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windows-server-2003/base/crts/crtw32/heap/sbheap.c

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/***
*sbheap.c - Small-block heap code
*
* Copyright (c) 1996-2001, Microsoft Corporation. All rights reserved.
*
*Purpose:
* Core code for small-block heap.
*
*Revision History:
* 03-06-96 GJF Module created.
* 04-03-96 GJF A couple of bug fixes courtesy of Steve Wood.
* 04-05-96 GJF Optimizations from Steve Wood (and John Vert)
* 1. all alloc_map[] entries are marked with
* _FREE_PARA except the first one (John Vert and
* Steve Wood).
* 2. depend on sentinel value to terminate loops in
* __sbh_alloc_block_in_page (me)
* 3. replace starting_para_index field with
* pstarting_alloc_map and added keep track of
* contiguous free paragraphs there (added
* free_paras_at_start field) (Steve Wood).
* 4. changed return type of __sbh_find_block, and
* type of the third args to __sbh_free_block and
* __sbh_resize_block to __map_t * (me).
* 05-22-96 GJF Deadly typo in __sbh_resize_block (had an = instead of
* an ==).
* 06-04-96 GJF Made several changes to the small-block heap types for
* better performance. Main idea was to reduce index
* expressions.
* 04-18-97 JWM Explicit cast added in __sbh_resize_block() to avoid
* new C4242 warnings.
* 05-22-97 RDK New small-block heap scheme implemented.
* 09-22-97 GJF #if 0 -ed out DumpEntry, a routine leftover from the
* debugging of the new small-block heap scheme.
* 12-05-97 GJF Release the address space for the heap data when a
* region is removed.
* 02-18-98 GJF Changes for Win64: replaced casts of pointers to
* (unsigned) int with casts to (u)intptr_t.
* 09-30-98 GJF Allow for initialization of small-block heap when
* _set_sbh_threshold is called.
* 10-13-98 GJF In __sbh_free_block, added check for already free
* blocks (simply return, with no action).
* 11-12-98 GJF Spliced in old small-block heap from VC++ 5.0.
* 12-18-98 GJF Changes for 64-bit size_t.
* 05-01-99 PML Disable small-block heap for Win64.
* 06-17-99 GJF Removed old small-block heap from static libs.
* 10-11-99 PML Supply stubs for _{get,set}_sbh_threshold on Win64.
* 11-30-99 PML Compile /Wp64 clean.
*
*******************************************************************************/
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <winheap.h>
#include <windows.h>
#ifndef _WIN64
/* Current (VC++ 6.0) small-block heap code and data */
size_t __sbh_threshold;
int __sbh_initialized;
PHEADER __sbh_pHeaderList; // pointer to list start
PHEADER __sbh_pHeaderScan; // pointer to list rover
int __sbh_sizeHeaderList; // allocated size of list
int __sbh_cntHeaderList; // count of entries defined
PHEADER __sbh_pHeaderDefer;
int __sbh_indGroupDefer;
/* Prototypes for user functions */
size_t __cdecl _get_sbh_threshold(void);
int __cdecl _set_sbh_threshold(size_t);
void DumpEntry(char *, int *);
#endif /* ndef _WIN64 */
/***
*size_t _get_sbh_threshold() - return small-block threshold
*
*Purpose:
* Return the current value of __sbh_threshold
*
*Entry:
* None.
*
*Exit:
* See above.
*
*Exceptions:
*
*******************************************************************************/
size_t __cdecl _get_sbh_threshold (void)
{
#ifndef _WIN64
if ( __active_heap == __V6_HEAP )
return __sbh_threshold;
#ifdef CRTDLL
else if ( __active_heap == __V5_HEAP )
return __old_sbh_threshold;
#endif /* CRTDLL */
else
#endif /* ndef _WIN64 */
return 0;
}
/***
*int _set_sbh_threshold(threshold) - set small-block heap threshold
*
*Purpose:
* Set the upper limit for the size of an allocation which will be
* supported from the small-block heap.
*
*Entry:
* size_t threshold - proposed new value for __sbh_theshold
*
*Exit:
* Returns 1 if successful. Returns 0 if threshold was too big.
*
*Exceptions:
*
*******************************************************************************/
int __cdecl _set_sbh_threshold (size_t threshold)
{
#ifndef _WIN64
if ( __active_heap == __V6_HEAP )
{
// test against maximum value - if too large, return error
if ( threshold <= MAX_ALLOC_DATA_SIZE )
{
__sbh_threshold = threshold;
return 1;
}
else
return 0;
}
#ifdef CRTDLL
if ( __active_heap == __V5_HEAP )
{
// Round up the proposed new value to the nearest paragraph
threshold = (threshold + _OLD_PARASIZE - 1) & ~(_OLD_PARASIZE - 1);
// Require that at least two allocations be can be made within a
// page.
if ( threshold <= (_OLD_PARASIZE * (_OLD_PARAS_PER_PAGE / 2)) ) {
__old_sbh_threshold = threshold;
return 1;
}
else
return 0;
}
// if necessary, initialize a small-block heap
if ( (__active_heap == __SYSTEM_HEAP) && (threshold > 0) )
{
LinkerVersion lv;
_GetLinkerVersion(&lv);
if (lv.bverMajor >= 6)
{
// Initialize the VC++ 6.0 small-block heap
if ( (threshold <= MAX_ALLOC_DATA_SIZE) &&
__sbh_heap_init(threshold) )
{
__sbh_threshold = threshold;
__active_heap = __V6_HEAP;
return 1;
}
}
else
{
// Initialize the old (VC++ 5.0) small-block heap
threshold = (threshold + _OLD_PARASIZE - 1) &
~(_OLD_PARASIZE - 1);
if ( (threshold <= (_OLD_PARASIZE * (_OLD_PARAS_PER_PAGE / 2)))
&& (__old_sbh_new_region() != NULL) )
{
__old_sbh_threshold = threshold;
__active_heap = __V5_HEAP;
return 1;
}
}
}
#else /* ndef CRTDLL */
// if necessary, initialize a small-block heap
if ( (__active_heap == __SYSTEM_HEAP) && (threshold > 0) )
{
// Initialize the VC++ 6.0 small-block heap
if ( (threshold <= MAX_ALLOC_DATA_SIZE) &&
__sbh_heap_init(threshold) )
{
__sbh_threshold = threshold;
__active_heap = __V6_HEAP;
return 1;
}
}
#endif /* CRTDLL */
#endif /* ndef _WIN64 */
return 0;
}
#ifndef _WIN64
/***
*int __sbh_heap_init() - set small-block heap threshold
*
*Purpose:
* Allocate space for initial header list and init variables.
*
*Entry:
* None.
*
*Exit:
* Returns 1 if successful. Returns 0 if initialization failed.
*
*Exceptions:
*
*******************************************************************************/
int __cdecl __sbh_heap_init (size_t threshold)
{
if (!(__sbh_pHeaderList = HeapAlloc(_crtheap, 0, 16 * sizeof(HEADER))))
return FALSE;
__sbh_threshold = threshold;
__sbh_pHeaderScan = __sbh_pHeaderList;
__sbh_pHeaderDefer = NULL;
__sbh_cntHeaderList = 0;
__sbh_sizeHeaderList = 16;
return TRUE;
}
/***
*PHEADER *__sbh_find_block(pvAlloc) - find block in small-block heap
*
*Purpose:
* Determine if the specified allocation block lies in the small-block
* heap and, if so, return the header to be used for the block.
*
*Entry:
* void * pvBlock - pointer to block to be freed
*
*Exit:
* If successful, a pointer to the header to use is returned.
* If unsuccessful, NULL is returned.
*
*Exceptions:
*
*******************************************************************************/
PHEADER __cdecl __sbh_find_block (void * pvAlloc)
{
PHEADER pHeaderLast = __sbh_pHeaderList + __sbh_cntHeaderList;
PHEADER pHeader;
unsigned int offRegion;
// scan through the header list to determine if entry
// is in the region heap data reserved address space
pHeader = __sbh_pHeaderList;
while (pHeader < pHeaderLast)
{
offRegion = (unsigned int)((uintptr_t)pvAlloc - (uintptr_t)pHeader->pHeapData);
if (offRegion < BYTES_PER_REGION)
return pHeader;
pHeader++;
}
return NULL;
}
#ifdef _DEBUG
/***
*int __sbh_verify_block(pHeader, pvAlloc) - verify pointer in sbh
*
*Purpose:
* Test if pointer is valid within the heap header given.
*
*Entry:
* pHeader - pointer to HEADER where entry should be
* pvAlloc - pointer to test validity of
*
*Exit:
* Returns 1 if pointer is valid, else 0.
*
*Exceptions:
*
*******************************************************************************/
int __cdecl __sbh_verify_block (PHEADER pHeader, void * pvAlloc)
{
unsigned int indGroup;
unsigned int offRegion;
// calculate region offset to determine the group index
offRegion = (unsigned int)((uintptr_t)pvAlloc - (uintptr_t)pHeader->pHeapData);
indGroup = offRegion / BYTES_PER_GROUP;
// return TRUE if:
// group is committed (bit in vector cleared) AND
// pointer is at paragraph boundary AND
// pointer is not at start of page
return (!(pHeader->bitvCommit & (0x80000000UL >> indGroup))) &&
(!(offRegion & 0xf)) &&
(offRegion & (BYTES_PER_PAGE - 1));
}
#endif
/***
*void __sbh_free_block(preg, ppage, pmap) - free block
*
*Purpose:
* Free the specified block from the small-block heap.
*
*Entry:
* pHeader - pointer to HEADER of region to free memory
* pvAlloc - pointer to memory to free
*
*Exit:
* No return value.
