1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481
|
/* heap.c: Glulxe code related to the dynamic allocation heap.
Designed by Andrew Plotkin <erkyrath@eblong.com>
http://eblong.com/zarf/glulx/index.html
*/
#include "glk.h"
#include "glulxe.h"
typedef struct heapblock_struct {
glui32 addr;
glui32 len;
int isfree;
struct heapblock_struct *next;
struct heapblock_struct *prev;
} heapblock_t;
static glui32 heap_start = 0; /* zero for inactive heap */
static int alloc_count = 0;
/* The heap_head/heap_tail is a doubly-linked list of blocks, both
free and allocated. It is kept in address order. It should be
complete -- that is, the first block starts at heap_start, and each
block ends at the beginning of the next block, until the last one,
which ends at endmem.
(Heap_start is never the same as end_mem; if there is no heap space,
then the heap is inactive and heap_start is zero.)
Adjacent free blocks may be merged at heap_alloc() time.
### To make alloc more efficient, we could keep a separate
free-list. To make free more efficient, we could keep a hash
table of allocations.
*/
static heapblock_t *heap_head = NULL;
static heapblock_t *heap_tail = NULL;
/* heap_clear():
Set the heap state to inactive, and free the block lists. This is
called when the game starts or restarts.
*/
void heap_clear()
{
while (heap_head) {
heapblock_t *blo = heap_head;
heap_head = blo->next;
blo->next = NULL;
blo->prev = NULL;
glulx_free(blo);
}
heap_tail = NULL;
if (heap_start) {
glui32 res = change_memsize(heap_start, TRUE);
if (res)
fatal_error_i("Unable to revert memory size when deactivating heap.",
heap_start);
}
heap_start = 0;
alloc_count = 0;
/* heap_sanity_check(); */
}
/* heap_is_active():
Returns whether the heap is active.
*/
int heap_is_active() {
return (heap_start != 0);
}
/* heap_get_start():
Returns the start address of the heap, or 0 if the heap is not active.
*/
glui32 heap_get_start() {
return heap_start;
}
/* heap_alloc():
Allocate a block. If necessary, activate the heap and/or extend memory.
This may not be available at all; #define FIXED_MEMSIZE if you want
the interpreter to unconditionally refuse.
Returns the memory address of the block, or 0 if the operation failed.
*/
glui32 heap_alloc(glui32 len)
{
heapblock_t *blo, *newblo;
#ifdef FIXED_MEMSIZE
return 0;
#else /* FIXED_MEMSIZE */
if (len <= 0)
fatal_error("Heap allocation length must be positive.");
blo = heap_head;
while (blo) {
if (blo->isfree && blo->len >= len)
break;
if (!blo->isfree) {
blo = blo->next;
continue;
}
if (!blo->next || !blo->next->isfree) {
blo = blo->next;
continue;
}
/* This is a free block, but the next block in the list is also
free, so we "advance" by merging rather than by going to
blo->next. */
newblo = blo->next;
blo->len += newblo->len;
if (newblo->next) {
blo->next = newblo->next;
newblo->next->prev = blo;
}
else {
blo->next = NULL;
heap_tail = blo;
}
newblo->next = NULL;
newblo->prev = NULL;
glulx_free(newblo);
newblo = NULL;
continue;
}
if (!blo) {
/* No free area is visible on the list. Try extending memory. How
much? Double the heap size, or by 256 bytes, or by the memory
length requested -- whichever is greatest. */
glui32 res;
glui32 extension;
glui32 oldendmem = endmem;
extension = 0;
if (heap_start)
extension = endmem - heap_start;
if (extension < len)
extension = len;
if (extension < 256)
extension = 256;
