lisp.h

/* Fundamental definitions for GNU Emacs Lisp interpreter.
   Copyright (C) 1985,86,87,93,94,95,97,1998 Free Software Foundation, Inc.

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
the Free Software Foundation; either version 2, or (at your option)
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
the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */


/* These are default choices for the types to use.  */
#ifndef EMACS_INT
#define EMACS_INT int
#define BITS_PER_EMACS_INT BITS_PER_INT
#endif
#ifndef EMACS_UINT
#define EMACS_UINT unsigned int
#endif

/* Define the fundamental Lisp data structures.  */

/* This is the set of Lisp data types.  */

enum Lisp_Type
  {
    /* Integer.  XINT (obj) is the integer value.  */
    Lisp_Int,

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

    /* Miscellaneous.  XMISC (object) points to a union Lisp_Misc,
       whose first member indicates the subtype.  */
    Lisp_Misc,

    /* String.  XSTRING (object) points to a struct Lisp_String.
       The length of the string, and its contents, are stored therein.  */
    Lisp_String,

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

    /* Cons.  XCONS (object) points to a struct Lisp_Cons.  */
    Lisp_Cons,

#ifdef LISP_FLOAT_TYPE
    Lisp_Float,
#endif /* LISP_FLOAT_TYPE */

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

/* This is the set of datatypes that share a common structure.
   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.  */
enum Lisp_Misc_Type
  {
    Lisp_Misc_Free = 0x5eab,
    Lisp_Misc_Marker,
    Lisp_Misc_Intfwd,
    Lisp_Misc_Boolfwd,
    Lisp_Misc_Objfwd,
    Lisp_Misc_Buffer_Objfwd,
    Lisp_Misc_Buffer_Local_Value,
    Lisp_Misc_Some_Buffer_Local_Value,
    Lisp_Misc_Overlay,
    Lisp_Misc_Kboard_Objfwd,
    /* 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
  };

/* These values are overridden by the m- file on some machines.  */
#ifndef VALBITS
#define VALBITS 28
#endif

#ifndef GCTYPEBITS
#define GCTYPEBITS 3
#endif

/* Make these values available in GDB, which sees enums but not macros.  */

enum gdb_lisp_params
{
  gdb_valbits = VALBITS,
  gdb_gctypebits = GCTYPEBITS,
  gdb_emacs_intbits = sizeof (EMACS_INT) * BITS_PER_CHAR,
#ifdef DATA_SEG_BITS
  gdb_data_seg_bits = DATA_SEG_BITS
#else
  gdb_data_seg_bits = 0
#endif
};

#ifndef NO_UNION_TYPE

#ifndef WORDS_BIG_ENDIAN

/* Definition of Lisp_Object for little-endian machines.  */

typedef
union Lisp_Object
  {
    /* Used for comparing two Lisp_Objects;
       also, positive integers can be accessed fast this way.  */
    int i;

    struct
      {
	int val: VALBITS;
	int type: GCTYPEBITS+1;
      } s;
    struct
      {
	unsigned int val: VALBITS;
	int type: GCTYPEBITS+1;
      } u;
    struct
      {
	unsigned int val: VALBITS;
	enum Lisp_Type type: GCTYPEBITS;
	/* The markbit is not really part of the value of a Lisp_Object,
	   and is always zero except during garbage collection.  */
	unsigned int markbit: 1;
      } gu;
  }
Lisp_Object;

#else /* If WORDS_BIG_ENDIAN */

typedef
union Lisp_Object
  {
    /* Used for comparing two Lisp_Objects;
       also, positive integers can be accessed fast this way.  */
    int i;

    struct
      {
	int type: GCTYPEBITS+1;
	int val: VALBITS;
      } s;
    struct
      {
	int type: GCTYPEBITS+1;
	unsigned int val: VALBITS;
      } u;
    struct
      {
	/* The markbit is not really part of the value of a Lisp_Object,
	   and is always zero except during garbage collection.  */
	unsigned int markbit: 1;
	enum Lisp_Type type: GCTYPEBITS;
	unsigned int val: VALBITS;
      } gu;
  }
Lisp_Object;

#endif /* WORDS_BIG_ENDIAN */

#endif /* NO_UNION_TYPE */


/* If union type is not wanted, define Lisp_Object as just a number.  */

#ifdef NO_UNION_TYPE
#define Lisp_Object EMACS_INT
#endif /* NO_UNION_TYPE */

#ifndef VALMASK
#define VALMASK ((((EMACS_INT) 1)<<VALBITS) - 1)
#endif
#define GCTYPEMASK ((((EMACS_INT) 1)<<GCTYPEBITS) - 1)

/* Two flags that are set during GC.  On some machines, these flags
   are defined differently by the m- file.  */

/* This is set in the car of a cons and in the plist slot of a symbol
   to indicate it is marked.  Likewise in the plist slot of an interval,
   the chain slot of a marker, the type slot of a float, and the name
   slot of a buffer.

