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0f2d19dd JB |
1 | /* classes: h_files */ |
2 | ||
22a52da1 DH |
3 | #ifndef SCM_TAGS_H |
4 | #define SCM_TAGS_H | |
8c494e99 | 5 | |
e2c2a699 | 6 | /* Copyright (C) 1995,1996,1997,1998,1999,2000,2001,2002,2003,2004,2008,2009,2010 |
5065b40d | 7 | * Free Software Foundation, Inc. |
8ce94504 | 8 | * |
73be1d9e | 9 | * This library is free software; you can redistribute it and/or |
53befeb7 NJ |
10 | * modify it under the terms of the GNU Lesser General Public License |
11 | * as published by the Free Software Foundation; either version 3 of | |
12 | * the License, or (at your option) any later version. | |
8ce94504 | 13 | * |
53befeb7 NJ |
14 | * This library is distributed in the hope that it will be useful, but |
15 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
73be1d9e MV |
16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
17 | * Lesser General Public License for more details. | |
8ce94504 | 18 | * |
73be1d9e MV |
19 | * You should have received a copy of the GNU Lesser General Public |
20 | * License along with this library; if not, write to the Free Software | |
53befeb7 NJ |
21 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
22 | * 02110-1301 USA | |
73be1d9e | 23 | */ |
1bbd0b84 | 24 | |
0f2d19dd JB |
25 | \f |
26 | ||
8ce94504 | 27 | /** This file defines the format of SCM values and cons pairs. |
0f2d19dd JB |
28 | ** It is here that tag bits are assigned for various purposes. |
29 | **/ | |
30 | ||
353d4770 RB |
31 | /* picks up scmconfig.h too */ |
32 | #include "libguile/__scm.h" | |
0f2d19dd | 33 | |
7e3b25bf DH |
34 | \f |
35 | ||
0f2d19dd | 36 | /* In the beginning was the Word: |
7e3b25bf DH |
37 | * |
38 | * For the representation of scheme objects and their handling, Guile provides | |
39 | * two types: scm_t_bits and SCM. | |
40 | * | |
41 | * - scm_t_bits values can hold bit patterns of non-objects and objects: | |
42 | * | |
43 | * Non-objects -- in this case the value may not be changed into a SCM value | |
44 | * in any way. | |
45 | * | |
46 | * Objects -- in this case the value may be changed into a SCM value using | |
47 | * the SCM_PACK macro. | |
48 | * | |
49 | * - SCM values can hold proper scheme objects only. They can be changed into | |
50 | * a scm_t_bits value using the SCM_UNPACK macro. | |
51 | * | |
52 | * When working in the domain of scm_t_bits values, programmers must keep | |
53 | * track of any scm_t_bits value they create that is not a proper scheme | |
54 | * object. This makes sure that in the domain of SCM values developers can | |
55 | * rely on the fact that they are dealing with proper scheme objects only. | |
56 | * Thus, the distinction between scm_t_bits and SCM values helps to identify | |
57 | * those parts of the code where special care has to be taken not to create | |
58 | * bad SCM values. | |
59 | */ | |
60 | ||
61 | /* For dealing with the bit level representation of scheme objects we define | |
62 | * scm_t_bits: | |
0f2d19dd | 63 | */ |
23c96d9b | 64 | |
114bc68a LC |
65 | typedef scm_t_intptr scm_t_signed_bits; |
66 | typedef scm_t_uintptr scm_t_bits; | |
23c96d9b | 67 | |
114bc68a LC |
68 | #define SCM_T_SIGNED_BITS_MAX SCM_T_INTPTR_MAX |
69 | #define SCM_T_SIGNED_BITS_MIN SCM_T_INTPTR_MIN | |
70 | #define SCM_T_BITS_MAX SCM_T_UINTPTR_MAX | |
23c96d9b | 71 | |
353d4770 | 72 | |
7e3b25bf DH |
73 | /* But as external interface, we define SCM, which may, according to the |
74 | * desired level of type checking, be defined in several ways: | |
8d3356e7 | 75 | */ |
729dbac3 | 76 | #if (SCM_DEBUG_TYPING_STRICTNESS == 2) |
92c2555f MV |
77 | typedef union { struct { scm_t_bits n; } n; } SCM; |
78 | static SCM scm_pack(scm_t_bits b) { SCM s; s.n.n = b; return s; } | |
076d6063 | 79 | # define SCM_UNPACK(x) ((x).n.n) |
92c2555f | 80 | # define SCM_PACK(x) (scm_pack ((scm_t_bits) (x))) |
729dbac3 | 81 | #elif (SCM_DEBUG_TYPING_STRICTNESS == 1) |
8d3356e7 DH |
82 | /* This is the default, which provides an intermediate level of compile time |
83 | * type checking while still resulting in very efficient code. | |
c209c88e | 84 | */ |
8a30946f | 85 | typedef struct scm_unused_struct { char scm_unused_field; } *SCM; |
702551e6 HWN |
86 | |
87 | /* | |
88 | The 0?: constructions makes sure that the code is never executed, | |
