* from predicate */
#define SSU_COMMIT_CLAUSE	(0x0100) /* Head => Body */
#define SSU_CHOICE_CLAUSE	(0x0200) /* Head ?=> Body */
#define CL_HEAD_TERMS		(0x0400) /* Head contains terms used in body */

#define CLAUSE_TYPE_MASK (UNIT_CLAUSE|SSU_COMMIT_CLAUSE|SSU_CHOICE_CLAUSE)
#define CLAUSE_SSU_FLAGS (SSU_COMMIT_CLAUSE|SSU_CHOICE_CLAUSE)

/* Flags on a DDI (Dirty Definition Info struct */

#define DDI_MARKING		0x0001	 /* Actively using the DDI */
#define DDI_INTERVALS		0x0002	 /* DDI collects an interval */

/* Flags on module.  Most of these flags are copied to the read context
   in pl-read.c.
*/

#define M_SYSTEM		(0x00000001) /* system module */
#define M_CHARESCAPE		(0x00000002) /* module */
#define DBLQ_CHARS		(0x00000004) /* "ab" --> ['a', 'b'] */
#define DBLQ_ATOM		(0x00000008) /* "ab" --> 'ab' */
#define DBLQ_STRING		(0x00000010) /* "ab" --> "ab" */
#define DBLQ_MASK		(DBLQ_CHARS|DBLQ_ATOM|DBLQ_STRING)
#define BQ_STRING		(0x00000020) /* `ab` --> "ab" */
#define BQ_CODES		(0x00000040) /* `ab` --> [97,98] */
#define BQ_CHARS		(0x00000080) /* `ab` --> [a,b] */
#define BQ_MASK			(BQ_STRING|BQ_CODES|BQ_CHARS)
#define RAT_COMPAT		(0)
#define RAT_NATURAL		(0x00000100) /* 1/3 */
#define RAT_MASK		(RAT_NATURAL)
#define UNKNOWN_FAIL		(0x00001000) /* module */
#define UNKNOWN_WARNING		(0x00002000) /* module */
#define UNKNOWN_ERROR		(0x00004000) /* module */
#define UNKNOWN_MASK		(UNKNOWN_ERROR|UNKNOWN_WARNING|UNKNOWN_FAIL)
#define M_VARPREFIX		(0x00008000) /* _var, Atom */
#define M_DESTROYED		(0x00010000)
#define M_WAITED_FOR		(0x00020000) /* thread_wait/2 on this module */

/* Flags on functors */

#define CONTROL_F		(0x0002) /* functor (compiled controlstruct) */
#define ARITH_F			(0x0004) /* functor (arithmetic operator) */
#define VALID_F			(0x0008) /* functor (fully defined) */

/* Flags on record lists (recorded database keys) */

#define RL_DIRTY		(0x0001) /* recordlist */

/* Flags on recorded database records (also PL_record()) */

#define R_ERASED		(0x0001) /* record: record is erased */
#define R_EXTERNAL		(0x0002) /* record: inline atoms */
#define R_DUPLICATE		(0x0004) /* record: include references */
#define R_NOLOCK		(0x0008) /* record: do not lock atoms */
#define R_DBREF			(0x0010) /* record: has DB-reference */

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Macros for environment frames (local stack frames)
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#define FR_HIDE_CHILDS		(0x0001) /* flag of pred after I_DEPART */
#define FR_SKIPPED		(0x0002) /* We have skipped on this frame */
#define FR_MARKED		(0x0004) /* GC */
#define FR_MARKED_PRED		(0x0008) /* GC predicates/clauses */
#define FR_DEBUG		(0x0010) /* GUI debugger */
#define FR_CATCHED		(0x0020) /* Frame caught an exception */
#define FR_INBOX		(0x0040) /* Inside box (for REDO in built-in) */
#define FR_CONTEXT		(0x0080) /* fr->context is set */
#define FR_CLEANUP		(0x0100) /* setup_call_cleanup/4 */
#define FR_INRESET		(0x0200) /* Continuations: inside reset/3 */
#define FR_SSU_DET		(0x0400) /* Demands det on => rules */
#define FR_DET			(0x0800) /* Declared det */
#define FR_DETGUARD		(0x1000) /* Frame is guarded for determinism */
#define FR_DETGUARD_SET		(0x2000) /* Flag was set on this frame */
#define FR_WATCHED (FR_CLEANUP|FR_DEBUG)

#define FR_MAGIC_MASK		(0xffff0000)
#define FR_MAGIC_MASK2		(0xfff00000)
#define FR_MAGIC		(0xc9d50000)

#define isFrame(fr)		(((fr)->flags&FR_MAGIC_MASK) == FR_MAGIC)
#define wasFrame(fr)		(((fr)->flags&FR_MAGIC_MASK2) == \
				 (FR_MAGIC&FR_MAGIC_MASK2))
#define killFrame(fr)		clear(fr, (FR_MAGIC_MASK&~FR_MAGIC_MASK2))

#define ARGOFFSET		((int)sizeof(struct localFrame))
#define VAROFFSET(var)		((var)+(ARGOFFSET/(int)sizeof(word)))
#define VARNUM(i)		((int)((i) - (ARGOFFSET / (int) sizeof(word))))

#define setLevelFrame(fr, l)	do { (fr)->level = (l); } while(0)
#define levelFrame(fr)		((fr)->level)
#define argFrameP(f, n)		((Word)((f)+1) + (n))
#define argFrame(f, n)		(*argFrameP((f), (n)) )
#define varFrameP(f, n)		((Word)(f) + (n))
#define varFrame(f, n)		(*varFrameP((f), (n)) )
#define refFliP(f, n)		((Word)((f)+1) + (n))
#define parentFrame(f)		((f)->parent \
				  ? (f)->parent \
				  : (LocalFrame)varFrame( \
				    (f), -QF_PARENT_ENV_OFFSET))
#define slotsFrame(f)		(true((f)->predicate, P_FOREIGN) ? \
				      (f)->predicate->functor->arity : \
				      (f)->clause->clause->prolog_vars)


		 /*******************************
		 *	 LOGICAL UPDATE		*
		 *******************************/
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Generations must be 64-bit to  avoid   overflow  in realistic scenarios.
This makes them the only 64-bit value in struct localFrame. Stack frames
mix with variables on the stacks and  are thus word-aligned. We have two
options here. One is to represent a  generation as a struct (used below)
or we must align frame at 8-byte  boundaries. The latter is probably the
best solution, but merely aligning lTop in   I_ENTER  doesn't seem to be
doing the trick: it causes failure of the  test suite for which I failed
to find the reason. Enabling the structure   on x86 causes a slowdown of
about 5%. I'd assume the difference is smaller on real 32-bit hardware.

We enable this  if the alignment  of an int64_t type  is not the same as
the alignment of pointers.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

typedef uint64_t gen_t;

#define GEN_INVALID   ((gen_t)0)
#define GEN_INFINITE  (~(gen_t)0)
#define GEN_NEW_DIRTY ((gen_t)0)
#define GEN_TRANSACTION_BASE 0x8000000000000000
#define GEN_TRANSACTION_SIZE 0x0000000100000000
#define GEN_MAX (GEN_TRANSACTION_BASE-1)
#define GEN_TRMAX(g0) ((g0)|(GEN_TRANSACTION_SIZE-1))

#if ALIGNOF_INT64_T != ALIGNOF_VOIDP
typedef struct lgen_t
{ uint32_t	gen_l;
  uint32_t	gen_u;
} lgen_t;

#define generationFrame(f) \
	((gen_t)(f)->generation.gen_u<<32 | (gen_t)(f)->generation.gen_l)
#define setGenerationFrameVal(f, g) \
	do { gen_t __gen = (g); \
	     (f)->generation.gen_u = (uint32_t)(__gen>>32); \
	     (f)->generation.gen_l = (uint32_t)(__gen); \
	   } while(0)
#else
typedef uint64_t lgen_t;
#define generationFrame(f)	((f)->generation)
#define setGenerationFrameVal(f, gen) \
	do { (f)->generation = (gen); } while(0)
#endif

#define FR_LCO_CLEAR	(FR_SKIPPED|FR_WATCHED|FR_CATCHED|\
			 FR_HIDE_CHILDS|FR_CLEANUP|FR_SSU_DET)
#define FR_CLEAR_NEXT	(FR_LCO_CLEAR|FR_DET|FR_DETGUARD)
#define FR_CLEAR_ALWAYS (FR_CONTEXT|FR_DETGUARD_SET)
#define FR_CLEAR_FLAGS	(FR_CLEAR_NEXT|FR_CLEAR_ALWAYS)

#define setNextFrameFlags(next, fr) \
	do \
	{ (next)->level = (fr)->level+1; \
	  (next)->flags = ((fr)->flags) & ~FR_CLEAR_FLAGS; \
	} while(0)

#define lcoSetNextFrameFlags2(next, fr) \
	do \
	{ (next)->level = (fr)->level+1; \
	  (next)->flags = ((fr)->flags) & ~(FR_LCO_CLEAR|FR_CLEAR_ALWAYS); \
	} while(0)

#define lcoSetNextFrameFlags(fr) \
	lcoSetNextFrameFlags2(fr,fr)

/* For a tail call we must not clear FR_CONTEXT.  The combination
 * of FR->context and FR_CONTEXT is always correct.
 */

#define tcallSetNextFrameFlags(fr) \
	do \
	{ (fr)->level = (fr)->level+1; \
	  (fr)->flags = ((fr)->flags) & ~(FR_LCO_CLEAR|FR_DETGUARD_SET); \
	} while(0)

#define setFramePredicate(fr, def) \
	do \
	{ (fr)->predicate = (def); \
	} while(0)

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Predicate reference counting. The aim  of   this  mechanism  is to avoid
modifying the predicate structure while  it   has  choicepoints  or (MT)
other threads running the predicate. For dynamic  code we allow to clean
the predicate as the reference-count drops to   zero. For static code we
introduce a garbage collector (TBD).
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#define enterDefinition(def) (void)0
#define leaveDefinition(def) (void)0


		 /*******************************
		 *	 INHIBIT SIGNALS	*
		 *******************************/

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
LIST processing macros.

    isNil(w)		word is the nil list ([]).
    isList(w)		word is a './2' term.
    HeadList(p)		Pointer to the head of list *p (NOT dereferenced).
    TailList(p)		Pointer to the tail of list *p (NOT dereferenced).
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#define HeadList(p)	(argTermP(*(p), 0) )
#define TailList(p)	(argTermP(*(p), 1) )

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Doubles. To and from are Word pointers pointing to the data of a double,
but generally not  satisfying  the   double  alignment  requirements. We
assume

  sizeof(*to) == sizeof(*from) &&
  sizeof(*to) * n == sizeof(*double)
	with n == 1 or n == 2.

