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/* Fundamental definitions for GNU Emacs Lisp interpreter.
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   Copyright (C) 1985, 1986, 1987, 1993, 1994, 1995, 1997, 1998, 1999, 2000,
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                 2001, 2002, 2003, 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
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This file is part of GNU Emacs.

GNU Emacs is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3, or (at your option)
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any later version.

GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Emacs; see the file COPYING.  If not, write to
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the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.  */
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#ifndef EMACS_LISP_H
#define EMACS_LISP_H

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/* Declare the prototype for a general external function.  */
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#if defined (PROTOTYPES) || defined (WINDOWSNT)
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#define P_(proto) proto
#else
#define P_(proto) ()
#endif

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#if 0
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/* Define this temporarily to hunt a bug.  If defined, the size of
   strings is redundantly recorded in sdata structures so that it can
   be compared to the sizes recorded in Lisp strings.  */

#define GC_CHECK_STRING_BYTES 1
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/* Define this to check for short string overrun.  */

#define GC_CHECK_STRING_OVERRUN 1

/* Define this to check the string free list.  */

#define GC_CHECK_STRING_FREE_LIST 1

/* Define this to check for malloc buffer overrun.  */

#define XMALLOC_OVERRUN_CHECK 1

/* Define this to check for errors in cons list.  */
/* #define GC_CHECK_CONS_LIST 1 */

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#endif /* 0 */
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#ifdef GC_CHECK_CONS_LIST
#define CHECK_CONS_LIST() check_cons_list()
#else
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#define CHECK_CONS_LIST() ((void)0)
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#endif
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/* These are default choices for the types to use.  */
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#ifdef _LP64
#ifndef EMACS_INT
#define EMACS_INT long
#define BITS_PER_EMACS_INT BITS_PER_LONG
#endif
#ifndef EMACS_UINT
#define EMACS_UINT unsigned long
#endif
#else /* not _LP64 */
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#ifndef EMACS_INT
#define EMACS_INT int
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#define BITS_PER_EMACS_INT BITS_PER_INT
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#endif
#ifndef EMACS_UINT
#define EMACS_UINT unsigned int
#endif
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#endif
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/* Extra internal type checking?  */
extern int suppress_checking;
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extern void die P_((const char *, const char *, int)) NO_RETURN;
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#ifdef ENABLE_CHECKING

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#define CHECK(check,msg) (((check) || suppress_checking		\
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			   ? (void) 0				\
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			   : die ((msg), __FILE__, __LINE__)),	\
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			  0)
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#else
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/* Produce same side effects and result, but don't complain.  */
#define CHECK(check,msg) ((check),0)
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#endif
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/* Used for making sure that Emacs is compilable in all
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   configurations.  */
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#ifdef USE_LISP_UNION_TYPE
#undef NO_UNION_TYPE
#endif

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/* Define an Emacs version of "assert", since some system ones are
   flaky.  */
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#ifndef ENABLE_CHECKING
#define eassert(X)	(void) 0
#else /* ENABLE_CHECKING */
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#if defined (__GNUC__) && __GNUC__ >= 2 && defined (__STDC__)
#define eassert(cond) CHECK(cond,"assertion failed: " #cond)
#else
#define eassert(cond) CHECK(cond,"assertion failed")
#endif
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#endif /* ENABLE_CHECKING */
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/* Define the fundamental Lisp data structures.  */
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/* This is the set of Lisp data types.  */
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enum Lisp_Type
  {
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    /* Integer.  XINT (obj) is the integer value.  */
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    Lisp_Int,

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    /* Symbol.  XSYMBOL (object) points to a struct Lisp_Symbol.  */
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    Lisp_Symbol,

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    /* Miscellaneous.  XMISC (object) points to a union Lisp_Misc,
       whose first member indicates the subtype.  */
    Lisp_Misc,
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    /* String.  XSTRING (object) points to a struct Lisp_String.
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       The length of the string, and its contents, are stored therein.  */
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    Lisp_String,

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    /* Vector of Lisp objects, or something resembling it.
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       XVECTOR (object) points to a struct Lisp_Vector, which contains
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       the size and contents.  The size field also contains the type
       information, if it's not a real vector object.  */
    Lisp_Vectorlike,
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    /* Cons.  XCONS (object) points to a struct Lisp_Cons.  */
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    Lisp_Cons,

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    Lisp_Float,
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    /* This is not a type code.  It is for range checking.  */
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    Lisp_Type_Limit
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  };

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/* This is the set of data types that share a common structure.
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   The first member of the structure is a type code from this set.
   The enum values are arbitrary, but we'll use large numbers to make it
   more likely that we'll spot the error if a random word in memory is
   mistakenly interpreted as a Lisp_Misc.  */
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enum Lisp_Misc_Type
  {
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    Lisp_Misc_Free = 0x5eab,
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    Lisp_Misc_Marker,
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    Lisp_Misc_Intfwd,
    Lisp_Misc_Boolfwd,
    Lisp_Misc_Objfwd,
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    Lisp_Misc_Buffer_Objfwd,
    Lisp_Misc_Buffer_Local_Value,
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    Lisp_Misc_Some_Buffer_Local_Value,
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    Lisp_Misc_Overlay,
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    Lisp_Misc_Kboard_Objfwd,
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    Lisp_Misc_Save_Value,
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    /* Currently floats are not a misc type,
       but let's define this in case we want to change that.  */
    Lisp_Misc_Float,
    /* This is not a type code.  It is for range checking.  */
    Lisp_Misc_Limit
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  };