89 | and that there is no performance hit. However, the alternative is | |
90 | compiled, and does generate a warning when used with the wrong | |
91 | pointer type. | |
95c6523b LC |
92 | |
93 | The Tru64 and ia64-hp-hpux11.23 compilers fail on `case (0?0=0:x)' | |
94 | statements, so for them type-checking is disabled. */ | |
95 | #if defined __DECC || defined __HP_cc | |
96 | # define SCM_UNPACK(x) ((scm_t_bits) (x)) | |
97 | #else | |
702551e6 | 98 | # define SCM_UNPACK(x) ((scm_t_bits) (0? (*(SCM*)0=(x)): x)) |
95c6523b | 99 | #endif |
702551e6 HWN |
100 | |
101 | /* | |
102 | There is no typechecking on SCM_PACK, since all kinds of types | |
103 | (unsigned long, void*) go in SCM_PACK | |
104 | */ | |
076d6063 | 105 | # define SCM_PACK(x) ((SCM) (x)) |
702551e6 | 106 | |
c209c88e | 107 | #else |
8d3356e7 DH |
108 | /* This should be used as a fall back solution for machines on which casting |
109 | * to a pointer may lead to loss of bit information, e. g. in the three least | |
110 | * significant bits. | |
111 | */ | |
92c2555f | 112 | typedef scm_t_bits SCM; |
076d6063 | 113 | # define SCM_UNPACK(x) (x) |
702551e6 | 114 | # define SCM_PACK(x) ((SCM) (x)) |
c209c88e | 115 | #endif |
0f2d19dd | 116 | |
8d3356e7 DH |
117 | |
118 | /* SCM values can not be compared by using the operator ==. Use the following | |
119 | * macro instead, which is the equivalent of the scheme predicate 'eq?'. | |
120 | */ | |
9c293a3d | 121 | #define scm_is_eq(x, y) (SCM_UNPACK (x) == SCM_UNPACK (y)) |
8d3356e7 | 122 | |
0f2d19dd | 123 | \f |
2549a709 | 124 | |
7e3b25bf DH |
125 | /* Representation of scheme objects: |
126 | * | |
127 | * Guile's type system is designed to work on systems where scm_t_bits and SCM | |
128 | * variables consist of at least 32 bits. The objects that a SCM variable can | |
129 | * represent belong to one of the following two major categories: | |
130 | * | |
131 | * - Immediates -- meaning that the SCM variable contains an entire Scheme | |
132 | * object. That means, all the object's data (including the type tagging | |
133 | * information that is required to identify the object's type) must fit into | |
134 | * 32 bits. | |
135 | * | |
136 | * - Non-immediates -- meaning that the SCM variable holds a pointer into the | |
137 | * heap of cells (see below). On systems where a pointer needs more than 32 | |
138 | * bits this means that scm_t_bits and SCM variables need to be large enough | |
139 | * to hold such pointers. In contrast to immediates, the object's data of | |
140 | * a non-immediate can consume arbitrary amounts of memory: The heap cell | |
141 | * being pointed to consists of at least two scm_t_bits variables and thus | |
142 | * can be used to hold pointers to malloc'ed memory of any size. | |
143 | * | |
144 | * The 'heap' is the memory area that is under control of Guile's garbage | |
145 | * collector. It holds 'single-cells' or 'double-cells', which consist of | |
146 | * either two or four scm_t_bits variables, respectively. It is guaranteed | |
147 | * that the address of a cell on the heap is 8-byte aligned. That is, since | |
148 | * non-immediates hold a cell address, the three least significant bits of a | |
149 | * non-immediate can be used to store additional information. The bits are | |
150 | * used to store information about the object's type and thus are called | |
151 | * tc3-bits, where tc stands for type-code. | |
152 | * | |
153 | * For a given SCM value, the distinction whether it holds an immediate or | |
154 | * non-immediate object is based on the tc3-bits (see above) of its scm_t_bits | |
155 | * equivalent: If the tc3-bits equal #b000, then the SCM value holds a | |
156 | * non-immediate, and the scm_t_bits variable's value is just the pointer to | |
157 | * the heap cell. | |
158 | * | |
159 | * Summarized, the data of a scheme object that is represented by a SCM | |
160 | * variable consists of a) the SCM variable itself, b) in case of | |
161 | * non-immediates the data of the single-cell or double-cell the SCM object | |
162 | * points to, c) in case of non-immediates potentially additional data outside | |
163 | * of the heap (like for example malloc'ed data), and d) in case of | |
164 | * non-immediates potentially additional data inside of the heap, since data | |