We assume the compiler will optimise this properly.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#define cpDoubleData(to, from) \
	{ Word _f = (Word)(from); \
	  switch(WORDS_PER_DOUBLE) \
	  { case 2: \
	      *(to)++ = *_f++; \
	    case 1: \
	      *(to)++ = *_f++; \
	      from = (void *)_f; \
	      break; \
	    default: \
	      assert(0); \
	  } \
	}

#define cpInt64Data(to, from) \
	{ Word _f = (Word)(from); \
	  switch(WORDS_PER_INT64) \
	  { case 2: \
	      *(to)++ = *_f++; \
	    case 1: \
	      *(to)++ = *_f++; \
	      from = (void *)_f; \
	      break; \
	    default: \
	      assert(0); \
	  } \
	}

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Structure declarations that must be shared across multiple files.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

struct atom
{ Atom		next;		/* next in chain */
  word		atom;		/* as appearing on the global stack */
#ifdef O_TERMHASH
  unsigned int  hash_value;	/* hash-key value */
#endif
#ifdef O_ATOMGC
  unsigned int	references;	/* reference-count */
#endif
  union
  { struct PL_blob_t * type;	/* blob-extension */
    uintptr_t	next_invalid;	/* next invalidated atom */
  };
  size_t	length;		/* length of the atom */
  char *	name;		/* name associated with atom */
};


typedef struct atom_array
{ Atom blocks[8*sizeof(void*)];
} atom_array;

typedef struct atom_table * AtomTable;

typedef struct atom_table
{ AtomTable	prev;
  int		buckets;
  Atom *	table;
} atom_table;


#ifdef O_ATOMGC

#define ATOM_STATE_MASK		((unsigned int)0xF << (INTBITSIZE-4))
#define ATOM_RESERVED_REFERENCE	((unsigned int)0x1 << (INTBITSIZE-1))
#define ATOM_VALID_REFERENCE	((unsigned int)0x1 << (INTBITSIZE-2))
#define ATOM_MARKED_REFERENCE	((unsigned int)0x1 << (INTBITSIZE-3))
#define ATOM_DESTROY_REFERENCE	((unsigned int)0x1 << (INTBITSIZE-4))

#define ATOM_IS_FREE(ref)	(((ref) & ATOM_STATE_MASK) == 0)
#define ATOM_IS_RESERVED(ref)	((ref) & ATOM_RESERVED_REFERENCE)
#define ATOM_IS_VALID(ref)	((ref) & ATOM_VALID_REFERENCE)
#define ATOM_IS_MARKED(ref)	((ref) & ATOM_MARKED_REFERENCE)
#define ATOM_IS_DESTROYED(ref)	((ref) & ATOM_DESTROY_REFERENCE)

#define ATOM_REF_COUNT_MASK	(~ATOM_STATE_MASK)
#define ATOM_REF_COUNT(ref)	((ref) & ATOM_REF_COUNT_MASK)

#define ATOM_TYPE_INVALID	((PL_blob_t*)0x007)

#ifdef O_DEBUG_ATOMGC
extern IOSTREAM *atomLogFd;
#define PL_register_atom(a) \
	_PL_debug_register_atom(a, __FILE__, __LINE__, __PRETTY_FUNCTION__)
#define PL_unregister_atom(a) \
	_PL_debug_unregister_atom(a, __FILE__, __LINE__, __PRETTY_FUNCTION__)
#endif
#else /*!O_ATOMGC*/
#define PL_register_atom(a)
#define PL_unregister_atom(a)
#endif

struct functorDef
{ FunctorDef	next;		/* next in chain */
  word		functor;	/* as appearing on the global stack */
  word		name;		/* Name of functor */
  size_t	arity;		/* arity of functor */
  unsigned      flags;		/* Flag field holding: */
		  /* CONTROL_F	   Compiled control-structure */
		  /* ARITH_F	   Arithmetic function */
		  /* VALID_F	   Fully defined functor */
};


typedef struct functor_array
{ FunctorDef *blocks[8*sizeof(void*)];
} functor_array;

typedef struct functor_table * FunctorTable;

typedef struct functor_table
{ FunctorTable	prev;
  int		buckets;
  FunctorDef *	table;
} functor_table;

#define FUNCTOR_IS_VALID(flags)		((flags) & VALID_F)

#define GLOBALLY_VISIBLE_CLAUSE(cl, gen) \
	( (cl)->generation.created <= (gen) && \
	  (cl)->generation.erased   > (gen) \
	)


/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Struct clause must be a  multiple   of  sizeof(word)  for compilation on
behalf  of  I_USERCALL.  This   is   verified    in   an   assertion  in
checkCodeTable().
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#define sizeofClause(n) (offsetof(struct clause, codes[n]))

struct clause
{ Definition		predicate;	/* Predicate I belong to */
#ifdef O_LOGICAL_UPDATE
  struct
  { volatile gen_t created;		/* Generation that created me */
    volatile gen_t erased;		/* Generation I was erased */
  } generation;
#endif /*O_LOGICAL_UPDATE*/
  unsigned int		variables;	/* # of variables for frame */
  unsigned int		prolog_vars;	/* # real Prolog variables */
  unsigned int		flags;		/* Flag field holding: */
  unsigned int		line_no;	/* Source line-number */
  unsigned int		source_no;	/* Index of source-file */
  unsigned int		owner_no;	/* Index of owning source-file */
  unsigned int		references;	/* # ClauseRef pointing at me */
  unsigned int		tr_erased_no;	/* # transactions that erased me */
  code			code_size;	/* size of ->codes */
  code			codes[1];	/* VM codes of clause */
};

typedef struct arg_info
{ float		speedup;		/* Computed speedup */
  unsigned	list	   : 1;		/* Index using lists */
  unsigned	ln_buckets : 5;		/* lg2(bucket count) */
  unsigned	assessed   : 1;		/* Value was assessed */
  unsigned	meta	   : 4;		/* Meta-argument info */
} arg_info;

typedef struct impl_any
{ arg_info     *args;			/* Meta and indexing info */
  void         *defined;		/* One of function or first_clause */
} impl_any, *ImplAny;

typedef struct impl_foreign
{ arg_info     *args;			/* Meta and indexing info */
  Func		function;		/* Function pointer */
} impl_foreign, *ImplForeign;

typedef struct impl_wrapped
{ arg_info     *args;			/* Meta and indexing info */
  Definition	predicate;		/* Wrapped predicate */
  Code		supervisor;		/* Supervisor to use */
} impl_wrapped, *ImplWrapped;

typedef struct impl_local
{ arg_info     *args;			/* Meta and indexing info */
  LocalDefinitions local;		/* P_THREAD_LOCAL predicates */
} impl_local, *ImplLocal;


typedef struct clause_list
{ arg_info     *args;			/* Meta and indexing info */
  ClauseRef	first_clause;		/* clause list of procedure */
  ClauseRef	last_clause;		/* last clause of list */
  ClauseIndex  *clause_indexes;		/* Hash index(es) */
  unsigned int	number_of_clauses;	/* number of associated clauses */
  unsigned int	erased_clauses;		/* number of erased clauses in set */
  unsigned int	number_of_rules;	/* number of real rules */
  unsigned int	jiti_tried;		/* number of times we tried to find */
} clause_list, *ClauseList;

typedef struct clause_ref
{ ClauseRef	next;			/* Next in list */
  union
  { word	key;			/* Index key */
    ClauseRef	gnext;			/* Next garbage clause reference */
  } d;
  union
  { Clause	clause;			/* Single clause value */
    clause_list	clauses;		/* Clause list (in hash-tables) */
  } value;
} clause_ref;

#define SIZEOF_CREF_CLAUSE	(offsetof(clause_ref, value.clause) + \
				 sizeof(Clause))
#define SIZEOF_CREF_LIST	sizeof(clause_ref)

typedef struct cgc_stats
{ int		threads;		/* # threads to scan */
  size_t	local_size;		/* Summed size of local stacks */
  size_t	dirty_pred_clauses;	/* # clauses in dirty predicates */
  int64_t	erased_skipped;		/* # skipped clauses that are erased  */
} cgc_stats;