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#ifndef GCTYPEBITS
#define GCTYPEBITS 3
#endif

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/* These values are overridden by the m- file on some machines.  */
#ifndef VALBITS
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#define VALBITS (BITS_PER_EMACS_INT - GCTYPEBITS)
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#endif

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#ifndef NO_UNION_TYPE

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#ifndef WORDS_BIG_ENDIAN
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/* Definition of Lisp_Object for little-endian machines.  */

typedef
union Lisp_Object
  {
    /* Used for comparing two Lisp_Objects;
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       also, positive integers can be accessed fast this way.  */
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    EMACS_INT i;
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    struct
      {
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	EMACS_INT val  : VALBITS;
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	enum Lisp_Type type : GCTYPEBITS;
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      } s;
    struct
      {
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	EMACS_UINT val : VALBITS;
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	enum Lisp_Type type : GCTYPEBITS;
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      } u;
  }
Lisp_Object;

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#else /* If WORDS_BIG_ENDIAN */
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typedef
union Lisp_Object
  {
    /* Used for comparing two Lisp_Objects;
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       also, positive integers can be accessed fast this way.  */
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    EMACS_INT i;
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    struct
      {
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	enum Lisp_Type type : GCTYPEBITS;
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	EMACS_INT val  : VALBITS;
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      } s;
    struct
      {
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	enum Lisp_Type type : GCTYPEBITS;
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	EMACS_UINT val : VALBITS;
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      } u;
  }
Lisp_Object;

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#endif /* WORDS_BIG_ENDIAN */
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#ifdef __GNUC__
static __inline__ Lisp_Object
LISP_MAKE_RVALUE (Lisp_Object o)
{
    return o;
}
#else
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/* This isn't quite right - it keeps the argument as an lvalue.
   Making it const via casting would help avoid code actually
   modifying the location in question, but the casting could cover
   other type-related bugs.  */
#define LISP_MAKE_RVALUE(o) (o)
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#endif

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#endif /* NO_UNION_TYPE */


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/* If union type is not wanted, define Lisp_Object as just a number.  */
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#ifdef NO_UNION_TYPE
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typedef EMACS_INT Lisp_Object;
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#define LISP_MAKE_RVALUE(o) (0+(o))
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#endif /* NO_UNION_TYPE */
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/* Two flags that are set during GC.  On some machines, these flags
   are defined differently by the m- file.  */

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/* In the size word of a vector, this bit means the vector has been marked.  */
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#ifndef ARRAY_MARK_FLAG
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#define ARRAY_MARK_FLAG ((EMACS_INT) ((EMACS_UINT) 1 << (VALBITS + GCTYPEBITS - 1)))
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#endif /* no ARRAY_MARK_FLAG */

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/* In the size word of a struct Lisp_Vector, this bit means it's really
   some other vector-like object.  */
#ifndef PSEUDOVECTOR_FLAG
#define PSEUDOVECTOR_FLAG ((ARRAY_MARK_FLAG >> 1) & ~ARRAY_MARK_FLAG)
#endif

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/* In a pseudovector, the size field actually contains a word with one
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   PSEUDOVECTOR_FLAG bit set, and exactly one of the following bits to
   indicate the actual type.  */
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enum pvec_type
{
  PVEC_NORMAL_VECTOR = 0,
  PVEC_PROCESS = 0x200,
  PVEC_FRAME = 0x400,
  PVEC_COMPILED = 0x800,
  PVEC_WINDOW = 0x1000,
  PVEC_WINDOW_CONFIGURATION = 0x2000,
  PVEC_SUBR = 0x4000,
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  PVEC_CHAR_TABLE = 0x8000,
  PVEC_BOOL_VECTOR = 0x10000,
  PVEC_BUFFER = 0x20000,
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  PVEC_HASH_TABLE = 0x40000,
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  PVEC_SUB_CHAR_TABLE = 0x80000,
  PVEC_TYPE_MASK = 0x0ffe00
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#if 0 /* This is used to make the value of PSEUDOVECTOR_FLAG available to
	 GDB.  It doesn't work on OS Alpha.  Moved to a variable in
	 emacs.c.  */
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  PVEC_FLAG = PSEUDOVECTOR_FLAG
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#endif
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};
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/* For convenience, we also store the number of elements in these bits.
   Note that this size is not necessarily the memory-footprint size, but
   only the number of Lisp_Object fields (that need to be traced by the GC).
   The distinction is used e.g. by Lisp_Process which places extra
   non-Lisp_Object fields at the end of the structure.  */
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#define PSEUDOVECTOR_SIZE_MASK 0x1ff
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/* Number of bits to put in each character in the internal representation
   of bool vectors.  This should not vary across implementations.  */
#define BOOL_VECTOR_BITS_PER_CHAR 8
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/***** Select the tagging scheme.  *****/
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/* There are basically two options that control the tagging scheme:
   - NO_UNION_TYPE says that Lisp_Object should be an integer instead
     of a union.
   - USE_LSB_TAG means that we can assume the least 3 bits of pointers are
     always 0, and we can thus use them to hold tag bits, without
     restricting our addressing space.

   If USE_LSB_TAG is not set, then we use the top 3 bits for tagging, thus
   restricting our possible address range.  Currently USE_LSB_TAG is not
   allowed together with a union.  This is not due to any fundamental
   technical (or political ;-) problem: nobody wrote the code to do it yet.

