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
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
|
/*
* tclAlloc.c --
*
* This is a very fast storage allocator. It allocates blocks of a
* small number of different sizes, and keeps free lists of each size.
* Blocks that don't exactly fit are passed up to the next larger size.
* Blocks over a certain size are directly allocated from the system.
*
* Copyright (c) 1983 Regents of the University of California.
* Copyright (c) 1996-1997 Sun Microsystems, Inc.
*
* Portions contributed by Chris Kingsley, Jack Jansen and Ray Johnson.
*
* See the file "license.terms" for information on usage and redistribution
* of this file, and for a DISCLAIMER OF ALL WARRANTIES.
*
* RCS: @(#) $Id: tclAlloc.c,v 1.3.4.1 1999/03/04 00:58:46 stanton Exp $
*/
#include "tclInt.h"
#include "tclPort.h"
#ifndef USE_NATIVEMALLOC
#ifdef TCL_DEBUG
# define DEBUG
/* #define MSTATS */
# define RCHECK
#endif
typedef unsigned long caddr_t;
/*
* The overhead on a block is at least 4 bytes. When free, this space
* contains a pointer to the next free block, and the bottom two bits must
* be zero. When in use, the first byte is set to MAGIC, and the second
* byte is the size index. The remaining bytes are for alignment.
* If range checking is enabled then a second word holds the size of the
* requested block, less 1, rounded up to a multiple of sizeof(RMAGIC).
* The order of elements is critical: ov_magic must overlay the low order
* bits of ov_next, and ov_magic can not be a valid ov_next bit pattern.
*/
union overhead {
union overhead *ov_next; /* when free */
struct {
unsigned char ovu_magic0; /* magic number */
unsigned char ovu_index; /* bucket # */
unsigned char ovu_unused; /* unused */
unsigned char ovu_magic1; /* other magic number */
#ifdef RCHECK
unsigned short ovu_rmagic; /* range magic number */
unsigned long ovu_size; /* actual block size */
#endif
} ovu;
#define ov_magic0 ovu.ovu_magic0
#define ov_magic1 ovu.ovu_magic1
#define ov_index ovu.ovu_index
#define ov_rmagic ovu.ovu_rmagic
#define ov_size ovu.ovu_size
};
#define MAGIC 0xef /* magic # on accounting info */
#define RMAGIC 0x5555 /* magic # on range info */
#ifdef RCHECK
#define RSLOP sizeof (unsigned short)
#else
#define RSLOP 0
#endif
#define OVERHEAD (sizeof(union overhead) + RSLOP)
/*
* nextf[i] is the pointer to the next free block of size 2^(i+3). The
* smallest allocatable block is 8 bytes. The overhead information
* precedes the data area returned to the user.
*/
#define NBUCKETS 13
#define MAXMALLOC (1<<(NBUCKETS+2))
static union overhead *nextf[NBUCKETS];
#ifdef MSTATS
/*
* nmalloc[i] is the difference between the number of mallocs and frees
* for a given block size.
*/
static unsigned int nmalloc[NBUCKETS+1];
#include <stdio.h>
#endif
#if defined(DEBUG) || defined(RCHECK)
#define ASSERT(p) if (!(p)) panic(# p)
#define RANGE_ASSERT(p) if (!(p)) panic(# p)
#else
#define ASSERT(p)
#define RANGE_ASSERT(p)
#endif
/*
* Prototypes for functions used only in this file.
*/
static void MoreCore _ANSI_ARGS_((int bucket));
/*
*----------------------------------------------------------------------
*
* TclpAlloc --
*
* Allocate more memory.
*
* Results:
* None.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
char *
TclpAlloc(
unsigned int nbytes) /* Number of bytes to allocate. */
{
register union overhead *op;
register long bucket;
register unsigned amt;
/*
* First the simple case: we simple allocate big blocks directly
*/
if (nbytes + OVERHEAD >= MAXMALLOC) {
op = (union overhead *)TclpSysAlloc(nbytes+OVERHEAD, 0);
if (op == NULL) {
return NULL;
}
op->ov_magic0 = op->ov_magic1 = MAGIC;
op->ov_index = 0xff;
#ifdef MSTATS
nmalloc[NBUCKETS]++;
#endif
#ifdef RCHECK
/*
* Record allocated size of block and
* bound space with magic numbers.