#define GC_STAT_WINDOW_SIZE 3
#define GC_GLOBAL_OVERFLOW	0x000000000001
#define GC_GLOBAL_REQUEST	0x000000000100
#define GC_TRAIL_OVERFLOW	0x000000010000
#define GC_TRAIL_REQUEST	0x000001000000
#define GC_EXCEPTION		0x000100000000
#define GC_USER			0x010000000000

typedef uint64_t gc_reason_t;

typedef struct gc_stat
{ size_t	global_before;
  size_t	global_after;
  size_t	trail_before;
  size_t	trail_after;
  size_t	local;
  double	gc_time;		/* time spent on last GC */
  double	prolog_time;		/* Real work CPU before this GC */
  gc_reason_t	reason;			/* why GC was run */
} gc_stat;

typedef struct gc_stats
{ gc_stat	last[GC_STAT_WINDOW_SIZE];
  gc_stat	aggr[GC_STAT_WINDOW_SIZE];
  int		last_index;
  int		aggr_index;
  double	thread_cpu;		/* Last thread CPU time */
  gc_reason_t	request;		/* Requesting stack */
  struct
  { int64_t	collections;
    int64_t	global_gained;		/* global stack bytes collected */
    int64_t	trail_gained;		/* trail stack bytes collected */
    double	time;			/* time spent in collections */
  } totals;
} gc_stats;


#define VM_DYNARGC    255	/* compute argcount dynamically */

#define CA1_PROC	1	/* code arg 1 is procedure */
#define CA1_FUNC	2	/* code arg 1 is functor */
#define CA1_DATA	3	/* code arg 2 is prolog data (H_ATOM, H_SMALLINT) */
#define CA1_INTEGER	4	/* intptr_t value */
#define CA1_INT64	5	/* int64 value */
#define CA1_FLOAT	6	/* next WORDS_PER_DOUBLE are double */
#define CA1_STRING	7	/* inlined string */
#define CA1_MPZ		8	/* GNU mpz number */
#define CA1_MPQ		9	/* GNU mpq number */
#define CA1_MODULE     10	/* a module */
#define CA1_VAR	       11	/* a variable(-offset) */
#define CA1_FVAR       12	/* a variable(-offset), used as `firstvar' */
#define CA1_CHP	       13	/* ChoicePoint (also variable(-offset)) */
#define CA1_FOREIGN    14	/* Foreign function pointer */
#define CA1_CLAUSEREF  15	/* Clause reference */
#define CA1_JUMP       16	/* Instructions to skip */
#define CA1_AFUNC      17	/* Number of arithmetic function */
#define CA1_TRIE_NODE  18	/* Tabling: answer trie node with delays */
#define CA1_END	       19	/* Highest+1 */

#define VIF_BREAK      0x01	/* Can be a breakpoint */
#define VIF_LCO        0x02	/* We have LCO support for this */

typedef enum
{ VMI_REPLACE,
  VMI_STEP_ARGUMENT
} vmi_merge_type;

typedef struct
{ vmi		code;		/* Code to merge with */
  vmi_merge_type how;		/* How to merge? */
  vmi		merge_op;	/* Opcode of merge */
  int		merge_ac;	/* #arguments of merged code */
  code		merge_av[1];	/* Argument vector */
} vmi_merge;

#if O_EMPTY_STRUCTS
#define VM_ARGC 4
#define VM_ARGTYPES(ci) (ci)->_argtype
#define VM_ARTYPE_PREFIX
#else
#define VM_ARGC 5
#define VM_ARGTYPES(ci) &(ci)->_argtype[1]
#define VM_ARTYPE_PREFIX 0,
#endif

typedef struct
{ char	       *name;		/* name of the code */
  vmi		code;		/* number of the code */
  unsigned char flags;		/* Addional flags (VIF_*) */
  unsigned char	arguments;	/* #args code takes (or VM_DYNARGC) */
  char	       _argtype[VM_ARGC]; /* Argument type(s) code takes */
} code_info;

struct mark
{ TrailEntry	trailtop;	/* top of the trail stack */
  Word		globaltop;	/* top of the global stack */
  Word		saved_bar;	/* saved LD->mark_bar */
};

struct functor
{ word		definition;	/* Tagged definition pointer */
  word		arguments[1];	/* arguments vector */
};

struct clause_bucket
{ ClauseRef	head;
  ClauseRef	tail;
  unsigned int	dirty;			/* # of garbage clauses */
};

#define MAX_MULTI_INDEX  4
#define MAXINDEXARG    254
#define MAXINDEXDEPTH    7
#define END_INDEX_POS  255

typedef unsigned char iarg_t;		/* index argument */

struct clause_index
{ unsigned int	 buckets;		/* # entries */
  unsigned int	 size;			/* # clauses */
  unsigned int	 resize_above;		/* consider resize > #clauses */
  unsigned int	 resize_below;		/* consider resize < #clauses */
  unsigned int	 dirty;			/* # chains that are dirty */
  unsigned	 is_list : 1;		/* Index with lists */
  unsigned	 incomplete : 1;	/* Index is incomplete */
  unsigned	 invalid : 1;		/* Index is invalid */
  iarg_t	 args[MAX_MULTI_INDEX];	/* Indexed arguments */
  iarg_t	 position[MAXINDEXDEPTH+1]; /* Deep index position */
  float		 speedup;		/* Estimated speedup */
  ClauseBucket	 entries;		/* chains holding the clauses */
};

#define MAX_BLOCKS 20			/* allows for 2M threads */

typedef struct local_definitions
{ Definition *blocks[MAX_BLOCKS];
  Definition preallocated[7];
} local_definitions;

struct definition
{ FunctorDef	functor;		/* Name/Arity of procedure */
  Module	module;			/* module of the predicate */
  Code		codes;			/* Executable code */
  union
  { impl_any	any;			/* has some value */
    clause_list	clauses;		/* (Indexed) list of clauses */
    impl_foreign foreign;		/* Foreign implementation */
    impl_wrapped wrapped;		/* Wrapped predicate */
    impl_local   local;			/* P_THREAD_LOCAL predicates */
  } impl;
  uint64_t	flags;			/* booleans (P_*) */
  unsigned int  shared;			/* #procedures sharing this def */
  struct linger_list  *lingering;	/* Assocated lingering objects */
  gen_t		last_modified;		/* Generation I was last modified */
  struct event_list  *events;		/* Forward update events */
  struct table_props *tabling;		/* Extended properties for tabling */
#if defined(__SANITIZE_ADDRESS__)
  char	       *name;			/* Name for debugging */
#endif
#ifdef O_PROF_PENTIUM
  int		prof_index;		/* index in profiling */
  char	       *prof_name;		/* name in profiling */
#endif
};

struct definition_chain
{ Definition		definition;	/* chain on definition */
  DefinitionChain	next;		/* next in chain */
};

#define PROC_DIRTY_GENS	10

struct dirty_def_info
{ unsigned short count;			/* # captured generations */
  unsigned short flags;			/* DDI_* */
  Definition	predicate;		/* The dirty predicate */
  gen_t		access[PROC_DIRTY_GENS];/* Accessed generations */
};

typedef struct definition_ref
{ Definition predicate;			/* Referenced definition */
  gen_t	     generation;		/* at generation */
} definition_ref;

typedef struct definition_refs
{ definition_ref *blocks[MAX_BLOCKS];
  definition_ref preallocated[7];
  size_t     top;
} definition_refs;

#define	PROC_WEAK	 (0x0001)	/* implicit import */
#define	PROC_MULTISOURCE (0x0002)	/* Assigned to multiple sources */
#define PROC_IMPORTED	 (0x0004)	/* Procedure is imported */

struct procedure
{ Definition	definition;		/* definition of procedure */
  unsigned int  flags;			/* PROC_WEAK */
  unsigned int	source_no;		/* Source I'm assigned to */
};

struct localFrame
{ Code		programPointer;		/* pointer into program */
  LocalFrame	parent;			/* parent local frame */
  ClauseRef	clause;			/* Current clause of frame */
  Definition	predicate;		/* Predicate we are running */
  Module	context;		/* context module of frame */
#ifdef O_PROFILE
  struct call_node *prof_node;		/* Profiling node */
#endif
#ifdef O_LOGICAL_UPDATE
  lgen_t	generation;		/* generation of the database */
#endif
  unsigned int	level;			/* recursion level */
  unsigned int	flags;			/* packed long holding: */
};


typedef enum
{ CHP_JUMP = 0,				/* A jump due to ; */
  CHP_CLAUSE,				/* Next clause of predicate */
  CHP_TOP,				/* First (toplevel) choice */
  CHP_CATCH,				/* $catch initiated choice */
  CHP_DEBUG				/* Enable redo */
} choice_type;

typedef enum
{ DBG_OFF = 0,				/* no debugging */
  DBG_ON,				/* switch on in current environment */
  DBG_ALL				/* switch on globally */
} debug_type;

#define SKIP_VERY_DEEP	  ((size_t)-1)	/* deep skiplevel */
#define SKIP_REDO_IN_SKIP (SKIP_VERY_DEEP-1)

struct clause_choice
{ ClauseRef	cref;			/* Next clause reference */
  word		key;			/* Search key */
};

#ifdef O_PLMT
#define acquire_def(def) \
	do { DEBUG(CHK_SECURE, assert(!LD->thread.info->access.predicate)); \
	     LD->thread.info->access.predicate = def; } while(0)
#define release_def(def) \
	do { LD->thread.info->access.predicate = NULL; } while(0)
#define acquire_def2(def, store) \
	do { store = LD->thread.info->access.predicate; \
	     DEBUG(CHK_SECURE, assert(!store || store == def)); \
	     LD->thread.info->access.predicate = def; } while(0)
#define release_def2(def, store) \
	do { LD->thread.info->access.predicate = store; } while(0)

#else
#define acquire_def(def) (void)0
#define release_def(def) (void)0
#define acquire_def2(def,store) (void)store
#define release_def2(def,store) (void)store
#endif

struct choice
{ choice_type	type;			/* CHP_* */
  Choice	parent;			/* Alternative if I fail */
  mark		mark;			/* data mark for undo */
  LocalFrame	frame;			/* Frame I am related to */
#ifdef O_PROFILE
  struct call_node *prof_node;		/* Profiling node */
#endif
  union
  { struct clause_choice clause;	/* Next candidate clause */
    Code	pc;			/* Next candidate program counter */
    word        foreign;		/* foreign redo handle */
  } value;
};