   USE_LSB_TAG not only requires the least 3 bits of pointers returned by
   malloc to be 0 but also needs to be able to impose a mult-of-8 alignment
   on the few static Lisp_Objects used: all the defsubr as well
   as the two special buffers buffer_defaults and buffer_local_symbols.  */
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/* First, try and define DECL_ALIGN(type,var) which declares a static
   variable VAR of type TYPE with the added requirement that it be
   TYPEBITS-aligned. */
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#ifndef NO_DECL_ALIGN
# ifndef DECL_ALIGN
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/* What compiler directive should we use for non-gcc compilers?  -stef  */
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#  if defined (__GNUC__)
#   define DECL_ALIGN(type, var) \
     type __attribute__ ((__aligned__ (1 << GCTYPEBITS))) var
#  endif
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# endif
#endif

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/* Let's USE_LSB_TAG on systems where we know malloc returns mult-of-8.  */
#if defined GNU_MALLOC || defined DOUG_LEA_MALLOC || defined __GLIBC__ || defined MAC_OSX
/* We also need to be able to specify mult-of-8 alignment on static vars.  */
# if defined DECL_ALIGN
/* We currently do not support USE_LSB_TAG with a union Lisp_Object.  */
#  if defined NO_UNION_TYPE
#   define USE_LSB_TAG
#  endif
# endif
#endif

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/* If we cannot use 8-byte alignment, make DECL_ALIGN a no-op.  */
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#ifndef DECL_ALIGN
# ifdef USE_LSB_TAG
#  error "USE_LSB_TAG used without defining DECL_ALIGN"
# endif
# define DECL_ALIGN(type, var) type var
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#endif

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/* These macros extract various sorts of values from a Lisp_Object.
 For example, if tem is a Lisp_Object whose type is Lisp_Cons,
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 XCONS (tem) is the struct Lisp_Cons * pointing to the memory for that cons.  */
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#ifdef NO_UNION_TYPE

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#ifdef USE_LSB_TAG

#define TYPEMASK ((((EMACS_INT) 1) << GCTYPEBITS) - 1)
#define XTYPE(a) ((enum Lisp_Type) (((EMACS_UINT) (a)) & TYPEMASK))
#define XINT(a) (((EMACS_INT) (a)) >> GCTYPEBITS)
#define XUINT(a) (((EMACS_UINT) (a)) >> GCTYPEBITS)
#define XSET(var, type, ptr)					\
    (eassert (XTYPE (ptr) == 0), /* Check alignment.  */	\
     (var) = ((EMACS_INT) (type)) | ((EMACS_INT) (ptr)))
#define make_number(N) (((EMACS_INT) (N)) << GCTYPEBITS)

/* XFASTINT and XSETFASTINT are for use when the integer is known to be
   positive, in which case the implementation can sometimes be faster
   depending on the tagging scheme.  With USE_LSB_TAG, there's no benefit.  */
#define XFASTINT(a) XINT (a)
#define XSETFASTINT(a, b) ((a) = make_number (b))

#define XPNTR(a) ((EMACS_INT) ((a) & ~TYPEMASK))

#else  /* not USE_LSB_TAG */

#define VALMASK ((((EMACS_INT) 1) << VALBITS) - 1)

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/* One need to override this if there must be high bits set in data space
   (doing the result of the below & ((1 << (GCTYPE + 1)) - 1) would work
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    on all machines, but would penalize machines which don't need it)
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 */
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#define XTYPE(a) ((enum Lisp_Type) (((EMACS_UINT) (a)) >> VALBITS))
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/* For integers known to be positive, XFASTINT provides fast retrieval
   and XSETFASTINT provides fast storage.  This takes advantage of the
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   fact that Lisp_Int is 0.  */
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#define XFASTINT(a) ((a) + 0)
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#define XSETFASTINT(a, b) ((a) = (b))
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/* Extract the value of a Lisp_Object as a signed integer.  */

#ifndef XINT   /* Some machines need to do this differently.  */
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#define XINT(a) ((((EMACS_INT) (a)) << (BITS_PER_EMACS_INT - VALBITS))	\
		 >> (BITS_PER_EMACS_INT - VALBITS))
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#endif

/* Extract the value as an unsigned integer.  This is a basis
   for extracting it as a pointer to a structure in storage.  */

#ifndef XUINT
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#define XUINT(a) ((EMACS_UINT) ((a) & VALMASK))
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#endif

#ifndef XSET
#define XSET(var, type, ptr) \
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   ((var) = ((EMACS_INT)(type) << VALBITS) + ((EMACS_INT) (ptr) & VALMASK))
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#endif

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/* Convert a C integer into a Lisp_Object integer.  */

#define make_number(N)		\
  ((((EMACS_INT) (N)) & VALMASK) | ((EMACS_INT) Lisp_Int) << VALBITS)

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#endif /* not USE_LSB_TAG */
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#define EQ(x, y) ((x) == (y))
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#else /* not NO_UNION_TYPE */
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#define XTYPE(a) ((enum Lisp_Type) (a).u.type)

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/* For integers known to be positive, XFASTINT provides fast retrieval
   and XSETFASTINT provides fast storage.  This takes advantage of the
   fact that Lisp_Int is 0.  */
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#define XFASTINT(a) ((a).i + 0)
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#define XSETFASTINT(a, b) ((a).i = (b))
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#ifdef EXPLICIT_SIGN_EXTEND
/* Make sure we sign-extend; compilers have been known to fail to do so.  */
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#define XINT(a) (((a).s.val << (BITS_PER_EMACS_INT - VALBITS)) \
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		 >> (BITS_PER_EMACS_INT - VALBITS))
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#else
#define XINT(a) ((a).s.val)
#endif /* EXPLICIT_SIGN_EXTEND */