*/
op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
op->ov_rmagic = RMAGIC;
*(unsigned short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
#endif
return (void *)(op+1);
}
/*
* Convert amount of memory requested into closest block size
* stored in hash buckets which satisfies request.
* Account for space used per block for accounting.
*/
#ifndef RCHECK
amt = 8; /* size of first bucket */
bucket = 0;
#else
amt = 16; /* size of first bucket */
bucket = 1;
#endif
while (nbytes + OVERHEAD > amt) {
amt <<= 1;
if (amt == 0) {
return (NULL);
}
bucket++;
}
ASSERT( bucket < NBUCKETS );
/*
* If nothing in hash bucket right now,
* request more memory from the system.
*/
if ((op = nextf[bucket]) == NULL) {
MoreCore(bucket);
if ((op = nextf[bucket]) == NULL) {
return (NULL);
}
}
/*
* Remove from linked list
*/
nextf[bucket] = op->ov_next;
op->ov_magic0 = op->ov_magic1 = MAGIC;
op->ov_index = (unsigned char) bucket;
#ifdef MSTATS
nmalloc[bucket]++;
#endif
#ifdef RCHECK
/*
* Record allocated size of block and
* bound space with magic numbers.
*/
op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
op->ov_rmagic = RMAGIC;
*(unsigned short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
#endif
return ((char *)(op + 1));
}
/*
*----------------------------------------------------------------------
*
* MoreCore --
*
* Allocate more memory to the indicated bucket.
*
* Results:
* None.
*
* Side effects:
* Attempts to get more memory from the system.
*
*----------------------------------------------------------------------
*/
static void
MoreCore(
int bucket) /* What bucket to allocat to. */
{
register union overhead *op;
register long sz; /* size of desired block */
long amt; /* amount to allocate */
int nblks; /* how many blocks we get */
/*
* sbrk_size <= 0 only for big, FLUFFY, requests (about
* 2^30 bytes on a VAX, I think) or for a negative arg.
*/
sz = 1 << (bucket + 3);
ASSERT(sz > 0);
amt = MAXMALLOC;
nblks = amt / sz;
ASSERT(nblks*sz == amt);
op = (union overhead *)TclpSysAlloc(amt, 1);
/* no more room! */
if (op == NULL) {
return;
}
/*
* Add new memory allocated to that on
* free list for this hash bucket.
*/
nextf[bucket] = op;
while (--nblks > 0) {
op->ov_next = (union overhead *)((caddr_t)op + sz);
op = (union overhead *)((caddr_t)op + sz);
}
op->ov_next = (union overhead *)NULL;
}
/*
*----------------------------------------------------------------------
*
* TclpFree --
*
* Free memory.
*
* Results:
* None.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
void
TclpFree(
char *cp) /* Pointer to memory to free. */
{
register long size;
register union overhead *op;
if (cp == NULL) {
return;
}
op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
ASSERT(op->ov_magic0 == MAGIC); /* make sure it was in use */
ASSERT(op->ov_magic1 == MAGIC);
if (op->ov_magic0 != MAGIC || op->ov_magic1 != MAGIC) {
return;
}
RANGE_ASSERT(op->ov_rmagic == RMAGIC);
RANGE_ASSERT(*(unsigned short *)((caddr_t)(op + 1) + op->ov_size) == RMAGIC);
size = op->ov_index;
if ( size == 0xff ) {
#ifdef MSTATS
nmalloc[NBUCKETS]--;
#endif
TclpSysFree(op);
return;
}
ASSERT(size < NBUCKETS);
op->ov_next = nextf[size]; /* also clobbers ov_magic */
nextf[size] = op;
#ifdef MSTATS
nmalloc[size]--;
#endif
}
/*
*----------------------------------------------------------------------
*
* TclpRealloc --
*
* Reallocate memory.