   In strings, this bit in the size field indicates that the string
   is a "large" one, one which was separately malloc'd
   rather than being part of a string block.  */

#ifndef MARKBIT
#define MARKBIT ((int) ((unsigned int) 1 << (VALBITS + GCTYPEBITS)))
#endif /*MARKBIT */

/* In the size word of a vector, this bit means the vector has been marked.
   In the size word of a large string, likewise.  */

#ifndef ARRAY_MARK_FLAG
#define ARRAY_MARK_FLAG ((MARKBIT >> 1) & ~MARKBIT)
#endif /* no ARRAY_MARK_FLAG */

/* 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

/* In a pseudovector, the size field actually contains a word with one
   PSEUDOVECTOR_FLAG bit set, and exactly one of the following bits to
   indicate the actual type.  */
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,
  PVEC_CHAR_TABLE = 0x8000,
  PVEC_BOOL_VECTOR = 0x10000,
  PVEC_BUFFER = 0x20000,
  PVEC_TYPE_MASK = 0x3fe00,
  PVEC_FLAG = PSEUDOVECTOR_FLAG
};

/* For convenience, we also store the number of elements in these bits.  */
#define PSEUDOVECTOR_SIZE_MASK 0x1ff

/* These macros extract various sorts of values from a Lisp_Object.
 For example, if tem is a Lisp_Object whose type is Lisp_Cons,
 XCONS (tem) is the struct Lisp_Cons * pointing to the memory for that cons.  */

#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
    on all machines, but would penalise machines which don't need it)
 */
#ifndef XTYPE
#define XTYPE(a) ((enum Lisp_Type) ((a) >> VALBITS))
#endif

#ifndef XSETTYPE
#define XSETTYPE(a, b) ((a)  =  XUINT (a) | ((EMACS_INT)(b) << VALBITS))
#endif

/* 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.  */
#define XFASTINT(a) ((a) + 0)
#define XSETFASTINT(a, b) ((a) = (b))

/* Extract the value of a Lisp_Object as a signed integer.  */

#ifndef XINT   /* Some machines need to do this differently.  */
#define XINT(a) (((a) << (BITS_PER_INT-VALBITS)) >> (BITS_PER_INT-VALBITS))
#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
#define XUINT(a) ((a) & VALMASK)
#endif

#ifndef XPNTR
#ifdef HAVE_SHM
/* In this representation, data is found in two widely separated segments.  */
extern int 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 */

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

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

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

/* During garbage collection, XGCTYPE must be used for extracting types
 so that the mark bit is ignored.  XMARKBIT accesses the markbit.
 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.  */

#ifndef XGCTYPE
#define XGCTYPE(a) ((enum Lisp_Type) (((a) >> VALBITS) & GCTYPEMASK))
#endif

#if VALBITS + GCTYPEBITS == BITS_PER_EMACS_INT - 1
/* Make XMARKBIT faster if mark bit is sign bit.  */
#ifndef XMARKBIT
#define XMARKBIT(a) ((a) < 0)
#endif
#endif /* markbit is sign bit */

#ifndef XMARKBIT
#define XMARKBIT(a) ((a) & MARKBIT)
#endif

#ifndef XSETMARKBIT
#define XSETMARKBIT(a,b) ((a) = ((a) & ~MARKBIT) | ((b) ? MARKBIT : 0))
#endif

#ifndef XMARK
#define XMARK(a) ((a) |= MARKBIT)
#endif

#ifndef XUNMARK
#define XUNMARK(a) ((a) &= ~MARKBIT)
#endif

#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))

/* 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.  */
#define XFASTINT(a) ((a).i + 0)
#define XSETFASTINT(a, b) ((a).i = (b))

#ifdef EXPLICIT_SIGN_EXTEND
/* Make sure we sign-extend; compilers have been known to fail to do so.  */
#define XINT(a) (((a).i << (BITS_PER_INT-VALBITS)) >> (BITS_PER_INT-VALBITS))
#else
#define XINT(a) ((a).s.val)
#endif /* EXPLICIT_SIGN_EXTEND */

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

#define XSET(var, vartype, ptr) \
   (((var).s.type = ((char) (vartype))), ((var).s.val = ((int) (ptr))))

extern Lisp_Object make_number ();

/* During garbage collection, XGCTYPE must be used for extracting types
 so that the mark bit is ignored.  XMARKBIT access the markbit.
 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.  */

