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comparison src/lisp-disunion.h @ 272:c5d627a313b1 r21-0b34

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Import from CVS: tag r21-0b34
author cvs
date Mon, 13 Aug 2007 10:28:48 +0200
parents 11cf20601dec
children 5a79be0ef6a8
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271:c7b7086b0a39 272:c5d627a313b1
18 the Free Software Foundation, Inc., 59 Temple Place - Suite 330, 18 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */ 19 Boston, MA 02111-1307, USA. */
20 20
21 /* Synched up with: FSF 19.30. Split out from lisp.h. */ 21 /* Synched up with: FSF 19.30. Split out from lisp.h. */
22 /* This file has diverged greatly from FSF Emacs. Syncing is no 22 /* This file has diverged greatly from FSF Emacs. Syncing is no
23 longer desired or possible */ 23 longer desirable or possible */
24 24
25 /* 25 /*
26 * Format of a non-union-type Lisp Object 26 Format of a non-union-type Lisp Object
27 *
28 * For the USE_MINIMAL_TAGBITS implementation:
29 *
30 * 3 2 1 0
31 * bit 10987654321098765432109876543210
32 * --------------------------------
33 * VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVTT
34 *
35 * For the non-USE_MINIMAL_TAGBITS implementation:
36 *
37 * 3 2 1 0
38 * bit 10987654321098765432109876543210
39 * --------------------------------
40 * TTTMVVVVVVVVVVVVVVVVVVVVVVVVVVVV
41 *
42 * V = value bits
43 * T = type bits
44 * M = mark bits
45 *
46 * For integral Lisp types, i.e. integers and characters, the value
47 * bits are the Lisp object.
48 *
49 * The object is obtained by masking off the type and mark
50 * bits. In the USE_MINIMAL_TAGBITS implementation, bit 1 is
51 * used as a value bit by splitting the Lisp integer type into
52 * two subtypes, Lisp_Type_Int_Even and Lisp_Type_Int_Odd. By
53 * this trickery we get 31 bits for integers instead of 30.
54 *
55 * In the non-USE_MINIMAL_TAGBITS world, Lisp integers are 28
56 * bits, or more properly (LONGBITS - GCTYPEBITS - 1) bits.
57 *
58 * For non-integral types, the value bits of Lisp_Object contain a
59 * pointer to structure containing the object. The pointer is
60 * obtained by masking off the type and mark bits.
61 *
62 * In the USE_MINIMAL_TAGBITS implementation, all
63 * pointer-based types are coalesced under a single type called
64 * Lisp_Type_Record. The type bits for this type are required
65 * by the implementation to be 00, just like the least
66 * significant bits of word-aligned struct pointers on 32-bit
67 * hardware. Because of this, Lisp_Object pointers don't have
68 * to be masked and are full-sized.
69 *
70 * In the non-USE_MINIMAL_TAGBITS implementation, the type and
71 * mark bits must be masked off and pointers are limited to 28
72 * bits (really LONGBITS - GCTYPEBITS - 1 bits).
73 */
74 27
75 #ifdef USE_MINIMAL_TAGBITS 28 For the USE_MINIMAL_TAGBITS implementation:
76 # define Qzero Lisp_Type_Int_Even 29
77 # define VALMASK (((1UL << (VALBITS)) - 1L) << (GCTYPEBITS)) 30 3 2 1 0
78 #else 31 bit 10987654321098765432109876543210
79 # define Qzero Lisp_Type_Int 32 --------------------------------
80 # define VALMASK ((1L << (VALBITS)) - 1L) 33 VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVTT
81 # define GCTYPEMASK ((1L << (GCTYPEBITS)) - 1L) 34
82 #endif 35 Integers are treated specially, and look like this:
36
37 3 2 1 0
38 bit 10987654321098765432109876543210
39 --------------------------------
40 VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVVT
41
42 For the non-USE_MINIMAL_TAGBITS implementation:
43
44 3 2 1 0
45 bit 10987654321098765432109876543210
46 --------------------------------
47 TTTMVVVVVVVVVVVVVVVVVVVVVVVVVVVV
48
49 V = value bits
50 T = type bits
51 M = mark bits
52
53 For integral Lisp types, i.e. integers and characters, the value
54 bits are the Lisp object.
55
56 The object is obtained by masking off the type and mark
57 bits. In the USE_MINIMAL_TAGBITS implementation, bit 1 is
58 used as a value bit by splitting the Lisp integer type into
59 two subtypes, Lisp_Type_Int_Even and Lisp_Type_Int_Odd. By
60 this trickery we get 31 bits for integers instead of 30.
