VPatch 2.0 final
git-svn-id: https://svn.code.sf.net/p/nsis/code/NSIS/trunk@2798 212acab6-be3b-0410-9dea-997c60f758d6
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245
Contrib/VPatch/Source/GenPat/TreeCode.pas
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245
Contrib/VPatch/Source/GenPat/TreeCode.pas
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unit TreeCode;
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{
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VPatch 2 - Binary Checksum Tree
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===============================
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(c) 2002-2003 Van de Sande Productions
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This unit implements a binary search tree, which is constructed from a memory
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block by BuildTree. This memory block is divided into equal-sized blocks of
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BlockSize, and for every block a checksum is calculated. Then, it is inserted
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in the binary tree, which is sorted on the checksum.
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The patch generator will search for the checksums using a binary search, which
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is O(log n) (much better than the old 1.x algoritm, which was O(n)).
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What's new
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----------
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2.0 20030811 Koen Initial documentation
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}
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interface
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type
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TSortStack=record
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lo,hi: Integer;
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end;
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PTreeNode = ^TTreeNode;
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TTreeNode = record
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Checksum: Cardinal;
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Offset: Cardinal;
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end;
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const
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TREENODE_SIZE = SizeOf(TTreeNode);
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procedure calculateChecksum(AData: Pointer; AStart, ASize: Cardinal; var K: Cardinal);
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procedure calculateNext(AData: Pointer; AStart, ASize: Cardinal; var K: Cardinal);
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function BuildTree(ASource: Pointer; var ATree: Pointer; ASourceSize, ABLOCKSIZE: Cardinal): Cardinal;
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procedure SortTree(ATree: Pointer; ANodeCount: Cardinal);
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procedure ClearTree(var ATree: Pointer; ANodeCount: Cardinal);
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function TreeFind(AChecksum: Cardinal; ABlockTree: Pointer; ABlockTreeNodeCount: Integer; var FoundCount: Integer): PTreeNode;
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function GetItem(ATree: Pointer; Index, ANodeCount: Cardinal): TTreeNode;
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procedure Test;
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implementation
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uses SysUtils;
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procedure calculateChecksum(AData: Pointer; AStart, ASize: Cardinal; var K: Cardinal);
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var
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A,B,i,j: Cardinal;
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begin
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A:=K and $0000FFFF;
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B:=(K and $FFFF0000) shr 16;
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j:=Cardinal(AData)+AStart;
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for i:=1 to ASize do begin
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A:=A + PByte(j)^;
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B:=B + (ASize-i+1)*PByte(j)^;
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Inc(j);
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end;
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K:=(A and $0000FFFF) or ((B and $0000FFFF) shl 16);
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end;
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procedure calculateNext(AData: Pointer; AStart, ASize: Cardinal; var K: Cardinal);
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var
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A,B,j: Cardinal;
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begin
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j:=Cardinal(AData)+AStart;
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A:=(K-PByte(j-1)^+PByte(j+ASize-1)^) and $0000FFFF;
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B:=((K shr 16)-ASize*PByte(j-1)^+A) and $0000FFFF;
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K:=A or (B shl 16);
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end;
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function BuildTree(ASource: Pointer; var ATree: Pointer; ASourceSize, ABLOCKSIZE: Cardinal): Cardinal;
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var
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i, NodeCount: Cardinal;
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Node: TTreeNode;
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begin
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Assert(not Assigned(ATree),'Cannot use initialized tree in BuildTree!');
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NodeCount:=ASourceSize div ABLOCKSIZE;
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GetMem(ATree,NodeCount*TREENODE_SIZE);
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if NodeCount > 0 then begin
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for i:=0 to Pred(NodeCount) do begin
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Node.Offset:=i*ABLOCKSIZE;
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Node.Checksum:=0;
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calculateChecksum(ASource,Node.Offset,ABLOCKSIZE,Node.Checksum);
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Move(Node,Pointer(Cardinal(ATree)+i*TREENODE_SIZE)^,TREENODE_SIZE);
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end;
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end;
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Result:=NodeCount;
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end;
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procedure SetItem(ATree: Pointer; Index, ANodeCount: Cardinal; New: TTreeNode);
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var
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p: PTreeNode;
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begin
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Assert(Index<ANodeCount,'Tree/GetItem: Index too big');
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p:=PTreeNode(Cardinal(ATree)+Index*TREENODE_SIZE);
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p^:=New;
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end;
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function GetItem(ATree: Pointer; Index, ANodeCount: Cardinal): TTreeNode;
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var
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p: PTreeNode;
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begin
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Assert(Index<ANodeCount,'Tree/GetItem: Index too big '+IntToStr(Index));
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p:=PTreeNode(Cardinal(ATree)+Index*TREENODE_SIZE);
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Result:=p^;
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end;
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procedure SortTree(ATree: Pointer; ANodeCount: Cardinal);
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var
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compare: Cardinal;
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aStack: Array[1..128] of TSortStack;
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StackPtr: Integer;
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Mid,i,j,low,hi: Integer;
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Switcher: TTreeNode;
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begin
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If ANodeCount = 0 Then Exit;