/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
EXCEPTION_GUARDED(code, cleanup) must be used  in environments that need
cleanup  should  a  PL_throw()  happen.  The   most  commpn  reason  for
PL_throw() instead of the nicely   synchronous PL_raise_exception() is a
stack overflow.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#define EXCEPTION_GUARDED(code, cleanup) \
	{ exception_frame __throw_env; \
	  __throw_env.parent = LD->exception.throw_environment; \
	  if ( setjmp(__throw_env.exception_jmp_env) != 0 ) \
	  { LD->exception.throw_environment = __throw_env.parent; \
	    cleanup; \
	  } else \
	  { __throw_env.magic = THROW_MAGIC; \
	    LD->exception.throw_environment = &__throw_env; \
	    code; \
	    assert(LD->exception.throw_environment == &__throw_env); \
	    __throw_env.magic = 41414141; \
	    LD->exception.throw_environment = __throw_env.parent; \
	  } \
	}

#define THROW_MAGIC 42424242

typedef struct exception_frame		/* PL_throw exception environments */
{ struct exception_frame * volatile parent;	/* parent frame */
  volatile int	  magic;			/* THROW_MAGIC */
  jmp_buf	exception_jmp_env;	/* longjmp environment */
} exception_frame;


typedef struct queryRef
{ PL_engine_t	engine;			/* Engine for the query */
  uintptr_t	offset;			/* queryFrane offset in local stack */
} *QueryRef;

#define QF_NODEBUG		0x0001	/* debug-able query */
#define QF_DETERMINISTIC	0x0002	/* deterministic success */
#define	QF_INTERACTIVE		0x0004	/* interactive goal (prolog()) */

struct queryFrame
{ uintptr_t magic;			/* Magic code for security */
  struct				/* Interpreter registers */
  { LocalFrame  fr;
    Word	argp;
    Code	pc;
  } registers;
  LocalFrame	next_environment;	/* See D_BREAK and get_vmi_state() */
#ifdef O_LIMIT_DEPTH
  size_t	saved_depth_limit;	/* saved values of these */
  size_t	saved_depth_reached;
#endif
#if O_CATCHTHROW
  term_t	exception;		/* Exception term */
#endif
  struct
  { term_t	term;			/* Handle to exchange data */
  } yield;
  fid_t		foreign_frame;		/* Frame after PL_next_solution() */
  unsigned int	flags;
  debug_type	debugSave;		/* saved debugstatus.debugging */
  unsigned int	flags_saved;		/* Saved boolean Prolog flags */
  int		solutions;		/* # of solutions produced */
  Word	       *aSave;			/* saved argument-stack */
  Choice	saved_bfr;		/* Saved choice-point */
  LocalFrame	saved_ltop;		/* Saved lTop */
  QueryFrame	parent;			/* Parent queryFrame */
  QueryRef	qid;			/* Opaque query id */
  struct choice	choice;			/* First (dummy) choice-point */
  LocalFrame	saved_environment;	/* Parent local-frame */
					/* Do not put anything between */
					/* or check parentFrame() */
  struct localFrame top_frame;		/* The (dummy) top local frame */
  struct localFrame frame;		/* The initial frame */
};

#define QF_PARENT_ENV_OFFSET \
	((ssize_t)((offsetof(struct queryFrame, top_frame) - \
		    offsetof(struct queryFrame, saved_environment)) / sizeof(word)))


#define FLI_MAGIC		82649821
#define FLI_MAGIC_CLOSED	42424242
#ifdef O_DEBUG
#define FLI_SET_VALID(fr)	((fr)->magic = FLI_MAGIC)
#define FLI_SET_CLOSED(fr)	((fr)->magic = FLI_MAGIC_CLOSED)
#define FLI_VALID(fr)		((fr)->magic == FLI_MAGIC)
#define FLI_ASSERT_VALID(fr)	assert(FLI_VALID(fr))
#else
#define FLI_SET_VALID(fr)	(void)0
#define FLI_SET_CLOSED(fr)	(void)0
#define FLI_VALID(fr)		(1)
#define FLI_ASSERT_VALID(fr)	(void)0
#endif

struct fliFrame
{
#ifdef O_DEBUG
  int		magic;			/* Magic code */
#endif
  size_t	size;			/* # slots on it */
  FliFrame	parent;			/* parent FLI frame */
  mark		mark;			/* data-stack mark */
};

#ifdef O_MAINTENANCE
#define REC_MAGIC 27473244
#endif

struct record
{ int		size;			/* # bytes of the record */
  unsigned      gsize;			/* Size on global stack */
  unsigned	nvars;			/* # variables in the term */
  unsigned	flags;			/* Flags, holding */
					/* R_ERASED */
					/* R_EXTERNAL */
					/* R_DUPLICATE */
					/* R_NOLOCK */
					/* R_DBREF */
#ifdef REC_MAGIC
  int		magic;			/* REC_MAGIC */
#endif
  int		references;		/* PL_duplicate_record() support */
  char		buffer[1];		/* array holding codes */
};

struct recordList
{ RecordRef	firstRecord;		/* first record associated with key */
  RecordRef	lastRecord;		/* last record associated with key */
  struct recordList *next;		/* Next recordList */
  word		key;			/* key of record */
  unsigned int	flags;			/* RL_DIRTY */
  int		references;		/* choicepoints reference count */
};

struct recordRef
{ RecordList	list;			/* list I belong to */
  RecordRef	next;			/* next in list */
  RecordRef	prev;			/* previous in list */
  Record	record;			/* the record itself */
};


		 /*******************************
		 *	EXCEPTION CLASSES	*
		 *******************************/

typedef enum except_class
{ EXCEPT_NONE = 0,			/* no exception */
  EXCEPT_OTHER,				/* any other exception */
  EXCEPT_ERROR,				/* ISO error(Formal,Context) */
  EXCEPT_RESOURCE,			/* ISO error(resource_error(_), _) */
  EXCEPT_TIMEOUT,			/* time_limit_exceeded */
  EXCEPT_ABORT				/* '$aborted' */
} except_class;


		 /*******************************
		 *	SOURCE FILE ADMIN	*
		 *******************************/

#define SF_MAGIC 0x14a3c90f
#define SF_MAGIC_DESTROYING 0x14a3c910

typedef struct p_reload
{ Definition	predicate;		/* definition we are working on */
  gen_t		generation;		/* generation we update */
  ClauseRef	current_clause;		/* currently reloading clause */
  arg_info     *args;			/* Meta info on arguments */
  uint64_t	flags;			/* new flags (P_DYNAMIC, etc.) */
  unsigned	number_of_clauses;	/* Number of clauses we've seen */
} p_reload;

typedef struct m_reload
{ Module	module;
  Table		public;			/* new export list */
} m_reload;

typedef struct sf_reload
{ Table		procedures;		/* Procedures being reloaded */
  gen_t		reload_gen;		/* Magic gen for reloading */
  size_t	pred_access_count;	/* Top of predicate access stack */
  Table		modules;		/* Modules seen during reload */
  unsigned	number_of_clauses;	/* reload clause count */
} sf_reload;


struct sourceFile
{ atom_t	name;			/* name of source file */
  double	mtime;			/* modification time when loaded */
  ListCell	procedures;		/* List of associated procedures */
  Procedure	current_procedure;	/* currently loading one */
  ListCell	modules;		/* Modules associated to this file */
  sf_reload     *reload;		/* Reloading context */
#ifdef O_PLMT
  counting_mutex *mutex;		/* Mutex to guard procedures */
#endif
  int		magic;			/* Magic number */
  int		count;			/* number of times loaded */
  unsigned int	number_of_clauses;	/* number of clauses */
  unsigned int	index;			/* index number (1,2,...) */
  unsigned int	references;		/* Reference count */
  unsigned	system     : 1;		/* system sourcefile: do not reload */
  unsigned	from_state : 1;		/* Loaded from resource DB state */
  unsigned	resource   : 1;		/* Loaded from resource DB file */
};

typedef struct srcfile_array
{ SourceFile *blocks[8*sizeof(void*)];
} srcfile_array;

struct list_cell
{ void *	value;		/* object in the cell */
  ListCell	next;		/* next in chain */
};


		 /*******************************
		 *	      MODULES		*
		 *******************************/

struct module
{ atom_t	name;		/* name of module */
  atom_t	class;		/* class of the module */
  SourceFile	file;		/* file from which module is loaded */
  Table		procedures;	/* predicates associated with module */
  Table		public;		/* public predicates associated */
  Table		operators;	/* local operator declarations */
  ListCell	supers;		/* Import predicates from here */
  ListCell	lingering;	/* Lingering definitions */
  size_t	code_size;	/* #Bytes used for its procedures */
  size_t	code_limit;	/* Limit for code_size */
#ifdef O_PLMT
  counting_mutex *mutex;	/* Mutex to guard module modifications */
  struct thread_wait_area *wait;/* Manage waiting threads */
#endif
#ifdef O_PROLOG_HOOK
  Procedure	hook;		/* Hooked module */
#endif
  int		level;		/* Distance to root (root=0) */
  unsigned int	line_no;	/* Source line-number */
  unsigned int  flags;		/* booleans: */
  int		references;	/* see acquireModule() */
  gen_t		last_modified;	/* Generation I was last modified */
};

#define MENUM_TEMP	0x1	/* Also enumerate temporary modules */

typedef struct module_enum
{ TableEnum	tenum;
  Module        current;
  int		flags;
} module_enum, *ModuleEnum;