61
62 In the non-USE_MINIMAL_TAGBITS world, Lisp integers are 28 bits,
63 or more properly (BITS_PER_EMACS_INT - GCTYPEBITS - 1) bits.
64
65 For non-integral types, the value bits of a Lisp_Object contain
66 a pointer to a structure containing the object. The pointer is
67 obtained by masking off the type and mark bits.
68
69 In the USE_MINIMAL_TAGBITS implementation, all
70 pointer-based types are coalesced under a single type called
71 Lisp_Type_Record. The type bits for this type are required
72 by the implementation to be 00, just like the least
73 significant bits of word-aligned struct pointers on 32-bit
74 hardware. Because of this, Lisp_Object pointers don't have
75 to be masked and are full-sized.
76
77 In the non-USE_MINIMAL_TAGBITS implementation, the type and
78 mark bits must be masked off and pointers are limited to 28
79 bits (really BITS_PER_EMACS_INT - GCTYPEBITS - 1 bits).
80
81 There are no mark bits in the USE_MINIMAL_TAGBITS implementation.
82 Integers and characters don't need to be marked. All other types
83 are lrecord-based, which means they get marked by incrementing
84 their ->implementation pointer.
85
86 In the non-USE_MINIMAL_TAGBITS implementation, the markbit is stored
87 in the Lisp_Object itself. It is stored in the middle so that the
88 type bits can be obtained by simply shifting them.
89
90 Outside of garbage collection, all mark bits are always zero.
91
92 Here is a brief description of the following macros:
93
94 XMARKBIT Extract the mark bit (non-USE_MINIMAL_TAGBITS)
95 XMARK Set the mark bit of this Lisp_Object (non-USE_MINIMAL_TAGBITS)
96 XUNMARK Clear the mark bit of this Lisp_Object (non-USE_MINIMAL_TAGBITS)
97 XTYPE The type bits of a Lisp_Object
98 XPNTRVAL The value bits of a Lisp_Object storing a pointer
99 XCHARVAL The value bits of a Lisp_Object storing a Emchar
100 XREALINT The value bits of a Lisp_Object storing an integer, signed
101 XUINT The value bits of a Lisp_Object storing an integer, unsigned
102 INTP Non-zero if this Lisp_Object an integer?
103 Qzero Lisp Integer 0
104 EQ Non-zero if two Lisp_Objects are identical
105 GC_EQ Version of EQ used during garbage collection
106 */
83 107
84 typedef EMACS_INT Lisp_Object; 108 typedef EMACS_INT Lisp_Object;
85 109
86 #define Qnull_pointer 0
87
88 /*
89 * There are no mark bits in the USE_MINIMAL_TAGBITS implementation.
90 * Integers and characters don't need to be marked. All other types
91 * are lrecord-based, which means they get marked by incrementing
92 * their ->implementation pointer.
93 */
94 #if GCMARKBITS > 0
95 /*
96 * XMARKBIT accesses the markbit. Markbits are used only in particular
97 * slots of particular structure types. Other markbits are always
98 * zero. Outside of garbage collection, all mark bits are always zero.
99 */
100 # define MARKBIT (1UL << (VALBITS))
101 # define XMARKBIT(a) ((a) & (MARKBIT))
102
103 # define XMARK(a) ((void) ((a) |= (MARKBIT)))
104 # define XUNMARK(a) ((void) ((a) &= (~(MARKBIT))))
105 #else
106 # define XUNMARK(a) DO_NOTHING
107 #endif
108
109 /*
110 * Extract the type bits from a Lisp_Object. If using USE_MINIMAL_TAGBITS,
111 * the least significant two bits are the type bits. Otherwise the
112 * most significant GCTYPEBITS bits are the type bits.
113 *
114 * In the non-USE_MINIMAL_TAGBITS case, one needs to override this
115 * if there must be high bits set in data space. Masking the bits
116 * (doing the result of the below & ((1 << (GCTYPEBITS)) - 1) would
117 * work on all machines, but would penalize machines which don't
118 * need it)
119 */
120 #ifdef USE_MINIMAL_TAGBITS
121 # define XTYPE(a) ((enum Lisp_Type) (((EMACS_UINT)(a)) & ~(VALMASK)))
122 #else
123 # define XTYPE(a) ((enum Lisp_Type) (((EMACS_UINT)(a)) >> ((VALBITS) + 1)))
124 #endif
125
126 /*
127 * This applies only to the non-USE_MINIMAL_TAGBITS Lisp_Object.