*
*Exceptions:
*
*******************************************************************************/
void __cdecl __sbh_free_block (PHEADER pHeader, void * pvAlloc)
{
PREGION pRegion;
PGROUP pGroup;
PENTRY pHead;
PENTRY pEntry;
PENTRY pNext;
PENTRY pPrev;
void * pHeapDecommit;
int sizeEntry;
int sizeNext;
int sizePrev;
unsigned int indGroup;
unsigned int indEntry;
unsigned int indNext;
unsigned int indPrev;
unsigned int offRegion;
// region is determined by the header
pRegion = pHeader->pRegion;
// use the region offset to determine the group index
offRegion = (unsigned int)(((uintptr_t)pvAlloc - (uintptr_t)pHeader->pHeapData));
indGroup = offRegion / BYTES_PER_GROUP;
pGroup = &pRegion->grpHeadList[indGroup];
// get size of entry - decrement value since entry is allocated
pEntry = (PENTRY)((char *)pvAlloc - sizeof(int));
sizeEntry = pEntry->sizeFront - 1;
// check if the entry is already free. note the size has already been
// decremented
if ( (sizeEntry & 1 ) != 0 )
return;
// point to next entry to get its size
pNext = (PENTRY)((char *)pEntry + sizeEntry);
sizeNext = pNext->sizeFront;
// get size from end of previous entry
sizePrev = ((PENTRYEND)((char *)pEntry - sizeof(int)))->sizeBack;
// test if next entry is free by an even size value
if ((sizeNext & 1) == 0)
{
// free next entry - disconnect and add its size to sizeEntry
// determine index of next entry
indNext = (sizeNext >> 4) - 1;
if (indNext > 63)
indNext = 63;
// test entry is sole member of bucket (next == prev),
if (pNext->pEntryNext == pNext->pEntryPrev)
{
// clear bit in group vector, decrement region count
// if region count is now zero, clear bit in header
// entry vector
if (indNext < 32)
{
pRegion->bitvGroupHi[indGroup] &= ~(0x80000000L >> indNext);
if (--pRegion->cntRegionSize[indNext] == 0)
pHeader->bitvEntryHi &= ~(0x80000000L >> indNext);
}
else
{
pRegion->bitvGroupLo[indGroup] &=
~(0x80000000L >> (indNext - 32));
if (--pRegion->cntRegionSize[indNext] == 0)
pHeader->bitvEntryLo &= ~(0x80000000L >> (indNext - 32));
}
}
// unlink entry from list
pNext->pEntryPrev->pEntryNext = pNext->pEntryNext;
pNext->pEntryNext->pEntryPrev = pNext->pEntryPrev;
// add next entry size to freed entry size
sizeEntry += sizeNext;
}
// compute index of free entry (plus next entry if it was free)
indEntry = (sizeEntry >> 4) - 1;
if (indEntry > 63)
indEntry = 63;
// test if previous entry is free by an even size value
if ((sizePrev & 1) == 0)
{
// free previous entry - add size to sizeEntry and
// disconnect if index changes
// get pointer to previous entry
pPrev = (PENTRY)((char *)pEntry - sizePrev);
// determine index of previous entry
indPrev = (sizePrev >> 4) - 1;
if (indPrev > 63)
indPrev = 63;
// add previous entry size to sizeEntry and determine
// its new index
sizeEntry += sizePrev;
indEntry = (sizeEntry >> 4) - 1;
if (indEntry > 63)
indEntry = 63;
// if index changed due to coalesing, reconnect to new size
if (indPrev != indEntry)
{
// disconnect entry from indPrev
// test entry is sole member of bucket (next == prev),
if (pPrev->pEntryNext == pPrev->pEntryPrev)
{
// clear bit in group vector, decrement region count
// if region count is now zero, clear bit in header
// entry vector
if (indPrev < 32)
{
pRegion->bitvGroupHi[indGroup] &=
~(0x80000000L >> indPrev);
if (--pRegion->cntRegionSize[indPrev] == 0)
pHeader->bitvEntryHi &= ~(0x80000000L >> indPrev);
}
else
{
pRegion->bitvGroupLo[indGroup] &=
~(0x80000000L >> (indPrev - 32));
if (--pRegion->cntRegionSize[indPrev] == 0)
pHeader->bitvEntryLo &=
~(0x80000000L >> (indPrev - 32));
}
}
// unlink entry from list
pPrev->pEntryPrev->pEntryNext = pPrev->pEntryNext;
pPrev->pEntryNext->pEntryPrev = pPrev->pEntryPrev;
}
// set pointer to connect it instead of the free entry
pEntry = pPrev;
}
// test if previous entry was free with an index change or allocated
if (!((sizePrev & 1) == 0 && indPrev == indEntry))
{
// connect pEntry entry to indEntry
// add entry to the start of the bucket list
pHead = (PENTRY)((char *)&pGroup->listHead[indEntry] - sizeof(int));
pEntry->pEntryNext = pHead->pEntryNext;
pEntry->pEntryPrev = pHead;
pHead->pEntryNext = pEntry;
pEntry->pEntryNext->pEntryPrev = pEntry;
// test entry is sole member of bucket (next == prev),
if (pEntry->pEntryNext == pEntry->pEntryPrev)
{
// if region count was zero, set bit in region vector
// set bit in header entry vector, increment region count
if (indEntry < 32)
{
if (pRegion->cntRegionSize[indEntry]++ == 0)
pHeader->bitvEntryHi |= 0x80000000L >> indEntry;
pRegion->bitvGroupHi[indGroup] |= 0x80000000L >> indEntry;
}
else
{
if (pRegion->cntRegionSize[indEntry]++ == 0)
pHeader->bitvEntryLo |= 0x80000000L >> (indEntry - 32);
pRegion->bitvGroupLo[indGroup] |= 0x80000000L >>
(indEntry - 32);
}
}
}
// adjust the entry size front and back
pEntry->sizeFront = sizeEntry;
((PENTRYEND)((char *)pEntry + sizeEntry -
sizeof(ENTRYEND)))->sizeBack = sizeEntry;
// one less allocation in group - test if empty
if (--pGroup->cntEntries == 0)
{
// if a group has been deferred, free that group
if (__sbh_pHeaderDefer)
{
// if now zero, decommit the group data heap
pHeapDecommit = (void *)((char *)__sbh_pHeaderDefer->pHeapData +
__sbh_indGroupDefer * BYTES_PER_GROUP);
VirtualFree(pHeapDecommit, BYTES_PER_GROUP, MEM_DECOMMIT);
// set bit in commit vector
__sbh_pHeaderDefer->bitvCommit |=
0x80000000 >> __sbh_indGroupDefer;
// clear entry vector for the group and header vector bit
// if needed
__sbh_pHeaderDefer->pRegion->bitvGroupLo[__sbh_indGroupDefer] = 0;
if (--__sbh_pHeaderDefer->pRegion->cntRegionSize[63] == 0)
__sbh_pHeaderDefer->bitvEntryLo &= ~0x00000001L;
// if commit vector is the initial value,
// remove the region if it is not the last
if (__sbh_pHeaderDefer->bitvCommit == BITV_COMMIT_INIT)
{
// release the address space for heap data
VirtualFree(__sbh_pHeaderDefer->pHeapData, 0, MEM_RELEASE);
// free the region memory area
HeapFree(_crtheap, 0, __sbh_pHeaderDefer->pRegion);
// remove entry from header list by copying over
memmove((void *)__sbh_pHeaderDefer,
(void *)(__sbh_pHeaderDefer + 1),
(int)((intptr_t)(__sbh_pHeaderList + __sbh_cntHeaderList) -
(intptr_t)(__sbh_pHeaderDefer + 1)));
__sbh_cntHeaderList--;
// if pHeader was after the one just removed, adjust it
if (pHeader > __sbh_pHeaderDefer)
pHeader--;
// initialize scan pointer to start of list
__sbh_pHeaderScan = __sbh_pHeaderList;
}
}
// defer the group just freed
__sbh_pHeaderDefer = pHeader;
__sbh_indGroupDefer = indGroup;
}
}
/***
*void * __sbh_alloc_block(intSize) - allocate a block
*
*Purpose:
* Allocate a block from the small-block heap, the specified number of
* bytes in size.
*
*Entry:
* intSize - size of the allocation request in bytes
*
*Exit:
* Returns a pointer to the newly allocated block, if successful.
* Returns NULL, if failure.
*
*Exceptions:
*
*******************************************************************************/
void * __cdecl __sbh_alloc_block (int intSize)
{
PHEADER pHeaderLast = __sbh_pHeaderList + __sbh_cntHeaderList;
PHEADER pHeader;
PREGION pRegion;
PGROUP pGroup;
PENTRY pEntry;
PENTRY pHead;
BITVEC bitvEntryLo;
BITVEC bitvEntryHi;
BITVEC bitvTest;
int sizeEntry;
int indEntry;
int indGroupUse;
int sizeNewFree;
int indNewFree;
// add 8 bytes entry overhead and round up to next para size
sizeEntry = (intSize + 2 * (int)sizeof(int) + (BYTES_PER_PARA - 1))
& ~(BYTES_PER_PARA - 1);
#ifdef _WIN64
if (sizeEntry < 32)
sizeEntry = 32;
#endif
// determine index and mask from entry size
// Hi MSB: bit 0 size: 1 paragraph
// bit 1 2 paragraphs
// ... ...
// bit 30 31 paragraphs
// bit 31 32 paragraphs
// Lo MSB: bit 0 size: 33 paragraph
// bit 1 34 paragraphs
// ... ...