		 /*******************************
		 *	      TRAIL		*
		 *******************************/

struct trail_entry
{ Word		address;	/* address of the variable */
};

struct gc_trail_entry
{ word		address;	/* address of the variable */
};

		 /*******************************
		 *	   META PREDICATE	*
		 *******************************/

/*0..9*/				/* 0..9: `Extra meta arguments' */
#define MA_META		10		/* : */
#define MA_VAR		11		/* - */
#define MA_ANY		12		/* ? */
#define MA_NONVAR	13		/* + */
#define MA_HAT		14		/* ^ */
#define MA_DCG		15		/* // */

#define MA_NEEDS_TRANSPARENT(m) \
	((m) < 10 || (m) == MA_META || (m) == MA_HAT || (m) == MA_DCG)

		 /*******************************
		 *	     MARK/UNDO		*
		 *******************************/

#define setVar(w)	((w) = (word) 0)

#ifdef O_DESTRUCTIVE_ASSIGNMENT

#define Undo(b)		do_undo(&b)

#else /*O_DESTRUCTIVE_ASSIGNMENT*/

#define Undo(b)		do { TrailEntry tt = tTop; \
			     TrailEntry mt = (b).trailtop; \
			     while(tt > mt) \
			     { tt--; \
			       setVar(*tt->address); \
			     } \
			     tTop = tt; \
			     gTop = (LD->frozen_bar > (b).globaltop ? \
				     LD->frozen_bar : (b).globaltop); \
			    } while(0)
#endif /*O_DESTRUCTIVE_ASSIGNMENT*/

#define NO_MARK_BAR	(Word)(~(uintptr_t)0)

#define Mark(b)		do { (b).trailtop  = tTop; \
			     (b).saved_bar = LD->mark_bar; \
			     DEBUG(CHK_SECURE, \
				   assert((b).saved_bar == NO_MARK_BAR || \
					  ((b).saved_bar >= gBase && \
					   (b).saved_bar <= gTop))); \
			     (b).globaltop = gTop; \
			     if ( LD->mark_bar != NO_MARK_BAR ) \
			       LD->mark_bar = (b).globaltop; \
			   } while(0)
#define DiscardMark(b)	do { LD->mark_bar = (LD->frozen_bar > (b).saved_bar ? \
					     LD->frozen_bar : (b).saved_bar); \
			     DEBUG(CHK_SECURE, \
				   assert(LD->mark_bar == NO_MARK_BAR || \
					  (LD->mark_bar >= gBase && \
					   LD->mark_bar <= gTop))); \
			   } while(0)
#define NOT_A_MARK	(TrailEntry)(~(word)0)
#define NoMark(b)	do { (b).trailtop = NOT_A_MARK; \
			   } while(0)
#define isRealMark(b)	((b).trailtop != NOT_A_MARK)


		 /*******************************
		 *	     TRAILING		*
		 *******************************/

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Note that all trail operations demand that   the caller ensures there is
at least one free cell on the trail-stack.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

					/* trail local stack pointer */
#define LTrail(p) \
  (void)((tTop++)->address = p)
					/* trail global stack pointer */
#define GTrail(p) \
  do { if ( p < LD->mark_bar ) \
	 (tTop++)->address = p; \
     } while(0)


		 /*******************************
		 *	    SUPERVISORS		*
		 *******************************/

#define SUPERVISOR(name)	(&PL_code_data.supervisors.name[1])



		 /*******************************
		 *	   FLI INTERNALS	*
		 *******************************/

#define consTermRef(p)	 ((Word)(p) - (Word)(lBase))
#define valTermRef(r)	 (&((Word)(lBase))[r])

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Temporary store/restore pointers to make them safe over GC/shift
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#define TMP_PTR_SIZE	(4)
#define PushPtr(p)	do { int i = LD->tmp.top++; \
			     assert(i<TMP_PTR_SIZE); \
			     *valTermRef(LD->tmp.h[i]) = makeRefLG(p); \
			   } while(0)
#define PopPtr(p)	do { int i = --LD->tmp.top; \
			     p = unRefLG(*valTermRef(LD->tmp.h[i])); \
			     setVar(*valTermRef(LD->tmp.h[i])); \
			   } while(0)
#define PushVal(w)	do { int i = LD->tmp.top++; \
			     assert(i<TMP_PTR_SIZE); \
			     *valTermRef(LD->tmp.h[i]) = w; \
			   } while(0)
#define PopVal(w)	do { int i = --LD->tmp.top; \
			     w = *valTermRef(LD->tmp.h[i]); \
			     setVar(*valTermRef(LD->tmp.h[i])); \
			   } while(0)


#define QidFromQuery(f)		((f)->qid)
#define QID_EXPORT_WAM_TABLE	(qid_t)(-1)


		 /*******************************
		 *	       SIGNALS		*
		 *******************************/

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
SWI-Prolog may be compiled without signal handling. Even in that case we
still have signals that trigger Prolog   housekeeping  events. These are
not bound to operating system signal handling though.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#define SIG_PROLOG_OFFSET	32	/* Start of Prolog signals - specified in docs */

#if HAVE_OS_SIGNALS

#define MINSIGNAL		1	/* number of first signal */
#define MAXSIGNAL		64	/* highest supported signal number */

#else /* HAVE_OS_SIGNALS */

#define MINSIGNAL		SIG_PROLOG_OFFSET /* No system signals, only Prolog sigs */
#define MAXSIGNAL		(SIG_PROLOG_OFFSET+31)	/* we'd like this to fit in 32 bits */

#endif /* HAVE_OS_SIGNALS */

#define NUM_SIGNALS (MAXSIGNAL - MINSIGNAL + 1)

#ifndef RETSIGTYPE
#define RETSIGTYPE void
#endif
typedef RETSIGTYPE (*handler_t)(int);

typedef struct
{ handler_t   saved_handler;		/* Original handler */
  handler_t   handler;			/* User signal handler */
  predicate_t predicate;		/* Prolog handler */
  unsigned int flags;			/* PLSIG_*, defined in pl-setup.c */
} sig_handler, *SigHandler;

/* Declare numbers for the virtual signals, in their own domain. For now, these
 * just map to the numbers starting at SIG_PROLOG_OFFSET. Note, we could omit
 * some of these definitions based on preprocessor statements, but there are
 * few enough of them that it doesn't seem necessary.
 */
typedef enum virtual_signum
{ VSIG_ATOM_GC,
  VSIG_GC,
  VSIG_THREAD_SIGNAL,
  VSIG_CLAUSE_GC,
  VSIG_PLABORT,
  VSIG_TUNE_GC,
  VSIG_MAX
} virtual_signum;

#define NUM_VSIGS 6 /* Preprocessor can see this constant */
static_assertion(NUM_VSIGS == VSIG_MAX); /* Make sure it matches the enum */
static_assertion(NUM_SIGNALS >= VSIG_MAX && NUM_SIGNALS < 128); /* Sanity check, 128 is arbitrary */
static_assertion(SIG_PROLOG_OFFSET >= MINSIGNAL && SIG_PROLOG_OFFSET + NUM_VSIGS <= MAXSIGNAL);

/* Define the macros that map vsignals into the signal domain. */
#ifdef O_ATOMGC
#define SIG_ATOM_GC	  (SIG_PROLOG_OFFSET+VSIG_ATOM_GC)
#endif
#define SIG_GC		  (SIG_PROLOG_OFFSET+VSIG_GC)
#ifdef O_ENGINES
#define SIG_THREAD_SIGNAL (SIG_PROLOG_OFFSET+VSIG_THREAD_SIGNAL)
#endif
#define SIG_CLAUSE_GC	  (SIG_PROLOG_OFFSET+VSIG_CLAUSE_GC)
#define SIG_PLABORT	  (SIG_PROLOG_OFFSET+VSIG_PLABORT)
#define SIG_TUNE_GC	  (SIG_PROLOG_OFFSET+VSIG_TUNE_GC)

/* The "search for a free signal" functionality of PL_sigaction starts after
 * the predefined VSIG numbers */
#define SIG_USER_OFFSET	  (SIG_PROLOG_OFFSET+VSIG_MAX)

/* Get a zero-based array index for this signal */
#define SIGNAL_INDEX(sig)	((sig) - MINSIGNAL)
/* Return the signal given an array index */
#define SIGNAL_FROM_INDEX(idx)	((idx) + MINSIGNAL)
/* Is this a valid signal number? */
#define IS_VALID_SIGNAL(sig)	((sig) >= MINSIGNAL && (sig) <= MAXSIGNAL)
/* Is this a virtual signal? */
#define IS_VSIG(sig)		((sig) >= SIG_PROLOG_OFFSET)

#if O_DEBUG
#undef SIGNAL_INDEX
static inline int
SIGNAL_INDEX(int sig)
{ assert(IS_VALID_SIGNAL(sig));
  return sig - MINSIGNAL;
}
#endif

/* We want fast types for signal bitmasks; on a 64-bit arch this is probably the same as uint64_t */
typedef uint_fast32_t		sigmask_t;

/* How many bits can fit in a single sigmask_t? */
#define SIGMASK_WIDTH		(sizeof(sigmask_t) * 8)
/* How many sigmask_t's does it take to store all supported signals? */
#define SIGMASK_WORDS		((NUM_SIGNALS + SIGMASK_WIDTH - 1) / SIGMASK_WIDTH)
/* Which sigmask word is this signal in? */
#define SIGMASK_WORD(sig)	(SIGNAL_INDEX(sig) / SIGMASK_WIDTH)
/* Which bit of the given word? */
#define SIGMASK_BIT(sig)	(SIGNAL_INDEX(sig) % SIGMASK_WIDTH)
/* Single-bit mask corresponding to SIGMASK_BIT */
#define SIGMASK_MASK(sig)	(((sigmask_t)1) << SIGMASK_BIT(sig))

/* Obtain signal given sigmask word and bit */
#define SIGNAL_FROM_SIGMASK(word, bit) SIGNAL_FROM_INDEX((word) * SIGMASK_WIDTH + (bit))

typedef sigmask_t		wsigmask_t[SIGMASK_WORDS];

/* Helper macros for interacting with sigmask_t arrays */
#define WSIGMASK_ISSET(wm, sig)	(((wm)[SIGMASK_WORD(sig)] & SIGMASK_MASK(sig)) != 0)
#define WSIGMASK_SET(wm, sig)	ATOMIC_OR(&(wm)[SIGMASK_WORD(sig)], SIGMASK_MASK(sig))
#define WSIGMASK_CLEAR(wm, sig)	ATOMIC_AND(&(wm)[SIGMASK_WORD(sig)], ~SIGMASK_MASK(sig))

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Guard against C-stack overflows. This is   done  for POSIX systems using
the  alternative  signal  stack.  The  signal    handling   is  done  by
alt_segv_handler().

