Re: To cast or not to cast?

Though fixed won't allocate any memory for you, so you're still where you
were before.

-Chris


""Ilya Tumanov [MS]"" <ilyatum@xxxxxxxxxxxxxxxxxxxx> wrote in message
news:MFm$3ThPFHA.1564@xxxxxxxxxxxxxxxxxxxxxxxx
> You don't need to do anything to pin memory with fixed(), fixed() will do
> it for you:
>
> fixed(void *ArrayPointer = MyManagedArray) {
> // MyManagedArray is pinned within fixed block and ArrayPointer points to
> it.
> // Assign it to IntPtr (might need some casting) and call native function
> within this block.
> }
>
> // MyManagedArray in longer pinned...
>
> Best regards,
>
> Ilya
>
> This posting is provided "AS IS" with no warranties, and confers no
> rights.
> --------------------
>> From: "Jeremy" <jezonline@xxxxxxxxxxx>
>> References: <umEpDi8OFHA.3880@xxxxxxxxxxxxxxxxxxxx>
> <64$0lp9OFHA.1564@xxxxxxxxxxxxxxxxxxxxx>
> <#t8wc#BPFHA.1268@xxxxxxxxxxxxxxxxxxxx>
> <tz30okGPFHA.920@xxxxxxxxxxxxxxxxxxxxx>
> <eTuV9uUPFHA.2568@xxxxxxxxxxxxxxxxxxxx>
> <SN73xxVPFHA.920@xxxxxxxxxxxxxxxxxxxxx>
> <#Hr63aWPFHA.3336@xxxxxxxxxxxxxxxxxxxx>
> <VMZf79WPFHA.920@xxxxxxxxxxxxxxxxxxxxx>
>> Subject: Re: To cast or not to cast?
>> Date: Sun, 10 Apr 2005 20:37:43 +0100
>> Lines: 335
>> X-Priority: 3
>> X-MSMail-Priority: Normal
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>> Message-ID: <Oo3kPTgPFHA.580@xxxxxxxxxxxxxxxxxxxx>
>> Newsgroups: microsoft.public.dotnet.framework.compactframework
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>> Xref: TK2MSFTNGXA01.phx.gbl
> microsoft.public.dotnet.framework.compactframework:26681
>> X-Tomcat-NG: microsoft.public.dotnet.framework.compactframework
>>
>> I did a little bit of research because I'm a newbie regarding
>> pointers/memory allocation. I found an interesting post by Brian Smith:
>>
> http://groups-beta.google.com/group/microsoft.public.dotnet.framework.compac
> tframework/browse_frm/thread/d628847ac90ac8a3/b92cb386364174f7?q=unmanaged+a
> llocate+memory&rnum=10#b92cb386364174f7
>>
>> I supose I could use LocalAlloc to allocate memory. The post seems to be
>> similar to my problem but I still don't understand how to pin managed
> memory
>> (by using Fixed()?), and have a pointer point to the byte array (which
>> is
>> probably what I would want to do) ?
>>
>> your help is really appreciated!
>>
>> ""Ilya Tumanov [MS]"" <ilyatum@xxxxxxxxxxxxxxxxxxxx> wrote in message
>> news:VMZf79WPFHA.920@xxxxxxxxxxxxxxxxxxxxxxxx
>> > Creating a new pointer is not enough. You need to allocate memory and
>> > assign value pointing to it to the pointer.
>> > You might allocate native memory via P/Invoke (which you would have to
>> free
>> > at some point).
>> > Or, you can obtain a pointer to a managed array you already have.
>> > Before you pass this pointer to a native code, you have to pin managed
>> > memory so GC won't move the array.
>> > You can use GCHandle class for it or you can use unsafe code.
>> > I would recommend using Fixed() with unsafe pointer. That would pin and
>> > unpin the array automatically.
>> > GCHandle has a bug (returns incorrect pointer - there's a workaround)
> and
>> > it's not automatic.
>> >
>> > Best regards,
>> >
>> > Ilya
>> >
>> > This posting is provided "AS IS" with no warranties, and confers no
>> rights.
>> >
>> > --------------------
>> > > From: "Jeremy" <jezonline@xxxxxxxxxxx>
>> > > References: <umEpDi8OFHA.3880@xxxxxxxxxxxxxxxxxxxx>
>> > <64$0lp9OFHA.1564@xxxxxxxxxxxxxxxxxxxxx>
>> > <#t8wc#BPFHA.1268@xxxxxxxxxxxxxxxxxxxx>
>> > <tz30okGPFHA.920@xxxxxxxxxxxxxxxxxxxxx>
>> > <eTuV9uUPFHA.2568@xxxxxxxxxxxxxxxxxxxx>
>> > <SN73xxVPFHA.920@xxxxxxxxxxxxxxxxxxxxx>
>> > > Subject: Re: To cast or not to cast?
