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dcfdbac7 | 1 | /* Block-relocating memory allocator. |
956ace37 | 2 | Copyright (C) 1992 Free Software Foundation, Inc. |
dcfdbac7 JB |
3 | |
4 | This file is part of GNU Emacs. | |
5 | ||
6 | GNU Emacs is free software; you can redistribute it and/or modify | |
7 | it under the terms of the GNU General Public License as published by | |
8 | the Free Software Foundation; either version 1, or (at your option) | |
9 | any later version. | |
10 | ||
11 | GNU Emacs is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | GNU General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
17 | along with GNU Emacs; see the file COPYING. If not, write to | |
18 | the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */ | |
19 | ||
20 | /* NOTES: | |
21 | ||
22 | Only relocate the blocs neccessary for SIZE in r_alloc_sbrk, | |
23 | rather than all of them. This means allowing for a possible | |
24 | hole between the first bloc and the end of malloc storage. */ | |
25 | ||
26 | #include "config.h" | |
956ace37 | 27 | #include "lisp.h" /* Needed for VALBITS. */ |
dcfdbac7 JB |
28 | #undef NULL |
29 | #include "mem_limits.h" | |
4746118a | 30 | #include "getpagesize.h" |
dcfdbac7 JB |
31 | |
32 | #define NIL ((POINTER) 0) | |
33 | ||
34 | \f | |
956ace37 JB |
35 | /* Declarations for working with the malloc, ralloc, and system breaks. */ |
36 | ||
dcfdbac7 JB |
37 | /* System call to set the break value. */ |
38 | extern POINTER sbrk (); | |
39 | ||
40 | /* The break value, as seen by malloc (). */ | |
41 | static POINTER virtual_break_value; | |
42 | ||
43 | /* The break value, viewed by the relocatable blocs. */ | |
44 | static POINTER break_value; | |
45 | ||
46 | /* The REAL (i.e., page aligned) break value of the process. */ | |
47 | static POINTER page_break_value; | |
48 | ||
49 | /* Macros for rounding. Note that rounding to any value is possible | |
50 | by changing the definition of PAGE. */ | |
51 | #define PAGE (getpagesize ()) | |
52 | #define ALIGNED(addr) (((unsigned int) (addr) & (PAGE - 1)) == 0) | |
53 | #define ROUNDUP(size) (((unsigned int) (size) + PAGE) & ~(PAGE - 1)) | |
54 | #define ROUND_TO_PAGE(addr) (addr & (~(PAGE - 1))) | |
dcfdbac7 | 55 | \f |
956ace37 JB |
56 | /* Managing "almost out of memory" warnings. */ |
57 | ||
dcfdbac7 JB |
58 | /* Level of warnings issued. */ |
59 | static int warnlevel; | |
60 | ||
61 | /* Function to call to issue a warning; | |
62 | 0 means don't issue them. */ | |
63 | static void (*warnfunction) (); | |
64 | ||
65 | static void | |
66 | check_memory_limits (address) | |
67 | POINTER address; | |
68 | { | |
69 | SIZE data_size = address - data_space_start; | |
70 | ||
71 | switch (warnlevel) | |
72 | { | |
73 | case 0: | |
74 | if (data_size > (lim_data / 4) * 3) | |
75 | { | |
76 | warnlevel++; | |
77 | (*warnfunction) ("Warning: past 75% of memory limit"); | |
78 | } | |
79 | break; | |
80 | ||
81 | case 1: | |
82 | if (data_size > (lim_data / 20) * 17) | |
83 | { | |
84 | warnlevel++; | |
85 | (*warnfunction) ("Warning: past 85% of memory limit"); | |
86 | } | |
87 | break; | |
88 | ||
89 | case 2: | |
90 | if (data_size > (lim_data / 20) * 19) | |
91 | { | |
92 | warnlevel++; | |
93 | (*warnfunction) ("Warning: past 95% of memory limit"); | |
94 | } | |
95 | break; | |
96 | ||
97 | default: | |
98 | (*warnfunction) ("Warning: past acceptable memory limits"); | |
99 | break; | |
100 | } | |
101 | ||
102 | if (EXCEEDS_ELISP_PTR (address)) | |
265a9e55 | 103 | memory_full (); |
dcfdbac7 JB |
104 | } |
105 | \f | |
956ace37 JB |
106 | /* Functions to get and return memory from the system. */ |
107 | ||