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StackPtr:=1;
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aStack[StackPtr].lo:=0;
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aStack[StackPtr].hi:=ANodeCount - 1;
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Inc(StackPtr);
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while not (StackPtr=1) do begin
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StackPtr:=StackPtr-1;
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low:=aStack[StackPtr].lo;
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hi:=aStack[StackPtr].hi;
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while true do begin
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i:=low;
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j:=hi;
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Mid:=(low + hi) div 2;
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compare:=PTreeNode(Integer(ATree)+Mid*TREENODE_SIZE)^.Checksum;
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while true do begin
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While PTreeNode(Integer(ATree)+i*TREENODE_SIZE)^.Checksum < compare do begin
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Inc(i);
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end;
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While PTreeNode(Integer(ATree)+j*TREENODE_SIZE)^.Checksum > compare do begin
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j:=j-1;
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end;
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If (i <= j) Then begin
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Move(Pointer(Integer(ATree)+j*TREENODE_SIZE)^,Switcher,TREENODE_SIZE);
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Move(Pointer(Integer(ATree)+i*TREENODE_SIZE)^,Pointer(Integer(ATree)+j*TREENODE_SIZE)^,TREENODE_SIZE);
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Move(Switcher,Pointer(Integer(ATree)+i*TREENODE_SIZE)^,TREENODE_SIZE);
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Inc(i);
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Dec(j);
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End;
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if not (i <= j) then break;
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end;
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If j - low < hi - i Then begin
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If i < hi Then begin
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aStack[StackPtr].lo:=i;
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aStack[StackPtr].hi:=hi;
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Inc(StackPtr);
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End;
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hi:=j;
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end Else begin
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If low < j Then begin
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aStack[StackPtr].lo:=low;
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aStack[StackPtr].hi:=j;
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Inc(StackPtr);
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End;
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low:=i;
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End;
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if not (low<hi) then break;
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end;
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if StackPtr=1 then break;
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end;
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end;
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procedure ClearTree(var ATree: Pointer; ANodeCount: Cardinal);
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begin
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FreeMem(ATree,ANodeCount*TREENODE_SIZE);
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ATree:=nil;
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end;
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function TreeFind(AChecksum: Cardinal; ABlockTree: Pointer; ABlockTreeNodeCount: Integer; var FoundCount: Integer): PTreeNode;
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var
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lo,mid,hi,m: Integer;
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tmp: Cardinal;
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begin
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lo:=0;
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hi:=ABlockTreeNodeCount-1;
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while true do begin
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mid:=(lo+hi) div 2;
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tmp:=PCardinal(Integer(ABlockTree)+mid*TREENODE_SIZE)^;
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if tmp = AChecksum then begin
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FoundCount:=1;
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m:=mid;
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Result:=PTreeNode(Integer(ABlockTree)+m*TREENODE_SIZE);
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while m > 0 do begin
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Dec(m);
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if PCardinal(Integer(ABlockTree)+m*TREENODE_SIZE)^ = tmp then begin
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Result:=PTreeNode(Integer(ABlockTree)+m*TREENODE_SIZE);
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Inc(FoundCount);
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end else
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Break;
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end;
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m:=mid;
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while m < ABlockTreeNodeCount-1 do begin
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Inc(m);
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if PCardinal(Integer(ABlockTree)+m*TREENODE_SIZE)^ = tmp then begin
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Inc(FoundCount);
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end else
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Break;
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end;
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Exit;
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end;
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if lo>=hi then Break;
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if AChecksum < tmp then begin
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hi:=mid-1;
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end else begin
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lo:=mid+1;
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end;
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end;
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FoundCount:=0; Result:=nil;
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end;
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procedure Test;
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var
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p: Pointer;
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t: TTreeNode;
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r: PTreeNode;
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i,q: Integer;
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NC: Integer;
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begin
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NC:=100;
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GetMem(p,800);
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for i:=0 to 99 do begin
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t.Offset:=i*100;
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t.Checksum:=i div 2;
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SetItem(p,i,NC,t);
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end;
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SortTree(p,NC);
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for i:=0 to 99 do begin
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t:=GetItem(p,i,NC);
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Write(IntToStr(t.Checksum)+' ');
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end;
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r:=TreeFind(7,p,NC,q);
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WriteLn(IntToStr(q));
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t:=r^;
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WriteLn(IntToStr(t.Checksum)+' ');
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end;
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end.
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