size_t __LastFree( void ) /* used by nheapgrow to know about adjustment */ { frlptr p1; unsigned brk_value; if( __nheapbeg == NULL ) { /* no heap? can't have free blocks */ return( 0 ); } p1 = __nheapbeg->freehead.prev; /* point to last free block */ brk_value = (unsigned)((PTR)p1 + p1->len + TAG_SIZE ); #if defined(__DOS_EXT__) if( _IsPharLap() && !__X32VM) _curbrk = SegmentLimit(); /*19-feb-94*/ #endif if( brk_value == _curbrk ) { /* if last free block is at the end */ return( p1->len ); } return( 0 ); }
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 }