// bit 30 63 paragraphs
// bit 31 64+ paragraphs
indEntry = (sizeEntry >> 4) - 1;
if (indEntry < 32)
{
bitvEntryHi = 0xffffffffUL >> indEntry;
bitvEntryLo = 0xffffffffUL;
}
else
{
bitvEntryHi = 0;
bitvEntryLo = 0xffffffffUL >> (indEntry - 32);
}
// scan header list from rover to end for region with a free
// entry with an adequate size
pHeader = __sbh_pHeaderScan;
while (pHeader < pHeaderLast)
{
if ((bitvEntryHi & pHeader->bitvEntryHi) |
(bitvEntryLo & pHeader->bitvEntryLo))
break;
pHeader++;
}
// if no entry, scan from list start up to the rover
if (pHeader == pHeaderLast)
{
pHeader = __sbh_pHeaderList;
while (pHeader < __sbh_pHeaderScan)
{
if ((bitvEntryHi & pHeader->bitvEntryHi) |
(bitvEntryLo & pHeader->bitvEntryLo))
break;
pHeader++;
}
// no free entry exists, scan list from rover to end
// for available groups to commit
if (pHeader == __sbh_pHeaderScan)
{
while (pHeader < pHeaderLast)
{
if (pHeader->bitvCommit)
break;
pHeader++;
}
// if no available groups, scan from start to rover
if (pHeader == pHeaderLast)
{
pHeader = __sbh_pHeaderList;
while (pHeader < __sbh_pHeaderScan)
{
if (pHeader->bitvCommit)
break;
pHeader++;
}
// if no available groups, create a new region
if (pHeader == __sbh_pHeaderScan)
if (!(pHeader = __sbh_alloc_new_region()))
return NULL;
}
// commit a new group in region associated with pHeader
if ((pHeader->pRegion->indGroupUse =
__sbh_alloc_new_group(pHeader)) == -1)
return NULL;
}
}
__sbh_pHeaderScan = pHeader;
pRegion = pHeader->pRegion;
indGroupUse = pRegion->indGroupUse;
// determine the group to allocate from
if (indGroupUse == -1 ||
!((bitvEntryHi & pRegion->bitvGroupHi[indGroupUse]) |
(bitvEntryLo & pRegion->bitvGroupLo[indGroupUse])))
{
// preferred group could not allocate entry, so
// scan through all defined vectors
indGroupUse = 0;
while (!((bitvEntryHi & pRegion->bitvGroupHi[indGroupUse]) |
(bitvEntryLo & pRegion->bitvGroupLo[indGroupUse])))
indGroupUse++;
}
pGroup = &pRegion->grpHeadList[indGroupUse];
// determine bucket index
indEntry = 0;
// get high entry intersection - if zero, use the lower one
if (!(bitvTest = bitvEntryHi & pRegion->bitvGroupHi[indGroupUse]))
{
indEntry = 32;
bitvTest = bitvEntryLo & pRegion->bitvGroupLo[indGroupUse];
}
while ((int)bitvTest >= 0)
{
bitvTest <<= 1;
indEntry++;
}
pEntry = pGroup->listHead[indEntry].pEntryNext;
// compute size and bucket index of new free entry
// for zero-sized entry, the index is -1
sizeNewFree = pEntry->sizeFront - sizeEntry;
indNewFree = (sizeNewFree >> 4) - 1;
if (indNewFree > 63)
indNewFree = 63;
// only modify entry pointers if bucket index changed
if (indNewFree != indEntry)
{
// test entry is sole member of bucket (next == prev),
if (pEntry->pEntryNext == pEntry->pEntryPrev)
{
// clear bit in group vector, decrement region count
// if region count is now zero, clear bit in region vector
if (indEntry < 32)
{
pRegion->bitvGroupHi[indGroupUse] &=
~(0x80000000L >> indEntry);
if (--pRegion->cntRegionSize[indEntry] == 0)
pHeader->bitvEntryHi &= ~(0x80000000L >> indEntry);
}
else
{
pRegion->bitvGroupLo[indGroupUse] &=
~(0x80000000L >> (indEntry - 32));
if (--pRegion->cntRegionSize[indEntry] == 0)
pHeader->bitvEntryLo &= ~(0x80000000L >> (indEntry - 32));
}
}
// unlink entry from list
pEntry->pEntryPrev->pEntryNext = pEntry->pEntryNext;
pEntry->pEntryNext->pEntryPrev = pEntry->pEntryPrev;
// if free entry size is still nonzero, reconnect it
if (sizeNewFree != 0)
{
// add entry to the start of the bucket list
pHead = (PENTRY)((char *)&pGroup->listHead[indNewFree] -
sizeof(int));
pEntry->pEntryNext = pHead->pEntryNext;
pEntry->pEntryPrev = pHead;
pHead->pEntryNext = pEntry;
pEntry->pEntryNext->pEntryPrev = pEntry;
// test entry is sole member of bucket (next == prev),
if (pEntry->pEntryNext == pEntry->pEntryPrev)
{
// if region count was zero, set bit in region vector
// set bit in group vector, increment region count
if (indNewFree < 32)
{
if (pRegion->cntRegionSize[indNewFree]++ == 0)
pHeader->bitvEntryHi |= 0x80000000L >> indNewFree;
pRegion->bitvGroupHi[indGroupUse] |=
0x80000000L >> indNewFree;
}
else
{
if (pRegion->cntRegionSize[indNewFree]++ == 0)
pHeader->bitvEntryLo |=
0x80000000L >> (indNewFree - 32);
pRegion->bitvGroupLo[indGroupUse] |=
0x80000000L >> (indNewFree - 32);
}
}
}
}
// change size of free entry (front and back)
if (sizeNewFree != 0)
{
pEntry->sizeFront = sizeNewFree;
((PENTRYEND)((char *)pEntry + sizeNewFree -
sizeof(ENTRYEND)))->sizeBack = sizeNewFree;
}
// mark the allocated entry
pEntry = (PENTRY)((char *)pEntry + sizeNewFree);
pEntry->sizeFront = sizeEntry + 1;
((PENTRYEND)((char *)pEntry + sizeEntry -
sizeof(ENTRYEND)))->sizeBack = sizeEntry + 1;
// one more allocation in group - test if group was empty
if (pGroup->cntEntries++ == 0)
{
// if allocating into deferred group, cancel deferral
if (pHeader == __sbh_pHeaderDefer &&
indGroupUse == __sbh_indGroupDefer)
__sbh_pHeaderDefer = NULL;
}
pRegion->indGroupUse = indGroupUse;
return (void *)((char *)pEntry + sizeof(int));
}
/***
*PHEADER __sbh_alloc_new_region()
*
*Purpose:
* Add a new HEADER structure in the header list. Allocate a new
* REGION structure and initialize. Reserve memory for future
* group commitments.
*
*Entry:
* None.
*
*Exit:
* Returns a pointer to newly created HEADER entry, if successful.
* Returns NULL, if failure.
*
*Exceptions:
*
*******************************************************************************/
PHEADER __cdecl __sbh_alloc_new_region (void)
{
PHEADER pHeader;
// create a new entry in the header list
// if list if full, realloc to extend its size
if (__sbh_cntHeaderList == __sbh_sizeHeaderList)
{
if (!(pHeader = (PHEADER)HeapReAlloc(_crtheap, 0, __sbh_pHeaderList,
(__sbh_sizeHeaderList + 16) * sizeof(HEADER))))
return NULL;
// update pointer and counter values
__sbh_pHeaderList = pHeader;
__sbh_sizeHeaderList += 16;
}
// point to new header in list
pHeader = __sbh_pHeaderList + __sbh_cntHeaderList;
// allocate a new region associated with the new header
if (!(pHeader->pRegion = (PREGION)HeapAlloc(_crtheap, HEAP_ZERO_MEMORY,
sizeof(REGION))))
return NULL;
// reserve address space for heap data in the region
if ((pHeader->pHeapData = VirtualAlloc(0, BYTES_PER_REGION,
MEM_RESERVE, PAGE_READWRITE)) == NULL)
{
HeapFree(_crtheap, 0, pHeader->pRegion);
return NULL;
}
// initialize alloc and commit group vectors
pHeader->bitvEntryHi = 0;
pHeader->bitvEntryLo = 0;
pHeader->bitvCommit = BITV_COMMIT_INIT;
// complete entry by incrementing list count
__sbh_cntHeaderList++;
// initialize index of group to try first (none defined yet)
pHeader->pRegion->indGroupUse = -1;
return pHeader;
}
/***
*int __sbh_alloc_new_group(pHeader)
*
*Purpose:
* Initializes a GROUP structure within HEADER pointed by pHeader.
* Commits and initializes the memory in the memory reserved by the
* REGION.
*
*Entry:
* pHeader - pointer to HEADER from which the GROUP is defined.
*
*Exit:
* Returns an index to newly created GROUP, if successful.
* Returns -1, if failure.
*
*Exceptions:
*
*******************************************************************************/
int __cdecl __sbh_alloc_new_group (PHEADER pHeader)
{
PREGION pRegion = pHeader->pRegion;
PGROUP pGroup;
PENTRY pEntry;
PENTRY pHead;
PENTRYEND pEntryEnd;
BITVEC bitvCommit;
int indCommit;
int index;
void * pHeapPage;
void * pHeapStartPage;
void * pHeapEndPage;
// determine next group to use by first bit set in commit vector
bitvCommit = pHeader->bitvCommit;
indCommit = 0;
while ((int)bitvCommit >= 0)
{
bitvCommit <<= 1;
indCommit++;
}
// allocate and initialize a new group
pGroup = &pRegion->grpHeadList[indCommit];
for (index = 0; index < 63; index++)
{
pEntry = (PENTRY)((char *)&pGroup->listHead[index] - sizeof(int));
pEntry->pEntryNext = pEntry->pEntryPrev = pEntry;
}
// commit heap memory for new group
pHeapStartPage = (void *)((char *)pHeader->pHeapData +
indCommit * BYTES_PER_GROUP);
if ((VirtualAlloc(pHeapStartPage, BYTES_PER_GROUP, MEM_COMMIT,
PAGE_READWRITE)) == NULL)
return -1;
// initialize heap data with empty page entries
pHeapEndPage = (void *)((char *)pHeapStartPage +
(PAGES_PER_GROUP - 1) * BYTES_PER_PAGE);
for (pHeapPage = pHeapStartPage; pHeapPage <= pHeapEndPage;
pHeapPage = (void *)((char *)pHeapPage + BYTES_PER_PAGE))
{
// set sentinel values at start and end of the page
*(int *)((char *)pHeapPage + 8) = -1;
*(int *)((char *)pHeapPage + BYTES_PER_PAGE - 4) = -1;
// set size and pointer info for one empty entry
pEntry = (PENTRY)((char *)pHeapPage + ENTRY_OFFSET);
pEntry->sizeFront = MAX_FREE_ENTRY_SIZE;
pEntry->pEntryNext = (PENTRY)((char *)pEntry +
BYTES_PER_PAGE);
pEntry->pEntryPrev = (PENTRY)((char *)pEntry -
BYTES_PER_PAGE);
pEntryEnd = (PENTRYEND)((char *)pEntry + MAX_FREE_ENTRY_SIZE -
sizeof(ENTRYEND));
pEntryEnd->sizeBack = MAX_FREE_ENTRY_SIZE;
}
// initialize group entry pointer for maximum size
// and set terminate list entries
pHead = (PENTRY)((char *)&pGroup->listHead[63] - sizeof(int));
pEntry = pHead->pEntryNext =
(PENTRY)((char *)pHeapStartPage + ENTRY_OFFSET);
pEntry->pEntryPrev = pHead;
pEntry = pHead->pEntryPrev =
(PENTRY)((char *)pHeapEndPage + ENTRY_OFFSET);
pEntry->pEntryNext = pHead;
pRegion->bitvGroupHi[indCommit] = 0x00000000L;
pRegion->bitvGroupLo[indCommit] = 0x00000001L;
if (pRegion->cntRegionSize[63]++ == 0)
pHeader->bitvEntryLo |= 0x00000001L;
// clear bit in commit vector
pHeader->bitvCommit &= ~(0x80000000L >> indCommit);
return indCommit;
}
/***
*int __sbh_resize_block(pHeader, pvAlloc, intNew) - resize block
*
*Purpose:
* Resize the specified block from the small-block heap.
* The allocation block is not moved.
*
*Entry:
* pHeader - pointer to HEADER containing block
* pvAlloc - pointer to block to resize
* intNew - new size of block in bytes
*
*Exit:
* Returns 1, if successful. Otherwise, 0 is returned.
