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+ optimization in tinyheap's reallocmem for the case when there's not enough

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space after the block, but it becomes enough when the space before the block
  is also reclaimed

git-svn-id: trunk@28786 -
This commit is contained in:
nickysn 2014-10-07 14:36:23 +00:00
parent c279efc9a5
commit d8a9860e92
1 changed files with 55 additions and 11 deletions
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66
rtl/inc/tinyheap.inc
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@ -260,8 +260,8 @@
function SysTinyReAllocMem(var p: pointer; size: ptruint):pointer;
var
oldsize, OldAllocSize, NewAllocSize: ptruint;
after_block, before_block: PTinyHeapBlock;
after_block_size: PtrUInt;
after_block, before_block, before_before_block: PTinyHeapBlock;
after_block_size, before_block_size: PtrUInt;
new_after_block: PTinyHeapBlock;
begin
{$ifdef DEBUG_TINY_HEAP}
@ -306,8 +306,10 @@
before and after our memory block. }
after_block := FreeList;
before_block := nil;
before_before_block := nil;
while (after_block<>HeapPtr) and (TTinyHeapPointerArithmeticType(after_block) < TTinyHeapPointerArithmeticType(p)) do
begin
before_before_block := before_block;
before_block := after_block;
after_block := after_block^.Next;
end;
@ -358,18 +360,60 @@
else
begin
{ is before_block immediately before our block? }
//if assigned(before_block) and (Pointer(TTinyHeapPointerArithmeticType(before_block)+DecodeTinyHeapFreeBlockSize(before_block^.Size))=Pointer(TTinyHeapPointerArithmeticType(p)-SizeOf(TTinyHeapMemBlockSize))) then
// ;
if assigned(before_block) and (Pointer(TTinyHeapPointerArithmeticType(before_block)+DecodeTinyHeapFreeBlockSize(before_block^.Size))=Pointer(TTinyHeapPointerArithmeticType(p)-SizeOf(TTinyHeapMemBlockSize))) then
before_block_size := DecodeTinyHeapFreeBlockSize(before_block^.Size)
else
before_block_size := 0;
result := AllocMem(size);
if result <> nil then
{ if there's enough space, we can slide our current block back and reclaim before_block }
if (before_block_size<NewAllocSize) and ((before_block_size+OldAllocSize+after_block_size)>=NewAllocSize) and
{ todo: implement this also for after_block_size>0 }
(after_block_size>0) then
begin
if oldsize > size then
oldsize := size;
move(pbyte(p)^, pbyte(result)^, oldsize);
if (before_block_size+OldAllocSize+after_block_size)=NewAllocSize then
begin
if after_block=HeapPtr then
begin
HeapPtr := HeapEnd;
if assigned(before_before_block) then
before_before_block^.Next := HeapPtr
else
FreeList := HeapPtr;
end
else
if assigned(before_before_block) then
before_before_block^.Next := after_block^.Next
else
FreeList := after_block^.Next;
end;
Result := Pointer(TTinyHeapPointerArithmeticType(before_block)+SizeOf(TTinyHeapMemBlockSize));
Move(p^, Result^, oldsize);
PTinyHeapMemBlockSize(before_block)^ := size;
if (before_block_size+OldAllocSize+after_block_size)>NewAllocSize then
begin
new_after_block := PTinyHeapBlock(TTinyHeapPointerArithmeticType(before_block)+NewAllocSize);
new_after_block^.Next:=after_block^.Next;
new_after_block^.Size:=EncodeTinyHeapFreeBlockSize(before_block_size+after_block_size-(NewAllocSize-OldAllocSize));
if assigned(before_before_block) then
before_before_block^.Next := new_after_block
else
FreeList := new_after_block;
end;
FillChar((TTinyHeapPointerArithmeticType(Result)+oldsize)^, size-oldsize, 0);
p := Result;
end
else
begin
result := AllocMem(size);
if result <> nil then
begin
if oldsize > size then
oldsize := size;
move(pbyte(p)^, pbyte(result)^, oldsize);
end;
SysTinyFreeMem(p);
p := result;
end;
SysTinyFreeMem(p);
p := result;
end;
end;
end;