dnyArray分析，动态数组分析

procedure setlength(p1,p2,p3,p4);
begin
VarArgStart(VAList);
DynArraySetLength(A, TypeInfo, DimCnt, PNativeInt(VAList));
end;

procedure DynArraySetLength(A, TypeInfo, DimCnt, PNativeInt(VAList));
begin
p := a;
newLength := lengthVec^;
if newLength <= 0 then
if newLength < 0 then
Error(reRangeError);
_DynArrayClear(a, typeInfo);
exit;
oldLength := 0;
if p <> nil then
Dec(PByte(p), SizeOf(TDynArrayRec));
oldLength := PDynArrayRec(p).Length;
Inc(PByte(typeInfo), PDynArrayTypeInfo(typeInfo).name);
elSize := PDynArrayTypeInfo(typeInfo).elSize;
if PDynArrayTypeInfo(typeInfo).elType <> nil then
ElTypeInfo := PDynArrayTypeInfo(typeInfo).elType^
ElTypeInfo := nil;
neededSize := newLength*elSize;
if neededSize div newLength <> elSize then
Error(reRangeError);
Inc(neededSize, SizeOf(TDynArrayRec));
if neededSize < 0 then
Error(reRangeError);
if (p = nil) or (PDynArrayRec(p).RefCnt = 1) then
pp := p;
if (newLength < oldLength) and (ElTypeInfo <> nil) then
FinalizeArray(PByte(p) + SizeOf(TDynArrayRec) + newLength*elSize, ElTypeInfo, oldLength - newLength);
ReallocMem(pp, neededSize);
p := pp;
GetMem(p, neededSize);
minLength := oldLength;
if minLength > newLength then
minLength := newLength;
if ElTypeInfo <> nil then
FillChar((PByte(p) + SizeOf(TDynArrayRec))^, minLength*elSize, 0);
__CopyArray(PByte(p) + SizeOf(TDynArrayRec), a, ElTypeInfo, minLength)
Move(PByte(a)^, (PByte(p) + SizeOf(TDynArrayRec))^, minLength*elSize);
_DynArrayClear(a, typeInfo);
PDynArrayRec(p).RefCnt := 1;
PDynArrayRec(p).Length := newLength;
Inc(PByte(p), SizeOf(TDynArrayRec));
if newLength > oldLength then
FillChar((PByte(p) + elSize * oldLength)^, elSize * (newLength - oldLength), 0);
if dimCnt > 1 then
Inc(lengthVec);
Dec(dimCnt);
i := 0;
try
DynArraySetLength(PPointerArray(p)[i], ElTypeInfo, dimCnt, lengthVec);
Inc(i);
while i < newLength do
_DynArrayClear(PPointerArray(p)[j], typeInfo);
for j := 0 to i  do
_DynArrayClear(p, ElTypeInfo);
raise;
a := p;
end;