#define XGCTYPE(a) ((a).gu.type)
#define XMARKBIT(a) ((a).gu.markbit)
#define XSETMARKBIT(a,b) (XMARKBIT(a) = (b))
#define XMARK(a) (XMARKBIT(a) = 1)
#define XUNMARK(a) (XMARKBIT(a) = 0)

#endif /* NO_UNION_TYPE */

/* Extract a value or address from a Lisp_Object.  */

#define XCONS(a) ((struct Lisp_Cons *) XPNTR(a))
#define XVECTOR(a) ((struct Lisp_Vector *) XPNTR(a))
#define XSTRING(a) ((struct Lisp_String *) XPNTR(a))
#define XSYMBOL(a) ((struct Lisp_Symbol *) XPNTR(a))
#define XFLOAT(a) ((struct Lisp_Float *) XPNTR(a))

/* Misc types.  */
#define XMISC(a)   ((union Lisp_Misc *) XPNTR(a))
#define XMISCTYPE(a)   (XMARKER (a)->type)
#define XMARKER(a) (&(XMISC(a)->u_marker))
#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))
#define XBUFFER_LOCAL_VALUE(a) (&(XMISC(a)->u_buffer_local_value))
#define XOVERLAY(a) (&(XMISC(a)->u_overlay))
#define XKBOARD_OBJFWD(a) (&(XMISC(a)->u_kboard_objfwd))

/* Pseudovector types.  */
#define XPROCESS(a) ((struct Lisp_Process *) XPNTR(a))
#define XWINDOW(a) ((struct window *) XPNTR(a))
#define XSUBR(a) ((struct Lisp_Subr *) XPNTR(a))
#define XBUFFER(a) ((struct buffer *) XPNTR(a))
#define XCHAR_TABLE(a) ((struct Lisp_Char_Table *) XPNTR(a))
#define XBOOL_VECTOR(a) ((struct Lisp_Bool_Vector *) XPNTR(a))


/* Construct a Lisp_Object from a value or address.  */

#define XSETINT(a, b) XSET (a, Lisp_Int, b)
#define XSETCONS(a, b) XSET (a, Lisp_Cons, b)
#define XSETVECTOR(a, b) XSET (a, Lisp_Vectorlike, b)
#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)

/* Misc types.  */
#define XSETMISC(a, b) XSET (a, Lisp_Misc, b)
#define XSETMARKER(a, b) (XSETMISC (a, b), XMISCTYPE (a) = Lisp_Misc_Marker)

/* Pseudovector types.  */
#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))
#define XSETBUFFER(a, b) (XSETPSEUDOVECTOR (a, b, PVEC_BUFFER))
#define XSETCHAR_TABLE(a, b) (XSETPSEUDOVECTOR (a, b, PVEC_CHAR_TABLE))
#define XSETBOOL_VECTOR(a, b) (XSETPSEUDOVECTOR (a, b, PVEC_BOOL_VECTOR))

#ifdef USE_TEXT_PROPERTIES
/* Basic data type for use of intervals.  See the macros in intervals.h.  */

struct interval
{
  /* The first group of entries deal with the tree structure.  */

  unsigned int total_length;	/* Length of myself and both children.  */
  unsigned int position;	/* Cache of interval's character position.  */
				/* This field is usually updated
				   simultaneously with an interval
				   traversal, there is no guaranty
				   that it is valid for a random
				   interval.  */
  struct interval *left;	/* Intervals which precede me.  */
  struct interval *right;	/* Intervals which succeed me.  */

  /* Parent in the tree, or the Lisp_Object containing this interval tree.

     The mark bit on the root interval of an interval tree says
     whether we have started (and possibly finished) marking the
     tree.  If GC comes across an interval tree whose root's parent
     field has its markbit set, it leaves the tree alone.

     You'd think we could store this information in the parent object
     somewhere (after all, that should be visited once and then
     ignored too, right?), but strings are GC'd strangely.  */
  struct interval *parent;

  /* The remaining components are `properties' of the interval.
     The first four are duplicates for things which can be on the list,
     for purposes of speed.  */

  unsigned char write_protect;	    /* Non-zero means can't modify.  */
  unsigned char visible;	    /* Zero means don't display.  */
  unsigned char front_sticky;	    /* Non-zero means text inserted just
				       before this interval goes into it.  */
  unsigned char rear_sticky;	    /* Likewise for just after it.  */

  /* Properties of this interval.
     The mark bit on this field says whether this particular interval
     tree node has been visited.  Since intervals should never be
     shared, GC aborts if it seems to have visited an interval twice.  */
  Lisp_Object plist;
};

typedef struct interval *INTERVAL;

/* Complain if object is not string or buffer type */
#define CHECK_STRING_OR_BUFFER(x, i) \
  { if (!STRINGP ((x)) && !BUFFERP ((x))) \
      x = wrong_type_argument (Qbuffer_or_string_p, (x)); }