#define XUINT(a) ((a).u.val)

#define XSET(var, vartype, ptr) \
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   (((var).s.val = ((EMACS_INT) (ptr))), ((var).s.type = ((char) (vartype))))
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#if __GNUC__ >= 2 && defined (__OPTIMIZE__)
#define make_number(N) \
  (__extension__ ({ Lisp_Object _l; _l.s.val = (N); _l.s.type = Lisp_Int; _l; }))
#else
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extern Lisp_Object make_number P_ ((EMACS_INT));
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#endif
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#define EQ(x, y) ((x).i == (y).i)
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#endif /* NO_UNION_TYPE */

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#ifndef XPNTR
#ifdef HAVE_SHM
/* In this representation, data is found in two widely separated segments.  */
extern size_t pure_size;
#define XPNTR(a) \
  (XUINT (a) | (XUINT (a) > pure_size ? DATA_SEG_BITS : PURE_SEG_BITS))
#else /* not HAVE_SHM */
#ifdef DATA_SEG_BITS
/* This case is used for the rt-pc.
   In the diffs I was given, it checked for ptr = 0
   and did not adjust it in that case.
   But I don't think that zero should ever be found
   in a Lisp object whose data type says it points to something.  */
#define XPNTR(a) (XUINT (a) | DATA_SEG_BITS)
#else
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/* Some versions of gcc seem to consider the bitfield width when
   issuing the "cast to pointer from integer of different size"
   warning, so the cast is here to widen the value back to its natural
   size.  */
#define XPNTR(a) ((EMACS_INT) XUINT (a))
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#endif
#endif /* not HAVE_SHM */
#endif /* no XPNTR */

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/* Largest and smallest representable fixnum values.  These are the C
   values.  */
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#define MOST_NEGATIVE_FIXNUM	- ((EMACS_INT) 1 << (VALBITS - 1))
#define MOST_POSITIVE_FIXNUM	(((EMACS_INT) 1 << (VALBITS - 1)) - 1)
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/* Mask indicating the significant bits of a Lisp_Int.
   I.e. (x & INTMASK) == XUINT (make_number (x)).  */
#define INTMASK ((((EMACS_INT) 1) << VALBITS) - 1)
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/* Value is non-zero if C integer I doesn't fit into a Lisp fixnum.  */

#define FIXNUM_OVERFLOW_P(i) \
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  ((EMACS_INT)(i) > MOST_POSITIVE_FIXNUM \
   || (EMACS_INT) (i) < MOST_NEGATIVE_FIXNUM)
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/* Extract a value or address from a Lisp_Object.  */
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#define XCONS(a) (eassert (CONSP(a)),(struct Lisp_Cons *) XPNTR(a))
#define XVECTOR(a) (eassert (VECTORLIKEP(a)),(struct Lisp_Vector *) XPNTR(a))
#define XSTRING(a) (eassert (STRINGP(a)),(struct Lisp_String *) XPNTR(a))
#define XSYMBOL(a) (eassert (SYMBOLP(a)),(struct Lisp_Symbol *) XPNTR(a))
#define XFLOAT(a) (eassert (FLOATP(a)),(struct Lisp_Float *) XPNTR(a))
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/* Misc types.  */
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#define XMISC(a)   ((union Lisp_Misc *) XPNTR(a))
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#define XMISCTYPE(a)   (XMARKER (a)->type)
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#define XMARKER(a) (&(XMISC(a)->u_marker))
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#define XINTFWD(a) (&(XMISC(a)->u_intfwd))
#define XBOOLFWD(a) (&(XMISC(a)->u_boolfwd))
#define XOBJFWD(a) (&(XMISC(a)->u_objfwd))
#define XBUFFER_OBJFWD(a) (&(XMISC(a)->u_buffer_objfwd))
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#define XBUFFER_LOCAL_VALUE(a) (&(XMISC(a)->u_buffer_local_value))
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#define XOVERLAY(a) (&(XMISC(a)->u_overlay))
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#define XKBOARD_OBJFWD(a) (&(XMISC(a)->u_kboard_objfwd))
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#define XSAVE_VALUE(a) (&(XMISC(a)->u_save_value))
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/* Pseudovector types.  */
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#define XPROCESS(a) (eassert (PROCESSP(a)),(struct Lisp_Process *) XPNTR(a))
#define XWINDOW(a) (eassert (WINDOWP(a)),(struct window *) XPNTR(a))
#define XSUBR(a) (eassert (SUBRP(a)),(struct Lisp_Subr *) XPNTR(a))
#define XBUFFER(a) (eassert (BUFFERP(a)),(struct buffer *) XPNTR(a))
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#define XCHAR_TABLE(a) ((struct Lisp_Char_Table *) XPNTR(a))
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#define XSUB_CHAR_TABLE(a) ((struct Lisp_Sub_Char_Table *) XPNTR(a))
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#define XBOOL_VECTOR(a) ((struct Lisp_Bool_Vector *) XPNTR(a))
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/* Construct a Lisp_Object from a value or address.  */
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#define XSETINT(a, b) (a) = make_number (b)
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#define XSETCONS(a, b) XSET (a, Lisp_Cons, b)
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#define XSETVECTOR(a, b) XSET (a, Lisp_Vectorlike, b)
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#define XSETSTRING(a, b) XSET (a, Lisp_String, b)
#define XSETSYMBOL(a, b) XSET (a, Lisp_Symbol, b)
#define XSETFLOAT(a, b) XSET (a, Lisp_Float, b)
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/* Misc types.  */
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#define XSETMISC(a, b) XSET (a, Lisp_Misc, b)
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#define XSETMARKER(a, b) (XSETMISC (a, b), XMISCTYPE (a) = Lisp_Misc_Marker)
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/* Pseudovector types.  */
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#define XSETPSEUDOVECTOR(a, b, code) \
  (XSETVECTOR (a, b), XVECTOR (a)->size |= PSEUDOVECTOR_FLAG | (code))
#define XSETWINDOW_CONFIGURATION(a, b) \
  (XSETPSEUDOVECTOR (a, b, PVEC_WINDOW_CONFIGURATION))
#define XSETPROCESS(a, b) (XSETPSEUDOVECTOR (a, b, PVEC_PROCESS))
#define XSETWINDOW(a, b) (XSETPSEUDOVECTOR (a, b, PVEC_WINDOW))
#define XSETSUBR(a, b) (XSETPSEUDOVECTOR (a, b, PVEC_SUBR))
#define XSETCOMPILED(a, b) (XSETPSEUDOVECTOR (a, b, PVEC_COMPILED))
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#define XSETBUFFER(a, b) (XSETPSEUDOVECTOR (a, b, PVEC_BUFFER))
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#define XSETCHAR_TABLE(a, b) (XSETPSEUDOVECTOR (a, b, PVEC_CHAR_TABLE))
#define XSETBOOL_VECTOR(a, b) (XSETPSEUDOVECTOR (a, b, PVEC_BOOL_VECTOR))
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#define XSETSUB_CHAR_TABLE(a, b) (XSETPSEUDOVECTOR (a, b, PVEC_SUB_CHAR_TABLE))
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/* Convenience macros for dealing with Lisp arrays.  */

