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1/* vmem.h
2 *
3 * (c) 1999 Microsoft Corporation. All rights reserved.
4 * Portions (c) 1999 ActiveState Tool Corp, http://www.ActiveState.com/
5 *
6 * You may distribute under the terms of either the GNU General Public
7 * License or the Artistic License, as specified in the README file.
8 *
9 *
10 * Knuth's boundary tag algorithm Vol #1, Page 440.
11 *
12 * Each block in the heap has tag words before and after it,
13 * TAG
14 * block
15 * TAG
16 * The size is stored in these tags as a long word, and includes the 8 bytes
17 * of overhead that the boundary tags consume. Blocks are allocated on long
18 * word boundaries, so the size is always multiples of long words. When the
19 * block is allocated, bit 0, (the tag bit), of the size is set to 1. When
20 * a block is freed, it is merged with adjacent free blocks, and the tag bit
21 * is set to 0.
22 *
23 * A linked list is used to manage the free list. The first two long words of
24 * the block contain double links. These links are only valid when the block
25 * is freed, therefore space needs to be reserved for them. Thus, the minimum
26 * block size (not counting the tags) is 8 bytes.
27 *
28 * Since memory allocation may occur on a single threaded, explict locks are
29 * provided.
30 *
31 */
32
33#ifndef ___VMEM_H_INC___
34#define ___VMEM_H_INC___
35
36const long lAllocStart = 0x00010000; /* start at 64K */
37const long minBlockSize = sizeof(void*)*2;
38const long sizeofTag = sizeof(long);
39const long blockOverhead = sizeofTag*2;
40const long minAllocSize = minBlockSize+blockOverhead;
41
42typedef BYTE* PBLOCK; /* pointer to a memory block */
43
44/*
45 * Macros for accessing hidden fields in a memory block:
46 *
47 * SIZE size of this block (tag bit 0 is 1 if block is allocated)
48 * PSIZE size of previous physical block
49 */
50
51#define SIZE(block) (*(ULONG*)(((PBLOCK)(block))-sizeofTag))
52#define PSIZE(block) (*(ULONG*)(((PBLOCK)(block))-(sizeofTag*2)))
53inline void SetTags(PBLOCK block, long size)
54{
55 SIZE(block) = size;
56 PSIZE(block+(size&~1)) = size;
57}
58
59/*
60 * Free list pointers
61 * PREV pointer to previous block
62 * NEXT pointer to next block
63 */
64
65#define PREV(block) (*(PBLOCK*)(block))
66#define NEXT(block) (*(PBLOCK*)((block)+sizeof(PBLOCK)))
67inline void SetLink(PBLOCK block, PBLOCK prev, PBLOCK next)
68{
69 PREV(block) = prev;
70 NEXT(block) = next;
71}
72inline void Unlink(PBLOCK p)
73{
74 PBLOCK next = NEXT(p);
75 PBLOCK prev = PREV(p);
76 NEXT(prev) = next;
77 PREV(next) = prev;
78}
79inline void AddToFreeList(PBLOCK block, PBLOCK pInList)
80{
81 PBLOCK next = NEXT(pInList);
82 NEXT(pInList) = block;
83 SetLink(block, pInList, next);
84 PREV(next) = block;
85}
86
87
88/* Macro for rounding up to the next sizeof(long) */
89#define ROUND_UP(n) (((ULONG)(n)+sizeof(long)-1)&~(sizeof(long)-1))
90#define ROUND_UP64K(n) (((ULONG)(n)+0x10000-1)&~(0x10000-1))
91#define ROUND_DOWN(n) ((ULONG)(n)&~(sizeof(long)-1))
92
93/*
94 * HeapRec - a list of all non-contiguous heap areas
95 *
96 * Each record in this array contains information about a non-contiguous heap area.