>> > > Date: Sun, 10 Apr 2005 01:46:03 +0100
>> > > Lines: 240
>> > > X-Priority: 3
>> > > X-MSMail-Priority: Normal
>> > > X-Newsreader: Microsoft Outlook Express 6.00.2800.1478
>> > > X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1478
>> > > Message-ID: <#Hr63aWPFHA.3336@xxxxxxxxxxxxxxxxxxxx>
>> > > Newsgroups: microsoft.public.dotnet.framework.compactframework
>> > > NNTP-Posting-Host: host-84-9-101-26.bulldogdsl.com 84.9.101.26
>> > > Path: TK2MSFTNGXA01.phx.gbl!TK2MSFTNGP08.phx.gbl!TK2MSFTNGP10.phx.gbl
>> > > Xref: TK2MSFTNGXA01.phx.gbl
>> > microsoft.public.dotnet.framework.compactframework:26658
>> > > X-Tomcat-NG: microsoft.public.dotnet.framework.compactframework
>> > >
>> > > Okay, so I used the 1040 length, it doesn't seem to complain, which
>> > > is
>> > good
>> > > news I guess. To make sure it stores the data correctly I'm trying to
>> > > retrieve it and feed it back to the biometric template matching
> method.
>> > >
>> > > Because it takes IntPtr's for BiometricData and Signature, I tried
>> > creating
>> > > new pointers and marshal copy the content that I retrieved earlier
> into
>> > > these pointers. I failed. I tried the following:
>> > >
>> > > System.IntPtr BiometricDataPtr;//create new pointer
>> > > BiometricData = (byte[])bioData[8];//BiometricData is an array of
>> > > type
>> > byte
>> > > Marshal.Copy(BiometricData, 0, BiometricDataPtr, 1040);//copy content
> of
>> > > BiometricData in an IntPtr
>> > >
>> > > "Use of unassigned local variable 'BiometricDataPtr'."
>> > > Obvsiously it's unused, it's meant to point to something... what am I
>> > > missing here?
>> > >
>> > > ""Ilya Tumanov [MS]"" <ilyatum@xxxxxxxxxxxxxxxxxxxx> wrote in message
>> > > news:SN73xxVPFHA.920@xxxxxxxxxxxxxxxxxxxxxxxx
>> > > > You should not guess the length, you should know it. It might be
> fixed
>> > or
>> > > > native code could return it somehow.
>> > > > Most likely you're correct and FirstBIRSample.Length contains this
>> size.
>> > > > You should check out the documentation for the function you're
> calling
>> > to
>> > > > make sure it's correct.
>> > > >
>> > > > If value of a pointer is 0, it's null pointer. It means this
>> > > > pointer
>> is
>> > > not
>> > > > valid and points to nothing.
>> > > > Since no data is available, you could store it as DBNull.
>> > > >
>> > > > Best regards,
>> > > >
>> > > > Ilya
>> > > >
>> > > > This posting is provided "AS IS" with no warranties, and confers no
>> > > rights.
>> > > >
>> > > > --------------------
>> > > > > From: "Jeremy" <jezonline@xxxxxxxxxxx>
>> > > > > References: <umEpDi8OFHA.3880@xxxxxxxxxxxxxxxxxxxx>
>> > > > <64$0lp9OFHA.1564@xxxxxxxxxxxxxxxxxxxxx>
>> > > > <#t8wc#BPFHA.1268@xxxxxxxxxxxxxxxxxxxx>
>> > > > <tz30okGPFHA.920@xxxxxxxxxxxxxxxxxxxxx>
>> > > > > Subject: Re: To cast or not to cast?
>> > > > > Date: Sat, 9 Apr 2005 22:32:29 +0100
>> > > > > Lines: 159
>> > > > > X-Priority: 3
>> > > > > X-MSMail-Priority: Normal
>> > > > > X-Newsreader: Microsoft Outlook Express 6.00.2800.1478
>> > > > > X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1478
>> > > > > Message-ID: <eTuV9uUPFHA.2568@xxxxxxxxxxxxxxxxxxxx>
>> > > > > Newsgroups: microsoft.public.dotnet.framework.compactframework
>> > > > > NNTP-Posting-Host: host-84-9-101-26.bulldogdsl.com 84.9.101.26
>> > > > > Path:
>> TK2MSFTNGXA01.phx.gbl!TK2MSFTNGP08.phx.gbl!TK2MSFTNGP14.phx.gbl
>> > > > > Xref: TK2MSFTNGXA01.phx.gbl
>> > > > microsoft.public.dotnet.framework.compactframework:26653
>> > > > > X-Tomcat-NG: microsoft.public.dotnet.framework.compactframework
>> > > > >
>> > > > > Thanks a lot for that! Before going to the UInt16 problem, I
> better
>> > try
>> > > to
>> > > > > solve that IntPtr problem.