/* And it must be rounded up to a multiple of 256. */
extension = (extension + 0xFF) & (~(glui32)0xFF);
res = change_memsize(endmem+extension, TRUE);
if (res)
return 0;
/* If we just started the heap, note that. */
if (heap_start == 0)
heap_start = oldendmem;
if (heap_tail && heap_tail->isfree) {
/* Append the new space to the last block. */
blo = heap_tail;
blo->len += extension;
}
else {
/* Append the new space to the block list, as a new block. */
newblo = glulx_malloc(sizeof(heapblock_t));
if (!newblo)
fatal_error("Unable to allocate record for heap block.");
newblo->addr = oldendmem;
newblo->len = extension;
newblo->isfree = TRUE;
newblo->next = NULL;
newblo->prev = NULL;
if (!heap_tail) {
heap_head = newblo;
heap_tail = newblo;
}
else {
blo = heap_tail;
heap_tail = newblo;
blo->next = newblo;
newblo->prev = blo;
}
blo = newblo;
newblo = NULL;
}
/* and continue forwards, using this new block (blo). */
}
/* Something strange happened. */
if (!blo || !blo->isfree || blo->len < len)
return 0;
/* We now have a free block of size len or longer. */
if (blo->len == len) {
blo->isfree = FALSE;
}
else {
newblo = glulx_malloc(sizeof(heapblock_t));
if (!newblo)
fatal_error("Unable to allocate record for heap block.");
newblo->isfree = TRUE;
newblo->addr = blo->addr + len;
newblo->len = blo->len - len;
blo->len = len;
blo->isfree = FALSE;
newblo->next = blo->next;
if (newblo->next)
newblo->next->prev = newblo;
newblo->prev = blo;
blo->next = newblo;
if (heap_tail == blo)
heap_tail = newblo;
}
alloc_count++;
/* heap_sanity_check(); */
return blo->addr;
#endif /* FIXED_MEMSIZE */
}
/* heap_free():
Free a heap block. If necessary, deactivate the heap.
*/
void heap_free(glui32 addr)
{
heapblock_t *blo;
for (blo = heap_head; blo; blo = blo->next) {
if (blo->addr == addr)
break;
};
if (!blo || blo->isfree)
fatal_error_i("Attempt to free unallocated address from heap.", addr);
blo->isfree = TRUE;
alloc_count--;
if (alloc_count <= 0) {
heap_clear();
}
/* heap_sanity_check(); */
}
/* heap_get_summary():
Create an array of words, in the VM serialization format:
heap_start
alloc_count
addr of first block
len of first block
...
(Note that these are glui32 values -- native byte ordering. Also,
the blocks will be in address order, which is a stricter guarantee
than the VM specifies; that'll help in heap_apply_summary().)
If the heap is inactive, store NULL. Return 0 for success;
otherwise, the operation failed.
The array returned in summary must be freed with glulx_free() after
the caller uses it.
*/
int heap_get_summary(glui32 *valcount, glui32 **summary)
{
glui32 *arr, len, pos;
heapblock_t *blo;
*valcount = 0;
*summary = NULL;
if (heap_start == 0)
return 0;
len = 2 + 2*alloc_count;
arr = glulx_malloc(len * sizeof(glui32));
if (!arr)
return 1;
pos = 0;
arr[pos++] = heap_start;
arr[pos++] = alloc_count;
for (blo = heap_head; blo; blo = blo->next) {
if (blo->isfree)
continue;
arr[pos++] = blo->addr;
arr[pos++] = blo->len;
}
if (pos != len)
fatal_error("Wrong number of active blocks in heap");
*valcount = len;
*summary = arr;
return 0;
}
/* heap_apply_summary():
Given an array of words in the above format, set up the heap to
contain it. As noted above, the caller must ensure that the blocks
are in address order. When this is called, the heap must be
inactive.
Return 0 for success. Otherwise the operation failed (and, most
likely, caused a fatal error).