97 */
98
99const int maxHeaps = 64;
100const long lAllocMax = 0x80000000; /* max size of allocation */
101
102typedef struct _HeapRec
103{
104 PBLOCK base; /* base of heap area */
105 ULONG len; /* size of heap area */
106} HeapRec;
107
108
109class VMem
110{
111public:
112 VMem();
113 ~VMem();
114 virtual void* Malloc(size_t size);
115 virtual void* Realloc(void* pMem, size_t size);
116 virtual void Free(void* pMem);
117 virtual void GetLock(void);
118 virtual void FreeLock(void);
119 virtual int IsLocked(void);
120 virtual long Release(void);
121 virtual long AddRef(void);
122
123 inline BOOL CreateOk(void)
124 {
125 return m_hHeap != NULL;
126 };
127
128 void ReInit(void);
129
130protected:
131 void Init(void);
132 int Getmem(size_t size);
133 int HeapAdd(void* ptr, size_t size);
134 void* Expand(void* block, size_t size);
135 void WalkHeap(void);
136
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137 HANDLE m_hHeap; // memory heap for this script
138 char m_FreeDummy[minAllocSize]; // dummy free block
139 PBLOCK m_pFreeList; // pointer to first block on free list
140 PBLOCK m_pRover; // roving pointer into the free list
141 HeapRec m_heaps[maxHeaps]; // list of all non-contiguous heap areas
142 int m_nHeaps; // no. of heaps in m_heaps
143 long m_lAllocSize; // current alloc size
144 long m_lRefCount; // number of current users
145 CRITICAL_SECTION m_cs; // access lock
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146#ifdef _DEBUG_MEM
147 FILE* m_pLog;
148#endif
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149};
150
52cbf511 151// #define _DEBUG_MEM
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152#ifdef _DEBUG_MEM
153#define ASSERT(f) if(!(f)) DebugBreak();
154
155inline void MEMODS(char *str)
156{
157 OutputDebugString(str);
158 OutputDebugString("\n");
159}
160
161inline void MEMODSlx(char *str, long x)
162{
163 char szBuffer[512];
164 sprintf(szBuffer, "%s %lx\n", str, x);
165 OutputDebugString(szBuffer);
166}
167
168#define WALKHEAP() WalkHeap()
169#define WALKHEAPTRACE() m_pRover = NULL; WalkHeap()
170
171#else
172
173#define ASSERT(f)
174#define MEMODS(x)
175#define MEMODSlx(x, y)
176#define WALKHEAP()
177#define WALKHEAPTRACE()
178
179#endif
180
181
182VMem::VMem()
183{
184 m_lRefCount = 1;
185 BOOL bRet = (NULL != (m_hHeap = HeapCreate(HEAP_NO_SERIALIZE,
186 lAllocStart, /* initial size of heap */
187 0))); /* no upper limit on size of heap */
188 ASSERT(bRet);
189
190 InitializeCriticalSection(&m_cs);
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191#ifdef _DEBUG_MEM
192 m_pLog = 0;
193#endif
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194
195 Init();
196}
197
198VMem::~VMem(void)
199{
200 ASSERT(HeapValidate(m_hHeap, HEAP_NO_SERIALIZE, NULL));
201 WALKHEAPTRACE();
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202#ifdef _DEBUG_MEM
203 MemoryUsageMessage(NULL, 0, 0, 0);
204#endif
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205 DeleteCriticalSection(&m_cs);
206 BOOL bRet = HeapDestroy(m_hHeap);
207 ASSERT(bRet);
208}
209
210void VMem::ReInit(void)
211{
212 for(int index = 0; index < m_nHeaps; ++index)
213 HeapFree(m_hHeap, HEAP_NO_SERIALIZE, m_heaps[index].base);
214
215 Init();
216}
217
218void VMem::Init(void)
219{ /*
220 * Initialize the free list by placing a dummy zero-length block on it.
221 * Set the number of non-contiguous heaps to zero.
222 */
223 m_pFreeList = m_pRover = (PBLOCK)(&m_FreeDummy[minBlockSize]);
224 PSIZE(m_pFreeList) = SIZE(m_pFreeList) = 0;
225 PREV(m_pFreeList) = NEXT(m_pFreeList) = m_pFreeList;
226
227 m_nHeaps = 0;
228 m_lAllocSize = lAllocStart;
229}
230
231void* VMem::Malloc(size_t size)
232{
233 WALKHEAP();
234
235 /*
236 * Adjust the real size of the block to be a multiple of sizeof(long), and add
237 * the overhead for the boundary tags. Disallow negative or zero sizes.
