_WCRTLINK void _WCNEAR *_nexpand( void _WCNEAR *stg, size_t req_size )
{
struct {
unsigned expanded : 1;
} flags;
int retval;
size_t growth_size;
flags.expanded = 0;
_AccessNHeap();
for( ;; ) {
retval = __HeapManager_expand( _DGroup(),
(unsigned) stg,
req_size,
&growth_size );
if( retval == __HM_SUCCESS ) {
_ReleaseNHeap();
return( stg );
}
if( retval == __HM_FAIL || !__IsCtsNHeap() ) break;
if( retval == __HM_TRYGROW ) {
if( flags.expanded ) break;
if( __ExpandDGROUP( growth_size ) == 0 ) {
break;
}
flags.expanded = 1;
}
}
_ReleaseNHeap();
return( NULL );
}
int __ExpandDGROUP( unsigned amount )
{
#if defined(__WINDOWS__) || defined(__WARP__) || defined(__NT__) \
|| defined(__CALL21__) || defined(__RDOS__)
// first try to free any available storage
_nheapshrink();
return( __CreateNewNHeap( amount ) );
#else
mheapptr p1;
frlptr flp;
unsigned brk_value;
tag *last_tag;
unsigned new_brk_value;
void _WCNEAR *brk_ret;
#if defined(__DOS_EXT__)
if( !__IsCtsNHeap() ) {
return( __CreateNewNHeap( amount ) ); // Won't slice either
}
// Rational non-zero based system should go through.
#endif
if( !__heap_enabled )
return( 0 );
if( _curbrk == ~1u )
return( 0 );
if( __AdjustAmount( &amount ) == 0 )
return( 0 );
#if defined(__DOS_EXT__)
if( _IsPharLap() && !_IsFlashTek() ) {
_curbrk = SegmentLimit();
}
#endif
new_brk_value = amount + _curbrk;
if( new_brk_value < _curbrk ) {
new_brk_value = ~1u;
}
brk_ret = __brk( new_brk_value );
if( brk_ret == (void _WCNEAR *)-1 ) {
return( 0 );
}
brk_value = (unsigned)brk_ret;
if( brk_value > /*0xfff8*/ ~7u ) {
return( 0 );
}
if( new_brk_value <= brk_value ) {
return( 0 );
}
amount = new_brk_value - brk_value;
if( amount - TAG_SIZE > amount ) {
return( 0 );
} else {
amount -= TAG_SIZE;
}
for( p1 = __nheapbeg; p1 != NULL; p1 = p1->next ) {
if( p1->next == NULL )
break;
if( (unsigned)p1 <= brk_value && ((unsigned)p1) + p1->len + TAG_SIZE >= brk_value ) {
break;
}
}
if( (p1 != NULL) && ((brk_value - TAG_SIZE) == (unsigned)( (PTR)p1 + p1->len) ) ) {
/* we are extending the previous heap block (slicing) */
/* nb. account for the end-of-heap tag */
brk_value -= TAG_SIZE;
amount += TAG_SIZE;
flp = (frlptr) brk_value;
/* adjust current entry in heap list */
p1->len += amount;
/* fix up end of heap links */
last_tag = (tag *) ( (PTR)flp + amount );
last_tag[0] = END_TAG;
} else {
if( amount < sizeof( miniheapblkp ) + sizeof( frl ) ) {
/* there isn't enough for a heap block (struct miniheapblkp) and
one free block (frl) */
return( 0 );
}
// Initializing the near heap if __nheapbeg == NULL,
// otherwise, a new mini-heap is getting linked up
p1 = (mheapptr)brk_value;
p1->len = amount;
flp = __LinkUpNewMHeap( p1 );
amount = flp->len;
}
/* build a block for _nfree() */
SET_MEMBLK_SIZE_USED( flp, amount );
++p1->numalloc; /* 28-dec-90 */
p1->largest_blk = ~0; /* set to largest value to be safe */
_nfree( (PTR)flp + TAG_SIZE );
return( 1 );
#endif
}
static int __AdjustAmount( unsigned *amount )
{
unsigned old_amount = *amount;
unsigned amt;
#if !( defined(__WINDOWS__) || defined(__WARP__) || defined(__NT__) )
unsigned last_free_amt;
#endif
amt = old_amount;
amt = __ROUND_UP_SIZE( amt + TAG_SIZE, ROUND_SIZE );
if( amt < old_amount ) {
return( 0 );
}
#if !( defined(__WINDOWS__) || defined(__WARP__) || defined(__NT__) )
#if defined(__DOS_EXT__)
if( !__IsCtsNHeap() ) {
// Allocating extra to identify the dpmi block
amt += sizeof( dpmi_hdr );
} else {
#endif
last_free_amt = __LastFree(); /* adjust for last free block */
if( last_free_amt >= amt ) {
amt = 0;
} else {
amt -= last_free_amt;
}
#if defined(__DOS_EXT__)
}
#endif
#endif
/* amount is even here */
/*
extra amounts (22-feb-91 AFS)
(1) adding a new heap needs:
frl free block req'd for _nmalloc request
(frl is the MINIMUM because the block
may be freed)
tag end of miniheap descriptor
struct miniheapblkp start of miniheap descriptor
(2) extending heap needs:
tag free block req'd for _nmalloc request
*/
*amount = amt;
amt += ( (TAG_SIZE) + sizeof( frl ) + sizeof( miniheapblkp ) );
if( amt < *amount )
return( 0 ); // Report request too large
if( amt < _amblksiz ) {
/*
_amblksiz may not be even so round down to an even number
nb. pathological case: where _amblksiz == 0xffff, we don't
want the usual round up to even
*/
amt = __ROUND_DOWN_SIZE( _amblksiz, 2 );
}
#if defined(__WINDOWS_386__) || defined(__WARP__) || defined(__NT__) \
|| defined(__CALL21__) || defined(__DOS_EXT__) || defined(__RDOS__)
/* make sure amount is a multiple of 4k/64k */
*amount = amt;
amt = __ROUND_UP_SIZE( amt, BLKSIZE_ALIGN );
if( amt < *amount )
return( 0 );
#endif
*amount = amt;
return( *amount != 0 );
}