*
*Exceptions:
*
*******************************************************************************/
int __cdecl __sbh_resize_block (PHEADER pHeader, void * pvAlloc, int intNew)
{
PREGION pRegion;
PGROUP pGroup;
PENTRY pHead;
PENTRY pEntry;
PENTRY pNext;
int sizeEntry;
int sizeNext;
int sizeNew;
unsigned int indGroup;
unsigned int indEntry;
unsigned int indNext;
unsigned int offRegion;
// add 8 bytes entry overhead and round up to next para size
sizeNew = (intNew + 2 * (int)sizeof(int) + (BYTES_PER_PARA - 1))
& ~(BYTES_PER_PARA - 1);
// region is determined by the header
pRegion = pHeader->pRegion;
// use the region offset to determine the group index
offRegion = (unsigned int)((uintptr_t)pvAlloc - (uintptr_t)pHeader->pHeapData);
indGroup = offRegion / BYTES_PER_GROUP;
pGroup = &pRegion->grpHeadList[indGroup];
// get size of entry - decrement value since entry is allocated
pEntry = (PENTRY)((char *)pvAlloc - sizeof(int));
sizeEntry = pEntry->sizeFront - 1;
// point to next entry to get its size
pNext = (PENTRY)((char *)pEntry + sizeEntry);
sizeNext = pNext->sizeFront;
// test if new size is larger than the current one
if (sizeNew > sizeEntry)
{
// if next entry not free, or not large enough, fail
if ((sizeNext & 1) || (sizeNew > sizeEntry + sizeNext))
return FALSE;
// disconnect next entry
// determine index of next entry
indNext = (sizeNext >> 4) - 1;
if (indNext > 63)
indNext = 63;
// test entry is sole member of bucket (next == prev),
if (pNext->pEntryNext == pNext->pEntryPrev)
{
// clear bit in group vector, decrement region count
// if region count is now zero, clear bit in header
// entry vector
if (indNext < 32)
{
pRegion->bitvGroupHi[indGroup] &= ~(0x80000000L >> indNext);
if (--pRegion->cntRegionSize[indNext] == 0)
pHeader->bitvEntryHi &= ~(0x80000000L >> indNext);
}
else
{
pRegion->bitvGroupLo[indGroup] &=
~(0x80000000L >> (indNext - 32));
if (--pRegion->cntRegionSize[indNext] == 0)
pHeader->bitvEntryLo &= ~(0x80000000L >> (indNext - 32));
}
}
// unlink entry from list
pNext->pEntryPrev->pEntryNext = pNext->pEntryNext;
pNext->pEntryNext->pEntryPrev = pNext->pEntryPrev;
// compute new size of the next entry, test if nonzero
if ((sizeNext = sizeEntry + sizeNext - sizeNew) > 0)
{
// compute start of next entry and connect it
pNext = (PENTRY)((char *)pEntry + sizeNew);
// determine index of next entry
indNext = (sizeNext >> 4) - 1;
if (indNext > 63)
indNext = 63;
// add next entry to the start of the bucket list
pHead = (PENTRY)((char *)&pGroup->listHead[indNext] -
sizeof(int));
pNext->pEntryNext = pHead->pEntryNext;
pNext->pEntryPrev = pHead;
pHead->pEntryNext = pNext;
pNext->pEntryNext->pEntryPrev = pNext;
// test entry is sole member of bucket (next == prev),
if (pNext->pEntryNext == pNext->pEntryPrev)
{
// if region count was zero, set bit in region vector
// set bit in header entry vector, increment region count
if (indNext < 32)
{
if (pRegion->cntRegionSize[indNext]++ == 0)
pHeader->bitvEntryHi |= 0x80000000L >> indNext;
pRegion->bitvGroupHi[indGroup] |= 0x80000000L >> indNext;
}
else
{
if (pRegion->cntRegionSize[indNext]++ == 0)
pHeader->bitvEntryLo |= 0x80000000L >> (indNext - 32);
pRegion->bitvGroupLo[indGroup] |=
0x80000000L >> (indNext - 32);
}
}
// adjust size fields of next entry
pNext->sizeFront = sizeNext;
((PENTRYEND)((char *)pNext + sizeNext -
sizeof(ENTRYEND)))->sizeBack = sizeNext;
}
// adjust pEntry to its new size (plus one since allocated)
pEntry->sizeFront = sizeNew + 1;
((PENTRYEND)((char *)pEntry + sizeNew -
sizeof(ENTRYEND)))->sizeBack = sizeNew + 1;
}
// not larger, test if smaller
else if (sizeNew < sizeEntry)
{
// adjust pEntry to new smaller size
pEntry->sizeFront = sizeNew + 1;
((PENTRYEND)((char *)pEntry + sizeNew -
sizeof(ENTRYEND)))->sizeBack = sizeNew + 1;
// set pEntry and sizeEntry to leftover space
pEntry = (PENTRY)((char *)pEntry + sizeNew);
sizeEntry -= sizeNew;
// determine index of entry
indEntry = (sizeEntry >> 4) - 1;
if (indEntry > 63)
indEntry = 63;
// test if next entry is free
if ((sizeNext & 1) == 0)
{
// if so, disconnect it
// determine index of next entry
indNext = (sizeNext >> 4) - 1;
if (indNext > 63)
indNext = 63;
// test entry is sole member of bucket (next == prev),
if (pNext->pEntryNext == pNext->pEntryPrev)
{
// clear bit in group vector, decrement region count
// if region count is now zero, clear bit in header
// entry vector
if (indNext < 32)
{
pRegion->bitvGroupHi[indGroup] &=
~(0x80000000L >> indNext);
if (--pRegion->cntRegionSize[indNext] == 0)
pHeader->bitvEntryHi &= ~(0x80000000L >> indNext);
}
else
{
pRegion->bitvGroupLo[indGroup] &=
~(0x80000000L >> (indNext - 32));
if (--pRegion->cntRegionSize[indNext] == 0)
pHeader->bitvEntryLo &=
~(0x80000000L >> (indNext - 32));
}
}
// unlink entry from list
pNext->pEntryPrev->pEntryNext = pNext->pEntryNext;
pNext->pEntryNext->pEntryPrev = pNext->pEntryPrev;
// add next entry size to present
sizeEntry += sizeNext;
indEntry = (sizeEntry >> 4) - 1;
if (indEntry > 63)
indEntry = 63;
}
// connect leftover space with any free next entry
// add next entry to the start of the bucket list
pHead = (PENTRY)((char *)&pGroup->listHead[indEntry] - sizeof(int));
pEntry->pEntryNext = pHead->pEntryNext;
pEntry->pEntryPrev = pHead;
pHead->pEntryNext = pEntry;
pEntry->pEntryNext->pEntryPrev = pEntry;
// test entry is sole member of bucket (next == prev),
if (pEntry->pEntryNext == pEntry->pEntryPrev)
{
// if region count was zero, set bit in region vector
// set bit in header entry vector, increment region count
if (indEntry < 32)
{
if (pRegion->cntRegionSize[indEntry]++ == 0)
pHeader->bitvEntryHi |= 0x80000000L >> indEntry;
pRegion->bitvGroupHi[indGroup] |= 0x80000000L >> indEntry;
}
else
{
if (pRegion->cntRegionSize[indEntry]++ == 0)
pHeader->bitvEntryLo |= 0x80000000L >> (indEntry - 32);
pRegion->bitvGroupLo[indGroup] |= 0x80000000L >>
(indEntry - 32);
}
}
// adjust size fields of entry
pEntry->sizeFront = sizeEntry;
((PENTRYEND)((char *)pEntry + sizeEntry -
sizeof(ENTRYEND)))->sizeBack = sizeEntry;
}
return TRUE;
}
/***
*int __sbh_heapmin() - minimize heap
*
*Purpose:
* Minimize the heap by freeing any deferred group.
*
*Entry:
* __sbh_pHeaderDefer - pointer to HEADER of deferred group
* __sbh_indGroupDefer - index of GROUP to defer
*
*Exit:
* None.
*
*Exceptions:
*
*******************************************************************************/
void __cdecl __sbh_heapmin (void)
{
void * pHeapDecommit;
// if a group has been deferred, free that group
if (__sbh_pHeaderDefer)
{
// if now zero, decommit the group data heap
pHeapDecommit = (void *)((char *)__sbh_pHeaderDefer->pHeapData +
__sbh_indGroupDefer * BYTES_PER_GROUP);
VirtualFree(pHeapDecommit, BYTES_PER_GROUP, MEM_DECOMMIT);
// set bit in commit vector
__sbh_pHeaderDefer->bitvCommit |= 0x80000000 >> __sbh_indGroupDefer;
// clear entry vector for the group and header vector bit
// if needed
__sbh_pHeaderDefer->pRegion->bitvGroupLo[__sbh_indGroupDefer] = 0;
if (--__sbh_pHeaderDefer->pRegion->cntRegionSize[63] == 0)
__sbh_pHeaderDefer->bitvEntryLo &= ~0x00000001L;
// if commit vector is the initial value,
// remove the region if it is not the last
if (__sbh_pHeaderDefer->bitvCommit == BITV_COMMIT_INIT &&
__sbh_cntHeaderList > 1)
{
// free the region memory area
HeapFree(_crtheap, 0, __sbh_pHeaderDefer->pRegion);
// remove entry from header list by copying over
memmove((void *)__sbh_pHeaderDefer, (void *)(__sbh_pHeaderDefer + 1),
(int)((intptr_t)(__sbh_pHeaderList + __sbh_cntHeaderList) -
(intptr_t)(__sbh_pHeaderDefer + 1)));
__sbh_cntHeaderList--;
}
// clear deferred condition
__sbh_pHeaderDefer = NULL;
}
}
/***
*int __sbh_heap_check() - check small-block heap
*
*Purpose:
* Perform validity checks on the small-block heap.
*
*Entry:
* There are no arguments.
*
*Exit:
* Returns 0 if the small-block is okay.
* Returns < 0 if the small-block heap has an error. The exact value
* identifies where, in the source code below, the error was detected.