#define AREF(ARRAY, IDX)	XVECTOR ((ARRAY))->contents[IDX]
#define ASET(ARRAY, IDX, VAL)	(AREF ((ARRAY), (IDX)) = (VAL))
#define ASIZE(ARRAY)		XVECTOR ((ARRAY))->size

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/* Convenience macros for dealing with Lisp strings.  */

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#define SREF(string, index)	(XSTRING (string)->data[index] + 0)
#define SSET(string, index, new) (XSTRING (string)->data[index] = (new))
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#define SDATA(string)		(XSTRING (string)->data + 0)
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#define SCHARS(string)		(XSTRING (string)->size + 0)
#define SBYTES(string)		(STRING_BYTES (XSTRING (string)) + 0)

#define STRING_SET_CHARS(string, newsize) \
    (XSTRING (string)->size = (newsize))
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#define STRING_COPYIN(string, index, new, count) \
    bcopy (new, XSTRING (string)->data + index, count)

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/* Type checking.  */

#define CHECK_TYPE(ok, Qxxxp, x) \
  do { if (!(ok)) wrong_type_argument (Qxxxp, (x)); } while (0)


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/* See the macros in intervals.h.  */
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typedef struct interval *INTERVAL;

/* Complain if object is not string or buffer type */
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#define CHECK_STRING_OR_BUFFER(x) \
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  CHECK_TYPE (STRINGP (x) || BUFFERP (x), Qbuffer_or_string_p, x)

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/* In a cons, the markbit of the car is the gc mark bit */

struct Lisp_Cons
  {
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    /* Please do not use the names of these elements in code other
       than the core lisp implementation.  Use XCAR and XCDR below.  */
#ifdef HIDE_LISP_IMPLEMENTATION
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    Lisp_Object car_;
    union
    {
      Lisp_Object cdr_;
      struct Lisp_Cons *chain;
    } u;
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#else
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    Lisp_Object car;
    union
    {
      Lisp_Object cdr;
      struct Lisp_Cons *chain;
    } u;
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#endif
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  };

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/* Take the car or cdr of something known to be a cons cell.  */
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/* The _AS_LVALUE macros shouldn't be used outside of the minimal set
   of code that has to know what a cons cell looks like.  Other code not
   part of the basic lisp implementation should assume that the car and cdr
   fields are not accessible as lvalues.  (What if we want to switch to
   a copying collector someday?  Cached cons cell field addresses may be
   invalidated at arbitrary points.)  */
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#ifdef HIDE_LISP_IMPLEMENTATION
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#define XCAR_AS_LVALUE(c) (XCONS ((c))->car_)
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#define XCDR_AS_LVALUE(c) (XCONS ((c))->u.cdr_)
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#else
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#define XCAR_AS_LVALUE(c) (XCONS ((c))->car)
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#define XCDR_AS_LVALUE(c) (XCONS ((c))->u.cdr)
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#endif
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/* Use these from normal code.  */
#define XCAR(c)	LISP_MAKE_RVALUE(XCAR_AS_LVALUE(c))
#define XCDR(c) LISP_MAKE_RVALUE(XCDR_AS_LVALUE(c))

/* Use these to set the fields of a cons cell.