/* Macro used to conditionally compile intervals into certain data
   structures.  See, e.g., struct Lisp_String below.  */
#define DECLARE_INTERVALS INTERVAL intervals;

/* Macro used to conditionally compile interval initialization into
   certain code.  See, e.g., alloc.c.  */
#define INITIALIZE_INTERVAL(ptr,val) ptr->intervals = val

#else  /* No text properties */

/* If no intervals are used, make the above definitions go away.  */

#define CHECK_STRING_OR_BUFFER(x, i)

#define INTERVAL
#define DECLARE_INTERVALS
#define INITIALIZE_INTERVAL(ptr,val)

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

struct Lisp_Cons
  {
    Lisp_Object car, cdr;
  };

/* Take the car or cdr of something known to be a cons cell.  */
#define XCAR(c) (XCONS ((c))->car)
#define XCDR(c) (XCONS ((c))->cdr)

/* 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)))

/* Like a cons, but records info on where the text lives that it was read from */
/* This is not really in use now */

struct Lisp_Buffer_Cons
  {
    Lisp_Object car, cdr;
    struct buffer *buffer;
    int bufpos;
  };

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

/* Return the length in bytes of STR.  */
#define STRING_BYTES(STR)  \
  ((STR)->size_byte < 0 ? (STR)->size : (STR)->size_byte)

/* Set the length in bytes of STR.  */
#define SET_STRING_BYTES(STR, SIZE)  ((STR)->size_byte = (SIZE))

/* In a string or vector, the sign bit of the `size' is the gc mark bit */

struct Lisp_String
  {
    EMACS_INT size;
    EMACS_INT size_byte;
    DECLARE_INTERVALS		/* `data' field must be last.  */
    unsigned char data[1];
  };

/* If a struct is made to look like a vector, this macro returns the length
   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 */     \
		       / sizeof (Lisp_Object))

struct Lisp_Vector
  {
    EMACS_INT size;
    struct Lisp_Vector *next;
    Lisp_Object contents[1];
  };

/* 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.  */

/* 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
   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).  */
#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

/* 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.  */
#define SUB_CHAR_TABLE_STANDARD_SLOTS (SUB_CHAR_TABLE_ORDINARY_SLOTS + 2)

/* 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)

/* Almost equivalent to Faref (CT, IDX) with optimization for ASCII
   and 8-bit Europeans characters.  For these characters, do not check
   validity of CT.  Do not follow parent.  */
#define CHAR_TABLE_REF(CT, IDX)				\
  ((IDX) >= 0 && (IDX) < CHAR_TABLE_SINGLE_BYTE_SLOTS	\
   ? (!NILP (XCHAR_TABLE (CT)->contents[IDX])		\
      ? XCHAR_TABLE (CT)->contents[IDX]			\
      : XCHAR_TABLE (CT)->defalt)			\
   : Faref (CT, make_number (IDX)))

/* 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))

/* Equivalent to Faset (CT, IDX, VAL) with optimization for ASCII and
   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);				\
  } while (0)

struct Lisp_Char_Table
  {
    /* This is the vector's size field, which also holds the
       pseudovector type information.  It holds the size, too.
       The size counts the top, defalt, purpose, and parent slots.
       The last three are not counted if this is a sub char table.  */
    EMACS_INT size;
    struct Lisp_Vector *next;
    /* This holds a flag to tell if this is a top level char table (t)
       or a sub char table (nil).  */
    Lisp_Object top;
    /* This holds a default value,
       which is used whenever the value for a specific character is nil.  */
    Lisp_Object defalt;
    /* 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.  */

    /* 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;
    /* 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;
    /* 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];
  };

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

struct Lisp_Symbol
  {
    struct Lisp_String *name;
    Lisp_Object value;
    Lisp_Object function;
    Lisp_Object plist;
    Lisp_Object obarray;
    struct Lisp_Symbol *next;	/* -> next symbol in this obarray bucket */
  };

/* 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.  */

struct Lisp_Subr
  {
    EMACS_INT size;
    Lisp_Object (*function) ();
    short min_args, max_args;
    char *symbol_name;
    char *prompt;
    char *doc;
  };

/* These structures are used for various misc types.  */

/* A miscellaneous object, when it's on the free list.  */
struct Lisp_Free
  {
    int type : 16;	/* = Lisp_Misc_Free */
    int spacer : 16;
    union Lisp_Misc *chain;
  };