165 | * stored in b) and c) may hold references to other cells. | |
166 | * | |
167 | * | |
168 | * Immediates | |
169 | * | |
170 | * Operations on immediate objects can typically be processed faster than on | |
171 | * non-immediates. The reason is that the object's data can be extracted | |
172 | * directly from the SCM variable (or rather a corresponding scm_t_bits | |
173 | * variable), instead of having to perform additional memory accesses to | |
174 | * obtain the object's data from the heap. In order to get the best possible | |
175 | * performance frequently used data types should be realized as immediates. | |
176 | * This is, as has been mentioned above, only possible if the objects can be | |
177 | * represented with 32 bits (including type tagging). | |
178 | * | |
179 | * In Guile, the following data types and special objects are realized as | |
180 | * immediates: booleans, characters, small integers (see below), the empty | |
181 | * list, the end of file object, the 'unspecified' object (which is delivered | |
182 | * as a return value by functions for which the return value is unspecified), | |
183 | * a 'nil' object used in the elisp-compatibility mode and certain other | |
184 | * 'special' objects which are only used internally in Guile. | |
185 | * | |
186 | * Integers in Guile can be arbitrarily large. On the other hand, integers | |
187 | * are one of the most frequently used data types. Especially integers with | |
188 | * less than 32 bits are commonly used. Thus, internally and transparently | |
189 | * for application code guile distinguishes between small and large integers. | |
190 | * Whether an integer is a large or a small integer depends on the number of | |
191 | * bits needed to represent its value. Small integers are those which can be | |
192 | * represented as immediates. Since they don't require more than a fixed | |
193 | * number of bits for their representation, they are also known as 'fixnums'. | |
194 | * | |
195 | * The tc3-combinations #b010 and #b110 are used to represent small integers, | |
196 | * which allows to use the most significant bit of the tc3-bits to be part of | |
197 | * the integer value being represented. This means that all integers with up | |
198 | * to 30 bits (including one bit for the sign) can be represented as | |
199 | * immediates. On systems where SCM and scm_t_bits variables hold more than | |
200 | * 32 bits, the amount of bits usable for small integers will even be larger. | |
201 | * The tc3-code #b100 is shared among booleans, characters and the other | |
202 | * special objects listed above. | |
203 | * | |
204 | * | |
205 | * Non-Immediates | |
206 | * | |
207 | * All object types not mentioned above in the list of immedate objects are | |
208 | * represented as non-immediates. Whether a non-immediate scheme object is | |
209 | * represented by a single-cell or a double-cell depends on the object's type, | |
210 | * namely on the set of attributes that have to be stored with objects of that | |
211 | * type. Every non-immediate type is allowed to define its own layout and | |
212 | * interpretation of the data stored in its cell (with some restrictions, see | |
213 | * below). | |
214 | * | |
215 | * One of the design goals of guile's type system is to make it possible to | |
216 | * store a scheme pair with as little memory usage as possible. The minimum | |
217 | * amount of memory that is required to store two scheme objects (car and cdr | |
218 | * of a pair) is the amount of memory required by two scm_t_bits or SCM | |
219 | * variables. Therefore pairs in guile are stored in single-cells. | |
220 | * | |
221 | * Another design goal for the type system is to store procedure objects | |
222 | * created by lambda expresssions (closures) and class instances (goops | |
223 | * objects) with as little memory usage as possible. Closures are represented | |
224 | * by a reference to the function code and a reference to the closure's | |
225 | * environment. Class instances are represented by a reference to the | |
226 | * instance's class definition and a reference to the instance's data. Thus, | |
227 | * closures as well as class instances also can be stored in single-cells. | |
228 | * | |
229 | * Certain other non-immediate types also store their data in single-cells. | |
