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1 /* Fundamental definitions for XEmacs Lisp interpreter -- non-union objects.
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2 Copyright (C) 1985, 1986, 1987, 1992, 1993 Free Software Foundation, Inc.
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3 Copyright (C) 2001, 2002 Ben Wing.
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4
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5 This file is part of XEmacs.
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6
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7 XEmacs is free software; you can redistribute it and/or modify it
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8 under the terms of the GNU General Public License as published by the
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9 Free Software Foundation; either version 2, or (at your option) any
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10 later version.
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11
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12 XEmacs is distributed in the hope that it will be useful, but WITHOUT
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13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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15 for more details.
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16
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17 You should have received a copy of the GNU General Public License
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18 along with XEmacs; see the file COPYING. If not, write to
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19 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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20 Boston, MA 02111-1307, USA. */
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21
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22 /* Synched up with: FSF 19.30. Split out from lisp.h. */
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23 /* This file has diverged greatly from FSF Emacs. Syncing is no
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24 longer desirable or possible */
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25
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26 /*
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27 Format of a non-union-type Lisp Object
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28
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29 3 2 1 0
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30 bit 10987654321098765432109876543210
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31 --------------------------------
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32 VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVTT
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33
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34 Integers are treated specially, and look like this:
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35
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36 3 2 1 0
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37 bit 10987654321098765432109876543210
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38 --------------------------------
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39 VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVT
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40
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41 For integral Lisp types, i.e. integers and characters, the value
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42 bits are the Lisp object. Some people call such Lisp_Objects "immediate".
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43
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44 The object is obtained by masking off the type bits.
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45 Bit 1 is used as a value bit by splitting the Lisp integer type
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46 into two subtypes, Lisp_Type_Int_Even and Lisp_Type_Int_Odd.
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47 By this trickery we get 31 bits for integers instead of 30.
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48
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49 For non-integral types, the value bits of a Lisp_Object contain
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50 a pointer to a structure containing the object. The pointer is
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51 obtained by masking off the type and mark bits.
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52
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53 All pointer-based types are coalesced under a single type called
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54 Lisp_Type_Record. The type bits for this type are required by the
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55 implementation to be 00, just like the least significant bits of
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56 word-aligned struct pointers on 32-bit hardware. This requires that
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57 all structs implementing Lisp_Objects have an alignment of at least 4
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58 bytes. Because of this, Lisp_Object pointers don't have to be masked
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59 and are full-sized.
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60
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61 There are no mark bits in the Lisp_Object itself (there used to be).
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62
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63 Integers and characters don't need to be marked. All other types are
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64 lrecord-based, which means they get marked by setting the mark bit in
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65 the struct lrecord_header.
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66
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67 Here is a brief description of the following macros:
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68
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69 XTYPE The type bits of a Lisp_Object
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70 XPNTRVAL The value bits of a Lisp_Object storing a pointer
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71 XCHARVAL The value bits of a Lisp_Object storing a Ichar
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72 XREALINT The value bits of a Lisp_Object storing an integer, signed
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73 XUINT The value bits of a Lisp_Object storing an integer, unsigned
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74 INTP Non-zero if this Lisp_Object is an integer
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75 Qzero Lisp Integer 0
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76 EQ Non-zero if two Lisp_Objects are identical, not merely equal. */
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77
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78
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79 typedef EMACS_INT Lisp_Object;
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80
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81 #define Lisp_Type_Int_Bit (Lisp_Type_Int_Even & Lisp_Type_Int_Odd)
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82 #define VALMASK (((1UL << VALBITS) - 1UL) << GCTYPEBITS)
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83 #define XTYPE(x) ((enum Lisp_Type) (((EMACS_UINT)(x)) & ~VALMASK))
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84 #define XPNTRVAL(x) (x) /* This depends on Lisp_Type_Record == 0 */
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85 #define XCHARVAL(x) ((x) >> GCBITS)
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86 #define XREALINT(x) ((x) >> INT_GCBITS)
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87 #define XUINT(x) ((EMACS_UINT)(x) >> INT_GCBITS)
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88
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89 #define wrap_pointer_1(ptr) ((Lisp_Object) (ptr))
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90
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91 DECLARE_INLINE_HEADER (
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92 Lisp_Object
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93 make_int_verify (EMACS_INT val)
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94 )
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95 {
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96 Lisp_Object obj = (Lisp_Object) ((val << INT_GCBITS) | Lisp_Type_Int_Bit);
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97 type_checking_assert (XREALINT (obj) == val);
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98 return obj;
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99 }
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100
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101 #define make_int(x) ((Lisp_Object) (((x) << INT_GCBITS) | Lisp_Type_Int_Bit))
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102
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103 #define make_char_1(x) ((Lisp_Object) (((x) << GCBITS) | Lisp_Type_Char))
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104
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105 #define INTP(x) ((EMACS_UINT)(x) & Lisp_Type_Int_Bit)
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106 #define INT_PLUS(x,y) ((x)+(y)-Lisp_Type_Int_Bit)
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107 #define INT_MINUS(x,y) ((x)-(y)+Lisp_Type_Int_Bit)
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108 #define INT_PLUS1(x) INT_PLUS (x, make_int (1))
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109 #define INT_MINUS1(x) INT_MINUS (x, make_int (1))
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110
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111 #define Qzero make_int (0)
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112 #define Qnull_pointer ((Lisp_Object) 0)
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113 #define EQ(x,y) ((x) == (y))
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114
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115 /* WARNING!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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116
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117 You can only VOID_TO_LISP something that had previously been
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118 LISP_TO_VOID'd. You cannot go the other way, i.e. create a bogus
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119 Lisp_Object. If you want to stuff a void * into a Lisp_Object, use
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120 make_opaque_ptr(). */
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121
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122 /* Convert between a (void *) and a Lisp_Object, as when the
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123 Lisp_Object is passed to a toolkit callback function */
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124 #define VOID_TO_LISP(varg) ((Lisp_Object) (varg))
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125 #define LISP_TO_VOID(larg) ((void *) (larg))
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126
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127 /* Convert a Lisp_Object into something that can't be used as an
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128 lvalue. Useful for type-checking. */
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129 #define NON_LVALUE(larg) ((larg) + 0)
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