/* In a marker, the markbit of the chain field is used as the gc mark bit.  */
struct Lisp_Marker
{
  int type : 16;		/* = Lisp_Misc_Marker */
  int spacer : 15;
  /* 1 means normal insertion at the marker's position
     leaves the marker after the inserted text.  */
  unsigned int insertion_type : 1;
  /* This is the buffer that the marker points into,
     or 0 if it points nowhere.  */
  struct buffer *buffer;

  /* 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.  */
  Lisp_Object chain;
  /* This is the char position where the marker points.  */
  int charpos;
  /* This is the byte position.  */
  int bytepos;
};

/* 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
  {
    int type : 16;	/* = Lisp_Misc_Intfwd */
    int spacer : 16;
    int *intvar;
  };

/* 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
  {
    int type : 16;	/* = Lisp_Misc_Boolfwd */
    int spacer : 16;
    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
  {
    int type : 16;	/* = Lisp_Misc_Objfwd */
    int spacer : 16;
    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
  {
    int type : 16;	/* = Lisp_Misc_Buffer_Objfwd */
    int spacer : 16;
    int offset;
  };

/* Used in a symbol value cell when the symbol's value is per-buffer.
   The actual contents resemble a cons cell which starts a list like this:
   (REALVALUE BUFFER CURRENT-ALIST-ELEMENT . DEFAULT-VALUE).

   The cons-like structure is for historical reasons; it might be better
   to just put these elements into the struct, now.

   BUFFER is the last buffer for which this symbol's value was
   made up to date.

   CURRENT-ALIST-ELEMENT is a pointer to an element of BUFFER's
   local_var_alist, that being the element whose car is this
   variable.  Or it can be a pointer to the
   (CURRENT-ALIST-ELEMENT . DEFAULT-VALUE),
   if BUFFER does not have an element in its alist for this
   variable (that is, if BUFFER sees the default value of this
   variable).

   If we want to examine or set the value and BUFFER is current,
   we just examine or set REALVALUE.  If BUFFER is not current, we
   store the current REALVALUE value into CURRENT-ALIST-ELEMENT,
   then find the appropriate alist element for the buffer now
   current and set up CURRENT-ALIST-ELEMENT.  Then we set
   REALVALUE out of that element, and store into BUFFER.

   If we are setting the variable and the current buffer does not
   have an alist entry for this variable, an alist entry is
   created.

   Note that REALVALUE can be a forwarding pointer.  Each time it
   is examined or set, forwarding must be done.  Each time we
   switch buffers, buffer-local variables which forward into C
   variables are swapped immediately, so the C code can assume
   that they are always up to date.

   Lisp_Misc_Buffer_Local_Value and Lisp_Misc_Some_Buffer_Local_Value
   use the same substructure.  The difference is that with the latter,
   merely setting the variable while some buffer is current
   does not cause that buffer to have its own local value of this variable.
   Only make-local-variable does that.  */
struct Lisp_Buffer_Local_Value
  {
    int type : 16;      /* = Lisp_Misc_Buffer_Local_Value
			   or Lisp_Misc_Some_Buffer_Local_Value */
    int spacer : 13;
    unsigned int check_frame : 1;
    unsigned int found_for_buffer : 1;
    unsigned int found_for_frame : 1;
    Lisp_Object realvalue;
    Lisp_Object buffer, frame;
    Lisp_Object cdr;
  };

/* In an overlay object, the mark bit of the plist is used as the GC mark.
   START and END are markers in the overlay's buffer, and
   PLIST is the overlay's property list.  */
struct Lisp_Overlay
  {
    int type : 16;	/* = Lisp_Misc_Overlay */
    int spacer : 16;
    Lisp_Object start, end, plist;
  };

/* Like Lisp_Objfwd except that value lives in a slot in the
   current kboard.  */
struct Lisp_Kboard_Objfwd
  {
    int type : 16;	/* = Lisp_Misc_Kboard_Objfwd */
    int spacer : 16;
    int offset;
  };


/* To get the type field of a union Lisp_Misc, use XMISCTYPE.
   It uses one of these struct subtypes to get the type field.  */

union Lisp_Misc
  {
    struct Lisp_Free u_free;
    struct Lisp_Marker u_marker;
    struct Lisp_Intfwd u_intfwd;
    struct Lisp_Boolfwd u_boolfwd;
    struct Lisp_Objfwd u_objfwd;
    struct Lisp_Buffer_Objfwd u_buffer_objfwd;
    struct Lisp_Buffer_Local_Value u_buffer_local_value;
    struct Lisp_Overlay u_overlay;
    struct Lisp_Kboard_Objfwd u_kboard_objfwd;
  };

#ifdef LISP_FLOAT_TYPE
/* Optional Lisp floating point type */
struct Lisp_Float
  {
    Lisp_Object type;		/* essentially used for mark-bit
				   and chaining when on free-list */
    double data;
  };
#endif /* LISP_FLOAT_TYPE */