*
*Exceptions:
*
*******************************************************************************/
int __cdecl __sbh_heap_check (void)
{
PHEADER pHeader;
PREGION pRegion;
PGROUP pGroup;
PENTRY pEntry;
PENTRY pNext;
PENTRY pEntryLast;
PENTRY pEntryHead;
PENTRY pEntryPage;
PENTRY pEntryPageLast;
int indHeader;
int indGroup;
int indPage;
int indEntry;
int indHead;
int sizeEntry;
int sizeTrue;
int cntAllocated;
int cntFree[64];
int cntEntries;
void * pHeapGroup;
void * pHeapPage;
void * pPageStart;
BITVEC bitvCommit;
BITVEC bitvGroupHi;
BITVEC bitvGroupLo;
BITVEC bitvEntryHi;
BITVEC bitvEntryLo;
// check validity of header list
if (IsBadWritePtr(__sbh_pHeaderList,
__sbh_cntHeaderList * (unsigned int)sizeof(HEADER)))
return -1;
// scan for all headers in list
pHeader = __sbh_pHeaderList;
for (indHeader = 0; indHeader < __sbh_cntHeaderList; indHeader++)
{
// define region and test if valid
pRegion = pHeader->pRegion;
if (IsBadWritePtr(pRegion, sizeof(REGION)))
return -2;
// scan for all groups in region
pHeapGroup = pHeader->pHeapData;
pGroup = &pRegion->grpHeadList[0];
bitvCommit = pHeader->bitvCommit;
bitvEntryHi = 0;
bitvEntryLo = 0;
for (indGroup = 0; indGroup < GROUPS_PER_REGION; indGroup++)
{
// initialize entry vector and entry counts for group
bitvGroupHi = 0;
bitvGroupLo = 0;
cntAllocated = 0;
for (indEntry = 0; indEntry < 64; indEntry++)
cntFree[indEntry] = 0;
// test if group is committed
if ((int)bitvCommit >= 0)
{
// committed, ensure addresses are accessable
if (IsBadWritePtr(pHeapGroup, BYTES_PER_GROUP))
return -4;
// for each page in group, check validity of entries
pHeapPage = pHeapGroup;
for (indPage = 0; indPage < PAGES_PER_GROUP; indPage++)
{
// define pointers to first and past last entry
pEntry = (PENTRY)((char *)pHeapPage + ENTRY_OFFSET);
pEntryLast = (PENTRY)((char *)pEntry
+ MAX_FREE_ENTRY_SIZE);
// check front and back page sentinel values
if (*(int *)((char *)pEntry - sizeof(int)) != -1 ||
*(int *)pEntryLast != -1)
return -5;
// loop through each entry in page
do
{
// get entry size and test if allocated
sizeEntry = sizeTrue = pEntry->sizeFront;
if (sizeEntry & 1)
{
// allocated entry - set true size
sizeTrue--;
// test against maximum allocated entry size
if (sizeTrue > MAX_ALLOC_ENTRY_SIZE)
return -6;
// increment allocated count for group
cntAllocated++;
}
else
{
// free entry - determine index and increment
// count for list head checking
indEntry = (sizeTrue >> 4) - 1;
if (indEntry > 63)
indEntry = 63;
cntFree[indEntry]++;
}
// check size validity
if (sizeTrue < 0x10 || sizeTrue & 0xf
|| sizeTrue > MAX_FREE_ENTRY_SIZE)
return -7;
// check if back entry size same as front
if (((PENTRYEND)((char *)pEntry + sizeTrue
- sizeof(int)))->sizeBack != sizeEntry)
return -8;
// move to next entry in page
pEntry = (PENTRY)((char *)pEntry + sizeTrue);
}
while (pEntry < pEntryLast);
// test if last entry did not overrun page end
if (pEntry != pEntryLast)
return -8;
// point to next page in data heap
pHeapPage = (void *)((char *)pHeapPage + BYTES_PER_PAGE);
}
// check if allocated entry count is correct
if (pGroup->cntEntries != cntAllocated)
return -9;
// check validity of linked-lists of free entries
pEntryHead = (PENTRY)((char *)&pGroup->listHead[0] -
sizeof(int));
for (indHead = 0; indHead < 64; indHead++)
{
// scan through list until head is reached or expected
// number of entries traversed
cntEntries = 0;
pEntry = pEntryHead;
while ((pNext = pEntry->pEntryNext) != pEntryHead &&
cntEntries != cntFree[indHead])
{
// test if next pointer is in group data area
if ((void *)pNext < pHeapGroup || (void *)pNext >=
(void *)((char *)pHeapGroup + BYTES_PER_GROUP))
return -10;
// determine page address of next entry
pPageStart = (void *)((uintptr_t)pNext &
~(uintptr_t)(BYTES_PER_PAGE - 1));
// point to first entry and past last in the page
pEntryPage = (PENTRY)((char *)pPageStart +
ENTRY_OFFSET);
pEntryPageLast = (PENTRY)((char *)pEntryPage +
MAX_FREE_ENTRY_SIZE);
// do scan from start of page
// no error checking since it was already scanned
while (pEntryPage != pEntryPageLast)
{
// if entry matches, exit loop
if (pEntryPage == pNext)
break;
// point to next entry
pEntryPage = (PENTRY)((char *)pEntryPage +
(pEntryPage->sizeFront & ~1));
}
// if page end reached, pNext was not valid
if (pEntryPage == pEntryPageLast)
return -11;
// entry valid, but check if entry index matches
// the header
indEntry = (pNext->sizeFront >> 4) - 1;
if (indEntry > 63)
indEntry = 63;
if (indEntry != indHead)
return -12;
// check if previous pointer in pNext points
// back to pEntry
if (pNext->pEntryPrev != pEntry)
return -13;
// update scan pointer and counter
pEntry = pNext;
cntEntries++;
}
// if nonzero number of entries, set bit in group
// and region vectors
if (cntEntries)
{
if (indHead < 32)
{
bitvGroupHi |= 0x80000000L >> indHead;
bitvEntryHi |= 0x80000000L >> indHead;
}
else
{
bitvGroupLo |= 0x80000000L >> (indHead - 32);
bitvEntryLo |= 0x80000000L >> (indHead - 32);
}
}
// check if list is exactly the expected size
if (pEntry->pEntryNext != pEntryHead ||
cntEntries != cntFree[indHead])
return -14;
// check if previous pointer in header points to
// last entry processed
if (pEntryHead->pEntryPrev != pEntry)
return -15;
// point to next linked-list header - note size
pEntryHead = (PENTRY)((char *)pEntryHead +
sizeof(LISTHEAD));
}
}
// test if group vector is valid
if (bitvGroupHi != pRegion->bitvGroupHi[indGroup] ||
bitvGroupLo != pRegion->bitvGroupLo[indGroup])
return -16;
// adjust for next group in region
pHeapGroup = (void *)((char *)pHeapGroup + BYTES_PER_GROUP);
pGroup++;
bitvCommit <<= 1;
}
// test if group vector is valid
if (bitvEntryHi != pHeader->bitvEntryHi ||
bitvEntryLo != pHeader->bitvEntryLo)
return -17;
// adjust for next header in list
pHeader++;
}
return 0;
}
#if 0
void DumpEntry (char * pLine, int * piValue)
{
HANDLE hdlFile;
char buffer[80];
int index;
int iTemp;
char chTemp[9];
DWORD dwWritten;
hdlFile = CreateFile("d:\\heap.log", GENERIC_READ | GENERIC_WRITE,
0, NULL, OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
SetFilePointer(hdlFile, 0, NULL, FILE_END);
strcpy(buffer, pLine);
if (piValue)
{
strcat(buffer, "0x");
iTemp = *piValue;
for (index = 7; index >= 0; index--)
{
if ((chTemp[index] = (iTemp & 0xf) + '0') > '9')
chTemp[index] += 'a' - ('9' + 1);
iTemp >>= 4;
}
chTemp[8] = '\0';
strcat(buffer, chTemp);
}
strcat(buffer, "\r\n");
WriteFile(hdlFile, buffer, strlen(buffer), &dwWritten, NULL);
CloseHandle(hdlFile);
}
#endif
#ifdef CRTDLL
/* Old (VC++ 5.0) small-block heap data and code */
__old_sbh_region_t __old_small_block_heap = {
&__old_small_block_heap, /* p_next_region */
&__old_small_block_heap, /* p_prev_region */
&__old_small_block_heap.region_map[0], /* p_starting_region_map */
&__old_small_block_heap.region_map[0], /* p_first_uncommitted */
(__old_sbh_page_t *)_OLD_NO_PAGES, /* p_pages_begin */
(__old_sbh_page_t *)_OLD_NO_PAGES, /* p_pages_end */
{ _OLD_PARAS_PER_PAGE, _OLD_NO_FAILED_ALLOC } /* region_map[] */
};
static __old_sbh_region_t *__old_sbh_p_starting_region = &__old_small_block_heap;
static int __old_sbh_decommitable_pages = 0;
size_t __old_sbh_threshold = _OLD_PARASIZE * (_OLD_PARAS_PER_PAGE / 8);
/* Prototypes for user functions */
size_t __cdecl _get_old_sbh_threshold(void);
int __cdecl _set_old_sbh_threshold(size_t);
/***
*size_t _get_old_sbh_threshold() - return small-block threshold
*
*Purpose:
* Return the current value of __old_sbh_threshold
*
*Entry:
* None.
*
*Exit:
* See above.
*
*Exceptions:
*
*******************************************************************************/
size_t __cdecl _get_old_sbh_threshold (
void
)
{
return __old_sbh_threshold;
}
/***
*int _set_old_sbh_threshold(size_t threshold) - set small-block heap threshold
*
*Purpose:
* Set the upper limit for the size of an allocation which will be
* supported from the small-block heap. It is required that at least two
* allocations can come from a page. This imposes an upper limit on how
* big the new threshold can be.
*
*Entry:
* size_t threshold - proposed new value for __sbh_theshold
*
*Exit:
* Returns 1 if successful. Returns 0 if threshold was too big.
*
*Exceptions:
*
*******************************************************************************/
int __cdecl _set_old_sbh_threshold (
size_t threshold
)
{
/*
* Round up the proposed new value to the nearest paragraph
*/
threshold = (threshold + _OLD_PARASIZE - 1) & ~(_OLD_PARASIZE - 1);
/*
* Require that at least two allocations be can be made within a
* page.
*/
if ( threshold <= (_OLD_PARASIZE * (_OLD_PARAS_PER_PAGE / 2)) ) {
__old_sbh_threshold = threshold;
return 1;
}
else
return 0;
}
/***
*__old_sbh_region_t * __old_sbh_new_region() - get a region for the small-block heap
*
*Purpose:
* Creates and adds a new region for the small-block heap. First, a
* descriptor (__old_sbh_region_t) is obtained for the new region. Next,
* VirtualAlloc() is used to reserved an address space of size
* _OLD_PAGES_PER_REGION * _OLD_PAGESIZE, and the first _PAGES_PER_COMMITTMENT
* pages are committed.
*
* Note that if __old_small_block_heap is available (i.e., the p_pages_begin
* field is _OLD_NO_PAGES), it becomes the descriptor for the new regions. This is
* basically the small-block heap initialization.
*
*Entry:
* No arguments.
*
*Exit:
* If successful, a pointer to the descriptor for the new region is
* returned. Otherwise, NULL is returned.
*
*******************************************************************************/
__old_sbh_region_t * __cdecl __old_sbh_new_region(
void
)
{
__old_sbh_region_t * pregnew;
__old_sbh_page_t * ppage;
int i;
/*
* Get a region descriptor (__old_sbh_region_t). If __old_small_block_heap is
* available, always use it.
*/
if ( __old_small_block_heap.p_pages_begin == _OLD_NO_PAGES ) {
pregnew = &__old_small_block_heap;
}
else {
/*
* Allocate space for the new __old_sbh_region_t structure. Note that
* this allocation comes out of the 'big block heap.
*/
if ( (pregnew = HeapAlloc( _crtheap, 0, sizeof(__old_sbh_region_t) ))
== NULL )
return NULL;
}
/*
* Reserve a new contiguous address range (i.e., a region).
*/
if ( (ppage = VirtualAlloc( NULL,
_OLD_PAGESIZE * _OLD_PAGES_PER_REGION,
MEM_RESERVE,
PAGE_READWRITE )) != NULL )
{
/*
* Commit the first _OLD_PAGES_PER_COMMITMENT of the new region.