>> > > > >
>> > > > > Managed to use Marshal.Copy. Not sure how I should 'guess' the
>> length
>> > of
>> > > > the
>> > > > > Byte array to copy to. When I type FirstBIRSample.BiometricData
>> (which
>> > > is
>> > > > > the IntPtr) in the command window, it returns to me: 2372256 - is
>> this
>> > > the
>> > > > > size?
>> > > > > I 'assumed' the size would be 1040 (which is stored in
>> > > > > FirstBIRSample.Length).
>> > > > >
>> > > > > Second Part: Seems like the FirstBIRSample.Signature (also a
>> pointer)
>> > is
>> > > > 0,
>> > > > > how should I store this?
>> > > > >
>> > > > > Thanks so much!
>> > > > >
>> > > > > ""Ilya Tumanov [MS]"" <ilyatum@xxxxxxxxxxxxxxxxxxxx> wrote in
>> message
>> > > > > news:tz30okGPFHA.920@xxxxxxxxxxxxxxxxxxxxxxxx
>> > > > > > While storing UInt16 as Int is OK, it will take more space. The
>> > > problem
>> > > > > > you're having is caused by range check. You might consider
>> > > > > > using
>> > > > > > unchecked() to disable it.
>> > > > > >
>> > > > > > System.Runtime.InteropServices.Marshal class allows you to copy
>> data
>> > > > from
>> > > > > > the pointer to the array. Look into Copy() methods of that
> class.
>> > > > > >
>> > > > > > Best regards,
>> > > > > >
>> > > > > > Ilya
>> > > > > >
>> > > > > > This posting is provided "AS IS" with no warranties, and
>> > > > > > confers
>> no
>> > > > > rights.
>> > > > > > --------------------
>> > > > > > > From: "Jeremy" <jezonline@xxxxxxxxxxx>
>> > > > > > > References: <umEpDi8OFHA.3880@xxxxxxxxxxxxxxxxxxxx>
>> > > > > > <64$0lp9OFHA.1564@xxxxxxxxxxxxxxxxxxxxx>
>> > > > > > > Subject: Re: To cast or not to cast?
>> > > > > > > Date: Fri, 8 Apr 2005 10:44:39 +0100
>> > > > > > > Lines: 91
>> > > > > > > X-Priority: 3
>> > > > > > > X-MSMail-Priority: Normal
>> > > > > > > X-Newsreader: Microsoft Outlook Express 6.00.2800.1478
>> > > > > > > X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1478
>> > > > > > > Message-ID: <#t8wc#BPFHA.1268@xxxxxxxxxxxxxxxxxxxx>
>> > > > > > > Newsgroups:
>> > > > > > > microsoft.public.dotnet.framework.compactframework
>> > > > > > > NNTP-Posting-Host: host-84-9-101-26.bulldogdsl.com
>> > > > > > > 84.9.101.26
>> > > > > > > Path:
>> > > TK2MSFTNGXA01.phx.gbl!TK2MSFTNGP08.phx.gbl!TK2MSFTNGP14.phx.gbl
>> > > > > > > Xref: TK2MSFTNGXA01.phx.gbl
>> > > > > > microsoft.public.dotnet.framework.compactframework:26572
>> > > > > > > X-Tomcat-NG:
> microsoft.public.dotnet.framework.compactframework
>> > > > > > >
>> > > > > > > Thanks so much for the replies Alex and Ilya!
>> > > > > > >
>> > > > > > > I changed the types in sql. It wasn't happy with Uint16
>> > > > > > > mapped
>> to
>> > > > > smallint
>> > > > > > > (sql says value is either too small or too large), so I just
>> went
>> > > for
>> > > > an
>> > > > > > > int.
>> > > > > > >
>> > > > > > > Not sure how to retrieve the data data an IntPtr is pointing
> to
>> > > > though.
>> > > > > > How
>> > > > > > > can I get that data as a byte array?
>> > > > > > >
>> > > > > > > thanks so much again!
>> > > > > > >
>> > > > > > > ""Ilya Tumanov [MS]"" <ilyatum@xxxxxxxxxxxxxxxxxxxx> wrote in
>> > > message
>> > > > > > > news:64$0lp9OFHA.1564@xxxxxxxxxxxxxxxxxxxxxxxx
>> > > > > > > >
>> > > > > > >
>> > > > > >
>> > > > >
>> > > >
>> > >
>> >
>>
> http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/
>> > > > > > > > frlrfsystemdatasqldbtypeclasstopic.asp
>> > > > > > > >
>> > > > > > > > UInt32: Int will do. Signed and Unsigned integers are
> actually
>> > the
>> > > > > same;
>> > > > > > > > just cast them to the right type.