/* A character, declared with the following typedef, is a member
   of some character set associated with the current buffer.  */
#ifndef _UCHAR_T  /* Protect against something in ctab.h on AIX.  */
#define _UCHAR_T
typedef unsigned char UCHAR;
#endif

/* Meanings of slots in a Lisp_Compiled:  */

#define COMPILED_ARGLIST 0
#define COMPILED_BYTECODE 1
#define COMPILED_CONSTANTS 2
#define COMPILED_STACK_DEPTH 3
#define COMPILED_DOC_STRING 4
#define COMPILED_INTERACTIVE 5

/* Flag bits in a character.  These also get used in termhooks.h.
   Richard Stallman <rms@gnu.ai.mit.edu> thinks that MULE
   (MUlti-Lingual Emacs) might need 22 bits for the character value
   itself, so we probably shouldn't use any bits lower than 0x0400000.  */
#define CHAR_ALT   (0x0400000)
#define CHAR_SUPER (0x0800000)
#define CHAR_HYPER (0x1000000)
#define CHAR_SHIFT (0x2000000)
#define CHAR_CTL   (0x4000000)
#define CHAR_META  (0x8000000)

/* Actually, the current Emacs uses 19 bits for the character value
   itself.  */
#define CHARACTERBITS 19

#ifdef USE_X_TOOLKIT
#ifdef NO_UNION_TYPE
/* Use this for turning a (void *) into a Lisp_Object, as when the
   Lisp_Object is passed into a toolkit callback function.  */
#define VOID_TO_LISP(larg,varg) \
  do { ((larg) = ((Lisp_Object) (varg))); } while (0)
#define CVOID_TO_LISP VOID_TO_LISP

/* Use this for turning a Lisp_Object into a  (void *), as when the
   Lisp_Object is passed into a toolkit callback function.  */
#define LISP_TO_VOID(larg) ((void *) (larg))
#define LISP_TO_CVOID(varg) ((const void *) (larg))

#else /* not NO_UNION_TYPE */
/* Use this for turning a (void *) into a Lisp_Object, as when the
  Lisp_Object is passed into a toolkit callback function.  */
#define VOID_TO_LISP(larg,varg) \
  do { ((larg).v = (void *) (varg)); } while (0)
#define CVOID_TO_LISP(larg,varg) \
  do { ((larg).cv = (const void *) (varg)); } while (0)

/* Use this for turning a Lisp_Object into a  (void *), as when the
   Lisp_Object is passed into a toolkit callback function.  */
#define LISP_TO_VOID(larg) ((larg).v)
#define LISP_TO_CVOID(larg) ((larg).cv)
#endif /* not NO_UNION_TYPE */
#endif /* USE_X_TOOLKIT */


/* The glyph datatype, used to represent characters on the display.  */

/* The low 19 bits (CHARACTERBITS) are the character code, and the
   bits above them except for the topmost two bits are the numeric
   face ID.  If FID is the face ID of a glyph on a frame F, then
   F->display.x->faces[FID] contains the description of that face.
   This is an int instead of a short, so we can support a good bunch
   of face ID's (i.e. 2^(32 - 19 - 2) = 2048 ID's) ; given that we
   have no mechanism for tossing unused frame face ID's yet, we'll
   probably run out of 255 pretty quickly.  */
#define GLYPH unsigned int

/* Mask bit for a glyph of a character which should be written from
   right to left.  */
#define GLYPH_MASK_REV_DIR 0x80000000
/* Mask bit for a padding glyph of a multi-column character.  */
#define GLYPH_MASK_PADDING 0x40000000
/* Mask bits for face.  */
#define GLYPH_MASK_FACE    0x3FF80000
/* Mask bits for character code.  */
#define GLYPH_MASK_CHAR    0x0007FFFF /* The lowest 19 bits */

#ifdef HAVE_FACES
/* The FAST macros assume that we already know we're in an X window.  */

/* Given a character code and a face ID, return the appropriate glyph.  */
#define FAST_MAKE_GLYPH(char, face) ((char) | ((face) << CHARACTERBITS))

/* Return a glyph's character code.  */
#define FAST_GLYPH_CHAR(glyph) ((glyph) & GLYPH_MASK_CHAR)

/* Return a glyph's face ID.  */
#define FAST_GLYPH_FACE(glyph) (((glyph) & GLYPH_MASK_FACE) >> CHARACTERBITS)

