[Mono-list] Managed equivalent of memset?

[Frederik Carlier]

Here's the C# code:

The declaration of the struct

    [StructLayout(LayoutKind.Sequential)]
    public struct TidyBuffer
    {
        public IntPtr allocator;  /**< Memory allocator */
        public IntPtr bp;           /**< Pointer to bytes */
        public uint size;         /**< # bytes currently in use */
        public uint allocated;    /**< # bytes allocated */
        public uint next;         /**< Offset of current input position */
    }

Calling setErrorBuffer
            // Assign the error buffer
            errorBuffer = new TidyBuffer();
            TidyWrapper.tidySetErrorBuffer(tidyDoc, errorBuffer);

The declaration of tidySetErrorBuffer
        [DllImport("libtidy")]
        public static extern int tidySetErrorBuffer(IntPtr tdoc,
TidyBuffer errbuf);

And the C equivalent for the buffer
 /** TidyBuffer - A chunk of memory */
 TIDY_STRUCT
 struct _TidyBuffer
 {
 TidyAllocator* allocator;  /**< Memory allocator */
 byte* bp;           /**< Pointer to bytes */
 uint  size;         /**< # bytes currently in use */
 uint  allocated;    /**< # bytes allocated */
 uint  next;         /**< Offset of current input position */
 };

The tidySetErrorBuffer function
int TIDY_CALL tidySetErrorBuffer(TidyDoc tdoc, TidyBuffer * errbuf)

TidyDoc itself is an opaque data type.

Thanks,

Frederik.

Robert Jordan schreef:
> Frederik Carlier wrote:
>   
>> Hi,
>>
>> As a quick introduction, I'm trying to convert a C++.NET wrapper around
>> HTML Tidy to C#, because of the lack of a C++.NET compiler for Linux.
>> I'm by no means an expert in unmanaged code, but things are going well.
>>
>> I am, however, hitting a problem with a struct. The C++ code that
>> initializes the struct reads as follows:
>>
>> [C++]
>> m_errbuf = new TidyBuffer;
>> memset(m_errbuf,0,sizeof(TidyBuffer));
>> tidySetErrorBuffer(m_tdoc,m_errbuf);
>>
>> Re-creating the struct and calling tidySetErrorBuffer is easy enough,
>> but what is the managed equivalent of memset? If I just 'omit' the
>> memset line, I get the following failed assertion:
>>     
>
> Zeroing memory is usually not necessary because structs allocated
> by C# are initialized with zero.
>
>   
>> mono: src/buffio.c:184: tidyBufPutByte: Assertion `buf != ((void *)0)'
>> failed.
>>     
>
> Assertion `buf != ((void *)0)' means that the unmanaged library
> is expecting something != 0 but it got a 0, so your problem is
> most likely not related to memset. Please post some code.
>
> Robert
>
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