128 *
129 * In the past, during garbage collection, XGCTYPE needed to be used
130 * for extracting types so that the mark bit was ignored. XGCTYPE
131 * did and exatr & operation to remove the mark bit. But the mark
132 * bit has been since moved so that the type bits could be extracted
133 * with a single shift operation, making XGCTYPE no more expensive
134 * than XTYPE, so the two operations are now equivalent.
135 */
136 #ifndef XGCTYPE
137 # define XGCTYPE(a) XTYPE(a)
138 #endif
139
140 #define EQ(x,y) ((x) == (y))
141
142 #ifdef USE_MINIMAL_TAGBITS
143 # define GC_EQ(x,y) EQ(x,y)
144 #else
145 # define GC_EQ(x,y) (XGCTYPE (x) == XGCTYPE (y) && XPNTR (x) == XPNTR (y))
146 #endif
147
148 /*
149 * Extract the value of a Lisp_Object as a signed integer.
150 *
151 * The right shifts below are non-portable because >> is allowed to
152 * sign extend or not signed extend signed integers depending on the
153 * compiler implementors preference. But this right-shifting of
154 * signed ints has been here forever, so the apparently reality is
155 * that all compilers of any consequence do sign extension, which is
156 * what is needed here.
157 */
158 #ifndef XREALINT /* Some machines need to do this differently. */
159 # ifdef USE_MINIMAL_TAGBITS
160 # define XREALINT(a) ((a) >> (LONGBITS-VALBITS-1))
161 # else
162 # define XREALINT(a) (((a) << (LONGBITS-VALBITS)) >> (LONGBITS-VALBITS))
163 # endif
164 #endif
165
166 /* Extract the value of a Lisp integer as an unsigned integer. */
167 #ifdef USE_MINIMAL_TAGBITS
168 # define XUINT(a) ((EMACS_UINT)(a) >> (LONGBITS-VALBITS-1))
169 #else
170 # define XUINT(a) XPNTRVAL(a)
171 #endif
172
173 /*
174 * Extract the pointer value bits of a pointer based type.
175 */
176 #ifdef USE_MINIMAL_TAGBITS
177 # define XPNTRVAL(a) (a) /* This depends on Lisp_Type_Record == 0 */
178 # define XCHARVAL(a) ((a) >> (LONGBITS-VALBITS))
179 #else
180 # define XPNTRVAL(a) ((a) & VALMASK)
181 # define XCHARVAL(a) XPNTRVAL(a)
182 #endif
183
184 #ifdef HAVE_SHM
185 /* In this representation, data is found in two widely separated segments. */
186 extern int pure_size;
187 # define XPNTR(a) \
188 (XPNTRVAL (a) | (XPNTRVAL (a) > pure_size ? DATA_SEG_BITS : PURE_SEG_BITS))
189 # else /* not HAVE_SHM */
190 # ifdef DATA_SEG_BITS
191 /* This case is used for the rt-pc.
192 In the diffs I was given, it checked for ptr = 0
193 and did not adjust it in that case.
194 But I don't think that zero should ever be found
195 in a Lisp object whose data type says it points to something. */
196 # define XPNTR(a) (XPNTRVAL (a) | DATA_SEG_BITS)
197 # else
198 # define XPNTR(a) XPNTRVAL (a)
199 # endif
200 #endif /* not HAVE_SHM */
201
202 #ifdef USE_MINIMAL_TAGBITS 110 #ifdef USE_MINIMAL_TAGBITS
203 111
204 /* XSETINT depends on Lisp_Type_Int_Even == 1 and Lisp_Type_Int_Odd == 3 */ 112 # define XUNMARK(x) DO_NOTHING
205 # define XSETINT(var, value) \ 113 # define make_obj(vartype, x) ((Lisp_Object) (x))
206 ((void) ((var) = ((value) << (LONGBITS-VALBITS-1)) + 1)) 114 # define make_int(x) ((Lisp_Object) (((x) << INT_GCBITS) + 1))
207 # define XSETCHAR(var, value) \ 115 # define make_char(x) ((Lisp_Object) (((x) << GCBITS) + Lisp_Type_Char))
208 ((void) ((var) = ((value) << (LONGBITS-VALBITS)) + Lisp_Type_Char)) 116 # define VALMASK (((1UL << VALBITS) - 1UL) << GCTYPEBITS)