/* Slower versions that test the frame type first.  */
#define MAKE_GLYPH(f, char, face) (FRAME_TERMCAP_P (f) ? (char) \
				   : FAST_MAKE_GLYPH (char, face))
#define GLYPH_CHAR(f, g) (FRAME_TERMCAP_P (f) ? (g) : FAST_GLYPH_CHAR (g))
#define GLYPH_FACE(f, g) (FRAME_TERMCAP_P (f) ? (0) : FAST_GLYPH_FACE (g))
#else /* not HAVE_FACES */
#define MAKE_GLYPH(f, char, face) (char)
#define FAST_MAKE_GLYPH(char, face) (char)
#define GLYPH_CHAR(f, g) ((g) & GLYPH_MASK_CHAR)
#define FAST_GLYPH_CHAR(g) ((g) & GLYPH_MASK_CHAR)
#define GLYPH_FACE(f, g) ((g) & GLYPH_MASK_FACE)
#define FAST_GLYPH_FACE(g) ((g) & GLYPH_MASK_FACE)
#endif /* not HAVE_FACES */

/* Return 1 iff GLYPH contains valid character code.  */
#define GLYPH_CHAR_VALID_P(glyph) \
  ((GLYPH) (FAST_GLYPH_CHAR (glyph)) <= MAX_CHAR)

/* The ID of the mode line highlighting face.  */
#define GLYPH_MODE_LINE_FACE 1

/* Data type checking */

#define NILP(x)  (XFASTINT (x) == XFASTINT (Qnil))
#define GC_NILP(x) GC_EQ (x, Qnil)

#ifdef LISP_FLOAT_TYPE
#define NUMBERP(x) (INTEGERP (x) || FLOATP (x))
#define GC_NUMBERP(x) (GC_INTEGERP (x) || GC_FLOATP (x))
#else
#define NUMBERP(x) (INTEGERP (x))
#define GC_NUMBERP(x) (GC_INTEGERP (x))
#endif
#define NATNUMP(x) (INTEGERP (x) && XINT (x) >= 0)
#define GC_NATNUMP(x) (GC_INTEGERP (x) && XINT (x) >= 0)

#define INTEGERP(x) (XTYPE ((x)) == Lisp_Int)
#define GC_INTEGERP(x) (XGCTYPE ((x)) == Lisp_Int)
#define SYMBOLP(x) (XTYPE ((x)) == Lisp_Symbol)
#define GC_SYMBOLP(x) (XGCTYPE ((x)) == Lisp_Symbol)
#define MISCP(x) (XTYPE ((x)) == Lisp_Misc)
#define GC_MISCP(x) (XGCTYPE ((x)) == Lisp_Misc)
#define VECTORLIKEP(x) (XTYPE ((x)) == Lisp_Vectorlike)
#define GC_VECTORLIKEP(x) (XGCTYPE ((x)) == Lisp_Vectorlike)
#define STRINGP(x) (XTYPE ((x)) == Lisp_String)
#define GC_STRINGP(x) (XGCTYPE ((x)) == Lisp_String)
#define CONSP(x) (XTYPE ((x)) == Lisp_Cons)
#define GC_CONSP(x) (XGCTYPE ((x)) == Lisp_Cons)

#ifdef LISP_FLOAT_TYPE
#define FLOATP(x) (XTYPE ((x)) == Lisp_Float)
#define GC_FLOATP(x) (XGCTYPE ((x)) == Lisp_Float)
#else
#define FLOATP(x) (0)
#define GC_FLOATP(x) (0)
#endif
#define VECTORP(x) (VECTORLIKEP (x) && !(XVECTOR (x)->size & PSEUDOVECTOR_FLAG))
#define GC_VECTORP(x) (GC_VECTORLIKEP (x) && !(XVECTOR (x)->size & PSEUDOVECTOR_FLAG))
#define OVERLAYP(x) (MISCP (x) && XMISCTYPE (x) == Lisp_Misc_Overlay)
#define GC_OVERLAYP(x) (GC_MISCP (x) && XMISCTYPE (x) == Lisp_Misc_Overlay)
#define MARKERP(x) (MISCP (x) && XMISCTYPE (x) == Lisp_Misc_Marker)
#define GC_MARKERP(x) (GC_MISCP (x) && XMISCTYPE (x) == Lisp_Misc_Marker)
#define INTFWDP(x) (MISCP (x) && XMISCTYPE (x) == Lisp_Misc_Intfwd)
#define GC_INTFWDP(x) (GC_MISCP (x) && XMISCTYPE (x) == Lisp_Misc_Intfwd)
#define BOOLFWDP(x) (MISCP (x) && XMISCTYPE (x) == Lisp_Misc_Boolfwd)
#define GC_BOOLFWDP(x) (GC_MISCP (x) && XMISCTYPE (x) == Lisp_Misc_Boolfwd)
#define OBJFWDP(x) (MISCP (x) && XMISCTYPE (x) == Lisp_Misc_Objfwd)
#define GC_OBJFWDP(x) (GC_MISCP (x) && XMISCTYPE (x) == Lisp_Misc_Objfwd)
#define BUFFER_OBJFWDP(x) (MISCP (x) && XMISCTYPE (x) == Lisp_Misc_Buffer_Objfwd)
#define GC_BUFFER_OBJFWDP(x) (GC_MISCP (x) && XMISCTYPE (x) == Lisp_Misc_Buffer_Objfwd)
#define BUFFER_LOCAL_VALUEP(x) (MISCP (x) && XMISCTYPE (x) == Lisp_Misc_Buffer_Local_Value)
#define GC_BUFFER_LOCAL_VALUEP(x) (GC_MISCP (x) && XMISCTYPE (x) == Lisp_Misc_Buffer_Local_Value)
#define SOME_BUFFER_LOCAL_VALUEP(x) (MISCP (x) && XMISCTYPE (x) == Lisp_Misc_Some_Buffer_Local_Value)
#define GC_SOME_BUFFER_LOCAL_VALUEP(x) (GC_MISCP (x) && XMISCTYPE (x) == Lisp_Misc_Some_Buffer_Local_Value)
#define KBOARD_OBJFWDP(x) (MISCP (x) && XMISCTYPE (x) == Lisp_Misc_Kboard_Objfwd)
#define GC_KBOARD_OBJFWDP(x) (GC_MISCP (x) && XMISCTYPE (x) == Lisp_Misc_Kboard_Objfwd)