dcfdbac7 JB |
108 | /* Obtain SIZE bytes of space. If enough space is not presently available |
109 | in our process reserve, (i.e., (page_break_value - break_value)), | |
110 | this means getting more page-aligned space from the system. */ | |
111 | ||
112 | static void | |
113 | obtain (size) | |
114 | SIZE size; | |
115 | { | |
116 | SIZE already_available = page_break_value - break_value; | |
117 | ||
118 | if (already_available < size) | |
119 | { | |
956ace37 | 120 | SIZE get = ROUNDUP (size - already_available); |
dcfdbac7 JB |
121 | |
122 | if (warnfunction) | |
123 | check_memory_limits (page_break_value); | |
124 | ||
125 | if (((int) sbrk (get)) < 0) | |
126 | abort (); | |
127 | ||
128 | page_break_value += get; | |
129 | } | |
130 | ||
131 | break_value += size; | |
132 | } | |
133 | ||
134 | /* Obtain SIZE bytes of space and return a pointer to the new area. */ | |
135 | ||
136 | static POINTER | |
137 | get_more_space (size) | |
138 | SIZE size; | |
139 | { | |
140 | POINTER ptr = break_value; | |
141 | obtain (size); | |
142 | return ptr; | |
143 | } | |
144 | ||
145 | /* Note that SIZE bytes of space have been relinquished by the process. | |
956ace37 | 146 | If SIZE is more than a page, return the space to the system. */ |
dcfdbac7 JB |
147 | |
148 | static void | |
149 | relinquish (size) | |
150 | SIZE size; | |
151 | { | |
956ace37 | 152 | POINTER new_page_break; |
dcfdbac7 | 153 | |
956ace37 JB |
154 | break_value -= size; |
155 | new_page_break = (POINTER) ROUNDUP (break_value); | |
156 | ||
157 | if (new_page_break != page_break_value) | |
dcfdbac7 | 158 | { |
956ace37 JB |
159 | if (((int) (sbrk ((char *) new_page_break |
160 | - (char *) page_break_value))) < 0) | |
dcfdbac7 JB |
161 | abort (); |
162 | ||
956ace37 | 163 | page_break_value = new_page_break; |
dcfdbac7 JB |
164 | } |
165 | ||
956ace37 JB |
166 | /* Zero the space from the end of the "official" break to the actual |
167 | break, so that bugs show up faster. */ | |
168 | bzero (break_value, ((char *) page_break_value - (char *) break_value)); | |
dcfdbac7 JB |
169 | } |
170 | \f | |
956ace37 JB |
171 | /* The meat - allocating, freeing, and relocating blocs. */ |
172 | ||
173 | /* These structures are allocated in the malloc arena. | |
174 | The linked list is kept in order of increasing '.data' members. | |
175 | The data blocks abut each other; if b->next is non-nil, then | |
176 | b->data + b->size == b->next->data. */ | |
dcfdbac7 JB |
177 | typedef struct bp |
178 | { | |
179 | struct bp *next; | |
180 | struct bp *prev; | |
181 | POINTER *variable; | |
182 | POINTER data; | |
183 | SIZE size; | |
184 | } *bloc_ptr; | |
185 | ||
186 | #define NIL_BLOC ((bloc_ptr) 0) | |
187 | #define BLOC_PTR_SIZE (sizeof (struct bp)) | |
188 | ||
189 | /* Head and tail of the list of relocatable blocs. */ | |
190 | static bloc_ptr first_bloc, last_bloc; | |
191 | ||
956ace37 JB |
192 | /* Declared in dispnew.c, this version doesn't screw up if regions |
193 | overlap. */ | |
dcfdbac7 JB |
194 | extern void safe_bcopy (); |
195 | ||
956ace37 | 196 | /* Find the bloc referenced by the address in PTR. Returns a pointer |
dcfdbac7 JB |
197 | to that block. */ |
198 | ||
199 | static bloc_ptr | |
200 | find_bloc (ptr) | |
201 | POINTER *ptr; | |
202 | { | |
203 | register bloc_ptr p = first_bloc; | |
204 | ||
205 | while (p != NIL_BLOC) | |
206 | { | |
207 | if (p->variable == ptr && p->data == *ptr) | |
208 | return p; | |
209 | ||
210 | p = p->next; | |
211 | } | |
212 | ||
213 | return p; | |
214 | } | |
215 | ||
216 | /* Allocate a bloc of SIZE bytes and append it to the chain of blocs. | |
217 | Returns a pointer to the new bloc. */ | |