238 */
239 size_t realsize = (size < blockOverhead) ? minAllocSize : (size_t)ROUND_UP(size) + minBlockSize;
240 if((int)realsize < minAllocSize || size == 0)
241 return NULL;
242
243 /*
244 * Start searching the free list at the rover. If we arrive back at rover without
245 * finding anything, allocate some memory from the heap and try again.
246 */
247 PBLOCK ptr = m_pRover; /* start searching at rover */
248 int loops = 2; /* allow two times through the loop */
249 for(;;) {
250 size_t lsize = SIZE(ptr);
251 ASSERT((lsize&1)==0);
252 /* is block big enough? */
253 if(lsize >= realsize) {
254 /* if the remainder is too small, don't bother splitting the block. */
255 size_t rem = lsize - realsize;
256 if(rem < minAllocSize) {
257 if(m_pRover == ptr)
258 m_pRover = NEXT(ptr);
259
260 /* Unlink the block from the free list. */
261 Unlink(ptr);
262 }
263 else {
264 /*
265 * split the block
266 * The remainder is big enough to split off into a new block.
267 * Use the end of the block, resize the beginning of the block
268 * no need to change the free list.
269 */
270 SetTags(ptr, rem);
271 ptr += SIZE(ptr);
272 lsize = realsize;
273 }
274 /* Set the boundary tags to mark it as allocated. */
275 SetTags(ptr, lsize | 1);
276 return ((void *)ptr);
277 }
278
279 /*
280 * This block was unsuitable. If we've gone through this list once already without
281 * finding anything, allocate some new memory from the heap and try again.
282 */
283 ptr = NEXT(ptr);
284 if(ptr == m_pRover) {
285 if(!(loops-- && Getmem(realsize))) {
286 return NULL;
287 }
288 ptr = m_pRover;
289 }
290 }
291}
292
293void* VMem::Realloc(void* block, size_t size)
294{
295 WALKHEAP();
296
297 /* if size is zero, free the block. */
298 if(size == 0) {
299 Free(block);
300 return (NULL);
301 }
302
303 /* if block pointer is NULL, do a Malloc(). */
304 if(block == NULL)
305 return Malloc(size);
306
307 /*
308 * Grow or shrink the block in place.
309 * if the block grows then the next block will be used if free
310 */
311 if(Expand(block, size) != NULL)
312 return block;
313
314 /*
315 * adjust the real size of the block to be a multiple of sizeof(long), and add the
316 * overhead for the boundary tags. Disallow negative or zero sizes.
317 */
318 size_t realsize = (size < blockOverhead) ? minAllocSize : (size_t)ROUND_UP(size) + minBlockSize;
319 if((int)realsize < minAllocSize)
320 return NULL;
321
322 /*
323 * see if the previous block is free, and is it big enough to cover the new size
324 * if merged with the current block.
325 */
326 PBLOCK ptr = (PBLOCK)block;
327 size_t cursize = SIZE(ptr) & ~1;
328 size_t psize = PSIZE(ptr);
329 if((psize&1) == 0 && (psize + cursize) >= realsize) {
330 PBLOCK prev = ptr - psize;
331 if(m_pRover == prev)
332 m_pRover = NEXT(prev);
333
334 /* Unlink the next block from the free list. */
335 Unlink(prev);
336
337 /* Copy contents of old block to new location, make it the current block. */
338 memmove(prev, ptr, cursize);
339 cursize += psize; /* combine sizes */
340 ptr = prev;
341
342 size_t rem = cursize - realsize;
343 if(rem >= minAllocSize) {
344 /*
345 * The remainder is big enough to be a new block. Set boundary
346 * tags for the resized block and the new block.
347 */
348 prev = ptr + realsize;
349 /*
350 * add the new block to the free list.