*/
int heap_apply_summary(glui32 valcount, glui32 *summary)
{
glui32 lx, jx, lastend;
if (heap_start)
fatal_error("Heap active when heap_apply_summary called");
if (valcount == 0 || summary == NULL)
return 0;
if (valcount == 2 && summary[0] == 0 && summary[1] == 0)
return 0;
#ifdef FIXED_MEMSIZE
return 1;
#else /* FIXED_MEMSIZE */
lx = 0;
heap_start = summary[lx++];
alloc_count = summary[lx++];
for (jx=lx; jx+2<valcount; jx+=2) {
if (summary[jx] >= summary[jx+2])
fatal_error("Heap block summary is out of order.");
}
lastend = heap_start;
while (lx < valcount || lastend < endmem) {
heapblock_t *blo;
blo = glulx_malloc(sizeof(heapblock_t));
if (!blo)
fatal_error("Unable to allocate record for heap block.");
if (lx >= valcount) {
blo->addr = lastend;
blo->len = endmem - lastend;
blo->isfree = TRUE;
}
else {
if (lastend < summary[lx]) {
blo->addr = lastend;
blo->len = summary[lx] - lastend;
blo->isfree = TRUE;
}
else {
blo->addr = summary[lx++];
blo->len = summary[lx++];
blo->isfree = FALSE;
}
}
blo->prev = NULL;
blo->next = NULL;
if (!heap_head) {
heap_head = blo;
heap_tail = blo;
}
else {
heap_tail->next = blo;
blo->prev = heap_tail;
heap_tail = blo;
}
lastend = blo->addr + blo->len;
}
/* heap_sanity_check(); */
return 0;
#endif /* FIXED_MEMSIZE */
}
#if 0
#include <stdio.h>
static void heap_dump(void);
/* heap_dump():
Print out the heap list (using printf). This exists for debugging,
which is why it's ifdeffed out.
*/
static void heap_dump()
{
heapblock_t *blo;
if (heap_start == 0) {
printf("# Heap is inactive.\n");
return;
}
printf("# Heap active: %d outstanding blocks\n", alloc_count);
printf("# Heap start: %ld\n", heap_start);
for (blo = heap_head; blo; blo = blo->next) {
printf("# %s at %ld..%ld, len %ld\n",
(blo->isfree ? " free" : "*used"),
blo->addr, blo->addr+blo->len, blo->len);
}
printf("# Heap end: %ld\n", endmem);
}
/* heap_sanity_check():
Check the validity of the heap. Throw a fatal error if anything is
wrong.
*/
void heap_sanity_check()
{
heapblock_t *blo, *last;
int livecount;
heap_dump();
if (heap_start == 0) {
if (heap_head || heap_tail)
fatal_error("Heap sanity: nonempty list when heap is inactive.");
if (alloc_count)
fatal_error_i("Heap sanity: outstanding blocks when heap is inactive.",
alloc_count);
return;
}
#ifdef FIXED_MEMSIZE
fatal_error("Heap sanity: heap is active, but interpreter is compiled with no allocation.");
#endif /* FIXED_MEMSIZE */
/* When the heap is active there may, briefly, be no heapblocks on the
list. */
last = NULL;
livecount = 0;
for (blo = heap_head; blo; last = blo, blo = blo->next) {
glui32 lastend;
if (blo->prev != last)
fatal_error("Heap sanity: prev pointer mismatch.");
if (!last)
lastend = heap_start;
else
lastend = last->addr + last->len;
if (lastend != blo->addr)
fatal_error("Heap sanity: addr+len mismatch.");
if (!blo->isfree)
livecount++;
}
if (!last) {
if (heap_start != endmem)
fatal_error_i("Heap sanity: empty list, but endmem is not heap start.",
heap_start);
if (heap_tail)
fatal_error("Heap sanity: empty list, but heap tail exists.");
}
else {
if (last->addr + last->len != endmem)
fatal_error_i("Heap sanity: last block does not end at endmem.",
last->addr + last->len);
if (last != heap_tail)
fatal_error("Heap sanity: heap tail points wrong.");
}
if (livecount != alloc_count)
fatal_error_i("Heap sanity: wrong number of live blocks.", livecount);
}
#endif /* 0 */
|