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/* Fundamental definitions for GNU Emacs Lisp interpreter.
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   Copyright (C) 1985,86,87,93,94,95,97,98,1999,2000, 2001, 2002, 2003
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     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 2, 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., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, 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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#endif /* 0 */
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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;
extern void die P_((const char *, const char *, int));
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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)

/* Let's get some compile-time checking too.  */
#undef NO_UNION_TYPE

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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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	EMACS_UINT type : GCTYPEBITS;
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      } s;
    struct
      {
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	EMACS_UINT val : VALBITS;
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	EMACS_UINT type : GCTYPEBITS;
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      } u;
    struct
      {
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	EMACS_UINT val		: VALBITS;
	enum Lisp_Type type	: GCTYPEBITS;
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      } gu;
  }
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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	EMACS_UINT type : GCTYPEBITS;
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	EMACS_INT val  : VALBITS;
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      } s;
    struct
      {
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	EMACS_UINT type : GCTYPEBITS;
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	EMACS_UINT val : VALBITS;
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      } u;
    struct
      {
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	enum Lisp_Type type	: GCTYPEBITS;
	EMACS_UINT val		: VALBITS;
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      } gu;
  }
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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#define Lisp_Object EMACS_INT
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#define LISP_MAKE_RVALUE(o) (0+(o))
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#endif /* NO_UNION_TYPE */
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#ifndef VALMASK
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#define VALMASK ((((EMACS_INT) 1)<<VALBITS) - 1)
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#endif
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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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/* This is set in the car of a cons to indicate it is marked.
   Likewise in the type slot of a float and in the size slot of strings.  */
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#ifndef MARKBIT
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#define MARKBIT ((EMACS_INT) ((EMACS_UINT) 1 << (VALBITS + GCTYPEBITS - 1)))
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#endif /*MARKBIT */
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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
#define ARRAY_MARK_FLAG ((MARKBIT >> 1) & ~MARKBIT)
#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_TYPE_MASK = 0x7fe00
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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.  */
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#define PSEUDOVECTOR_SIZE_MASK 0x1ff
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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

/* 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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 */
#ifndef XTYPE
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#define XTYPE(a) ((enum Lisp_Type) (((EMACS_UINT) (a)) >> VALBITS))
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#endif

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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.
   Beware: XFASTINT applied to a non-positive integer or to something
   else than an integer should return something that preserves all the
   info that was in the Lisp_Object, because it is used in EQ.  */
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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 /* NO_UNION_TYPE */

#ifndef NO_UNION_TYPE

#define XTYPE(a) ((enum Lisp_Type) (a).u.type)
#define XSETTYPE(a, b) ((a).u.type = (char) (b))

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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).i << (BITS_PER_EMACS_INT - VALBITS)) \
		 >> (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 ();
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#endif
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#endif /* NO_UNION_TYPE */

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/* During garbage collection, XGCTYPE must be used for extracting types
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 so that the mark bit is ignored.  XMARKBIT accesses the markbit.
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 Markbits are used only in particular slots of particular structure types.
 Other markbits are always zero.
 Outside of garbage collection, all mark bits are always zero.  */

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#ifndef XGCTYPE
/* The distinction does not exist now that the MARKBIT has been eliminated.  */
#define XGCTYPE(a) XTYPE(a)
#endif
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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
#define XPNTR(a) XUINT (a)
#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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/* 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 (GC_CONSP(a)),(struct Lisp_Cons *) XPNTR(a))
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#define XVECTOR(a) (eassert (GC_VECTORLIKEP(a)),(struct Lisp_Vector *) XPNTR(a))
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#define XSTRING(a) (eassert (GC_STRINGP(a)),(struct Lisp_String *) XPNTR(a))
#define XSYMBOL(a) (eassert (GC_SYMBOLP(a)),(struct Lisp_Symbol *) XPNTR(a))
#define XFLOAT(a) (eassert (GC_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 (GC_PROCESSP(a)),(struct Lisp_Process *) XPNTR(a))
#define XWINDOW(a) (eassert (GC_WINDOWP(a)),(struct window *) XPNTR(a))
#define XSUBR(a) (eassert (GC_SUBRP(a)),(struct Lisp_Subr *) XPNTR(a))
#define XBUFFER(a) (eassert (GC_BUFFERP(a)),(struct buffer *) XPNTR(a))
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#define XCHAR_TABLE(a) ((struct Lisp_Char_Table *) XPNTR(a))
#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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/* 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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/* 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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  { if (!STRINGP ((x)) && !BUFFERP ((x))) \
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      x = wrong_type_argument (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
    Lisp_Object car_, cdr_;
#else
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    Lisp_Object car, cdr;
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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_)
#define XCDR_AS_LVALUE(c) (XCONS ((c))->cdr_)
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#else
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#define XCAR_AS_LVALUE(c) (XCONS ((c))->car)
#define XCDR_AS_LVALUE(c) (XCONS ((c))->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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/* 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.  */
#define STRING_SET_UNIBYTE(STR)      (XSTRING (STR)->size_byte = -1)

