Re: How to get/put(VARIANT newVal) ?? - C / C++ / MFC Discussion Boards

Hamid_RT9-Jan-09 1:22

9-Jan-09 1:22

I could said where's your question or why did you delete your question
but I said thanks,it was equivocal(thanks doesnt have real mean here Wink | ;)

Of one Essence is the human race
thus has Creation put the base
One Limb impacted is sufficient
For all Others to feel the Mace
(Saadi )

Re: [Message Deleted]

toxcct9-Jan-09 1:24

toxcct

9-Jan-09 1:24

oh, that was rethorical... I thought you knew much than me Smile | :)

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Re: [Message Deleted]

Hamid_RT9-Jan-09 1:35

Hamid_RT

9-Jan-09 1:35

Of one Essence is the human race
thus has Creation put the base
One Limb impacted is sufficient
For all Others to feel the Mace
(Saadi )

Re: [Message Deleted]

Stuart Dootson9-Jan-09 1:24

Stuart Dootson

9-Jan-09 1:24

The OP was setting WS_EX_LAYOUT_RTL on a (to be created) window in PreCreateWindow, but he had some (unstated) issue with it - which is why I asked him to describe what he was expecting vs what he saw.

Re: [Message Deleted]

Hamid_RT9-Jan-09 1:35

Hamid_RT

9-Jan-09 1:35

Thanks for your reply.
Smile | :)

Of one Essence is the human race
thus has Creation put the base
One Limb impacted is sufficient
For all Others to feel the Mace
(Saadi )

How to get/put(VARIANT newVal) ??

komofilms8-Jan-09 21:30

komofilms

8-Jan-09 21:30

Hello guys!

Im new in C++ programing, and I want to
get and put same data in my COM.
I dont have problems with basic data types.

My IDL:

[propget, id(FW_DISPID_OFFSET), helpstring("property Offset")] HRESULT Offset([out, retval] short *pVal);
[propput, id(FW_DISPID_OFFSET), helpstring("property Offset")] HRESULT Offset([in] short newVal);

My Cpp:

STDMETHODIMP CYslider::get_Offset(short *pVal)
{
*pVal = m_Offset;
return S_OK;
}

STDMETHODIMP CYslider::put_Offset(short newVal)
{
m_Offset = newVal;
SetDirty(TRUE);
FireViewChange();
return S_OK;
}

So far so good Smile | :)

, but now I dont know how to deal with arrays,
I googled a lot and I have found that solution is with VARIANT and safearray
but I dont know how to fill STDMETHODIMP for array.

My IDL:

[propget, id(FW_DISPID_ARRAYTEST), helpstring("property ArrayTest")] HRESULT ArrayTest([out, retval] VARIANT *pVal);
[propput, id(FW_DISPID_ARRAYTEST), helpstring("property ArrayTest")] HRESULT ArrayTest([in] VARIANT newVal);

My Cpp:

STDMETHODIMP CYslider::get_ArrayTest(VARIANT *pVal)
{
????????????????????????????????
return S_OK;
}

STDMETHODIMP CYslider::put_ArrayTest(VARIANT newVal)
{
????????????????????????????????
return S_OK;
}

I will be very happy if somebody could help me, with example, advice...

Bye,
Komofilms

Re: How to get/put(VARIANT newVal) ??

Randor 8-Jan-09 22:01

Randor

8-Jan-09 22:01

I haven't worked with COM in quite a few months. The sample code below demonstrates everything you need to know based on your inquiry/statements.

STDMETHODIMP CYslider::get_ArrayTest(VARIANT v)
{
	SAFEARRAY *pArrayVal = v.parray;
	char HUGEP *pArray = NULL;
	HRESULT hr = SafeArrayAccessData(pArrayVal,(void HUGEP * FAR *)&pArray );
	//Your array Length is: pArrayVal->rgsabound[0].cElements
	//Pointer to first element in your array is:pArray
	SafeArrayUnaccessData(pArrayVal);
	return S_OK;
}

HRESULT CYslider::put_ArrayTest(BYTE* data, LONG iLen)
{
	VARIANT v;
	SAFEARRAY *pArrayVal = NULL;
	SAFEARRAYBOUND arrayBound;
	CHAR HUGEP *pArray = NULL;
	arrayBound.lLbound = 0;
	arrayBound.cElements = iLen;

	pArrayVal = SafeArrayCreate(VT_UI1, 1, &arrayBound);

	if (NULL != pArrayVal)
	{
		HRESULT hr = SafeArrayAccessData(pArrayVal,(void HUGEP * FAR *)&pArray);

		if (SUCCEEDED(hr))
		{
			memcpy(pArray, data, arrayBound.cElements);
			V_VT(&v) = VT_ARRAY | VT_UI1;
			V_ARRAY(&v) = pArrayVal;
		}
		else
		{
			if (NULL != pArrayVal)
			{
				SafeArrayDestroy(pArrayVal);
				return S_FALSE;
			}
		}
		//You can do whatever with your array here
		//Here I am just sending it back to the get function.
		hr = SUCCEEDED(get_ArrayTest(&v));
		SafeArrayUnaccessData(pArrayVal);
	}
	VariantClear(&v);
	return S_OK;
}

Hopefully its enough to get you started. You can tweak it so it works with your application. If you have any questions feel free to ask.