*/
if ( VirtualAlloc( ppage,
_OLD_PAGESIZE * _OLD_PAGES_PER_COMMITMENT,
MEM_COMMIT,
PAGE_READWRITE ) != NULL )
{
/*
* Insert *pregnew into the linked list of regions (just
* before __old_small_block_heap)
*/
if ( pregnew == &__old_small_block_heap ) {
if ( __old_small_block_heap.p_next_region == NULL )
__old_small_block_heap.p_next_region =
&__old_small_block_heap;
if ( __old_small_block_heap.p_prev_region == NULL )
__old_small_block_heap.p_prev_region =
&__old_small_block_heap;
}
else {
pregnew->p_next_region = &__old_small_block_heap;
pregnew->p_prev_region = __old_small_block_heap.p_prev_region;
__old_small_block_heap.p_prev_region = pregnew;
pregnew->p_prev_region->p_next_region = pregnew;
}
/*
* Fill in the rest of *pregnew
*/
pregnew->p_pages_begin = ppage;
pregnew->p_pages_end = ppage + _OLD_PAGES_PER_REGION;
pregnew->p_starting_region_map = &(pregnew->region_map[0]);
pregnew->p_first_uncommitted =
&(pregnew->region_map[_OLD_PAGES_PER_COMMITMENT]);
/*
* Initialize pregnew->region_map[].
*/
for ( i = 0 ; i < _OLD_PAGES_PER_REGION ; i++ ) {
if ( i < _OLD_PAGES_PER_COMMITMENT )
pregnew->region_map[i].free_paras_in_page =
_OLD_PARAS_PER_PAGE;
else
pregnew->region_map[i].free_paras_in_page =
_OLD_UNCOMMITTED_PAGE;
pregnew->region_map[i].last_failed_alloc =
_OLD_NO_FAILED_ALLOC;
}
/*
* Initialize pages
*/
memset( ppage, 0, _OLD_PAGESIZE * _OLD_PAGES_PER_COMMITMENT );
while ( ppage < pregnew->p_pages_begin +
_OLD_PAGES_PER_COMMITMENT )
{
ppage->p_starting_alloc_map = &(ppage->alloc_map[0]);
ppage->free_paras_at_start = _OLD_PARAS_PER_PAGE;
(ppage++)->alloc_map[_OLD_PARAS_PER_PAGE] = (__old_page_map_t)-1;
}
/*
* Return success
*/
return pregnew;
}
else {
/*
* Couldn't commit the pages. Release the address space .
*/
VirtualFree( ppage, 0, MEM_RELEASE );
}
}
/*
* Unable to create the new region. Free the region descriptor, if necessary.
*/
if ( pregnew != &__old_small_block_heap )
HeapFree(_crtheap, 0, pregnew);
/*
* Return failure.
*/
return NULL;
}
/***
*void __old_sbh_release_region(preg) - release region
*
*Purpose:
* Release the address space associated with the specified region
* descriptor. Also, free the specified region descriptor and update
* the linked list of region descriptors if appropriate.
*
*Entry:
* __old_sbh_region_t * preg - pointer to descriptor for the region to
* be released.
*
*Exit:
* No return value.
*
*Exceptions:
*
*******************************************************************************/
void __cdecl __old_sbh_release_region(
__old_sbh_region_t * preg
)
{
/*
* Release the passed region
*/
VirtualFree( preg->p_pages_begin, 0, MEM_RELEASE);
/*
* Update __old_sbh_p_starting_region, if necessary
*/
if ( __old_sbh_p_starting_region == preg )
__old_sbh_p_starting_region = preg->p_prev_region;
if ( preg != &__old_small_block_heap ) {
/*
* Update linked list of region descriptors.
*/
preg->p_prev_region->p_next_region = preg->p_next_region;
preg->p_next_region->p_prev_region = preg->p_prev_region;
/*
* Free the region desciptor
*/
HeapFree(_crtheap, 0, preg);
}
else {
/*
* Mark p_pages_begin as _OLD_NO_PAGES to indicate __old_small_block_heap
* is not associated with any region (and can be reused). This the
* only region descriptor for which this is supported.
*/
__old_small_block_heap.p_pages_begin = _OLD_NO_PAGES;
}
}
/***
*void __old_sbh_decommit_pages(count) - decommit specified number of pages
*
*Purpose:
* Decommit count pages, if possible, in reverse (i.e., last to
* first) order. If this results in all the pages in any region being
* uncommitted, the region is released.
*
*Entry:
* int count - number of pages to decommit
*
*Exit:
* No return value.
*
*Exceptions:
*
*******************************************************************************/
void __cdecl __old_sbh_decommit_pages(
int count
)
{
__old_sbh_region_t * preg1;
__old_sbh_region_t * preg2;
__old_region_map_t * pregmap;
int page_decommitted_flag;
int i;
/*
* Scan the regions of the small-block heap, in reverse order. looking
* for pages which can be decommitted.
*/
preg1 = __old_small_block_heap.p_prev_region;
do {
if ( preg1->p_pages_begin != _OLD_NO_PAGES ) {
/*
* Scan the pages in *preg1, in reverse order, looking for
* pages which can be decommitted.
*/
for ( i = _OLD_PAGES_PER_REGION - 1, page_decommitted_flag = 0,
pregmap = &(preg1->region_map[i]) ;
i >= 0 ; i--, pregmap-- )
{
/*
* Check if the pool page is unused and, if so, decommit it.
*/
if ( pregmap->free_paras_in_page == _OLD_PARAS_PER_PAGE ) {
if ( VirtualFree((preg1->p_pages_begin) + i, _OLD_PAGESIZE,
MEM_DECOMMIT) )
{
/*
* Mark the page as uncommitted, update the count
* (global) decommitable pages, update the
* first_uncommitted_index field of the region
* descriptor, set the flag indicating at least
* one page has been decommitted in the region,
* and decrement count.
*/
pregmap->free_paras_in_page = _OLD_UNCOMMITTED_PAGE;
__old_sbh_decommitable_pages--;
if ( (preg1->p_first_uncommitted == NULL)
|| (preg1->p_first_uncommitted > pregmap) )
preg1->p_first_uncommitted = pregmap;
page_decommitted_flag++;
if ( --count == 0 )
break;
}
}
}
/*
* 'Decrement' the preg1 pointer, but save a copy in preg2 in
* case the region needs to be released.
*/
preg2 = preg1;
preg1 = preg1->p_prev_region;
/*
* If appropriate, determine if all the pages in the region
* are uncommitted so that the region can be released.
*/
if ( page_decommitted_flag &&
(preg2->region_map[0].free_paras_in_page ==
_OLD_UNCOMMITTED_PAGE) )
{
for ( i = 1, pregmap = &(preg2->region_map[1]) ;
(i < _OLD_PAGES_PER_REGION) &&
(pregmap->free_paras_in_page ==
_OLD_UNCOMMITTED_PAGE) ;
i++, pregmap++ );
if ( i == _OLD_PAGES_PER_REGION )
__old_sbh_release_region(preg2);
}
}
}
while ( (preg1 != __old_small_block_heap.p_prev_region) && (count > 0) );
}
/***
*__old_page_map_t *__old_sbh_find_block(pblck, ppreg, pppage) - find block in
* small-block heap
*
*Purpose:
* Determine if the specified allocation block lies in the small-block
* heap and, if so, return the region, page and starting paragraph index
* of the block.
*
*Entry:
* void * pblck - pointer to block to be freed
* __old_sbh_region_t ** ppreg - pointer to a pointer to the region
* holding *pblck, if found
* __old_sbh_page_t ** pppage - pointer to a pointer to the page holding
* *pblck, if found
*
*Exit:
* If successful, a pointer to the starting alloc_map[] entry for the
* allocation block is returned.
* If unsuccessful, NULL is returned.
*
*Exceptions:
*
*******************************************************************************/
__old_page_map_t * __cdecl __old_sbh_find_block (
void * pblck,
__old_sbh_region_t ** ppreg,
__old_sbh_page_t ** pppage
)
{
__old_sbh_region_t * preg;
__old_sbh_page_t * ppage;
preg = &__old_small_block_heap;
do
{
/*
* Does the block lie within this small heap region?
*/
if ( (pblck > (void *)preg->p_pages_begin) &&
(pblck < (void *)preg->p_pages_end) )
{
/*
* pblck lies within the region! Carry out a couple of
* important validity checks.
*/
if ( (((uintptr_t)pblck & (_OLD_PARASIZE - 1)) == 0) &&
(((uintptr_t)pblck & (_OLD_PAGESIZE - 1)) >=
offsetof(struct __old_sbh_page_struct, alloc_blocks[0])) )
{
/*
* Copy region and page pointers back through the passed
* pointers.
*/
*ppreg = preg;
*pppage = ppage = (__old_sbh_page_t *)((uintptr_t)pblck &
~(_OLD_PAGESIZE - 1));
/*
* Return pointer to the alloc_map[] entry of the block.
*/
return ( &(ppage->alloc_map[0]) + ((__old_para_t *)pblck -
&(ppage->alloc_blocks[0])) );
}
return NULL;
}
}
while ( (preg = preg->p_next_region) != &__old_small_block_heap );
return NULL;
}
/***
*void __old_sbh_free_block(preg, ppage, pmap) - free block
*
*Purpose:
* Free the specified block from the small-block heap.
*
*Entry:
* __old_sbh_region_t *preg - pointer to the descriptor for the
* region containing the block
* __old_sbh_page_t * ppage - pointer to the page containing the
* block
* __old_page_map_t * pmap - pointer to the initial alloc_map[]
* entry for the allocation block
*
*Exit:
* No return value.
*
*Exceptions:
*
*******************************************************************************/
void __cdecl __old_sbh_free_block (
__old_sbh_region_t * preg,
__old_sbh_page_t * ppage,
__old_page_map_t * pmap
)
{
__old_region_map_t * pregmap;
pregmap = &(preg->region_map[0]) + (ppage - preg->p_pages_begin);
/*
* Update the region_map[] entry.
*/
pregmap->free_paras_in_page += (int)*pmap;
/*
* Mark the alloc_map[] entry as free
*/
*pmap = _OLD_FREE_PARA;
/*
* Clear the last_failed_alloc[] entry for the page.
*/
pregmap->last_failed_alloc = _OLD_NO_FAILED_ALLOC;
/*
* Check if the count of decommitable pages needs to be updated, and
* if some pages need to be decommited.
*/
if ( pregmap->free_paras_in_page == _OLD_PARAS_PER_PAGE )
if ( ++__old_sbh_decommitable_pages == (2 * _OLD_PAGES_PER_COMMITMENT) )
__old_sbh_decommit_pages(_OLD_PAGES_PER_COMMITMENT);
}
/***
*void * __old_sbh_alloc_block(para_req) - allocate a block
*
*Purpose:
* Allocate a block from the small-block heap, the specified number of
* paragraphs in size.
*
*Entry:
* size_t para_req - size of the allocation request in paragraphs.
*
*Exit:
* Returns a pointer to the newly allocated block, if successful.
* Returns NULL, if failure.