Note that we  use  setjmp()  rather   than  sigsetjmp().  The  latter is
simpler, but a lot slower as it  implies   a  system  call. We assume no
other signals are involved and unblock SIGSEGV by hand.

Note that AddressSanitizer doesn't like these tricks, so we must disable
stack guarding when compiling with the address sanitizer.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#if O_SIGNALS && defined(HAVE_SIGALTSTACK) && \
    !defined(__SANITIZE_ADDRESS__)
#define O_C_STACK_GUARDED 1
#define C_STACK_OVERFLOW_GUARDED(rc, code, cleanup) \
	do						\
	{ LD->signal.sig_critical = TRUE;		\
	  if ( setjmp(LD->signal.context) )		\
	  { cleanup;					\
	    unblockSignal(SIGSEGV);			\
	    rc = PL_resource_error("c_stack");		\
	  } else					\
	  { rc = code;					\
	  }						\
	  LD->signal.sig_critical = FALSE;		\
	} while(0)
#else
#define C_STACK_OVERFLOW_GUARDED(rc, code, cleanup) \
	do						\
	{ rc = code;						\
	} while(0)
#endif


		 /*******************************
		 *	       COMPARE		*
		 *******************************/

/* Results from comparison operations.  Mostly used by compareStandard() */

#define CMP_COMPOUND -3			/* compare_primitive */
#define CMP_ERROR    -2			/* Error (out of memory) */
#define CMP_LESS     -1			/* < */
#define CMP_EQUAL     0			/* == */
#define CMP_GREATER   1			/* > */
#define CMP_NOTEQ     2			/* \== */

/* Convert <0, 0, >0 to -1, 0, 1 (or CMP*) */
#ifdef _MSC_VER
#define SCALAR_TO_CMP(a,b) (((a) > (b)) - ((a) < (b)))
#else
#define SCALAR_TO_CMP(a,b) ( \
	{ __auto_type __a = (a); __auto_type __b = (b);	\
	  (__a > __b) - (__a < __b);			\
	})
#endif


		/********************************
		*             STACKS            *
		*********************************/

#ifdef small				/* defined by MSVC++ 2.0 windows.h */
#undef small
#endif

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
If we have access to the virtual   memory management of the machine, use
this to enlarge the runtime stacks.  Otherwise use the stack-shifter.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#define GC_FAST_POLICY 0x1		/* not really used yet */

#define STACK(type) \
	{ type		base;		/* base address of the stack */     \
	  type		top;		/* current top of the stack */      \
	  type		max;		/* allocated maximum */		    \
	  size_t	gced_size;	/* size after last GC */	    \
	  size_t	small;		/* Do not GC below this size */	    \
	  size_t	spare;		/* Current reserved area */	    \
	  size_t	def_spare;	/* Desired reserved area */	    \
	  size_t	min_free;	/* Free left when trimming */	    \
	  bool		gc;		/* Can be GC'ed? */		    \
	  int		factor;		/* How eager we are */		    \
	  int		policy;		/* Time, memory optimization */	    \
	  int		overflow_id;	/* OVERFLOW_* */		    \
	  const char   *name;		/* Symbolic name of the stack */    \
	}

struct stack STACK(caddress);		/* Anonymous stack */

typedef struct
{ size_t limit;				/* Total stack limit */
  struct STACK(LocalFrame) local;	/* local (environment) stack */
  struct STACK(Word)	   global;	/* local (environment) stack */
  struct STACK(TrailEntry) trail;	/* trail stack */
  struct STACK(Word *)	   argument;	/* argument stack */
} pl_stacks_t;

#define tBase	(LD->stacks.trail.base)
#define tTop	(LD->stacks.trail.top)
#define tMax	(LD->stacks.trail.max)

#define lBase	(LD->stacks.local.base)
#define lTop	(LD->stacks.local.top)
#define lMax	(LD->stacks.local.max)

#define gBase	(LD->stacks.global.base)
#define gTop	(LD->stacks.global.top)
#define gMax	(LD->stacks.global.max)

#define aBase	(LD->stacks.argument.base)
#define aTop	(LD->stacks.argument.top)
#define aMax	(LD->stacks.argument.max)

#define tSpare	(LD->stacks.trail.spare)

#define onStack(name, addr) \
	((char *)(addr) >= (char *)LD->stacks.name.base && \
	 (char *)(addr) <  (char *)LD->stacks.name.top)
#define onStackArea(name, addr) \
	((char *)(addr) >= (char *)LD->stacks.name.base && \
	 (char *)(addr) <  (char *)LD->stacks.name.max)
#define onTrailArea(addr) \
	((char *)(addr) >= (char *)tBase && \
	 (char *)(addr) <  (char *)tMax + tSpare)
#define onGlobalArea(addr) \
	((char *)(addr) >= (char *)gBase && \
	 (char *)(addr) <  (char *)lBase)
#define usedStackP(s) ((intptr_t)((char *)(s)->top - (char *)(s)->base))
#define sizeStackP(s) ((intptr_t)((char *)(s)->max - (char *)(s)->base))
#define roomStackP(s) ((intptr_t)((char *)(s)->max - (char *)(s)->top))
#define spaceStackP(s) (limitStackP(s)-usedStackP(s))
#define narrowStackP(s) (roomStackP(s) < (intptr_t)(s)->minfree)

#define usedStack(name) usedStackP(&LD->stacks.name)
#define sizeStack(name) sizeStackP(&LD->stacks.name)
#define roomStack(name) roomStackP(&LD->stacks.name)
#define spaceStack(name) spaceStackP(&LD->stacks.name)
#define narrowStack(name) narrowStackP(&LD->stacks.name)

#define globalStackLimit() (LD->stacks.limit > (MAXTAGGEDPTR+1) ? \
					       (MAXTAGGEDPTR+1) : \
					       LD->stacks.limit)

#define GROW_TRIM  ((size_t)-1)
#define GROW_TIGHT ((size_t)1)

#define	LOCAL_OVERFLOW	  (-1)
#define	GLOBAL_OVERFLOW	  (-2)
#define	TRAIL_OVERFLOW	  (-3)
#define	ARGUMENT_OVERFLOW (-4)
#define STACK_OVERFLOW    (-5)		/* total stack limit overflow */
#define	MEMORY_OVERFLOW   (-6)		/* out of malloc()-heap */
#define CHECK_INTERRUPT   (-7)		/* Procedure was signalled */

#define ALLOW_NOTHING	0x0
#define ALLOW_GC	0x1		/* allow GC on stack overflow */
#define ALLOW_SHIFT	0x2		/* allow shift on stack overflow */
#define ALLOW_CHECKED	0x4		/* we already verified space */
#define ALLOW_RETCODE	0x8		/* do not allow anything; return status */

typedef enum
{ STACK_OVERFLOW_RAISE,
  STACK_OVERFLOW_THROW
} stack_overflow_action;

#define pushArgumentStack(p) \
	do { if ( likely(aTop+1 < aMax) ) \
	       *aTop++ = (p); \
	     else \
	       f_pushArgumentStack(p); \
	   } while(0)

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
hasGlobalSpace(n) is true if we have enough space to create an object of
size N on the global stack AND  can   use  bindConst()  to bind it to an
(attributed) variable.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#define BIND_GLOBAL_SPACE (7)
#define BIND_TRAIL_SPACE (6)
#define hasGlobalSpace(n) \
	hasStackSpace(n,0)
#define hasStackSpace(g, t) \
	(likely(gTop+(g)+BIND_GLOBAL_SPACE <= gMax) && \
	 likely(tTop+(t)+BIND_TRAIL_SPACE <= tMax))
#define hasTrailSpace(t) \
	likely(tTop+(t) <= tMax)
#define hasLocalSpace(bytes) \
	likely((char*)lTop + bytes <= (char*)lMax)
#define overflowCode(n) \
	( (gTop+(n)+BIND_GLOBAL_SPACE > gMax) ? GLOBAL_OVERFLOW \
					      : TRAIL_OVERFLOW )
#define GLOBAL_TRAIL_RATIO (6)


		 /*******************************
		 *	     NUMBERVARS		*
		 *******************************/

typedef enum
{ AV_BIND,
  AV_SKIP,
  AV_ERROR
} av_action;

#define NV_ERROR (PLMINTAGGEDINT-1)

typedef struct
{ functor_t functor;			/* Functor to use ($VAR/1) */
  intptr_t  offset;			/* offset */
  av_action on_attvar;			/* How to handle attvars */
  int	    singletons;			/* Write singletons as $VAR('_') */
  int	    numbered_check;		/* Check for already numbered */
} nv_options;