218 | ||
219 | static bloc_ptr | |
220 | get_bloc (size) | |
221 | SIZE size; | |
222 | { | |
223 | register bloc_ptr new_bloc = (bloc_ptr) malloc (BLOC_PTR_SIZE); | |
224 | ||
225 | new_bloc->data = get_more_space (size); | |
226 | new_bloc->size = size; | |
227 | new_bloc->next = NIL_BLOC; | |
228 | new_bloc->variable = NIL; | |
229 | ||
230 | if (first_bloc) | |
231 | { | |
232 | new_bloc->prev = last_bloc; | |
233 | last_bloc->next = new_bloc; | |
234 | last_bloc = new_bloc; | |
235 | } | |
236 | else | |
237 | { | |
238 | first_bloc = last_bloc = new_bloc; | |
239 | new_bloc->prev = NIL_BLOC; | |
240 | } | |
241 | ||
242 | return new_bloc; | |
243 | } | |
244 | ||
245 | /* Relocate all blocs from BLOC on upward in the list to the zone | |
246 | indicated by ADDRESS. Direction of relocation is determined by | |
247 | the position of ADDRESS relative to BLOC->data. | |
248 | ||
249 | Note that ordering of blocs is not affected by this function. */ | |
250 | ||
251 | static void | |
252 | relocate_some_blocs (bloc, address) | |
253 | bloc_ptr bloc; | |
254 | POINTER address; | |
255 | { | |
256 | register bloc_ptr b; | |
257 | POINTER data_zone = bloc->data; | |
258 | register SIZE data_zone_size = 0; | |
259 | register SIZE offset = bloc->data - address; | |
260 | POINTER new_data_zone = data_zone - offset; | |
261 | ||
262 | for (b = bloc; b != NIL_BLOC; b = b->next) | |
263 | { | |
264 | data_zone_size += b->size; | |
265 | b->data -= offset; | |
266 | *b->variable = b->data; | |
267 | } | |
268 | ||
269 | safe_bcopy (data_zone, new_data_zone, data_zone_size); | |
270 | } | |
271 | ||
272 | /* Free BLOC from the chain of blocs, relocating any blocs above it | |
273 | and returning BLOC->size bytes to the free area. */ | |
274 | ||
275 | static void | |
276 | free_bloc (bloc) | |
277 | bloc_ptr bloc; | |
278 | { | |
279 | if (bloc == first_bloc && bloc == last_bloc) | |
280 | { | |
281 | first_bloc = last_bloc = NIL_BLOC; | |
282 | } | |
283 | else if (bloc == last_bloc) | |
284 | { | |
285 | last_bloc = bloc->prev; | |
286 | last_bloc->next = NIL_BLOC; | |
287 | } | |
288 | else if (bloc == first_bloc) | |
289 | { | |
290 | first_bloc = bloc->next; | |
291 | first_bloc->prev = NIL_BLOC; | |
292 | relocate_some_blocs (bloc->next, bloc->data); | |
293 | } | |
294 | else | |
295 | { | |
296 | bloc->next->prev = bloc->prev; | |
297 | bloc->prev->next = bloc->next; | |
298 | relocate_some_blocs (bloc->next, bloc->data); | |
299 | } | |
300 | ||
301 | relinquish (bloc->size); | |
302 | free (bloc); | |
303 | } | |
304 | \f | |
956ace37 JB |
305 | /* Interface routines. */ |
306 | ||
dcfdbac7 JB |
307 | static int use_relocatable_buffers; |
308 | ||
309 | /* Obtain SIZE bytes of storage from the free pool, or the system, | |
310 | as neccessary. If relocatable blocs are in use, this means | |
311 | relocating them. */ | |
312 | ||
313 | POINTER | |
314 | r_alloc_sbrk (size) | |
315 | long size; | |
316 | { | |
317 | POINTER ptr; | |
318 | ||
319 | if (! use_relocatable_buffers) | |
320 | return sbrk (size); | |
321 | ||
322 | if (size > 0) | |
323 | { | |
324 | obtain (size); | |
325 | if (first_bloc) | |
326 | { | |
327 | relocate_some_blocs (first_bloc, first_bloc->data + size); | |
956ace37 JB |
328 | |
329 | /* Zero out the space we just allocated, to help catch bugs | |
330 | quickly. */ | |
dcfdbac7 JB |
331 | bzero (virtual_break_value, size); |
332 | } | |
333 | } | |
334 | else if (size < 0) | |
335 | { | |
336 | if (first_bloc) | |
337 | relocate_some_blocs (first_bloc, first_bloc->data + size); | |
338 | relinquish (- size); | |
339 | } | |
340 | ||
341 | ptr = virtual_break_value; | |