230 | * By design decision, the heap is split into areas for single-cells and | |
231 | * double-cells, but not into areas for single-cells-holding-pairs and areas | |
232 | * for single-cells-holding-non-pairs. Any single-cell on the heap therefore | |
233 | * can hold pairs (consisting of two scm_t_bits variables representing two | |
234 | * scheme objects - the car and cdr of the pair) and non-pairs (consisting of | |
235 | * two scm_t_bits variables that hold bit patterns as defined by the layout of | |
236 | * the corresponding object's type). | |
237 | * | |
238 | * | |
239 | * Garbage collection | |
240 | * | |
241 | * During garbage collection, unreachable cells on the heap will be freed. | |
242 | * That is, the garbage collector will detect cells which have no SCM variable | |
243 | * pointing towards them. In order to properly release all memory belonging | |
244 | * to the object to which a cell belongs, the gc needs to be able to interpret | |
245 | * the cell contents in the correct way. That means that the gc needs to be | |
246 | * able to determine the object type associated with a cell only from the cell | |
247 | * itself. | |
248 | * | |
249 | * Consequently, if the gc detects an unreachable single-cell, those two | |
250 | * scm_t_bits variables must provide enough information to determine whether | |
251 | * they belong to a pair (i. e. both scm_t_bits variables represent valid | |
252 | * scheme objects), to a closure, a class instance or if they belong to any | |
253 | * other non-immediate. Guile's type system is designed to make it possible | |
254 | * to determine a the type to which a cell belongs in the majority of cases | |
255 | * from the cell's first scm_t_bits variable. (Given a SCM variable X holding | |
256 | * a non-immediate object, the macro SCM_CELL_TYPE(X) will deliver the | |
257 | * corresponding cell's first scm_t_bits variable.) | |
258 | * | |
259 | * If the cell holds a scheme pair, then we already know that the first | |
260 | * scm_t_bits variable of the cell will hold a scheme object with one of the | |
261 | * following tc3-codes: #b000 (non-immediate), #b010 (small integer), #b100 | |
262 | * (small integer), #b110 (non-integer immediate). All these tc3-codes have | |
263 | * in common, that their least significant bit is #b0. This fact is used by | |
264 | * the garbage collector to identify cells that hold pairs. The remaining | |
265 | * tc3-codes are assigned as follows: #b001 (class instance or, more | |
266 | * precisely, a struct, of which a class instance is a special case), #b011 | |
267 | * (closure), #b101/#b111 (all remaining non-immediate types). | |
268 | * | |
269 | * | |
270 | * Summary of type codes of scheme objects (SCM variables) | |
271 | * | |
272 | * Here is a summary of tagging bits as they might occur in a scheme object. | |
273 | * The notation is as follows: tc stands for type code as before, tc<n> with n | |
274 | * being a number indicates a type code formed by the n least significant bits | |
275 | * of the SCM variables corresponding scm_t_bits value. | |
276 | * | |
277 | * Note that (as has been explained above) tc1==1 can only occur in the first | |
278 | * scm_t_bits variable of a cell belonging to a non-immediate object that is | |
279 | * not a pair. For an explanation of the tc tags with tc1==1, see the next | |
280 | * section with the summary of the type codes on the heap. | |
281 | * | |
282 | * tc1: | |
283 | * 0: For scheme objects, tc1==0 must be fulfilled. | |
284 | * (1: This can never be the case for a scheme object.) | |
285 | * | |
286 | * tc2: | |
287 | * 00: Either a non-immediate or some non-integer immediate | |
288 | * (01: This can never be the case for a scheme object.) | |
289 | * 10: Small integer | |
290 | * (11: This can never be the case for a scheme object.) | |
291 | * | |
292 | * tc3: | |
293 | * 000: a non-immediate object (pair, closure, class instance etc.) | |
294 | * (001: This can never be the case for a scheme object.) | |
295 | * 010: an even small integer (least significant bit is 0). | |
296 | * (011: This can never be the case for a scheme object.) | |
297 | * 100: Non-integer immediate | |
298 | * (101: This can never be the case for a scheme object.) | |