#define BEGIN_NUMBERVARS(save) \
	{ fid_t _savedf; \
	  if ( save ) \
	  { _savedf = LD->var_names.numbervars_frame; \
	    LD->var_names.numbervars_frame = PL_open_foreign_frame(); \
	  } else \
	  { _savedf = 0; /* avoid (false) uninitialized */  \
	  }
#define END_NUMBERVARS(save) \
	  if ( save ) \
	  { PL_discard_foreign_frame(LD->var_names.numbervars_frame); \
	    LD->var_names.numbervars_frame = _savedf; \
	  } \
	}


		 /*******************************
		 *	      WAKEUP		*
		 *******************************/

#define WAKEUP_STATE_WAKEUP          0x1 /* State contains a wakeup */
#define WAKEUP_STATE_EXCEPTION	     0x2 /* State contains an exception */
#define WAKEUP_STATE_SKIP_EXCEPTION  0x4 /* Do not restore exception from state */
#define WAKEUP_KEEP_URGENT_EXCEPTION 0x8 /* Keep the most urgent exception */

typedef struct wakeup_state
{ fid_t		fid;			/* foreign frame reference */
  Stack		outofstack;		/* Stack we are out of */
  unsigned int	flags;			/* WAKEUP_STATE_* */
} wakeup_state;




		 /*******************************
		 *	    STREAM I/O		*
		 *******************************/

#define REDIR_MAGIC 0x23a9bef3

typedef struct redir_context
{ int		magic;			/* REDIR_MAGIC */
  IOSTREAM     *stream;			/* temporary output */
  int		is_stream;		/* redirect to stream */
  int		redirected;		/* output is redirected */
  term_t	term;			/* redirect target */
  int		out_format;		/* output type */
  int		out_arity;		/* 2 for difference-list versions */
  size_t	size;			/* size of I/O buffer */
  char	       *data;			/* data written */
  char		buffer[1024];		/* fast temporary buffer */
} redir_context;


		/********************************
		*       READ WARNINGS           *
		*********************************/

#define ReadingSource (source_line_no >= 0 && \
		       source_file_name != NULL_ATOM)


		/********************************
		*        FAST DISPATCHING	*
		********************************/

#if VMCODE_IS_ADDRESS
#define encode(wam) (wam_table[wam])		/* WAM --> internal */
						/* internal --> WAM */
#define decode(c)   ((code) (dewam_table[(uintptr_t)(c) - \
					 dewam_table_offset]))
#else /* VMCODE_IS_ADDRESS */
#define encode(wam) (wam)
#define decode(wam) (wam)
#endif /* VMCODE_IS_ADDRESS */

		/********************************
		*            STATUS             *
		*********************************/

typedef struct
{ int		blocked;		/* GC is blocked now */
  bool		active;			/* Currently running? */
} pl_gc_status_t;


typedef struct
{ int		blocked;		/* No shifts allowed */
  double	time;			/* time spent in stack shifts */
  int		local_shifts;		/* Shifts of the local stack */
  int		global_shifts;		/* Shifts of the global stack */
  int		trail_shifts;		/* Shifts of the trail stack */
} pl_shift_status_t;


		/********************************
		*            MODULES            *
		*********************************/

#define MODULE_user	(GD->modules.user)
#define MODULE_system	(GD->modules.system)
#define MODULE_parse	(ReadingSource ? LD->modules.source \
				       : LD->modules.typein)


		/********************************
		*         PREDICATES            *
		*********************************/

#define PROCEDURE_catch3		(GD->procedures.catch3)
#define PROCEDURE_reset3		(GD->procedures.reset3)
#define PROCEDURE_true0			(GD->procedures.true0)
#define PROCEDURE_fail0			(GD->procedures.fail0)
#define PROCEDURE_print_message2	(GD->procedures.print_message2)
#define PROCEDURE_dcall1		(GD->procedures.dcall1)
#define PROCEDURE_dwakeup1		(GD->procedures.dwakeup1)
#define PROCEDURE_dthread_init0		(GD->procedures.dthread_init0)
#define PROCEDURE_exception_hook5	(GD->procedures.exception_hook5)
#define PROCEDURE_dc_call_prolog	(GD->procedures.dc_call_prolog0)
#define PROCEDURE_dinit_goal		(GD->procedures.dinit_goal3)
#define PROCEDURE_tune_gc3		(GD->procedures.tune_gc3)

extern const code_info codeTable[]; /* Instruction info (read-only) */

		 /*******************************
		 *	  TEXT PROCESSING	*
		 *******************************/

typedef enum
{ CVT_ok = 0,				/* Conversion ok */
  CVT_wide,				/* Conversion needs wide characters */
  CVT_partial,				/* Input list is partial */
  CVT_nolist,				/* Input list is not a list */
  CVT_nocode,				/* List contains a non-code */
  CVT_nochar,				/* List contains a non-char */
  CVT_representation			/* List contains non-reprentable code */
} CVT_status;

typedef struct
{ CVT_status status;
  word culprit;				/* for CVT_nocode/CVT_nochar */
} CVT_result;


		/********************************
		*            DEBUGGER           *
		*********************************/

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Tracer communication declarations.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#define ACTION_CONTINUE	0
#define ACTION_RETRY	1
#define ACTION_FAIL	2
#define ACTION_IGNORE	3
#define ACTION_AGAIN	4
#define ACTION_ABORT	5		/* only for Prolog interception */

#define CALL_PORT	0x001		/* port masks */
#define EXIT_PORT	0x002
#define FAIL_PORT	0x004
#define REDO_PORT	0x008
#define UNIFY_PORT	0x010
#define CUT_CALL_PORT   0x040
#define CUT_EXIT_PORT   0x080
#define EXCEPTION_PORT	0x100
#define CUT_PORT	(CUT_CALL_PORT|CUT_EXIT_PORT)
#define PORT_MASK	0x1ff

/* keep in sync with style_name/1 in boot/prims.pl */

#define SINGLETON_CHECK	    0x0002	/* read/1: check singleton vars */
#define MULTITON_CHECK	    0x0004	/* read/1: check multiton vars */
#define DISCONTIGUOUS_STYLE 0x0008	/* warn on discontiguous predicates */
/* reserved		    0x0010 */
#define CHARSET_CHECK	    0x0020	/* warn on unquoted characters */
#define SEMSINGLETON_CHECK  0x0040	/* Semantic singleton checking */
#define NOEFFECT_CHECK	    0x0080	/* Check for meaningless statements */
#define VARBRANCH_CHECK	    0x0100	/* warn on unbalanced variables */

/* checkDataEx() flags */

#define CHK_DATA_NOATTVAR_CHAIN 0x001	/* attvars might not be on chain */

typedef struct debuginfo
{ size_t	skiplevel;		/* current skip level */
  bool		tracing;		/* are we tracing? */
  debug_type	debugging;		/* are we debugging? */
  int		leashing;		/* ports we are leashing */
  int		visible;		/* ports that are visible */
  bool		showContext;		/* tracer shows context module */
  int		styleCheck;		/* source style checking */
  int		suspendTrace;		/* tracing is suspended now */
  intptr_t	retryFrame;		/* Frame to retry (local stack offset) */
} pl_debugstatus_t;

#if O_DEBUG
typedef struct internaldebuginfo
{ int depth;           /* how many nested DEBUG() calls we are in */
  const char *channel; /* string representation of the debug channel */
} pl_internaldebugstatus_t;
#endif

#define FT_ATOM		0		/* atom feature */
#define FT_BOOL		1		/* boolean feature (true, false) */
#define FT_INTEGER	2		/* integer feature */
#define FT_FLOAT	3		/* float feature */
#define FT_TERM		4		/* term feature */
#define FT_INT64	5		/* passed as int64_t */
#define FT_FROM_VALUE	0x0f		/* Determine type from value */
#define FT_MASK		0x0f		/* mask to get type */

/* Note: the FF_* flags are defines in SWI-Prolog.h using mask
 * 0xf000
 */

typedef enum plflag
{ PLFLAG_CHARESCAPE = 1,		/* handle \ in atoms */
  PLFLAG_CHARESCAPE_UNICODE,		/* Write escape as \uXXXX */
  PLFLAG_GC,				/* do GC */
  PLFLAG_TRACE_GC,			/* verbose gc */
  PLFLAG_GCTHREAD,			/* Do atom/clause GC in a thread */
  PLFLAG_TTY_CONTROL,			/* allow for tty control */
  PLFLAG_DEBUG_ON_ERROR,		/* start tracer on error */
  PLFLAG_REPORT_ERROR,			/* print error message */
  PLFLAG_FILE_CASE,			/* file names are case sensitive */
  PLFLAG_FILE_CASE_PRESERVING,		/* case preserving file names */
  PLFLAG_ERROR_AMBIGUOUS_STREAM_PAIR,	/* Ambigous actions on stream pair */
  ALLOW_VARNAME_FUNCTOR,		/* Read Foo(x) as 'Foo'(x) */
  PLFLAG_ISO,				/* Strict ISO compliance */
  PLFLAG_OPTIMISE,			/* -O: optimised compilation */
  PLFLAG_FILEVARS,			/* Expand $var and ~ in filename */
  PLFLAG_AUTOLOAD,			/* do autoloading */
  PLFLAG_CHARCONVERSION,		/* do character-conversion */
  PLFLAG_LASTCALL,			/* Last call optimization enabled? */
  PLFLAG_VMI_BUILTIN,			/* Use VMI for simple built-ins */
  PLFLAG_PORTABLE_VMI,			/* Generate portable VMI code */
  PLFLAG_SIGNALS,			/* Handle signals */
  PLFLAG_DEBUGINFO,			/* generate debug info */
  PLFLAG_FILEERRORS,			/* Edinburgh file errors */
  PLFLAG_WARN_OVERRIDE_IMPLICIT_IMPORT, /* Warn overriding weak symbols */
  PLFLAG_QUASI_QUOTES,			/* Support quasi quotes */
  PLFLAG_DOT_IN_ATOM,			/* Allow atoms a.b.c */
  PLFLAG_VARPREFIX,			/* Variable must start with _ */
  PLFLAG_PROTECT_STATIC_CODE,		/* Deny clause/2 on static code */
  PLFLAG_MITIGATE_SPECTRE,		/* Mitigate spectre attacks */
  PLFLAG_TABLE_INCREMENTAL,		/* By default incremental tabling */
  PLFLAG_TABLE_SHARED,			/* By default shared tabling */
  PLFLAG_RATIONAL,			/* Natural rational numbers */
  PLFLAG_DEBUG_ON_INTERRUPT,		/* Debug on Control-C */
  PLFLAG_OPTIMISE_UNIFY,		/* Move unifications in clauses */
  PLFLAG_SHIFT_CHECK,			/* Check suspicious shifts */
  PLFLAG_AGC_CLOSE_STREAMS		/* AGC may close open streams */
} plflag;

typedef struct
{ unsigned int flags[2];	/* Fast access to some boolean Prolog flags */
} pl_features_t;