*
*Exceptions:
*
*******************************************************************************/
void * __cdecl __old_sbh_alloc_block (
size_t para_req
)
{
__old_sbh_region_t * preg;
__old_sbh_page_t * ppage;
__old_sbh_page_t * ppage2;
__old_region_map_t * pregmap;
__old_region_map_t * pregmap2;
void * retp;
int i, j;
/*
* First pass through the small-block heap. Try to satisfy the current
* request from already committed pages.
*/
preg = __old_sbh_p_starting_region;
do {
if ( preg->p_pages_begin != _OLD_NO_PAGES ) {
/*
* Search from *p_starting_region_map to the end of the
* region_map[] array.
*/
for ( pregmap = preg->p_starting_region_map,
pregmap2 = &(preg->region_map[_OLD_PAGES_PER_REGION]),
ppage = preg->p_pages_begin +
(int)(pregmap - &(preg->region_map[0])) ;
pregmap < pregmap2 ;
pregmap++, ppage++ )
{
/*
* If the page has at least para_req free paragraphs, try
* to satisfy the request in this page.
*/
if ( (pregmap->free_paras_in_page >= (int)para_req) &&
(pregmap->last_failed_alloc > para_req) )
{
if ( (retp = __old_sbh_alloc_block_from_page(
ppage,
pregmap->free_paras_in_page,
para_req)) != NULL )
{
/*
* Success.
* Update __old_sbh_p_starting_region.
* Update free_paras_in_page field for the page.
* Update the p_starting_region_map field in the
* region.
* Return a pointer to the allocated block.
*/
__old_sbh_p_starting_region = preg;
pregmap->free_paras_in_page -= (int)para_req;
preg->p_starting_region_map = pregmap;
return retp;
}
else {
/*
* Update last_failed_alloc field.
*/
pregmap->last_failed_alloc = para_req;
}
}
}
/*
* If necessary, search from 0 page to search_start_index.
*/
for ( pregmap = &(preg->region_map[0]),
pregmap2 = preg->p_starting_region_map,
ppage = preg->p_pages_begin ;
pregmap < pregmap2 ;
pregmap++, ppage++ )
{
/*
* If the page has at least para_req free paragraphs, try
* to satisfy the request in this page.
*/
if ( (pregmap->free_paras_in_page >= (int)para_req) &&
(pregmap->last_failed_alloc > para_req) )
{
if ( (retp = __old_sbh_alloc_block_from_page(
ppage,
pregmap->free_paras_in_page,
para_req)) != NULL )
{
/*
* Success.
* Update __old_sbh_p_starting_region.
* Update free_paras_in_page field for the page.
* Update the p_starting_region_map field in the
* region.
* Return a pointer to the allocated block.
*/
__old_sbh_p_starting_region = preg;
pregmap->free_paras_in_page -= (int)para_req;
preg->p_starting_region_map = pregmap;
return retp;
}
else {
/*
* Update last_failed_alloc field.
*/
pregmap->last_failed_alloc = para_req;
}
}
}
}
}
while ( (preg = preg->p_next_region) != __old_sbh_p_starting_region );
/*
* Second pass through the small-block heap. This time, look for an
* uncommitted page. Also, start at __old_small_block_heap rather than at
* *__old_sbh_p_starting_region.
*/
preg = &__old_small_block_heap;
do
{
if ( (preg->p_pages_begin != _OLD_NO_PAGES) &&
(preg->p_first_uncommitted != NULL) )
{
pregmap = preg->p_first_uncommitted;
ppage = preg->p_pages_begin +
(pregmap - &(preg->region_map[0]));
/*
* Determine how many adjacent pages, up to
* _OLD_PAGES_PER_COMMITMENT, are uncommitted (and can now be
* committed)
*/
for ( i = 0, pregmap2 = pregmap ;
(pregmap2->free_paras_in_page == _OLD_UNCOMMITTED_PAGE) &&
(i < _OLD_PAGES_PER_COMMITMENT) ;
pregmap2++, i++ ) ;
/*
* Commit the pages.
*/
if ( VirtualAlloc( (void *)ppage,
i * _OLD_PAGESIZE,
MEM_COMMIT,
PAGE_READWRITE ) == ppage )
{
/*
* Initialize the committed pages.
*/
memset(ppage, 0, i * _OLD_PAGESIZE);
for ( j = 0, ppage2 = ppage, pregmap2 = pregmap ;
j < i ;
j++, ppage2++, pregmap2++ )
{
/*
* Initialize fields in the page header
*/
ppage2->p_starting_alloc_map = &(ppage2->alloc_map[0]);
ppage2->free_paras_at_start = _OLD_PARAS_PER_PAGE;
ppage2->alloc_map[_OLD_PARAS_PER_PAGE] = (__old_page_map_t)(-1);
/*
* Initialize region_map[] entry for the page.
*/
pregmap2->free_paras_in_page = _OLD_PARAS_PER_PAGE;
pregmap2->last_failed_alloc = _OLD_NO_FAILED_ALLOC;
}
/*
* Update __old_sbh_p_starting_region
*/
__old_sbh_p_starting_region = preg;
/*
* Update the p_first_uncommitted for the region.
*/
while ( (pregmap2 < &(preg->region_map[_OLD_PAGES_PER_REGION]))
&& (pregmap2->free_paras_in_page
!= _OLD_UNCOMMITTED_PAGE) )
pregmap2++;
preg->p_first_uncommitted = (pregmap2 <
&(preg->region_map[_OLD_PAGES_PER_REGION])) ? pregmap2 :
NULL;
/*
* Fulfill the allocation request using the first of the
* newly committed pages.
*/
ppage->alloc_map[0] = (__old_page_map_t)para_req;
/*
* Update the p_starting_region_map field in the region
* descriptor and region_map[] entry for the page.
*/
preg->p_starting_region_map = pregmap;
pregmap->free_paras_in_page -= (int)para_req;
/*
* Update the p_starting_alloc_map and free_paras_at_start
* fields of the page.
*/
ppage->p_starting_alloc_map = &(ppage->alloc_map[para_req]);
ppage->free_paras_at_start -= para_req;
/*
* Return pointer to allocated paragraphs.
*/
return (void *)&(ppage->alloc_blocks[0]);
}
else {
/*
* Attempt to commit the pages failed. Return failure, the
* allocation will be attempted in the Win32 heap manager.
*/
return NULL;
}
}
}
while ( (preg = preg->p_next_region) != &__old_small_block_heap );
/*
* Failure so far. None of the pages have a big enough free area to
* fulfill the pending request. All of the pages in all of the current
* regions are committed. Therefore, try to create a new region.
*/
if ( (preg = __old_sbh_new_region()) != NULL ) {
/*
* Success! A new region has been created and the first few pages
* (_OLD_PAGES_PER_COMMITMENT to be exact) have been committed.
* satisfy the request out of the first page of the new region.
*/
ppage = preg->p_pages_begin;
ppage->alloc_map[0] = (__old_page_map_t)para_req;
__old_sbh_p_starting_region = preg;
ppage->p_starting_alloc_map = &(ppage->alloc_map[para_req]);
ppage->free_paras_at_start = _OLD_PARAS_PER_PAGE - para_req;
(preg->region_map[0]).free_paras_in_page -= (__old_page_map_t)para_req;
return (void *)&(ppage->alloc_blocks[0]);
}
/*
* Everything has failed, return NULL
*/
return NULL;
}
/***
*void * __old_sbh_alloc_block_from_page(ppage, free_para_count, para_req) -
* allocate a block from the given page.
*
*Purpose:
* Allocate a block from the specified page of the small-block heap, of
* the specified number of paragraphs in size.
*
*Entry:
* __old_sbh_page_t * ppage - pointer to a page in the small-block
* heap
* int free_para_count - number of free paragraphs in *ppage
* size_t para_req - size of the allocation request in
* paragraphs.
*
*Exit:
* Returns a pointer to the newly allocated block, if successful.
* Returns NULL, otherwise.
*
*Exceptions:
* It is assumed that free_para_count >= para_req on entry. This must be
* guaranteed by the caller. The behavior is undefined if this condition
* is violated.
*
*******************************************************************************/
void * __cdecl __old_sbh_alloc_block_from_page (
__old_sbh_page_t * ppage,
size_t free_para_count,
size_t para_req
)
{
__old_page_map_t * pmap1;
__old_page_map_t * pmap2;
__old_page_map_t * pstartmap;
__old_page_map_t * pendmap;
size_t contiguous_free;
pmap1 = pstartmap = ppage->p_starting_alloc_map;
pendmap = &(ppage->alloc_map[_OLD_PARAS_PER_PAGE]);
/*
* Start at start_para_index and walk towards the end of alloc_map[],
* looking for a string of free paragraphs big enough to satisfy the
* the current request.
*
* Check if there are enough free paragraphs are p_starting_alloc_map
* to satisfy the pending allocation request.
*/
if ( ppage->free_paras_at_start >= para_req ) {
/*
* Success right off!
* Mark the alloc_map entry with the size of the allocation
* request.
*/
*pmap1 = (__old_page_map_t)para_req;
/*
* Update the p_starting_alloc_map and free_paras_at_start fields
* in the page.
*/
if ( (pmap1 + para_req) < pendmap ) {
ppage->p_starting_alloc_map += para_req;
ppage->free_paras_at_start -= para_req;
}
else {
ppage->p_starting_alloc_map = &(ppage->alloc_map[0]);
ppage->free_paras_at_start = 0;
}
/*
* Derive and return a pointer to the newly allocated
* paragraphs.
*/
return (void *)&(ppage->alloc_blocks[pmap1 -
&(ppage->alloc_map[0])]);
}
/*
* See if the search loop can be started just beyond the paragraphs
* examined above. Note, this test assumes alloc_map[_OLD_PARAS_PER_PAGE]
* != _OLD_FREE_PARA!
*/
if ( *(pmap1 + ppage->free_paras_at_start) != _OLD_FREE_PARA )
pmap1 += ppage->free_paras_at_start;
while ( pmap1 + para_req < pendmap ) {
if ( *pmap1 == _OLD_FREE_PARA ) {
/*
* pmap1 refers to a free paragraph. Determine if there are
* enough free paragraphs contiguous with it to satisfy the
* allocation request. Note that the loop below requires that
* alloc_map[_OLD_PARAS_PER_PAGE] != _OLD_FREE_PARA to guarantee
* termination.
*/
for ( pmap2 = pmap1 + 1, contiguous_free = 1 ;
*pmap2 == _OLD_FREE_PARA ;
pmap2++, contiguous_free++ );
if ( contiguous_free < para_req ) {
/*
* There were not enough contiguous free paragraphs. Do
* a little bookkeeping before going on to the next
* interation.
*/
/* If pmap1 != pstartmap then these free paragraphs
* cannot be revisited.
*/
if ( pmap1 == pstartmap ) {
/*
* Make sure free_paras_at_start is up-to-date.
*/
ppage->free_paras_at_start = contiguous_free;
}
else {
/*
* These free paragraphs will not be revisited!
*/
if ( (free_para_count -= contiguous_free) < para_req )
/*
* There are not enough unvisited free paragraphs
* to satisfy the current request. Return failure
* to the caller.