   Note that both arguments may refer to the same object, so 'n'
   should not be read after 'c' is first modified.  Also, neither
   argument should be evaluated more than once; side effects are
   especially common in the second argument.  */
#define XSETCAR(c,n) (XCAR_AS_LVALUE(c) = (n))
#define XSETCDR(c,n) (XCDR_AS_LVALUE(c) = (n))

/* For performance: Fast storage of positive integers into the
   fields of a cons cell.  See above caveats.  */
#define XSETCARFASTINT(c,n)  XSETFASTINT(XCAR_AS_LVALUE(c),(n))
#define XSETCDRFASTINT(c,n)  XSETFASTINT(XCDR_AS_LVALUE(c),(n))

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/* Take the car or cdr of something whose type is not known.  */
#define CAR(c)					\
 (CONSP ((c)) ? XCAR ((c))			\
  : NILP ((c)) ? Qnil				\
  : wrong_type_argument (Qlistp, (c)))

#define CDR(c)					\
 (CONSP ((c)) ? XCDR ((c))			\
  : NILP ((c)) ? Qnil				\
  : wrong_type_argument (Qlistp, (c)))

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/* Take the car or cdr of something whose type is not known.  */
#define CAR_SAFE(c)				\
  (CONSP ((c)) ? XCAR ((c)) : Qnil)

#define CDR_SAFE(c)				\
  (CONSP ((c)) ? XCDR ((c)) : Qnil)

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/* Nonzero if STR is a multibyte string.  */
#define STRING_MULTIBYTE(STR)  \
  (XSTRING (STR)->size_byte >= 0)

/* Return the length in bytes of STR.  */
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#ifdef GC_CHECK_STRING_BYTES

struct Lisp_String;
extern int string_bytes P_ ((struct Lisp_String *));
#define STRING_BYTES(S) string_bytes ((S))

#else /* not GC_CHECK_STRING_BYTES */

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#define STRING_BYTES(STR)  \
  ((STR)->size_byte < 0 ? (STR)->size : (STR)->size_byte)

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#endif /* not GC_CHECK_STRING_BYTES */

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/* Mark STR as a unibyte string.  */
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#define STRING_SET_UNIBYTE(STR)  \
  do { if (EQ (STR, empty_multibyte_string))  \
      (STR) = empty_unibyte_string;  \
    else XSTRING (STR)->size_byte = -1; } while (0)
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/* Get text properties.  */
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#define STRING_INTERVALS(STR)  (XSTRING (STR)->intervals + 0)

/* Set text properties.  */
#define STRING_SET_INTERVALS(STR, INT) (XSTRING (STR)->intervals = (INT))
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/* In a string or vector, the sign bit of the `size' is the gc mark bit */

struct Lisp_String
  {
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    EMACS_INT size;
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    EMACS_INT size_byte;
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    INTERVAL intervals;		/* text properties in this string */
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    unsigned char *data;
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  };

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#ifdef offsetof
#define OFFSETOF(type,field) offsetof(type,field)
#else
#define OFFSETOF(type,field) \
  ((int)((char*)&((type*)0)->field - (char*)0))
#endif
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struct Lisp_Vector
  {
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    EMACS_INT size;
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    struct Lisp_Vector *next;
    Lisp_Object contents[1];
  };

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/* If a struct is made to look like a vector, this macro returns the length
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   of the shortest vector that would hold that struct.  */
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#define VECSIZE(type) ((sizeof (type)					  \
			- OFFSETOF (struct Lisp_Vector, contents[0])      \
                        + sizeof(Lisp_Object) - 1) /* round up */	  \
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		       / sizeof (Lisp_Object))

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/* Like VECSIZE, but used when the pseudo-vector has non-Lisp_Object fields
   at the end and we need to compute the number of Lisp_Object fields (the
   ones that the GC needs to trace).  */
#define PSEUDOVECSIZE(type, nonlispfield) \
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  ((OFFSETOF(type, nonlispfield) - OFFSETOF(struct Lisp_Vector, contents[0])) \
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   / sizeof (Lisp_Object))

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/* A char-table is a kind of vectorlike, with contents are like a
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   vector but with a few other slots.  For some purposes, it makes
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   sense to handle a char-table with type struct Lisp_Vector.  An
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   element of a char table can be any Lisp objects, but if it is a sub
   char-table, we treat it a table that contains information of a
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   specific range of characters.  A sub char-table has the same
   structure as a vector.  A sub char table appears only in an element
   of a char-table, and there's no way to access it directly from
   Emacs Lisp program.  */
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/* This is the number of slots that every char table must have.  This
   counts the ordinary slots and the top, defalt, parent, and purpose
   slots.  */
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#define CHAR_TABLE_STANDARD_SLOTS (VECSIZE (struct Lisp_Char_Table) - 1)
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/* Return the number of "extra" slots in the char table CT.  */

#define CHAR_TABLE_EXTRA_SLOTS(CT)	\
  (((CT)->size & PSEUDOVECTOR_SIZE_MASK) - CHAR_TABLE_STANDARD_SLOTS)