351 * next block cannot be free
352 */
353 SetTags(prev, rem);
354 AddToFreeList(prev, m_pFreeList);
355 cursize = realsize;
356 }
357 /* Set the boundary tags to mark it as allocated. */
358 SetTags(ptr, cursize | 1);
359 return ((void *)ptr);
360 }
361
362 /* Allocate a new block, copy the old to the new, and free the old. */
363 if((ptr = (PBLOCK)Malloc(size)) != NULL) {
364 memmove(ptr, block, cursize-minBlockSize);
365 Free(block);
366 }
367 return ((void *)ptr);
368}
369
370void VMem::Free(void* p)
371{
372 WALKHEAP();
373
374 /* Ignore null pointer. */
375 if(p == NULL)
376 return;
377
378 PBLOCK ptr = (PBLOCK)p;
379
380 /* Check for attempt to free a block that's already free. */
381 size_t size = SIZE(ptr);
382 if((size&1) == 0) {
383 MEMODSlx("Attempt to free previously freed block", (long)p);
384 return;
385 }
386 size &= ~1; /* remove allocated tag */
387
388 /* if previous block is free, add this block to it. */
389 int linked = FALSE;
390 size_t psize = PSIZE(ptr);
391 if((psize&1) == 0) {
392 ptr -= psize; /* point to previous block */
393 size += psize; /* merge the sizes of the two blocks */
394 linked = TRUE; /* it's already on the free list */
395 }
396
397 /* if the next physical block is free, merge it with this block. */
398 PBLOCK next = ptr + size; /* point to next physical block */
399 size_t nsize = SIZE(next);
400 if((nsize&1) == 0) {
401 /* block is free move rover if needed */
402 if(m_pRover == next)
403 m_pRover = NEXT(next);
404
405 /* unlink the next block from the free list. */
406 Unlink(next);
407
408 /* merge the sizes of this block and the next block. */
409 size += nsize;
410 }
411
412 /* Set the boundary tags for the block; */
413 SetTags(ptr, size);
414
415 /* Link the block to the head of the free list. */
416 if(!linked) {
417 AddToFreeList(ptr, m_pFreeList);
418 }
419}
420
421void VMem::GetLock(void)
422{
423 EnterCriticalSection(&m_cs);
424}
425
426void VMem::FreeLock(void)
427{
428 LeaveCriticalSection(&m_cs);
429}
430
431int VMem::IsLocked(void)
432{
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433#if 0
434 /* XXX TryEnterCriticalSection() is not available in some versions
435 * of Windows 95. Since this code is not used anywhere yet, we
436 * skirt the issue for now. */
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437 BOOL bAccessed = TryEnterCriticalSection(&m_cs);
438 if(bAccessed) {
439 LeaveCriticalSection(&m_cs);
440 }
441 return !bAccessed;
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442#else
443 ASSERT(0); /* alarm bells for when somebody calls this */
444 return 0;
445#endif
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446}
447
448
449long VMem::Release(void)
450{
451 long lCount = InterlockedDecrement(&m_lRefCount);
452 if(!lCount)
453 delete this;
454 return lCount;
455}
456
457long VMem::AddRef(void)
458{
459 long lCount = InterlockedIncrement(&m_lRefCount);
460 return lCount;
461}
462
463
464int VMem::Getmem(size_t requestSize)
465{ /* returns -1 is successful 0 if not */
466 void *ptr;
467
468 /* Round up size to next multiple of 64K. */
469 size_t size = (size_t)ROUND_UP64K(requestSize);
470
471 /*
472 * if the size requested is smaller than our current allocation size
473 * adjust up
474 */
475 if(size < (unsigned long)m_lAllocSize)
476 size = m_lAllocSize;
477
478 /* Update the size to allocate on the next request */
479 if(m_lAllocSize != lAllocMax)
480 m_lAllocSize <<= 1;
481
482 if(m_nHeaps != 0) {
483 /* Expand the last allocated heap */
484 ptr = HeapReAlloc(m_hHeap, HEAP_REALLOC_IN_PLACE_ONLY|HEAP_ZERO_MEMORY|HEAP_NO_SERIALIZE,
485 m_heaps[m_nHeaps-1].base,
486 m_heaps[m_nHeaps-1].len + size);
487 if(ptr != 0) {
488 HeapAdd(((char*)ptr) + m_heaps[m_nHeaps-1].len, size);
489 return -1;
490 }
491 }
492
493 /*
494 * if we didn't expand a block to cover the requested size
495 * allocate a new Heap
496 * the size of this block must include the additional dummy tags at either end
497 * the above ROUND_UP64K may not have added any memory to include this.
