;This object creates a list of these elements: ;-labeled code chunks ;-branch instructions ;-unlabelled code following a branch instruction SECTION_ALIGNMENT equ 512 ;PageSize by which segment size can grow ;Segments hold a list of two kinds of elements: CODE_ELEMENT equ 0 BRANCH_ELEMENT equ 1 ;Contains binary data for one or more completely resolved opcodes. CodeElement struct dType dword ? pLabel Pointer ? ;Optional pointer to a Label for the start of this code chunk pBuffer Pointer ? ;Buffer for the binary data dSize dword ? ;#bytes in buffer CodeElement ends ;Represents a logical branch instruction BranchElement struct dType dword ? pLabel Pointer ? dBranchInstruction dd ? pTargetLabel Pointer ? bIsResolved BOOL ? ;Can only be resolved when no unresolved Branches exist between this one and its target BranchElement ends ;Labeled elements can appear anywhere in the list _Label struct pName LPWSTR ? pElement Pointer ? _Label ends Object _Segment, 4354353, DataCollection RedefineMethod Init, Pointer, Pointer RedefineMethod Done RedefineMethod Insert, Pointer ;append an input element to list StaticMethod Emit, Pointer, dword ;spit out some binary code to final output segment StaticMethod FindLabel, LPWSTR ;search for label by name - local to this segment StaticMethod MergeCode,Pointer,Pointer ;join two code elements DefineVariable pName, Pointer, NULL ;Name of this segment (SysAllocString) DefineVariable dFlags, DWORD, NULL ;SEGMENT_XXX flags (see XASM class) DefineVariable pBuffer, Pointer, NULL ;Buffer for final output binary data DefineVariable dSizeAllocated ;Allocated size of above DefineVariable dSizeUsed ;Consumed size of above Embed Labels, DataCollection ;List of labels, local to this segment ObjectEnd Method _Segment.Init, uses esi, pOwner, pName:LPWSTR SetObject esi DbgUStr pName, "Creating Segment" mov [esi].pBuffer,$MemAlloc(SECTION_ALIGNMENT,MEM_INIT_ZERO) mov [esi].dSizeAllocated,SECTION_ALIGNMENT OCall [esi].Labels::DataCollection.Init, esi, 16,256,-1 mov [esi].pName,$invoke(SysAllocString,pName) MethodEnd Method _Segment.Done, uses esi ebx SetObject esi invoke SysFreeString,[esi].pName MemFree [esi].pBuffer xor ebx,ebx .while [esi].Labels.dCount!=0 OCall [esi].Labels::DataCollection.DeleteAt,0 push eax invoke SysFreeString,[eax]._Label.pName pop eax MemFree eax .endw ACall Done MethodEnd Method _Segment.Emit, uses esi, pData, dLen SetObject esi ;check if we have enough memory @@: mov eax,[esi].dSizeAllocated sub eax,[esi].dSizeUsed .if eax>dLen ;no? grow by filesection alignment mov eax,[esi].dSizeAllocated add eax,SECTION_ALIGNMENT push eax MemReAlloc [esi].pBuffer,eax,MEM_INIT_ZERO pop edx .if eax!=0 mov [esi].pBuffer,eax mov [esi].dSizeAllocated,edx .endif jmp @B ;check if we NOW have enough space, usually we will .endif ;copy the data mov eax,[esi].pBuffer add eax,[esi].dSizeUsed invoke RtlMoveMemory,eax,pData,dLen ;increment #used counter mov eax,dLen add [esi].dSizeUsed,eax MethodEnd ;Remarks: If last element is code, and input is unlabelled code, we merge them Method _Segment.Insert,uses esi, pElement SetObject esi mov edx,pElement .if [edx].CodeElement.dType==BRANCH_ELEMENT ACall Insert,pElement .elseif [edx].CodeElement.pLabel==0 ;if this opcode carries no label ;If the last element is a code element mov eax,[esi].dCount dec eax OCall esi.ItemAt,eax .if [eax].CodeElement.dType==CODE_ELEMENT ;Store the input code element's data in the last code element OCall esi.MergeCode,eax,pElement .else ;Append the unlabeled code element ACall Insert,pElement .endif .else ACall Insert,pElement .endif MethodEnd ;Method: Segment.MergeCode ;Purpose: Append an input code element (pSource) to the buffer of existing code element (pTarget) Method _Segment.MergeCode, uses esi edi, pTarget, pSource SetObject esi mov edi, pTarget mov edx,[edi].CodeElement.dSize mov eax, pSource add edx,[eax].CodeElement.dSize MemReAlloc [edi].CodeElement.pBuffer,eax .if eax!=0 mov [edi].CodeElement.pBuffer,eax mov edx,[edi].CodeElement.dSize push edx mov eax, pSource add edx,[eax].CodeElement.dSize mov [edi].CodeElement.dSize,edx pop edx add edx,[edi].CodeElement.pBuffer invoke RtlMoveMemory,edx,[eax].CodeElement.pBuffer,[eax].CodeElement.dSize mov eax,pSource MemFree [eax].CodeElement.pBuffer MemFree pSource mov eax,pTarget .else DbgWarning "Out of memory" int 3 .endif MethodEnd ;Search for Label with matching name Method _Segment.FindLabel, uses esi ebx, pName:LPWSTR SetObject esi xor ebx,ebx .while ebx<[esi].Labels.dCount OCall [esi].Labels::DataCollection.ItemAt,ebx push eax invoke WideCompare,[eax]._Label.pName,pName pop edx .if eax==0 return edx .endif inc ebx .endw xor eax,eax MethodEnd ;Create a new Label... ;Set the Label of a Code or Branch Element by Name Method _Segment.SetLabel, uses esi, pElement, pName SetObject esi OCall esi.FindLabel,pName .if eax!=0 DbgWarning "Error: Attempt to redefine Label detected" int 3 .endif invoke SysAllocString, pName push eax MemAlloc sizeof _Label pop [eax]._Label.pName m2m [eax]._Label.pElement, pElement, edx ;Label points to Element mov [edx].CodeElement.pLabel, eax ;Element points to Label OCall [esi].Labels::DataCollection.Insert,eax MethodEnd ;Determine best branch encodings, finalize segment ;Method Segment.Optimize,uses esi ; ;MethodEnd