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/* Almost equivalent to Faref (CT, IDX) with optimization for ASCII
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   characters.  Do not check validity of CT.  */
#define CHAR_TABLE_REF(CT, IDX)						 \
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  ((ASCII_CHAR_P (IDX)							 \
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    && SUB_CHAR_TABLE_P (XCHAR_TABLE (CT)->ascii)			 \
    && !NILP (XSUB_CHAR_TABLE (XCHAR_TABLE (CT)->ascii)->contents[IDX])) \
   ? XSUB_CHAR_TABLE (XCHAR_TABLE (CT)->ascii)->contents[IDX]		 \
   : char_table_ref ((CT), (IDX)))
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/* Almost equivalent to Faref (CT, IDX).  However, if the result is
   not a character, return IDX.
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   For these characters, do not check validity of CT
   and do not follow parent.  */
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#define CHAR_TABLE_TRANSLATE(CT, IDX)	\
  char_table_translate (CT, IDX)
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/* Equivalent to Faset (CT, IDX, VAL) with optimization for ASCII and
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   8-bit European characters.  Do not check validity of CT.  */
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#define CHAR_TABLE_SET(CT, IDX, VAL)					\
  (((IDX) >= 0 && ASCII_CHAR_P (IDX)					\
    && SUB_CHAR_TABLE_P (XCHAR_TABLE (CT)->ascii))			\
   ? XSUB_CHAR_TABLE (XCHAR_TABLE (CT)->ascii)->contents[IDX] = VAL	\
   : char_table_set (CT, IDX, VAL))

#define CHARTAB_SIZE_BITS_0 6
#define CHARTAB_SIZE_BITS_1 4
#define CHARTAB_SIZE_BITS_2 5
#define CHARTAB_SIZE_BITS_3 7

extern const int chartab_size[4];

struct Lisp_Sub_Char_Table;
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struct Lisp_Char_Table
  {
    /* This is the vector's size field, which also holds the
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       pseudovector type information.  It holds the size, too.  The size
       counts the defalt, parent, purpose, ascii, contents, and extras
       slots.  */
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    EMACS_INT size;
    struct Lisp_Vector *next;
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    /* This holds a default value,
       which is used whenever the value for a specific character is nil.  */
    Lisp_Object defalt;
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    /* This points to another char table, which we inherit from when the
       value for a specific character is nil.  The `defalt' slot takes
       precedence over this.  */
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    Lisp_Object parent;
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    /* This is a symbol which says what kind of use this char-table is
       meant for.  */
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    Lisp_Object purpose;
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    /* The bottom sub char-table for characters of the range 0..127.  It
       is nil if none of ASCII character has a specific value.  */
    Lisp_Object ascii;
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    Lisp_Object contents[(1 << CHARTAB_SIZE_BITS_0)];
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    /* These hold additional data.  It is a vector.  */
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    Lisp_Object extras[1];
  };

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struct Lisp_Sub_Char_Table
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  {
    /* This is the vector's size field, which also holds the
       pseudovector type information.  It holds the size, too.  */
    EMACS_INT size;
    struct Lisp_Vector *next;
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    /* Depth of this sub char-table.  It should be 1, 2, or 3.  A sub
       char-table of depth 1 contains 16 elments, and each element
       covers 4096 (128*32) characters.  A sub char-table of depth 2
       contains 32 elements, and each element covers 128 characters.  A
       sub char-table of depth 3 contains 128 elements, and each element
       is for one character.  */
    Lisp_Object depth;
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    /* Minimum character covered by the sub char-table.  */
    Lisp_Object min_char;
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    Lisp_Object contents[1];
  };
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/* A boolvector is a kind of vectorlike, with contents are like a string.  */
struct Lisp_Bool_Vector
  {
    /* This is the vector's size field.  It doesn't have the real size,
       just the subtype information.  */
    EMACS_INT vector_size;
    struct Lisp_Vector *next;
    /* This is the size in bits.  */
    EMACS_INT size;
    /* This contains the actual bits, packed into bytes.  */
    unsigned char data[1];
  };

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/* This structure describes a built-in function.
   It is generated by the DEFUN macro only.
   defsubr makes it into a Lisp object.

   This type is treated in most respects as a pseudovector,
   but since we never dynamically allocate or free them,
   we don't need a next-vector field.  */
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struct Lisp_Subr
  {
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    EMACS_INT size;
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    Lisp_Object (*function) ();
    short min_args, max_args;
    char *symbol_name;
    char *prompt;
    char *doc;
  };
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/***********************************************************************
			       Symbols
 ***********************************************************************/

/* Interned state of a symbol.  */

enum symbol_interned
{
  SYMBOL_UNINTERNED = 0,
  SYMBOL_INTERNED = 1,
  SYMBOL_INTERNED_IN_INITIAL_OBARRAY = 2
};

/* In a symbol, the markbit of the plist is used as the gc mark bit */

struct Lisp_Symbol
{
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  unsigned gcmarkbit : 1;

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  /* Non-zero means symbol serves as a variable alias.  The symbol
     holding the real value is found in the value slot.  */
  unsigned indirect_variable : 1;

  /* Non-zero means symbol is constant, i.e. changing its value
     should signal an error.  */
  unsigned constant : 1;

  /* Interned state of the symbol.  This is an enumerator from
     enum symbol_interned.  */
  unsigned interned : 2;

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  /* The symbol's name, as a Lisp string.