498 */
499 if(size == requestSize)
500 size = (size_t)ROUND_UP64K(requestSize+(sizeofTag*2));
501
502 ptr = HeapAlloc(m_hHeap, HEAP_ZERO_MEMORY|HEAP_NO_SERIALIZE, size);
503 if(ptr == 0) {
504 MEMODSlx("HeapAlloc failed on size!!!", size);
505 return 0;
506 }
507
508 HeapAdd(ptr, size);
509 return -1;
510}
511
512int VMem::HeapAdd(void *p, size_t size)
513{ /* if the block can be succesfully added to the heap, returns 0; otherwise -1. */
514 int index;
515
516 /* Check size, then round size down to next long word boundary. */
517 if(size < minAllocSize)
518 return -1;
519
520 size = (size_t)ROUND_DOWN(size);
521 PBLOCK ptr = (PBLOCK)p;
522
523 /*
524 * Search for another heap area that's contiguous with the bottom of this new area.
525 * (It should be extremely unusual to find one that's contiguous with the top).
526 */
527 for(index = 0; index < m_nHeaps; ++index) {
528 if(ptr == m_heaps[index].base + (int)m_heaps[index].len) {
529 /*
530 * The new block is contiguous with a previously allocated heap area. Add its
531 * length to that of the previous heap. Merge it with the the dummy end-of-heap
532 * area marker of the previous heap.
533 */
534 m_heaps[index].len += size;
535 break;
536 }
537 }
538
539 if(index == m_nHeaps) {
540 /* The new block is not contiguous. Add it to the heap list. */
541 if(m_nHeaps == maxHeaps) {
542 return -1; /* too many non-contiguous heaps */
543 }
544 m_heaps[m_nHeaps].base = ptr;
545 m_heaps[m_nHeaps].len = size;
546 m_nHeaps++;
547
548 /*
549 * Reserve the first LONG in the block for the ending boundary tag of a dummy
550 * block at the start of the heap area.
551 */
552 size -= minBlockSize;
553 ptr += minBlockSize;
554 PSIZE(ptr) = 1; /* mark the dummy previous block as allocated */
555 }
556
557 /*
558 * Convert the heap to one large block. Set up its boundary tags, and those of
559 * marker block after it. The marker block before the heap will already have
560 * been set up if this heap is not contiguous with the end of another heap.
561 */
562 SetTags(ptr, size | 1);
563 PBLOCK next = ptr + size; /* point to dummy end block */
564 SIZE(next) = 1; /* mark the dummy end block as allocated */
565
566 /*
567 * Link the block to the start of the free list by calling free().
568 * This will merge the block with any adjacent free blocks.
569 */
570 Free(ptr);
571 return 0;
572}
573
574
575void* VMem::Expand(void* block, size_t size)
576{
577 /*
578 * Adjust the size of the block to be a multiple of sizeof(long), and add the
579 * overhead for the boundary tags. Disallow negative or zero sizes.
580 */
581 size_t realsize = (size < blockOverhead) ? minAllocSize : (size_t)ROUND_UP(size) + minBlockSize;
582 if((int)realsize < minAllocSize || size == 0)
583 return NULL;
584
585 PBLOCK ptr = (PBLOCK)block;
586
587 /* if the current size is the same as requested, do nothing. */
588 size_t cursize = SIZE(ptr) & ~1;
589 if(cursize == realsize) {
590 return block;
591 }
592
593 /* if the block is being shrunk, convert the remainder of the block into a new free block. */
594 if(realsize <= cursize) {
595 size_t nextsize = cursize - realsize; /* size of new remainder block */
596 if(nextsize >= minAllocSize) {
597 /*
598 * Split the block
599 * Set boundary tags for the resized block and the new block.
600 */
601 SetTags(ptr, realsize | 1);
602 ptr += realsize;
603
604 /*
605 * add the new block to the free list.