299 | * 110: an odd small integer (least significant bit is 1). | |
300 | * (111: This can never be the case for a scheme object.) | |
301 | * | |
302 | * The remaining bits of the non-immediate objects form the pointer to the | |
303 | * heap cell. The remaining bits of the small integers form the integer's | |
304 | * value and sign. Thus, the only scheme objects for which a further | |
305 | * subdivision is of interest are the ones with tc3==100. | |
306 | * | |
5065b40d DH |
307 | * tc8 (for objects with tc3==100): |
308 | * 00000-100: special objects ('flags') | |
309 | * 00001-100: characters | |
b7742c6b AW |
310 | * 00010-100: unused |
311 | * 00011-100: unused | |
7e3b25bf DH |
312 | * |
313 | * | |
314 | * Summary of type codes on the heap | |
315 | * | |
316 | * Here is a summary of tagging in scm_t_bits values as they might occur in | |
317 | * the first scm_t_bits variable of a heap cell. | |
318 | * | |
319 | * tc1: | |
320 | * 0: the cell belongs to a pair. | |
321 | * 1: the cell belongs to a non-pair. | |
322 | * | |
323 | * tc2: | |
324 | * 00: the cell belongs to a pair with no short integer in its car. | |
325 | * 01: the cell belongs to a non-pair (struct or some other non-immediate). | |
326 | * 10: the cell belongs to a pair with a short integer in its car. | |
327 | * 11: the cell belongs to a non-pair (closure or some other non-immediate). | |
328 | * | |
329 | * tc3: | |
330 | * 000: the cell belongs to a pair with a non-immediate in its car. | |
331 | * 001: the cell belongs to a struct | |
332 | * 010: the cell belongs to a pair with an even short integer in its car. | |
333 | * 011: the cell belongs to a closure | |
334 | * 100: the cell belongs to a pair with a non-integer immediate in its car. | |
335 | * 101: the cell belongs to some other non-immediate. | |
336 | * 110: the cell belongs to a pair with an odd short integer in its car. | |
337 | * 111: the cell belongs to some other non-immediate. | |
338 | * | |
339 | * tc7 (for tc3==1x1): | |
340 | * See below for the list of types. Note the special case of scm_tc7_vector | |
341 | * and scm_tc7_wvect: vectors and weak vectors are treated the same in many | |
342 | * cases. Thus, their tc7-codes are chosen to only differ in one bit. This | |
343 | * makes it possible to check an object at the same time for being a vector | |
344 | * or a weak vector by comparing its tc7 code with that bit masked (using | |
534c55a9 DH |
345 | * the TYP7S macro). Three more special tc7-codes are of interest: |
346 | * numbers, ports and smobs in fact each represent collections of types, | |
347 | * which are subdivided using tc16-codes. | |
7e3b25bf DH |
348 | * |
349 | * tc16 (for tc7==scm_tc7_smob): | |
350 | * The largest part of the space of smob types is not subdivided in a | |
351 | * predefined way, since smobs can be added arbitrarily by user C code. | |
7e3b25bf | 352 | */ |
0f2d19dd | 353 | |
7e3b25bf DH |
354 | \f |
355 | ||
356 | /* Checking if a SCM variable holds an immediate or a non-immediate object: | |
357 | * This check can either be performed by checking for tc3==000 or tc3==00x, | |
358 | * since for a SCM variable it is known that tc1==0. */ | |
f1267706 | 359 | #define SCM_IMP(x) (6 & SCM_UNPACK (x)) |
76189127 | 360 | #define SCM_NIMP(x) (!SCM_IMP (x)) |
0f2d19dd | 361 | |
7e3b25bf DH |
362 | /* Checking if a SCM variable holds an immediate integer: See numbers.h for |
363 | * the definition of the following macros: SCM_I_FIXNUM_BIT, | |
e11e83f3 | 364 | * SCM_MOST_POSITIVE_FIXNUM, SCM_I_INUMP, SCM_I_MAKINUM, SCM_I_INUM. */ |
0f2d19dd | 365 | |
7e3b25bf DH |
366 | /* Checking if a SCM variable holds a pair (for historical reasons, in Guile |
367 | * also known as a cons-cell): This is done by first checking that the SCM | |
368 | * variable holds a non-immediate, and second, by checking that tc1==0 holds | |
6fcc7d48 MV |
369 | * for the SCM_CELL_TYPE of the SCM variable. |
370 | */ | |
371 | ||
372 | #define SCM_I_CONSP(x) (!SCM_IMP (x) && ((1 & SCM_CELL_TYPE (x)) == 0)) | |
0f2d19dd | 373 | |
0f2d19dd JB |
374 | \f |
375 | ||
7e3b25bf | 376 | /* Definitions for tc2: */ |
0f2d19dd | 377 | |
6375e040 DH |
378 | #define scm_tc2_int 2 |
379 | ||
7e3b25bf DH |
380 | |
381 | /* Definitions for tc3: */ | |
382 | ||
904a077d MV |
383 | #define SCM_ITAG3(x) (7 & SCM_UNPACK (x)) |