209 # define XSETOBJ(var, type_tag, value) \ 117 # define XTYPE(x) ((enum Lisp_Type) (((EMACS_UINT)(x)) & ~VALMASK))
210 ((void) ((var) = ((EMACS_UINT) (value)))) 118 # define XPNTRVAL(x) (x) /* This depends on Lisp_Type_Record == 0 */
119 # define XCHARVAL(x) ((x) >> GCBITS)
120 # define GC_EQ(x,y) EQ (x,y)
121 # define XREALINT(x) ((x) >> INT_GCBITS)
122 # define XUINT(x) ((EMACS_UINT)(x) >> INT_GCBITS)
123 # define INTP(x) ((EMACS_UINT)(x) & 1)
124 # define Qzero ((Lisp_Object) 1UL)
211 125
212 #else 126 #else /* !USE_MINIMAL_TAGBITS */
213 127
214 # define XSETINT(a, b) XSETOBJ (a, Lisp_Type_Int, b) 128 # define MARKBIT (1UL << VALBITS)
215 # define XSETCHAR(var, value) XSETOBJ (var, Lisp_Type_Char, value) 129 # define XMARKBIT(x) ((x) & MARKBIT)
216 # define XSETOBJ(var, type_tag, value) \ 130 # define XMARK(x) ((void) ((x) |= MARKBIT))
217 ((void) ((var) = (((EMACS_UINT) (type_tag) << ((VALBITS) + 1)) \ 131 # define XUNMARK(x) ((void) ((x) &= ~MARKBIT))
218 + ((EMACS_INT) (value) & VALMASK)))) 132 # define make_obj(vartype, value) \
219 #endif 133 ((Lisp_Object) (((EMACS_UINT) (vartype) << (VALBITS + GCMARKBITS)) \
134 + ((EMACS_UINT) (value) & VALMASK)))
135 # define make_int(value) make_obj (Lisp_Type_Int, value)
136 # define make_char(value) make_obj (Lisp_Type_Char, value)
137 # define VALMASK ((1UL << VALBITS) - 1UL)
138 # define XTYPE(x) ((enum Lisp_Type) (((EMACS_UINT)(x)) >> (VALBITS + GCMARKBITS)))
139 # define XPNTRVAL(x) ((x) & VALMASK)
140 # define XCHARVAL(x) XPNTRVAL(x)
141 # define GC_EQ(x,y) (((x) & ~MARKBIT) == ((y) & ~MARKBIT))
142 # define XREALINT(x) (((x) << INT_GCBITS) >> INT_GCBITS)
143 # define XUINT(x) ((EMACS_UINT) ((x) & VALMASK))
144 # define INTP(x) (XTYPE (x) == Lisp_Type_Int)
145 # define Qzero ((Lisp_Object) Lisp_Type_Int)
220 146
221 /* Use this for turning a (void *) into a Lisp_Object, as when the 147 #endif /* !USE_MINIMAL_TAGBITS */
222 Lisp_Object is passed into a toolkit callback function */ 148
149 #define Qnull_pointer 0
150 #define XGCTYPE(x) XTYPE(x)
151 #define EQ(x,y) ((x) == (y))
152 #define XSETINT(var, value) ((void) ((var) = make_int (value)))
153 #define XSETCHAR(var, value) ((void) ((var) = make_char (value)))
154 #define XSETOBJ(var, vartype, value) ((void) ((var) = make_obj (vartype, value)))
155
156 /* Convert between a (void *) and a Lisp_Object, as when the
157 Lisp_Object is passed to a toolkit callback function */
223 #define VOID_TO_LISP(larg,varg) ((void) ((larg) = ((Lisp_Object) (varg)))) 158 #define VOID_TO_LISP(larg,varg) ((void) ((larg) = ((Lisp_Object) (varg))))
224 #define CVOID_TO_LISP VOID_TO_LISP 159 #define CVOID_TO_LISP VOID_TO_LISP
225
226 /* Use this for turning a Lisp_Object into a (void *), as when the
227 Lisp_Object is passed into a toolkit callback function */
228 #define LISP_TO_VOID(larg) ((void *) (larg)) 160 #define LISP_TO_VOID(larg) ((void *) (larg))
229 #define LISP_TO_CVOID(varg) ((CONST void *) (larg)) 161 #define LISP_TO_CVOID(varg) ((CONST void *) (larg))
230 162
231 /* Convert a Lisp_Object into something that can't be used as an 163 /* Convert a Lisp_Object into something that can't be used as an
232 lvalue. Useful for type-checking. */ 164 lvalue. Useful for type-checking. */