/* True if object X is a pseudovector whose code is CODE.  */
#define PSEUDOVECTORP(x, code)					\
  (VECTORLIKEP (x)						\
   && (((XVECTOR (x)->size & (PSEUDOVECTOR_FLAG | (code))))	\
       == (PSEUDOVECTOR_FLAG | (code))))

/* True if object X is a pseudovector whose code is CODE.
   This one works during GC.  */
#define GC_PSEUDOVECTORP(x, code)				\
  (GC_VECTORLIKEP (x)						\
   && (((XVECTOR (x)->size & (PSEUDOVECTOR_FLAG | (code))))	\
       == (PSEUDOVECTOR_FLAG | (code))))

/* Test for specific pseudovector types.  */
#define WINDOW_CONFIGURATIONP(x) PSEUDOVECTORP (x, PVEC_WINDOW_CONFIGURATION)
#define GC_WINDOW_CONFIGURATIONP(x) GC_PSEUDOVECTORP (x, PVEC_WINDOW_CONFIGURATION)
#define PROCESSP(x) PSEUDOVECTORP (x, PVEC_PROCESS)
#define GC_PROCESSP(x) GC_PSEUDOVECTORP (x, PVEC_PROCESS)
#define WINDOWP(x) PSEUDOVECTORP (x, PVEC_WINDOW)
#define GC_WINDOWP(x) GC_PSEUDOVECTORP (x, PVEC_WINDOW)
#define SUBRP(x) PSEUDOVECTORP (x, PVEC_SUBR)
#define GC_SUBRP(x) GC_PSEUDOVECTORP (x, PVEC_SUBR)
#define COMPILEDP(x) PSEUDOVECTORP (x, PVEC_COMPILED)
#define GC_COMPILEDP(x) GC_PSEUDOVECTORP (x, PVEC_COMPILED)
#define BUFFERP(x) PSEUDOVECTORP (x, PVEC_BUFFER)
#define GC_BUFFERP(x) GC_PSEUDOVECTORP (x, PVEC_BUFFER)
#define CHAR_TABLE_P(x) PSEUDOVECTORP (x, PVEC_CHAR_TABLE)
#define GC_CHAR_TABLE_P(x) GC_PSEUDOVECTORP (x, PVEC_CHAR_TABLE)
#define BOOL_VECTOR_P(x) PSEUDOVECTORP (x, PVEC_BOOL_VECTOR)
#define GC_BOOL_VECTOR_P(x) GC_PSEUDOVECTORP (x, PVEC_BOOL_VECTOR)
#define FRAMEP(x) PSEUDOVECTORP (x, PVEC_FRAME)
#define GC_FRAMEP(x) GC_PSEUDOVECTORP (x, PVEC_FRAME)

#define SUB_CHAR_TABLE_P(x) (CHAR_TABLE_P (x) && NILP (XCHAR_TABLE (x)->top))

#define EQ(x, y) (XFASTINT (x) == XFASTINT (y))
#define GC_EQ(x, y) (XGCTYPE (x) == XGCTYPE (y) && XPNTR (x) == XPNTR (y))

#define CHECK_LIST(x, i) \
  do { if (!CONSP ((x)) && !NILP (x)) x = wrong_type_argument (Qlistp, (x)); } while (0)