384 | #define SCM_TYP3(x) (7 & SCM_CELL_TYPE (x)) | |
7e3b25bf | 385 | |
904a077d MV |
386 | #define scm_tc3_cons 0 |
387 | #define scm_tc3_struct 1 | |
6375e040 | 388 | #define scm_tc3_int_1 (scm_tc2_int + 0) |
314b8716 | 389 | #define scm_tc3_unused 3 |
c209c88e GB |
390 | #define scm_tc3_imm24 4 |
391 | #define scm_tc3_tc7_1 5 | |
6375e040 | 392 | #define scm_tc3_int_2 (scm_tc2_int + 4) |
c209c88e | 393 | #define scm_tc3_tc7_2 7 |
0f2d19dd JB |
394 | |
395 | ||
7e3b25bf | 396 | /* Definitions for tc7: */ |
0f2d19dd | 397 | |
d1ca2c64 | 398 | #define SCM_ITAG7(x) (127 & SCM_UNPACK (x)) |
445f675c DH |
399 | #define SCM_TYP7(x) (0x7f & SCM_CELL_TYPE (x)) |
400 | #define SCM_TYP7S(x) ((0x7f & ~2) & SCM_CELL_TYPE (x)) | |
0f2d19dd | 401 | |
28b06554 | 402 | #define scm_tc7_symbol 5 |
e5aca4b5 | 403 | #define scm_tc7_variable 7 |
0f2d19dd JB |
404 | |
405 | /* couple */ | |
406 | #define scm_tc7_vector 13 | |
407 | #define scm_tc7_wvect 15 | |
408 | ||
0f2d19dd | 409 | #define scm_tc7_string 21 |
534c55a9 | 410 | #define scm_tc7_number 23 |
fddf6000 | 411 | #define scm_tc7_stringbuf 39 |
807e5a66 | 412 | #define scm_tc7_bytevector 77 |
0f2d19dd | 413 | |
e2c2a699 | 414 | #define scm_tc7_foreign 31 |
c99de5aa | 415 | #define scm_tc7_hashtable 29 |
9ea31741 AW |
416 | #define scm_tc7_fluid 37 |
417 | #define scm_tc7_dynamic_state 45 | |
418 | ||
6f3b0cc2 AW |
419 | #define scm_tc7_frame 47 |
420 | #define scm_tc7_objcode 53 | |
421 | #define scm_tc7_vm 55 | |
422 | #define scm_tc7_vm_cont 71 | |
afe5177e | 423 | |
adaf86ec | 424 | #define scm_tc7_prompt 61 |
bb0229b5 | 425 | #define scm_tc7_with_fluids 63 |
8a1f4f98 | 426 | #define scm_tc7_unused_19 69 |
2fb924f6 | 427 | #define scm_tc7_program 79 |
df338a22 AW |
428 | #define scm_tc7_unused_9 85 |
429 | #define scm_tc7_unused_10 87 | |
f36878ba | 430 | #define scm_tc7_unused_20 93 |
df338a22 AW |
431 | #define scm_tc7_unused_11 95 |
432 | #define scm_tc7_unused_12 101 | |
31d845b4 | 433 | #define scm_tc7_unused_18 103 |
df338a22 AW |
434 | #define scm_tc7_unused_13 109 |
435 | #define scm_tc7_unused_14 111 | |
436 | #define scm_tc7_unused_15 117 | |
437 | #define scm_tc7_unused_16 119 | |
0f2d19dd | 438 | |
7e3b25bf | 439 | /* There are 256 port subtypes. */ |
0f2d19dd JB |
440 | #define scm_tc7_port 125 |
441 | ||
6375e040 DH |
442 | /* There are 256 smob subtypes. [**] If you change scm_tc7_smob, you must |
443 | * also change the places it is hard coded in this file and possibly others. | |
444 | * Dirk:FIXME:: Any hard coded reference to scm_tc7_smob must be replaced by a | |
7e3b25bf | 445 | * symbolic reference. */ |
0f2d19dd JB |
446 | #define scm_tc7_smob 127 /* DO NOT CHANGE [**] */ |
447 | ||
0f2d19dd | 448 | |
7e3b25bf DH |
449 | /* Definitions for tc16: */ |
450 | #define SCM_TYP16(x) (0xffff & SCM_CELL_TYPE (x)) | |
7e3b25bf DH |
451 | #define SCM_TYP16_PREDICATE(tag, x) (!SCM_IMP (x) && SCM_TYP16 (x) == (tag)) |
452 | ||
f03314f9 | 453 | |
0f2d19dd | 454 | \f |
5065b40d | 455 | |
8ce94504 | 456 | /* {Immediate Values} |
0f2d19dd JB |
457 | */ |
458 | ||
5065b40d | 459 | enum scm_tc8_tags |
0f2d19dd | 460 | { |
5065b40d DH |
461 | scm_tc8_flag = scm_tc3_imm24 + 0x00, /* special objects ('flags') */ |
462 | scm_tc8_char = scm_tc3_imm24 + 0x08, /* characters */ | |
b7742c6b AW |
463 | scm_tc8_unused_0 = scm_tc3_imm24 + 0x10, |
464 | scm_tc8_unused_1 = scm_tc3_imm24 + 0x18 | |
0f2d19dd JB |
465 | }; |
466 | ||
f1267706 MD |
467 | #define SCM_ITAG8(X) (SCM_UNPACK (X) & 0xff) |
468 | #define SCM_MAKE_ITAG8(X, TAG) SCM_PACK (((X) << 8) + TAG) | |
469 | #define SCM_ITAG8_DATA(X) (SCM_UNPACK (X) >> 8) | |
0f2d19dd | 470 | |
0f2d19dd | 471 | \f |
0f2d19dd | 472 | |
5065b40d DH |
473 | /* Flags (special objects). The indices of the flags must agree with the |
474 | * declarations in print.c: iflagnames. */ | |
475 | ||
476 | #define SCM_IFLAGP(n) (SCM_ITAG8 (n) == scm_tc8_flag) | |
477 | #define SCM_MAKIFLAG(n) SCM_MAKE_ITAG8 ((n), scm_tc8_flag) | |
478 | #define SCM_IFLAGNUM(n) (SCM_ITAG8_DATA (n)) | |
e17d318f | 479 | |
45f4cbdf MW |
480 | /* |
481 | * IMPORTANT NOTE regarding IFLAG numbering!!! | |
482 | * | |
483 | * Several macros depend upon careful IFLAG numbering of SCM_BOOL_F, | |
484 | * SCM_BOOL_T, SCM_ELISP_NIL, SCM_EOL, and the two SCM_XXX_*_DONT_USE | |