*/
return NULL;
}
/*
* Update pmap1 for the next iteration of the loop.
*/
pmap1 = pmap2;
}
else {
/*
* Success!
*
* Update the p_starting_alloc_map and free_paras_at_start
* fields in the page.
*/
if ( (pmap1 + para_req) < pendmap ) {
ppage->p_starting_alloc_map = pmap1 + para_req;
ppage->free_paras_at_start = contiguous_free -
para_req;
}
else {
ppage->p_starting_alloc_map = &(ppage->alloc_map[0]);
ppage->free_paras_at_start = 0;
}
/*
* Mark the alloc_map entry with the size of the
* allocation request.
*/
*pmap1 = (__old_page_map_t)para_req;
/*
* Derive and return a pointer to the newly allocated
* paragraphs.
*/
return (void *)&(ppage->alloc_blocks[pmap1 -
&(ppage->alloc_map[0])]);
}
}
else {
/*
* pmap1 points to start of an allocated block in alloc_map[].
* Skip over it.
*/
pmap1 = pmap1 + *pmap1;
}
}
/*
* Now start at index 0 in alloc_map[] and walk towards, but not past,
* index starting_para_index, looking for a string of free paragraphs
* big enough to satisfy the allocation request.
*/
pmap1 = &(ppage->alloc_map[0]);
while ( (pmap1 < pstartmap) &&
(pmap1 + para_req < pendmap) )
{
if ( *pmap1 == _OLD_FREE_PARA ) {
/*
* pmap1 refers to a free paragraph. Determine if there are
* enough free paragraphs contiguous with it to satisfy the
* allocation request.
*/
for ( pmap2 = pmap1 + 1, contiguous_free = 1 ;
*pmap2 == _OLD_FREE_PARA ;
pmap2++, contiguous_free++ );
if ( contiguous_free < para_req ) {
/*
* There were not enough contiguous free paragraphs.
*
* Update the count of unvisited free paragraphs.
*/
if ( (free_para_count -= contiguous_free) < para_req )
/*
* There are not enough unvisited free paragraphs
* to satisfy the current request. Return failure
* to the caller.
*/
return NULL;
/*
* Update pmap1 for the next iteration of the loop.
*/
pmap1 = pmap2;
}
else {
/*
* Success!
*
* Update the p_starting_alloc_map and free_paras_at_start
* fields in the page..
*/
if ( (pmap1 + para_req) < pendmap ) {
ppage->p_starting_alloc_map = pmap1 + para_req;
ppage->free_paras_at_start = contiguous_free -
para_req;
}
else {
ppage->p_starting_alloc_map = &(ppage->alloc_map[0]);
ppage->free_paras_at_start = 0;
}
/*
* Mark the alloc_map entry with the size of the
* allocation request.
*/
*pmap1 = (__old_page_map_t)para_req;
/*
* Derive and return a pointer to the newly allocated
* paragraphs.
*/
return (void *)&(ppage->alloc_blocks[pmap1 -
&(ppage->alloc_map[0])]);
}
}
else {
/*
* pmap1 points to start of an allocated block in alloc_map[].
* Skip over it.
*/
pmap1 = pmap1 + *pmap1;
}
}
/*
* Return failure.
*/
return NULL;
}
/***
*size_t __old_sbh_resize_block(preg, ppage, pmap, new_para_sz) -
* resize block
*
*Purpose:
* Resize the specified block from the small-block heap. The allocation
* block is not moved.
*
*Entry:
* __old_sbh_region_t *preg - pointer to the descriptor for the
* region containing the block
* __old_sbh_page_t * ppage - pointer to the page containing the
* block
* __old_page_map_t * pmap - pointer to the initial alloc_map[]
* entry for the allocation block
* size_t new_para_sz - requested new size for the allocation
* block, in paragraphs.
*
*Exit:
* Returns 1, if successful. Otherwise, 0 is returned.
*
*Exceptions:
*
*******************************************************************************/
int __cdecl __old_sbh_resize_block (
__old_sbh_region_t * preg,
__old_sbh_page_t * ppage,
__old_page_map_t * pmap,
size_t new_para_sz
)
{
__old_page_map_t * pmap2;
__old_page_map_t * pmap3;
__old_region_map_t * pregmap;
size_t old_para_sz;
size_t free_para_count;
int retval = 0;
pregmap = &(preg->region_map[ppage - preg->p_pages_begin]);
if ( (old_para_sz = *pmap) > new_para_sz ) {
/*
* The allocation block is to be shrunk.
*/
*pmap = (__old_page_map_t)new_para_sz;
pregmap->free_paras_in_page += (int)(old_para_sz - new_para_sz);
pregmap->last_failed_alloc = _OLD_NO_FAILED_ALLOC;
retval++;
}
else if ( old_para_sz < new_para_sz ) {
/*
* The allocation block is to be grown to new_para_sz paragraphs
* (if possible).
*/
if ( (pmap + new_para_sz) <= &(ppage->alloc_map[_OLD_PARAS_PER_PAGE]) )
{
/*
* Determine if there are sufficient free paragraphs to
* expand the block to the desired new size.
*/
for ( pmap2 = pmap + old_para_sz,
pmap3 = pmap + new_para_sz ;
(pmap2 < pmap3) && (*pmap2 == _OLD_FREE_PARA) ;
pmap2++ ) ;
if ( pmap2 == pmap3 ) {
/*
* Success, mark the resized allocation
*/
*pmap = (__old_page_map_t)new_para_sz;
/*
* Check whether the p_starting_alloc_map and the
* free_paras_at_start fields need to be updated.
*/
if ( (pmap <= ppage->p_starting_alloc_map) &&
(pmap3 > ppage->p_starting_alloc_map) )
{
if ( pmap3 < &(ppage->alloc_map[_OLD_PARAS_PER_PAGE]) ) {
ppage->p_starting_alloc_map = pmap3;
/*
* Determine how many contiguous free paragraphs
* there are starting a *pmap3. Note, this assumes
* that alloc_map[_OLD_PARAS_PER_PAGE] != _OLD_FREE_PARA.
*/
for ( free_para_count = 0 ; *pmap3 == _OLD_FREE_PARA ;
free_para_count++, pmap3++ ) ;
ppage->free_paras_at_start = free_para_count;
}
else {
ppage->p_starting_alloc_map = &(ppage->alloc_map[0]);
ppage->free_paras_at_start = 0;
}
}
/*
* Update the region_map[] entry.
*/
pregmap->free_paras_in_page += (int)(old_para_sz - new_para_sz);
retval++;
}
}
}
return retval;
}
/***
*void * __old_sbh_heap_check() - check small-block heap
*
*Purpose:
* Perform validity checks on the small-block heap.
*
*Entry:
* There are no arguments.
*
*Exit:
* Returns 0 if the small-block is okay.
* Returns < 0 if the small-block heap has an error. The exact value
* identifies where, in the source code below, the error was detected.
*
*Exceptions:
* There is no protection against memory access error (exceptions).
*
*******************************************************************************/
int __cdecl __old_sbh_heap_check (
void
)
{
__old_sbh_region_t * preg;
__old_sbh_page_t * ppage;
int uncommitted_pages;
int free_paras_in_page;
int contiguous_free_paras;
int starting_region_found;
int p_starting_alloc_map_found;
int i, j, k;
starting_region_found = 0;
preg = &__old_small_block_heap;
do {
if ( __old_sbh_p_starting_region == preg )
starting_region_found++;
if ( (ppage = preg->p_pages_begin) != _OLD_NO_PAGES ) {
/*
* Scan the pages of the region looking for
* inconsistencies.
*/
for ( i = 0, uncommitted_pages = 0,
ppage = preg->p_pages_begin ;
i < _OLD_PAGES_PER_REGION ;
i++, ppage++ )
{
if ( preg->region_map[i].free_paras_in_page ==
_OLD_UNCOMMITTED_PAGE )
{
/*
* Verify the first_uncommitted_index field.
*/
if ( (uncommitted_pages == 0) &&
(preg->p_first_uncommitted !=
&(preg->region_map[i])) )
/*
* Bad first_uncommitted_index field!
*/
return -1;
uncommitted_pages++;
}
else {
if ( ppage->p_starting_alloc_map >=
&(ppage->alloc_map[_OLD_PARAS_PER_PAGE]) )
/*
* Bad p_starting_alloc_map field
*/
return -2;
if ( ppage->alloc_map[_OLD_PARAS_PER_PAGE] !=
(__old_page_map_t)-1 )
/*
* Bad alloc_map[_OLD_PARAS_PER_PAGE] field
*/
return -3;
/*
* Scan alloc_map[].
*/
j = 0;
p_starting_alloc_map_found = 0;
free_paras_in_page = 0;
contiguous_free_paras = 0;
while ( j < _OLD_PARAS_PER_PAGE ) {
/*
* Look for the *p_starting_alloc_map.
*/
if ( &(ppage->alloc_map[j]) ==
ppage->p_starting_alloc_map )
p_starting_alloc_map_found++;
if ( ppage->alloc_map[j] == _OLD_FREE_PARA ) {
/*
* Free paragraph, increment the count.
*/
free_paras_in_page++;
contiguous_free_paras++;
j++;
}
else {
/*
* First paragraph of an allocated block.
*/
/*
* Make sure the preceding free block, if any,
* was smaller than the last_failed_alloc[]
* entry for the page.
*/
if ( contiguous_free_paras >=
(int)preg->region_map[i].last_failed_alloc )
/*
* last_failed_alloc[i] was mismarked!
*/
return -4;
/*
* If this is the end of the string of free
* paragraphs starting at *p_starting_alloc_map,
* verify that free_paras_at_start is
* reasonable.
*/
if ( p_starting_alloc_map_found == 1 ) {
if ( contiguous_free_paras <
(int)ppage->free_paras_at_start )
return -5;
else
/*
* Set flag to 2 so the check is not
* repeated.
*/
p_starting_alloc_map_found++;
}
contiguous_free_paras = 0;
/*
* Scan the remaining paragraphs and make
* sure they are marked properly (they should
* look like free paragraphs).
*/
for ( k = j + 1 ;
k < j + ppage->alloc_map[j] ; k++ )
{
if ( ppage->alloc_map[k] != _OLD_FREE_PARA )
/*
* alloc_map[k] is mismarked!
*/
return -6;
}
j = k;
}
}
if ( free_paras_in_page !=
preg->region_map[i].free_paras_in_page )
/*
* region_map[i] does not match the number of
* free paragraphs in the page!
*/
return -7;
if ( p_starting_alloc_map_found == 0 )
/*
* Bad p_starting_alloc_map field!
*/
return -8;
}
}
}
}
while ( (preg = preg->p_next_region) != &__old_small_block_heap );
if ( starting_region_found == 0 )
/*
* Bad __old_sbh_p_starting_region!
*/
return -9;
return 0;
}
#endif /* CRTDLL */
#endif /* ndef _WIN64 */