342 | virtual_break_value += size; | |
343 | return ptr; | |
344 | } | |
345 | ||
346 | /* Allocate a relocatable bloc of storage of size SIZE. A pointer to | |
347 | the data is returned in *PTR. PTR is thus the address of some variable | |
348 | which will use the data area. */ | |
349 | ||
350 | POINTER | |
351 | r_alloc (ptr, size) | |
352 | POINTER *ptr; | |
353 | SIZE size; | |
354 | { | |
355 | register bloc_ptr new_bloc; | |
356 | ||
dcfdbac7 JB |
357 | new_bloc = get_bloc (size); |
358 | new_bloc->variable = ptr; | |
359 | *ptr = new_bloc->data; | |
dcfdbac7 JB |
360 | |
361 | return *ptr; | |
362 | } | |
363 | ||
364 | /* Free a bloc of relocatable storage whose data is pointed to by PTR. */ | |
365 | ||
366 | void | |
367 | r_alloc_free (ptr) | |
368 | register POINTER *ptr; | |
369 | { | |
370 | register bloc_ptr dead_bloc; | |
371 | ||
dcfdbac7 JB |
372 | dead_bloc = find_bloc (ptr); |
373 | if (dead_bloc == NIL_BLOC) | |
374 | abort (); | |
375 | ||
376 | free_bloc (dead_bloc); | |
dcfdbac7 JB |
377 | } |
378 | ||
379 | /* Given a pointer at address PTR to relocatable data, resize it | |
380 | to SIZE. This is done by obtaining a new block and freeing the | |
381 | old, unless SIZE is less than or equal to the current bloc size, | |
382 | in which case nothing happens and the current value is returned. | |
383 | ||
384 | The contents of PTR is changed to reflect the new bloc, and this | |
385 | value is returned. */ | |
386 | ||
387 | POINTER | |
388 | r_re_alloc (ptr, size) | |
389 | POINTER *ptr; | |
390 | SIZE size; | |
391 | { | |
392 | register bloc_ptr old_bloc, new_bloc; | |
393 | ||
dcfdbac7 JB |
394 | old_bloc = find_bloc (ptr); |
395 | if (old_bloc == NIL_BLOC) | |
396 | abort (); | |
397 | ||
398 | if (size <= old_bloc->size) | |
956ace37 | 399 | /* Wouldn't it be useful to actually resize the bloc here? */ |
dcfdbac7 JB |
400 | return *ptr; |
401 | ||
402 | new_bloc = get_bloc (size); | |
403 | new_bloc->variable = ptr; | |
404 | safe_bcopy (old_bloc->data, new_bloc->data, old_bloc->size); | |
405 | *ptr = new_bloc->data; | |
406 | ||
407 | free_bloc (old_bloc); | |
dcfdbac7 JB |
408 | |
409 | return *ptr; | |
410 | } | |
411 | \f | |
412 | /* The hook `malloc' uses for the function which gets more space | |
413 | from the system. */ | |
414 | extern POINTER (*__morecore) (); | |
415 | ||
956ace37 JB |
416 | /* A flag to indicate whether we have initialized ralloc yet. For |
417 | Emacs's sake, please do not make this local to malloc_init; on some | |
418 | machines, the dumping procedure makes all static variables | |
419 | read-only. On these machines, the word static is #defined to be | |
420 | the empty string, meaning that malloc_initialized becomes an | |
421 | automatic variable, and loses its value each time Emacs is started | |
422 | up. */ | |
423 | static int malloc_initialized = 0; | |
424 | ||
dcfdbac7 JB |
425 | /* Intialize various things for memory allocation. */ |
426 | ||
427 | void | |
428 | malloc_init (start, warn_func) | |
429 | POINTER start; | |
430 | void (*warn_func) (); | |
431 | { | |
dcfdbac7 JB |
432 | if (start) |
433 | data_space_start = start; | |
434 | ||
435 | if (malloc_initialized) | |
436 | return; | |
437 | ||
438 | malloc_initialized = 1; | |
439 | __morecore = r_alloc_sbrk; | |
440 | virtual_break_value = break_value = sbrk (0); | |
441 | page_break_value = (POINTER) ROUNDUP (break_value); | |
442 | bzero (break_value, (page_break_value - break_value)); | |
443 | use_relocatable_buffers = 1; | |
444 | ||
445 | lim_data = 0; | |
446 | warnlevel = 0; | |
447 | warnfunction = warn_func; | |
448 | ||
449 | get_lim_data (); | |
450 | } |