#define prologFlagMask(flag) (1u<<(((flag)-1)%(sizeof(int)*8)))
#define prologFlagMaskInt(ld, flag) \
	(ld->prolog_flag.mask.flags[(flag-1)/(sizeof(int)*8)])
#define truePrologFlag(flag) \
	(prologFlagMaskInt(LD, flag) & prologFlagMask(flag))
#define setPrologFlagMask_LD(ld, flag) \
	ATOMIC_OR(&prologFlagMaskInt(ld, flag), prologFlagMask(flag))
#define clearPrologFlagMask(flag) \
	ATOMIC_AND(&prologFlagMaskInt(LD, flag), ~prologFlagMask(flag))
#define setPrologFlagMask(flag) setPrologFlagMask_LD(LD, flag)

#define RUN_MODE_NORMAL \
	(prologFlagMask(PLFLAG_LASTCALL)| \
	 prologFlagMask(PLFLAG_VMI_BUILTIN))
#define setPrologRunMode_LD(ld, mask) \
	ATOMIC_OR(&prologFlagMaskInt(ld, PLFLAG_LASTCALL), mask)
#define clearPrologRunMode_LD(ld, mask) \
	ATOMIC_AND(&prologFlagMaskInt(ld, PLFLAG_LASTCALL), ~(mask))
#define setPrologRunMode(mask) \
	setPrologRunMode_LD(LD, mask)
#define clearPrologRunMode(mask) \
	clearPrologRunMode_LD(LD, mask)

typedef enum
{ OCCURS_CHECK_FALSE = 0,	/* allow rational trees */
  OCCURS_CHECK_TRUE,		/* fail if rational tree would result */
  OCCURS_CHECK_ERROR		/* exception if rational tree would result */
} occurs_check_t;

typedef enum
{ ACCESS_LEVEL_USER = 0,	/* Default user view */
  ACCESS_LEVEL_SYSTEM		/* Allow low-level access */
} access_level_t;

#define SYSTEM_MODE	    (LD->prolog_flag.access_level == ACCESS_LEVEL_SYSTEM)

#ifdef O_LIMIT_DEPTH
#define DEPTH_NO_LIMIT ((size_t)-1) /* Highest value */
#endif

#ifdef O_INFERENCE_LIMIT
#define INFERENCE_NO_LIMIT 0x7fffffffffffffffLL /* Highest value */
#endif

#define CACHED_DICT_FUNCTORS 128	/* Max size of dict to cache */

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Administration of loaded intermediate code files  (see  pl-qlf.c).  Used
with the -c option to include all these if necessary.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

typedef struct state * State;

struct state
{ char *	name;			/* name of state */
  State		next;			/* next state loaded */
};

#define QLF_TOPLEVEL 0x1		/* toplevel wic file */
#define QLF_OPTIONS  0x2		/* only load options */
#define QLF_EXESTATE 0x4		/* probe qlf exe state */

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Sourcelocation information (should be used at more places).
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

typedef struct
{ atom_t	file;			/* name of the file */
  int		line;			/* line number */
} sourceloc, *SourceLoc;


/* Initialise the preallocated parts of a dynamic array.  The block
 * pointers must be 1 before the preallocated data.  Unfortunately
 * clang using -fsanitize=undefined considers this invalid.  It does
 * not see that this does actually the same.
 */

#define INIT_DYN_ARRAY(t)						\
  static_assertion(sizeof(t->preallocated)/sizeof(t->preallocated[0]) == 7); \
  t->blocks[0] = t->preallocated; t->blocks[0]--;			\
  t->blocks[1] = t->blocks[0];						\
  t->blocks[2] = t->blocks[0];						\

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Include debugging info to make it (very) verbose.  SECURE adds  code  to
check  consistency mainly in the WAM interpreter.  Prolog gets VERY slow
if SECURE is  used.   DEBUG  is  not  too  bad  (about  20%  performance
decrease).
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#define REL(a)		((Word)(a) - (Word)(lBase))

#if defined(_DEBUG) && !defined(O_MAINTENANCE)
#define O_MAINTENANCE
#endif

#if defined(O_DEBUG) || defined(SECURE_GC) || defined(O_MAINTENANCE)
word		checkData(Word p);
word		checkStacks(void *vm_state);
bool		scan_global(int marked);
char *		print_addr(Word p, char *buf);
char *		print_val(word w, char *buf);
#endif
int		trap_gdb(void);

#include "os/pl-os.h"			/* OS dependencies */

#ifdef SYSLIB_H
#include SYSLIB_H
#endif

#define NULL_ATOM ((atom_t)0)
#define MK_ATOM(n)		((atom_t)((n)<<7|TAG_ATOM|STG_STATIC))
#include "pl-atom.ih"
#include "pl-funct.ih"

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Some functions can be inlined for some files only. These functions get
declared with usual attributes for most files, including their original
sources; files that want the inlines can define USE_XYZ_INLINES prior to
including pl-incl.h, and for that file the function will be declared as
static. This may cause a small amount of code bloat in object files, but
with any luck LTO could address that.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#if USE_ALLOC_INLINES
# define ALLOC_INLINE static MAYBE_UNUSED
#else
# define ALLOC_INLINE
#endif

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Helpers for weak function references, where we want our behavior to change
based on if we've been linked against a specific library or not. To use a
weak function, you should (e.g. for weak-importing malloc):

1. WEAK_DECLARE(void *, malloc, (size_t size)); at .c file scope
2. WEAK_IMPORT(malloc) in startup code (returns success)
3. if (WEAK_FUNC(malloc)) to check if the import succeeded
4a. WEAK_FUNC(malloc)(sizeof(x)) to call the function, if import worked, or
4b. WEAK_TRY_CALL(malloc, sizeof(x)) to combine check and call.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

static inline int __ptr_to_bool(const intptr_t ptr) { return ptr != 0; }
#if HAVE_WEAK_ATTRIBUTE
# define WEAK_DECLARE(RType, Name, Params) \
	extern RType __attribute__((weak)) Name Params
# define WEAK_IMPORT(Name) __ptr_to_bool((intptr_t)Name)
# define WEAK_FUNC(Name) (&Name)
#elif defined(HAVE_DLOPEN) || defined(HAVE_SHL_LOAD) || defined(EMULATE_DLOPEN)
# define WEAK_DECLARE(RType, Name, Params) \
	static RType (*wf##Name) Params = NULL
# define WEAK_IMPORT(Name) \
	__ptr_to_bool((intptr_t)(wf##Name = PL_dlsym(NULL, #Name)))
# define WEAK_FUNC(Name) (wf##Name)
#else
# define WEAK_DECLARE(RType, Name, Params) \
	extern RType Name Params
# define WEAK_IMPORT(Name) 0
# define WEAK_FUNC(Name) 0
#endif
#define WEAK_TRY_CALL(Name, ...) \
	(WEAK_FUNC(Name) != NULL ? WEAK_FUNC(Name)(__VA_ARGS__) : 0)
#define WEAK_TRY_CALL_VOID(Name, ...) \
	(WEAK_FUNC(Name) != NULL ? WEAK_FUNC(Name)(__VA_ARGS__) : (void)0)

#include "pl-util.h"			/* (Debug) utilities */
#include "pl-alloc.h"			/* Allocation primitives */
#include "pl-init.h"			/* Declarations needed by pl-init.c */
#include "pl-error.h"			/* Exception generation */
#include "pl-thread.h"			/* thread manipulation */
#include "pl-data.h"			/* Access Prolog data */
#include "pl-segstack.h"		/* Segmented stacks */
#include "pl-gmp.h"			/* GNU-GMP support */
#include "os/pl-locale.h"		/* Locale objects */
#include "os/pl-file.h"			/* Stream management */
#include "pl-global.h"			/* global data */
#include "pl-hash.h"			/* Murmurhash function */
#include "pl-inline.h"			/* Inline facilities */
#include "pl-privitf.h"			/* private foreign interface */
#include "os/pl-text.h"			/* text manipulation */
#include "os/pl-option.h"		/* Option processing */
#include "os/pl-files.h"		/* File management */
#include "os/pl-string.h"		/* Basic string functions */
#include "pl-ressymbol.h"		/* Meta atom handling */

#ifdef __DECC				/* Dec C-compiler: avoid conflicts */
#undef leave
#undef except
#undef try
#endif

/* include the appropriate inlines, when requested */
#if USE_ALLOC_INLINES
#include "pl-alloc-inline.h"
#endif
#endif /*_PL_INCLUDE_H*/