>> > > > > > > > UInt16: SmallInt, see warning above
>> > > > > > > > Byte: TinyInt
>> > > > > > > > BioAPI_*: look up underlying type definition and use it.
> Enums
>> > are
>> > > > > Int32
>> > > > > > > by
>> > > > > > > > default.
>> > > > > > > > IntPtr: it's Int32, so store it as Int.
>> > > > > > > >
>> > > > > > > > Note, however, it's probably pointless to store pointers in
>> the
>> > > data
>> > > > > > base.
>> > > > > > > > Pointer itself is not important, most likely you need to
> store
>> > > > > whatever
>> > > > > > > > it's pointing to.
>> > > > > > > >
>> > > > > > > > Best regards,
>> > > > > > > >
>> > > > > > > > Ilya
>> > > > > > > >
>> > > > > > > > This posting is provided "AS IS" with no warranties, and
>> confers
>> > > no
>> > > > > > > rights.
>> > > > > > > >
>> > > > > > > > --------------------
>> > > > > > > > > From: "Jeremy" <jezonline@xxxxxxxxxxx>
>> > > > > > > > > Subject: To cast or not to cast?
>> > > > > > > > > Date: Fri, 8 Apr 2005 00:21:17 +0100
>> > > > > > > > > Lines: 25
>> > > > > > > > > X-Priority: 3
>> > > > > > > > > X-MSMail-Priority: Normal
>> > > > > > > > > X-Newsreader: Microsoft Outlook Express 6.00.2800.1478
>> > > > > > > > > X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1478
>> > > > > > > > > Message-ID: <umEpDi8OFHA.3880@xxxxxxxxxxxxxxxxxxxx>
>> > > > > > > > > Newsgroups:
>> microsoft.public.dotnet.framework.compactframework
>> > > > > > > > > NNTP-Posting-Host: host-84-9-101-26.bulldogdsl.com
>> 84.9.101.26
>> > > > > > > > > Path:
>> > > > > TK2MSFTNGXA01.phx.gbl!TK2MSFTNGP08.phx.gbl!tk2msftngp13.phx.gbl
>> > > > > > > > > Xref: TK2MSFTNGXA01.phx.gbl
>> > > > > > > > microsoft.public.dotnet.framework.compactframework:26546
>> > > > > > > > > X-Tomcat-NG:
>> > microsoft.public.dotnet.framework.compactframework
>> > > > > > > > >
>> > > > > > > > > Hi,
>> > > > > > > > >
>> > > > > > > > > I'm trying to convert the following types into types that
> I
>> > can
>> > > > > insert
>> > > > > > > in
>> > > > > > > > an
>> > > > > > > > > SQL database (via a webservice). None of these however
>> > > > > > > > > are
>> > > > accepted
>> > > > > by
>> > > > > > > Sql
>> > > > > > > > > (i.e., there is no OleDbType for them). I could only use
>> > integer
>> > > > > type
>> > > > > > > for
>> > > > > > > > > UInt32, that's about it. I'm totally unsure about the
> other
>> > > types.
>> > > > > > What
>> > > > > > > > I've
>> > > > > > > > > tried doing so far is casting them prior to sending them
> to
>> > the
>> > > > > > > > webservice.
>> > > > > > > > > When inserting them I get errors though. Would anyone
>> > know/could
>> > > > > point
>> > > > > > > me
>> > > > > > > > to
>> > > > > > > > > types that I could use? Any help would be really
>> appreciated,
>> > > i'm
>> > > > > > lost!
>> > > > > > > > >
>> > > > > > > > > Thanks so much!
>> > > > > > > > >
>> > > > > > > > >
>> > > > > > > > > System.UInt32 Length;
>> > > > > > > > > System.Byte HeaderVersion;
>> > > > > > > > > BioAPI_BIR_DATA_TYPE Type;
>> > > > > > > > > System.UInt16 FormatOwner;
>> > > > > > > > > System.UInt16 FormatID;
>> > > > > > > > > System.Byte Quality; /*INT8 BioAPI_QUALITY*/
>> > > > > > > > > BioAPI_BIR_PURPOSE Purpose;
>> > > > > > > > > BioAPI_BIR_AUTH_FACTORS FactorsMask;
>> > > > > > > > > System.IntPtr BiometricData;
>> > > > > > > > > System.IntPtr Signature;
>> > > > > > > > >
>> > > > > > > > >
>> > > > > > > > >
>> > > > > > > >
>> > > > > > >
>> > > > > > >
>> > > > > > >
>> > > > > >
>> > > > >
>> > > > >
>> > > > >
>> > > >
>> > >
>> > >
>> > >
>> >
>>
>>
>>
>


.

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