*
* Results:
* None.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
char *
TclpRealloc(
char *cp, /* Pointer to alloced block. */
unsigned int nbytes) /* New size of memory. */
{
int i;
union overhead *op;
int expensive;
unsigned long maxsize;
if (cp == NULL) {
return (TclpAlloc(nbytes));
}
op = (union overhead *)((caddr_t)cp - sizeof (union overhead));
ASSERT(op->ov_magic0 == MAGIC); /* make sure it was in use */
ASSERT(op->ov_magic1 == MAGIC);
if (op->ov_magic0 != MAGIC || op->ov_magic1 != MAGIC) {
return NULL;
}
RANGE_ASSERT(op->ov_rmagic == RMAGIC);
RANGE_ASSERT(*(unsigned short *)((caddr_t)(op + 1) + op->ov_size) == RMAGIC);
i = op->ov_index;
/*
* If the block isn't in a bin, just realloc it.
*/
if (i == 0xff) {
op = (union overhead *) TclpSysRealloc(op, nbytes+OVERHEAD);
if (op == NULL) {
return NULL;
}
#ifdef MSTATS
nmalloc[NBUCKETS]++;
#endif
#ifdef RCHECK
/*
* Record allocated size of block and update magic number bounds.
*/
op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
*(unsigned short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
#endif
return (char *)(op+1);
}
maxsize = 1 << (i+3);
expensive = 0;
if ( nbytes + OVERHEAD > maxsize ) {
expensive = 1;
} else if ( i > 0 && nbytes + OVERHEAD < (maxsize/2) ) {
expensive = 1;
}
if (expensive) {
void *newp;
newp = TclpAlloc(nbytes);
if ( newp == NULL ) {
return NULL;
}
maxsize -= OVERHEAD;
if ( maxsize < nbytes )
nbytes = maxsize;
memcpy((VOID *) newp, (VOID *) cp, (size_t) nbytes);
TclpFree(cp);
return newp;
}
/*
* Ok, we don't have to copy, it fits as-is
*/
#ifdef RCHECK
op->ov_size = (nbytes + RSLOP - 1) & ~(RSLOP - 1);
*(unsigned short *)((caddr_t)(op + 1) + op->ov_size) = RMAGIC;
#endif
return(cp);
}
/*
*----------------------------------------------------------------------
*
* mstats --
*
* Prints two lines of numbers, one showing the length of the
* free list for each size category, the second showing the
* number of mallocs - frees for each size category.
*
* Results:
* None.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
#ifdef MSTATS
void
mstats(
char *s) /* Where to write info. */
{
register int i, j;
register union overhead *p;
int totfree = 0,
totused = 0;
fprintf(stderr, "Memory allocation statistics %s\nTclpFree:\t", s);
for (i = 0; i < NBUCKETS; i++) {
for (j = 0, p = nextf[i]; p; p = p->ov_next, j++)
fprintf(stderr, " %d", j);
totfree += j * (1 << (i + 3));
}
fprintf(stderr, "\nused:\t");
for (i = 0; i < NBUCKETS; i++) {
fprintf(stderr, " %d", nmalloc[i]);
totused += nmalloc[i] * (1 << (i + 3));
}
fprintf(stderr, "\n\tTotal small in use: %d, total free: %d\n",
totused, totfree);
fprintf(stderr, "\n\tNumber of big (>%d) blocks in use: %d\n",
MAXMALLOC, nmalloc[NBUCKETS]);
}
#endif
#else /* USE_NATIVEMALLOC */
/*
*----------------------------------------------------------------------
*
* TclpAlloc --
*
* Allocate more memory.
*
* Results:
* None.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
char *
TclpAlloc(
unsigned int nbytes) /* Number of bytes to allocate. */
{
return (char*) malloc(nbytes);
}
/*
*----------------------------------------------------------------------
*
* TclpFree --
*
* Free memory.
*
* Results:
* None.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
void
TclpFree(
char *cp) /* Pointer to memory to free. */
{
free(cp);
return;
}
/*
*----------------------------------------------------------------------
*
* TclpRealloc --
*
* Reallocate memory.
*
* Results:
* None.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
char *
TclpRealloc(
char *cp, /* Pointer to alloced block. */
unsigned int nbytes) /* New size of memory. */
{
return (char*) realloc(cp, nbytes);
}
#endif /* USE_NATIVEMALLOC */
|