Translate from C/C++ to VB

[koobelek]

I'm not C/C++ expert and I've been struggling with converting this
piece of code to VB. I would appreciate any help. Thanks.

/*
* uint16 calcBlockCRC(size_t count, uint16 crc, void *buffer)
*
* ARGUMENTS
* size_t count :Number of bytes in the buffer
* uint16 crc : Preload value of the CRC
* void *buffer : Buffer whose CRC is to be calculated
*
* DESCRIPTION
* This routine is called to calculate the CCITT CRC value of a block
of data.
* RETURNS
* CRC value.
*/

uint16 calcBlockCRC(size_t count, uint16 crc, void *buffer)
{
const uint8 *pBuf = (const uint8*)buffer;

while (count--)
crc = (uint16)((crc >> 8) ^ crcTable[(uint8)(crc ^ *pBuf++)]);
return (crc ^ ((uint16)0xFFFF));
}

[Victor Bazarov]

ko******@hotmail.com wrote:

I'm not C/C++ expert and I've been struggling with converting this
piece of code to VB. I would appreciate any help. Thanks.

/*[...]

Please ask in a Visual Basic newsgroup (any of microsoft.public.vb.*)

V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask

[Alex Buell]

On Mon, 22 May 2006 10:06:56 -0400, I waved a wand and this message
magically appeared from Victor Bazarov:

I'm not C/C++ expert and I've been struggling with converting this
piece of code to VB. I would appreciate any help. Thanks.

/*[...]

Please ask in a Visual Basic newsgroup (any of microsoft.public.vb.*)

Quite right, what he's trying to do is to "dumb down" C++ code. How dare
he!
--
http://www.munted.org.uk

Take a nap, it saves lives.

[Alf P. Steinbach]

* ko******@hotmail.com:

I'm not C/C++ expert and I've been struggling with converting this
piece of code to VB. I would appreciate any help. Thanks.

/*
* uint16 calcBlockCRC(size_t count, uint16 crc, void *buffer)
*
* ARGUMENTS
* size_t count :Number of bytes in the buffer
* uint16 crc : Preload value of the CRC
* void *buffer : Buffer whose CRC is to be calculated
*
* DESCRIPTION
* This routine is called to calculate the CCITT CRC value of a block
of data.
* RETURNS
* CRC value.
*/
First, know that the 'void*' means that this is really bad code, if the
argument order etc. hadn't already told as much.

uint16 calcBlockCRC(size_t count, uint16 crc, void *buffer)
'count' is an integer of the largest size you have in VB.

'crc' is a 16-bit integer.

'buffer' is an array of bytes.

{
const uint8 *pBuf = (const uint8*)buffer;

while (count--)
'count--' means

temp = count;
count = count - 1;
"the value of temp as result"

When the expression produces 0 as result it's regarded as False,
otherwise it's regarded as True.

crc = (uint16)((crc >> 8) ^ crcTable[(uint8)(crc ^ *pBuf++)]);
'>>' is a bitlevel right shift, here 8 bits; same as dividing by 256.

'^' is logical Xor.

'crcTable[...]' is, as you probably already think, array indexing.

'*pBuf++' is analogous to

temp = buffer[bufferIndex];
bufferIndex = bufferIndex + 1;
"the value of temp"

with 'bufferIndex' playing the role of 'pBuf'.

return (crc ^ ((uint16)0xFFFF));
}

'0xFFFF' is an integer value expressed in hexadecimal notation.
--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?

[red floyd]

Alf P. Steinbach wrote:

* ko******@hotmail.com:

I'm not C/C++ expert and I've been struggling with converting this
piece of code to VB. I would appreciate any help. Thanks.

/*
* uint16 calcBlockCRC(size_t count, uint16 crc, void *buffer)
*
* ARGUMENTS
* size_t count :Number of bytes in the buffer
* uint16 crc : Preload value of the CRC
* void *buffer : Buffer whose CRC is to be calculated
*
* DESCRIPTION
* This routine is called to calculate the CCITT CRC value of a block
of data.
* RETURNS
* CRC value.
*/

First, know that the 'void*' means that this is really bad code, if the
argument order etc. hadn't already told as much.

I assume you mean that it should be 'const void *'. Otherwise how would
you pass a generic block of memory to a CRC routine?

[koobelek]

Problem solved. I can post the solution if there is anybody interested.
I never had any problems with understanding the function I posted.
However, I don't know VB very well and I was hoping there might be
somebody
who is familiar with both VB and C/C++ and would like to help me
translating
the function.

Thanks everybody for your input.

Alf P. Steinbach wrote:

* ko******@hotmail.com:

I'm not C/C++ expert and I've been struggling with converting this
piece of code to VB. I would appreciate any help. Thanks.

/*
* uint16 calcBlockCRC(size_t count, uint16 crc, void *buffer)
*
* ARGUMENTS
* size_t count :Number of bytes in the buffer
* uint16 crc : Preload value of the CRC
* void *buffer : Buffer whose CRC is to be calculated
*
* DESCRIPTION
* This routine is called to calculate the CCITT CRC value of a block
of data.
* RETURNS
* CRC value.
*/

First, know that the 'void*' means that this is really bad code, if the
argument order etc. hadn't already told as much.

uint16 calcBlockCRC(size_t count, uint16 crc, void *buffer)

'count' is an integer of the largest size you have in VB.

'crc' is a 16-bit integer.

'buffer' is an array of bytes.

{
const uint8 *pBuf = (const uint8*)buffer;

while (count--)

'count--' means

temp = count;
count = count - 1;
"the value of temp as result"

When the expression produces 0 as result it's regarded as False,
otherwise it's regarded as True.

crc = (uint16)((crc >> 8) ^ crcTable[(uint8)(crc ^ *pBuf++)]);

'>>' is a bitlevel right shift, here 8 bits; same as dividing by 256.

'^' is logical Xor.

'crcTable[...]' is, as you probably already think, array indexing.

'*pBuf++' is analogous to

temp = buffer[bufferIndex];
bufferIndex = bufferIndex + 1;
"the value of temp"

with 'bufferIndex' playing the role of 'pBuf'.

return (crc ^ ((uint16)0xFFFF));
}

'0xFFFF' is an integer value expressed in hexadecimal notation.
--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?

[Alf P. Steinbach]

* ko******@hotmail.com:

[all wrong]

Don't top-post.

Don't quote signatures.

Don't post VB problems in this group.

--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?