/* 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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/* 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.  */
#define VECSIZE(type) ((sizeof (type) - (sizeof (struct Lisp_Vector)  \
                                         - sizeof (Lisp_Object))      \
                        + sizeof(Lisp_Object) - 1) /* round up */     \
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		       / sizeof (Lisp_Object))

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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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/* A char table is a kind of vectorlike, with contents are like a
   vector but with a few other slots.  For some purposes, it makes
   sense to handle a chartable with type struct Lisp_Vector.  An
   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
   group of characters of the same charsets or a specific character of
   a charset.  A sub char-table has the same structure as a char table
   except for that the former omits several slots at the tail.  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 apply to characters or character
   sets.  The first 128 are for ASCII, the next 128 are for 8-bit
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   European characters, and the last 128 are for multibyte characters.
   The first 256 are indexed by the code itself, but the last 128 are
   indexed by (charset-id + 128).  */
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#define CHAR_TABLE_ORDINARY_SLOTS 384

/* This is the number of slots that apply to characters of ASCII and
   8-bit Europeans only.  */
#define CHAR_TABLE_SINGLE_BYTE_SLOTS 256
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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.  */
#define CHAR_TABLE_STANDARD_SLOTS (CHAR_TABLE_ORDINARY_SLOTS + 4)

/* This is the number of slots that apply to position-code-1 and
   position-code-2 of a multibyte character at the 2nd and 3rd level
   sub char tables respectively.  */
#define SUB_CHAR_TABLE_ORDINARY_SLOTS 128

/* This is the number of slots that every sub char table must have.
   This counts the ordinary slots and the top and defalt slot.  */
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#define SUB_CHAR_TABLE_STANDARD_SLOTS (SUB_CHAR_TABLE_ORDINARY_SLOTS + 2)
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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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   and 8-bit Europeans characters.  For these characters, do not check
   validity of CT.  Do not follow parent.  */
#define CHAR_TABLE_REF(CT, IDX)				\
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  ((IDX) >= 0 && (IDX) < CHAR_TABLE_SINGLE_BYTE_SLOTS	\
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   ? (!NILP (XCHAR_TABLE (CT)->contents[IDX])		\
      ? XCHAR_TABLE (CT)->contents[IDX]			\
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      : XCHAR_TABLE (CT)->defalt)			\
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   : Faref (CT, make_number (IDX)))
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/* Almost equivalent to Faref (CT, IDX) with optimization for ASCII
   and 8-bit Europeans characters.  However, if the result is nil,
   return IDX.

   For these characters, do not check validity of CT
   and do not follow parent.  */
#define CHAR_TABLE_TRANSLATE(CT, IDX)			\
  ((IDX) < CHAR_TABLE_SINGLE_BYTE_SLOTS			\
   ? (!NILP (XCHAR_TABLE (CT)->contents[IDX])		\
      ? XINT (XCHAR_TABLE (CT)->contents[IDX])		\
      : 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 Europeans characters.  Do not check validity of CT.  */
#define CHAR_TABLE_SET(CT, IDX, VAL)			\
  do {							\
    if (XFASTINT (IDX) < CHAR_TABLE_SINGLE_BYTE_SLOTS)	\
      XCHAR_TABLE (CT)->contents[XFASTINT (IDX)] = VAL;	\
    else						\
      Faset (CT, IDX, VAL);				\
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  } while (0)

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struct Lisp_Char_Table
  {
    /* This is the vector's size field, which also holds the
       pseudovector type information.  It holds the size, too.
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       The size counts the top, defalt, purpose, and parent slots.
       The last three are not counted if this is a sub char table.  */
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    EMACS_INT size;
    struct Lisp_Vector *next;
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    /* This holds a flag to tell if this is a top level char table (t)
       or a sub char table (nil).  */
    Lisp_Object top;
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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 holds an actual value of each element.  A sub char table
       has only SUB_CHAR_TABLE_ORDINARY_SLOTS number of elements.  */
    Lisp_Object contents[CHAR_TABLE_ORDINARY_SLOTS];

    /* A sub char table doesn't has the following slots.  */

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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.  */
    Lisp_Object parent;
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    /* This should be a symbol which says what kind of use
       this char-table is meant for.
       Typically now the values can be `syntax-table' and `display-table'.  */
    Lisp_Object purpose;
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    /* These hold additional data.  */
    Lisp_Object extras[1];
  };

/* 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;

  /* Next weak hash table if this is a weak hash table.  The head
     of the list is in Vweak_hash_tables.  */
  Lisp_Object next_weak;

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

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

  /* 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)
#define GC_HASH_TABLE_P(x) GC_PSEUDOVECTORP (x, PVEC_HASH_TABLE)