     The name "xname" is used to intentionally break code referring to
     the old field "name" of type pointer to struct Lisp_String.  */
  Lisp_Object xname;
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  /* Value of the symbol or Qunbound if unbound.  If this symbol is a
     defvaralias, `value' contains the symbol for which it is an
     alias.  Use the SYMBOL_VALUE and SET_SYMBOL_VALUE macros to get
     and set a symbol's value, to take defvaralias into account.  */
  Lisp_Object value;

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  /* Function value of the symbol or Qunbound if not fboundp.  */
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  Lisp_Object function;

  /* The symbol's property list.  */
  Lisp_Object plist;
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  /* Next symbol in obarray bucket, if the symbol is interned.  */
  struct Lisp_Symbol *next;
};

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/* Value is name of symbol.  */

#define SYMBOL_NAME(sym)  \
     LISP_MAKE_RVALUE (XSYMBOL (sym)->xname)

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/* Value is non-zero if SYM is an interned symbol.  */

#define SYMBOL_INTERNED_P(sym)  \
     (XSYMBOL (sym)->interned != SYMBOL_UNINTERNED)

/* Value is non-zero if SYM is interned in initial_obarray.  */

#define SYMBOL_INTERNED_IN_INITIAL_OBARRAY_P(sym) \
     (XSYMBOL (sym)->interned == SYMBOL_INTERNED_IN_INITIAL_OBARRAY)

/* Value is non-zero if symbol is considered a constant, i.e. its
   value cannot be changed (there is an exception for keyword symbols,
   whose value can be set to the keyword symbol itself).  */

#define SYMBOL_CONSTANT_P(sym)   XSYMBOL (sym)->constant

/* Value is the value of SYM, with defvaralias taken into
   account.  */

#define SYMBOL_VALUE(sym)			\
   (XSYMBOL (sym)->indirect_variable		\
    ? XSYMBOL (indirect_variable (sym))->value	\
    : XSYMBOL (sym)->value)

/* Set SYM's value to VAL, taking defvaralias into account.  */

#define SET_SYMBOL_VALUE(sym, val)				\
     do {							\
       if (XSYMBOL (sym)->indirect_variable)			\
	 XSYMBOL (indirect_variable ((sym)))->value = (val);	\
       else							\
	 XSYMBOL (sym)->value = (val);				\
     } while (0)
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/***********************************************************************
			     Hash Tables
 ***********************************************************************/

/* The structure of a Lisp hash table.  */

struct Lisp_Hash_Table
{
  /* Vector fields.  The hash table code doesn't refer to these.  */
  EMACS_INT size;
  struct Lisp_Vector *vec_next;
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  /* Function used to compare keys.  */
  Lisp_Object test;

  /* Nil if table is non-weak.  Otherwise a symbol describing the
     weakness of the table.  */
  Lisp_Object weak;
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  /* When the table is resized, and this is an integer, compute the
     new size by adding this to the old size.  If a float, compute the
     new size by multiplying the old size with this factor.  */
  Lisp_Object rehash_size;

  /* Resize hash table when number of entries/ table size is >= this
     ratio, a float.  */
  Lisp_Object rehash_threshold;

  /* Number of key/value entries in the table.  */
  Lisp_Object count;

  /* Vector of keys and values.  The key of item I is found at index
     2 * I, the value is found at index 2 * I + 1.  */
  Lisp_Object key_and_value;

  /* Vector of hash codes.. If hash[I] is nil, this means that that
     entry I is unused.  */
  Lisp_Object hash;

  /* Vector used to chain entries.  If entry I is free, next[I] is the
     entry number of the next free item.  If entry I is non-free,
     next[I] is the index of the next entry in the collision chain.  */
  Lisp_Object next;

  /* Index of first free entry in free list.  */
  Lisp_Object next_free;

  /* Bucket vector.  A non-nil entry is the index of the first item in
     a collision chain.  This vector's size can be larger than the
     hash table size to reduce collisions.  */
  Lisp_Object index;

  /* User-supplied hash function, or nil.  */
  Lisp_Object user_hash_function;

  /* User-supplied key comparison function, or nil.  */
  Lisp_Object user_cmp_function;

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  /* Next weak hash table if this is a weak hash table.  The head
     of the list is in weak_hash_tables.  */
  struct Lisp_Hash_Table *next_weak;

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  /* C function to compare two keys.  */
  int (* cmpfn) P_ ((struct Lisp_Hash_Table *, Lisp_Object,
		     unsigned, Lisp_Object, unsigned));

  /* C function to compute hash code.  */
  unsigned (* hashfn) P_ ((struct Lisp_Hash_Table *, Lisp_Object));
};


#define XHASH_TABLE(OBJ) \
     ((struct Lisp_Hash_Table *) XPNTR (OBJ))

#define XSET_HASH_TABLE(VAR, PTR) \
     (XSETPSEUDOVECTOR (VAR, PTR, PVEC_HASH_TABLE))

#define HASH_TABLE_P(OBJ)  PSEUDOVECTORP (OBJ, PVEC_HASH_TABLE)

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#define CHECK_HASH_TABLE(x) \
  CHECK_TYPE (HASH_TABLE_P (x), Qhash_table_p, x)
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/* Value is the key part of entry IDX in hash table H.  */

#define HASH_KEY(H, IDX)   AREF ((H)->key_and_value, 2 * (IDX))

/* Value is the value part of entry IDX in hash table H.  */

#define HASH_VALUE(H, IDX) AREF ((H)->key_and_value, 2 * (IDX) + 1)

/* Value is the index of the next entry following the one at IDX
   in hash table H.  */

#define HASH_NEXT(H, IDX)  AREF ((H)->next, (IDX))

/* Value is the hash code computed for entry IDX in hash table H.  */

#define HASH_HASH(H, IDX)  AREF ((H)->hash, (IDX))

/* Value is the index of the element in hash table H that is the
   start of the collision list at index IDX in the index vector of H.  */

#define HASH_INDEX(H, IDX)  AREF ((H)->index, (IDX))

/* Value is the size of hash table H.  */

#define HASH_TABLE_