485 | * constants. In particular: | |
486 | * | |
487 | * - SCM_BOOL_F and SCM_BOOL_T must differ in exactly one bit position. | |
488 | * (used to implement scm_is_bool_and_not_nil, aka scm_is_bool) | |
489 | * | |
490 | * - SCM_ELISP_NIL and SCM_BOOL_F must differ in exactly one bit position. | |
491 | * (used to implement scm_is_false_or_nil and | |
492 | * scm_is_true_and_not_nil) | |
493 | * | |
494 | * - SCM_ELISP_NIL and SCM_EOL must differ in exactly one bit position. | |
495 | * (used to implement scm_is_null_or_nil) | |
496 | * | |
497 | * - SCM_ELISP_NIL, SCM_BOOL_F, SCM_EOL, SCM_XXX_ANOTHER_LISP_FALSE_DONT_USE | |
498 | * must all be equal except for two bit positions. | |
499 | * (used to implement scm_is_lisp_false) | |
500 | * | |
f60c2c4e | 501 | * - SCM_ELISP_NIL, SCM_BOOL_F, SCM_BOOL_T, SCM_XXX_ANOTHER_BOOLEAN_DONT_USE_0 |
45f4cbdf MW |
502 | * must all be equal except for two bit positions. |
503 | * (used to implement scm_is_bool_or_nil) | |
504 | * | |
505 | * These properties allow the aforementioned macros to be implemented | |
506 | * by bitwise ANDing with a mask and then comparing with a constant, | |
507 | * using as a common basis the macro SCM_MATCHES_BITS_IN_COMMON, | |
508 | * defined below. The properties are checked at compile-time using | |
509 | * `verify' macros near the top of boolean.c and pairs.c. | |
510 | */ | |
e17d318f | 511 | #define SCM_BOOL_F SCM_MAKIFLAG (0) |
45f4cbdf MW |
512 | #define SCM_ELISP_NIL SCM_MAKIFLAG (1) |
513 | ||
514 | #ifdef BUILDING_LIBGUILE | |
515 | #define SCM_XXX_ANOTHER_LISP_FALSE_DONT_USE SCM_MAKIFLAG (2) | |
516 | #endif | |
517 | ||
518 | #define SCM_EOL SCM_MAKIFLAG (3) | |
519 | #define SCM_BOOL_T SCM_MAKIFLAG (4) | |
520 | ||
521 | #ifdef BUILDING_LIBGUILE | |
f60c2c4e MW |
522 | #define SCM_XXX_ANOTHER_BOOLEAN_DONT_USE_0 SCM_MAKIFLAG (5) |
523 | #define SCM_XXX_ANOTHER_BOOLEAN_DONT_USE_1 SCM_MAKIFLAG (6) | |
524 | #define SCM_XXX_ANOTHER_BOOLEAN_DONT_USE_2 SCM_MAKIFLAG (7) | |
45f4cbdf MW |
525 | #endif |
526 | ||
f60c2c4e MW |
527 | #define SCM_UNSPECIFIED SCM_MAKIFLAG (8) |
528 | #define SCM_UNDEFINED SCM_MAKIFLAG (9) | |
529 | #define SCM_EOF_VAL SCM_MAKIFLAG (10) | |
e17d318f DH |
530 | |
531 | /* When a variable is unbound this is marked by the SCM_UNDEFINED | |
532 | * value. The following is an unbound value which can be handled on | |
533 | * the Scheme level, i.e., it can be stored in and retrieved from a | |
534 | * Scheme variable. This value is only intended to mark an unbound | |
535 | * slot in GOOPS. It is needed now, but we should probably rewrite | |
536 | * the code which handles this value in C so that SCM_UNDEFINED can be | |
537 | * used instead. It is not ideal to let this kind of unique and | |
538 | * strange values loose on the Scheme level. */ | |
f60c2c4e | 539 | #define SCM_UNBOUND SCM_MAKIFLAG (11) |
e17d318f | 540 | |
68fb32d2 | 541 | #define SCM_UNBNDP(x) (scm_is_eq ((x), SCM_UNDEFINED)) |
e17d318f | 542 | |
45f4cbdf MW |
543 | /* |
544 | * SCM_MATCHES_BITS_IN_COMMON(x,a,b) returns 1 if and only if x | |
545 | * matches both a and b in every bit position where a and b are equal; | |
546 | * otherwise it returns 0. Bit positions where a and b differ are | |
547 | * ignored. | |
548 | * | |
549 | * This is used to efficiently compare against two values which differ | |
550 | * in exactly one bit position, or against four values which differ in | |
551 | * exactly two bit positions. It is the basis for the following | |
552 | * macros: | |
553 | * | |
554 | * scm_is_null_or_nil, | |
555 | * scm_is_false_or_nil, | |
556 | * scm_is_true_and_not_nil, | |
557 | * scm_is_lisp_false, | |
558 | * scm_is_lisp_true, | |
559 | * scm_is_bool_and_not_nil (aka scm_is_bool) | |
560 | * scm_is_bool_or_nil. | |
561 | */ | |
562 | #define SCM_MATCHES_BITS_IN_COMMON(x,a,b) \ | |
563 | ((SCM_UNPACK(x) & ~(SCM_UNPACK(a) ^ SCM_UNPACK(b))) == \ | |
564 | (SCM_UNPACK(a) & SCM_UNPACK(b))) | |
565 | ||
566 | /* | |
567 | * These macros are used for compile-time verification that the | |
568 | * constants have the properties needed for the above macro to work | |
569 | * properly. | |
570 | */ | |
571 | #ifdef BUILDING_LIBGUILE | |
572 | #define SCM_WITH_LEAST_SIGNIFICANT_1_BIT_CLEARED(x) ((x) & ((x)-1)) | |
573 | #define SCM_HAS_EXACTLY_ONE_BIT_SET(x) \ | |