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#define CHECK_HASH_TABLE(x)					\
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     do								\
       {							\
	 if (!HASH_TABLE_P ((x)))				\
	   x = wrong_type_argument (Qhash_table_p, (x));	\
       }							\
     while (0)

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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_SIZE(H) XVECTOR ((H)->next)->size

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/* Default size for hash tables if not specified.  */

#define DEFAULT_HASH_SIZE 65

/* Default threshold specifying when to resize a hash table.  The
   value gives the ratio of current entries in the hash table and the
   size of the hash table.  */

#define DEFAULT_REHASH_THRESHOLD 0.8

/* Default factor by which to increase the size of a hash table.  */

#define DEFAULT_REHASH_SIZE 1.5

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/* These structures are used for various misc types.  */

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/* A miscellaneous object, when it's on the free list.  */
struct Lisp_Free
  {
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    int type : 16;	/* = Lisp_Misc_Free */
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    unsigned gcmarkbit : 1;
    int spacer : 15;
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    union Lisp_Misc *chain;
  };
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struct Lisp_Marker
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{
  int type : 16;		/* = Lisp_Misc_Marker */
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  unsigned gcmarkbit : 1;
  int spacer : 14;
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  /* 1 means normal insertion at the marker's position
     leaves the marker after the inserted text.  */
  unsigned int insertion_type : 1;
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  /* This is the buffer that the marker points into,
     or 0 if it points nowhere.  */
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  struct buffer *buffer;
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  /* The remaining fields are meaningless in a marker that
     does not point anywhere.  */

  /* For markers that point somewhere,
     this is used to chain of all the markers in a given buffer.  */
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  struct Lisp_Marker *next;
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  /* This is the char position where the marker points.  */
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  EMACS_INT charpos;
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  /* This is the byte position.  */
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  EMACS_INT bytepos;
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};
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/* Forwarding pointer to an int variable.
   This is allowed only in the value cell of a symbol,
   and it means that the symbol's value really lives in the
   specified int variable.  */
struct Lisp_Intfwd
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  {
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    int type : 16;	/* = Lisp_Misc_Intfwd */
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    unsigned gcmarkbit : 1;
    int spacer : 15;
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    EMACS_INT *intvar;
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  };

/* Boolean forwarding pointer to an int variable.
   This is like Lisp_Intfwd except that the ostensible
   "value" of the symbol is t if the int variable is nonzero,
   nil if it is zero.  */
struct Lisp_Boolfwd
  {
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    int type : 16;	/* = Lisp_Misc_Boolfwd */
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    unsigned gcmarkbit : 1;
    int spacer : 15;
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    int *boolvar;
  };

/* Forwarding pointer to a Lisp_Object variable.
   This is allowed only in the value cell of a symbol,
   and it means that the symbol's value really lives in the
   specified variable.  */
struct Lisp_Objfwd
  {
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    int type : 16;	/* = Lisp_Misc_Objfwd */
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    unsigned gcmarkbit : 1;
    int spacer : 15;
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    Lisp_Object *objvar;
  };

/* Like Lisp_Objfwd except that value lives in a slot in the
   current buffer.  Value is byte index of slot within buffer.  */
struct Lisp_Buffer_Objfwd
  {
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    int type : 16;	/* = Lisp_Misc_Buffer_Objfwd */
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    unsigned gcmarkbit : 1;
    int spacer : 15;
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    int offset;
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  };

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/* struct Lisp_Buffer_Local_Value is used in a symbol value cell when
   the symbol has buffer-local or frame-local bindings.  (Exception:
   some buffer-local variables are built-in, with their values stored
   in the buffer structure itself.  They are handled differently,
   using struct Lisp_Buffer_Objfwd.)

   The `realvalue' slot holds the variable's current value, or a
   forwarding pointer to where that value is kept.  This value is the
   one that corresponds to the loaded binding.  To read or set the
   variable, you must first make sure the right binding is loaded;
   then you can access the value in (or through) `realvalue'.
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   `buffer' and `frame' are the buffer and frame for which the loaded
   binding was found.  If those have changed, to make sure the right
   binding is loaded it is necessary to find which binding goes with
   the current buffer and selected frame, then load it.  To load it,
   first unload the previous binding, then copy the value of the new
   binding into `realvalue' (or through it).  Also update
   LOADED-BINDING to point to the newly loaded binding.
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   Lisp_Misc_Buffer_Local_Value and Lisp_Misc_Some_Buffer_Local_Value
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   both use this kind of structure.  With the former, merely setting
   the variable creates a local binding for the current buffer.  With
   the latter, setting the variable does not do that; only
   make-local-variable does that.  */

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struct Lisp_Buffer_Local_Value
  {
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    int type : 16;      /* = Lisp_Misc_Buffer_Local_Value
			   or Lisp_Misc_Some_Buffer_Local_Value */