求助，能否帮忙解释一下代码，看糊涂了
Public Sub Open()if p_Error=-1 then
p_Error=0
else
Exit Sub
end if
Dim lngRequestSize,binRequestData,strFormItem,strFileItem
Const strSplit="'"">"
lngRequestSize=Request.TotalBytes
if lngRequestSize<1 then
p_Error=3 '文件太小或没有选择文件
Exit Sub
end if
binRequestData=Request.BinaryRead(lngRequestSize)
binForm.Type = 1
binForm.Open
binForm.Write binRequestData
Dim bCrLf,strSeparator,intSeparator
bCrLf=ChrB(13)&ChrB(10)'回车和空格
intSeparator=InstrB(1,binRequestData,bCrLf)-1
strSeparator=LeftB(binRequestData,intSeparator)'提取分隔符回车和空格
Dim p_start,p_end,strItem,strInam,intTemp,strTemp
Dim strFtyp,strFnam,strFext,lngFsiz
p_start=intSeparator+2
Do
p_end =InStrB(p_start,binRequestData,bCrLf&bCrLf)+3
binItem.Type=1
binItem.Open
binForm.Position=p_start
binForm.CopyTo binItem,p_end-p_start
binItem.Position=0
binItem.Type=2
binItem.Charset="gb2312"
strItem=binItem.ReadText
binItem.Close()
p_start=p_end
p_end =InStrB(p_start,binRequestData,strSeparator)-1
binItem.Type=1
binItem.Open
binForm.Position=p_start
lngFsiz=p_end-p_start-2
binForm.CopyTo binItem,lngFsiz
intTemp=Instr(39,strItem,"""")
strInam=Mid(strItem,39,intTemp-39)
if Instr(intTemp,strItem,"filename=""")<>0 then
if not objForm.Exists(strInam&"_From") then
strFileItem=strFileItem&strSplit&strInam
if binItem.Size<>0 then
intTemp=intTemp+13
strFtyp=Mid(strItem,Instr(intTemp,strItem,"Content-Type: ")+14)
strTemp=Mid(strItem,intTemp,Instr(intTemp,strItem,"""")-intTemp)
intTemp=InstrRev(strTemp,"\")
strFnam=Mid(strTemp,intTemp+1)
objForm.Add strInam&"_Type",strFtyp
objForm.Add strInam&"_Name",strFnam
objForm.Add strInam&"_Path",Left(strTemp,intTemp)
objForm.Add strInam&"_Size",lngFsiz
if Instr(intTemp,strTemp,".")<>0 then
strFext=Mid(strTemp,InstrRev(strTemp,".")+1)
else
strFext=""
end if
if left(strFtyp,6)="image/" then
binItem.Position=0
binItem.Type=1
strTemp=binItem.read(10)
if strcomp(strTemp,chrb(255) & chrb(216) & chrb(255) & chrb(224) & chrb(0) & chrb(16) & chrb(74) & chrb(70) & chrb(73) & chrb(70),0)=0 then
if Lcase(strFext)<>"jpg" then strFext="jpg"
binItem.Position=3
do while not binItem.EOS
do
intTemp = ascb(binItem.Read(1))
loop while intTemp = 255 and not binItem.EOS
if intTemp < 192 or intTemp > 195 then
binItem.read(Bin2Val(binItem.Read(2))-2)
else
Exit do
end if
do
intTemp = ascb(binItem.Read(1))
loop while intTemp < 255 and not binItem.EOS
loop
binItem.Read(3)
objForm.Add strInam&"_Height",Bin2Val(binItem.Read(2))
objForm.Add strInam&"_Width",Bin2Val(binItem.Read(2))
elseif strcomp(leftB(strTemp,8),chrb(137) & chrb(80) & chrb(78) & chrb(71) & chrb(13) & chrb(10) & chrb(26) & chrb(10),0)=0 then
if Lcase(strFext)<>"png" then strFext="png"
binItem.Position=18
objForm.Add strInam&"_Width",Bin2Val(binItem.Read(2))
binItem.Read(2)
objForm.Add strInam&"_Height",Bin2Val(binItem.Read(2))
elseif strcomp(leftB(strTemp,6),chrb(71) & chrb(73) & chrb(70) & chrb(56) & chrb(57) & chrb(97),0)=0 or strcomp(leftB(strTemp,6),chrb(71) & chrb(73) & chrb(70) & chrb(56) & chrb(55) & chrb(97),0)=0 then
if Lcase(strFext)<>"gif" then strFext="gif"
binItem.Position=6
objForm.Add strInam&"_Width",BinVal2(binItem.Read(2))
objForm.Add strInam&"_Height",BinVal2(binItem.Read(2))
elseif strcomp(leftB(strTemp,2),chrb(66) & chrb(77),0)=0 then
if Lcase(strFext)<>"bmp" then strFext="bmp"
binItem.Position=18
objForm.Add strInam&"_Width",BinVal2(binItem.Read(4))
objForm.Add strInam&"_Height",BinVal2(binItem.Read(4))
end if
end if
objForm.Add strInam&"_Ext",strFext
objForm.Add strInam&"_From",p_start
intTemp=GetFerr(lngFsiz,strFext)
if p_AutoSave<>2 then
objForm.Add strInam&"_Err",intTemp
if intTemp=0 then
if p_AutoSave=0 then
strFnam=GetTimeStr()
if strFext<>"" then strFnam=strFnam&"."&strFext
end if
binItem.SaveToFile Server.MapPath(p_SavePath&strFnam),2
objForm.Add strInam,strFnam
end if
end if
else
objForm.Add strInam&"_Err",-1
end if
end if
else
binItem.Position=0
binItem.Type=2
binItem.Charset="gb2312"
strTemp=binItem.ReadText
if objForm.Exists(strInam) then
objForm(strInam) = objForm(strInam)&","&strTemp
else
strFormItem=strFormItem&strSplit&strInam
objForm.Add strInam,strTemp
end if
end if
binItem.Close()
p_start = p_end+intSeparator+2
loop Until p_start+3>lngRequestSize
FormItem=split(strFormItem,strSplit)
FileItem=split(strFileItem,strSplit)
End Sub
请解释的详细点，最好每个变量时是什么意思讲一下，这是ASP文件上传的部分代码，被写在一个类中了，先谢谢了!