574 | ((x) != 0 && SCM_WITH_LEAST_SIGNIFICANT_1_BIT_CLEARED (x) == 0) | |
575 | #define SCM_HAS_EXACTLY_TWO_BITS_SET(x) \ | |
576 | (SCM_HAS_EXACTLY_ONE_BIT_SET (SCM_WITH_LEAST_SIGNIFICANT_1_BIT_CLEARED (x))) | |
577 | ||
578 | #define SCM_VALUES_DIFFER_IN_EXACTLY_ONE_BIT_POSITION(a,b) \ | |
579 | (SCM_HAS_EXACTLY_ONE_BIT_SET (SCM_UNPACK(a) ^ SCM_UNPACK(b))) | |
580 | #define SCM_VALUES_DIFFER_IN_EXACTLY_TWO_BIT_POSITIONS(a,b,c,d) \ | |
581 | (SCM_HAS_EXACTLY_TWO_BITS_SET ((SCM_UNPACK(a) ^ SCM_UNPACK(b)) | \ | |
582 | (SCM_UNPACK(b) ^ SCM_UNPACK(c)) | \ | |
583 | (SCM_UNPACK(c) ^ SCM_UNPACK(d)))) | |
584 | #endif /* BUILDING_LIBGUILE */ | |
5065b40d | 585 | \f |
e17d318f | 586 | |
904a077d | 587 | /* Dispatching aids: |
0f2d19dd | 588 | |
904a077d MV |
589 | When switching on SCM_TYP7 of a SCM value, use these fake case |
590 | labels to catch types that use fewer than 7 bits for tagging. */ | |
0f2d19dd | 591 | |
8ce94504 | 592 | /* For cons pairs with immediate values in the CAR |
0f2d19dd JB |
593 | */ |
594 | ||
6375e040 DH |
595 | #define scm_tcs_cons_imcar \ |
596 | scm_tc2_int + 0: case scm_tc2_int + 4: case scm_tc3_imm24 + 0:\ | |
597 | case scm_tc2_int + 8: case scm_tc2_int + 12: case scm_tc3_imm24 + 8:\ | |
598 | case scm_tc2_int + 16: case scm_tc2_int + 20: case scm_tc3_imm24 + 16:\ | |
599 | case scm_tc2_int + 24: case scm_tc2_int + 28: case scm_tc3_imm24 + 24:\ | |
600 | case scm_tc2_int + 32: case scm_tc2_int + 36: case scm_tc3_imm24 + 32:\ | |
601 | case scm_tc2_int + 40: case scm_tc2_int + 44: case scm_tc3_imm24 + 40:\ | |
602 | case scm_tc2_int + 48: case scm_tc2_int + 52: case scm_tc3_imm24 + 48:\ | |
603 | case scm_tc2_int + 56: case scm_tc2_int + 60: case scm_tc3_imm24 + 56:\ | |
604 | case scm_tc2_int + 64: case scm_tc2_int + 68: case scm_tc3_imm24 + 64:\ | |
605 | case scm_tc2_int + 72: case scm_tc2_int + 76: case scm_tc3_imm24 + 72:\ | |
606 | case scm_tc2_int + 80: case scm_tc2_int + 84: case scm_tc3_imm24 + 80:\ | |
607 | case scm_tc2_int + 88: case scm_tc2_int + 92: case scm_tc3_imm24 + 88:\ | |
608 | case scm_tc2_int + 96: case scm_tc2_int + 100: case scm_tc3_imm24 + 96:\ | |
609 | case scm_tc2_int + 104: case scm_tc2_int + 108: case scm_tc3_imm24 + 104:\ | |
610 | case scm_tc2_int + 112: case scm_tc2_int + 116: case scm_tc3_imm24 + 112:\ | |
611 | case scm_tc2_int + 120: case scm_tc2_int + 124: case scm_tc3_imm24 + 120 | |
0f2d19dd JB |
612 | |
613 | /* For cons pairs with non-immediate values in the SCM_CAR | |
614 | */ | |
6375e040 DH |
615 | #define scm_tcs_cons_nimcar \ |
616 | scm_tc3_cons + 0:\ | |
617 | case scm_tc3_cons + 8:\ | |
618 | case scm_tc3_cons + 16:\ | |
619 | case scm_tc3_cons + 24:\ | |
620 | case scm_tc3_cons + 32:\ | |
621 | case scm_tc3_cons + 40:\ | |
622 | case scm_tc3_cons + 48:\ | |
623 | case scm_tc3_cons + 56:\ | |
624 | case scm_tc3_cons + 64:\ | |
625 | case scm_tc3_cons + 72:\ | |
626 | case scm_tc3_cons + 80:\ | |
627 | case scm_tc3_cons + 88:\ | |
628 | case scm_tc3_cons + 96:\ | |
629 | case scm_tc3_cons + 104:\ | |
630 | case scm_tc3_cons + 112:\ | |
631 | case scm_tc3_cons + 120 | |
0f2d19dd | 632 | |
904a077d | 633 | /* For structs |
0f2d19dd | 634 | */ |
6375e040 DH |
635 | #define scm_tcs_struct \ |
636 | scm_tc3_struct + 0:\ | |
637 | case scm_tc3_struct + 8:\ | |
638 | case scm_tc3_struct + 16:\ | |
639 | case scm_tc3_struct + 24:\ | |
640 | case scm_tc3_struct + 32:\ | |
641 | case scm_tc3_struct + 40:\ | |
642 | case scm_tc3_struct + 48:\ | |
643 | case scm_tc3_struct + 56:\ | |
644 | case scm_tc3_struct + 64:\ | |
645 | case scm_tc3_struct + 72:\ | |
646 | case scm_tc3_struct + 80:\ | |
647 | case scm_tc3_struct + 88:\ | |
648 | case scm_tc3_struct + 96:\ | |
649 | case scm_tc3_struct + 104:\ | |
650 | case scm_tc3_struct + 112:\ | |
651 | case scm_tc3_struct + 120 | |
0f2d19dd | 652 | |
f5f2dcff DH |
653 | \f |
654 | ||
8c494e99 | 655 | #if (SCM_ENABLE_DEPRECATED == 1) |
22a52da1 | 656 | |
228a24ef | 657 | #define SCM_CELLP(x) (((sizeof (scm_t_cell) - 1) & SCM_UNPACK (x)) == 0) |
8c494e99 | 658 | #define SCM_NCELLP(x) (!SCM_CELLP (x)) |
28b06554 | 659 | |
8c494e99 | 660 | #endif |
f5f2dcff | 661 | |
22a52da1 | 662 | #endif /* SCM_TAGS_H */ |
89e00824 ML |
663 | |
664 | /* | |
665 | Local Variables: | |
666 | c-file-style: "gnu" | |
667 | End: | |
668 | */ |