606 * call Free to merge this block with next block if free
607 */
608 SetTags(ptr, nextsize | 1);
609 Free(ptr);
610 }
611
612 return block;
613 }
614
615 PBLOCK next = ptr + cursize;
616 size_t nextsize = SIZE(next);
617
618 /* Check the next block for consistency.*/
619 if((nextsize&1) == 0 && (nextsize + cursize) >= realsize) {
620 /*
621 * The next block is free and big enough. Add the part that's needed
622 * to our block, and split the remainder off into a new block.
623 */
624 if(m_pRover == next)
625 m_pRover = NEXT(next);
626
627 /* Unlink the next block from the free list. */
628 Unlink(next);
629 cursize += nextsize; /* combine sizes */
630
631 size_t rem = cursize - realsize; /* size of remainder */
632 if(rem >= minAllocSize) {
633 /*
634 * The remainder is big enough to be a new block.
635 * Set boundary tags for the resized block and the new block.
636 */
637 next = ptr + realsize;
638 /*
639 * add the new block to the free list.
640 * next block cannot be free
641 */
642 SetTags(next, rem);
643 AddToFreeList(next, m_pFreeList);
644 cursize = realsize;
645 }
646 /* Set the boundary tags to mark it as allocated. */
647 SetTags(ptr, cursize | 1);
648 return ((void *)ptr);
649 }
650 return NULL;
651}
652
653#ifdef _DEBUG_MEM
df3728a2 654#define LOG_FILENAME ".\\MemLog.txt"
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655
656void MemoryUsageMessage(char *str, long x, long y, int c)
657{
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658 char szBuffer[512];
659 if(str) {
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660 if(!m_pLog)
661 m_pLog = fopen(LOG_FILENAME, "w");
7766f137 662 sprintf(szBuffer, str, x, y, c);
df3728a2 663 fputs(szBuffer, m_pLog);
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664 }
665 else {
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666 fflush(m_pLog);
667 fclose(m_pLog);
668 m_pLog = 0;
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669 }
670}
671
672void VMem::WalkHeap(void)
673{
674 if(!m_pRover) {
675 MemoryUsageMessage("VMem heaps used %d\n", m_nHeaps, 0, 0);
676 }
677
678 /* Walk all the heaps - verify structures */
679 for(int index = 0; index < m_nHeaps; ++index) {
680 PBLOCK ptr = m_heaps[index].base;
681 size_t size = m_heaps[index].len;
682 ASSERT(HeapValidate(m_hHeap, HEAP_NO_SERIALIZE, p));
683
684 /* set over reserved header block */
685 size -= minBlockSize;
686 ptr += minBlockSize;
687 PBLOCK pLast = ptr + size;
688 ASSERT(PSIZE(ptr) == 1); /* dummy previous block is allocated */
689 ASSERT(SIZE(pLast) == 1); /* dummy next block is allocated */
690 while(ptr < pLast) {
691 ASSERT(ptr > m_heaps[index].base);
692 size_t cursize = SIZE(ptr) & ~1;
693 ASSERT((PSIZE(ptr+cursize) & ~1) == cursize);
694 if(!m_pRover) {
695 MemoryUsageMessage("Memory Block %08x: Size %08x %c\n", (long)ptr, cursize, (SIZE(p)&1) ? 'x' : ' ');
696 }
697 if(!(SIZE(ptr)&1)) {
698 /* this block is on the free list */
699 PBLOCK tmp = NEXT(ptr);
700 while(tmp != ptr) {
701 ASSERT((SIZE(tmp)&1)==0);
702 if(tmp == m_pFreeList)
703 break;
704 ASSERT(NEXT(tmp));
705 tmp = NEXT(tmp);
706 }
707 if(tmp == ptr) {
708 MemoryUsageMessage("Memory Block %08x: Size %08x free but not in free list\n", (long)ptr, cursize, 0);
709 }
710 }
711 ptr += cursize;
712 }
713 }
714 if(!m_pRover) {
715 MemoryUsageMessage(NULL, 0, 0, 0);
716 }
717}
718#endif
719
720#endif /* ___VMEM_H_INC___ */