Best Wishes,
-David Delaune

Re: How to get/put(VARIANT newVal) ??

Stuart Dootson8-Jan-09 22:11

Stuart Dootson

8-Jan-09 22:11

Here's an example of creating a SAFEARRAY of doubles and returning it through an output parameter (as you have in your get_ArrayTest method):

SAFEARRAYBOUND saBound[2] = { {10, 0}, {5, 0} };
pSA = ::SafeArrayCreate(VT_R8, 2, saBound);

for(int i=0;i<10;++i)
   {
   for(int j=0;j<5;++j)
   {
      static long indices[2];
      indices[0] = i;
      indices[1] = j;
      double value = i *5 + j;
      ::SafeArrayPutElement(pSA, indices, (void*)&value);
   }
}

pVal->vt = VT_ARRAY|VT_R8;
V_ARRAY(pVal) = pSA;

Accessing a SAFEARRAY is similar - you use SafeArrayGetElement rather than SafeArrayPutElement and don't need to create or destroy the array.

The vt member of the VARIANT holding the array should define the type of the array as shown, with a VT_type defining the element type, ORed with VT_ARRAY. SafeArrayGetVartype interrogates the SAFEARRAY to get the element type directly.

HTH!!!

Re: How to get/put(VARIANT newVal) ??

komofilms14-Jan-09 1:28

komofilms

14-Jan-09 1:28

I made it this way....

STDMETHODIMP CYslider::put_VrednostArray(VARIANT newVal)
{
if (!(newVal.vt & VT_ARRAY)) return S_OK;

if (newVal.parray == NULL) return S_OK;
VARTYPE vt = newVal.vt & VT_TYPEMASK;
SAFEARRAY* psaSafeArray = newVal.parray;

SafeArrayLock(psaSafeArray);

long j;
long LBound, HBound;
unsigned long elementsToWrite;
int writeBufferCn;

LBound = psaSafeArray->rgsabound[0].lLbound;
//write minimum of: TotElements, array size
elementsToWrite = m_TotElements;
if (elementsToWrite > 10) { //psaSafeArray->rgsabound[0].cElements) {
elementsToWrite = psaSafeArray->rgsabound[0].cElements;
}
HBound = LBound + elementsToWrite;

VARIANT varValToWriteTableElement;
V_VT(&varValToWriteTableElement) = vt;

writeBufferCn =0;

for(j = LBound; j < HBound; j++)
{
switch( vt )
{
case VT_R4:
SafeArrayGetElement(psaSafeArray, &j, &V_R4(&varValToWriteTableElement));

m_VrednostArray[writeBufferCn++] =(varValToWriteTableElement.fltVal);

break;
default:
break;
}

}

SafeArrayUnlock(psaSafeArray);

FireViewChange();
return S_OK;
}

It Works Smile | :)

Thanks all for help!

How to inverse a variable in bit level?

Joseph Marzbani8-Jan-09 21:14

Joseph Marzbani

8-Jan-09 21:14

Suppose I've got a variable of type BYTE. It looks something like 10001011 in the memory. Now I want to inverse it so that I get 11010001.

Thank you masters!

Re: How to inverse a variable in bit level?

Randor 8-Jan-09 21:42

Randor

8-Jan-09 21:42

BYTE b = 139;
b = ((b * 0x0802LU & 0x22110LU) | (b * 0x8020LU & 0x88440LU)) * 0x10101LU >> 16;

Credit for the discovery of this little neat trick goes to Sean Anderson at stanford university.

Best Wishes,
-David Delaune

Re: How to inverse a variable in bit level?

Cedric Moonen8-Jan-09 21:58

Cedric Moonen

8-Jan-09 21:58

Ok, now explain it Poke tongue | ;-P

Cédric Moonen
Software developer

Charting control [v1.5]
OpenGL game tutorial in C++

Re: How to inverse a variable in bit level?

Randor 8-Jan-09 23:05

Randor

8-Jan-09 23:05

It works by masking bits/using the AND operator to get the bits in the proper location. It is very beautiful, you can see it working here:

DWORD iTmp =0;
BYTE b = 139;			// 00000000 00000000 00000000 10001011

DWORD c = (b * 0x0802LU);	// 00000000 00000100 01011001 00010110
c &= 0x22110LU;		// 00000000 00000000 00000001 00010000

DWORD d = (b * 0x8020LU);	// 00000000 01000101 10010001 01100000
d &= 0x88440LU;		// 00000000 00000000 10000000 01000000

iTmp = (c | d);		// 00000000 00000000 10000001 01010000
iTmp = iTmp * 0x10101LU;	// 10000001 11010001 11010001 01010000

iTmp >>= 16;			// 00000000 00000000 10000001 11010001
b = iTmp;			// 00000000 00000000 00000000 11010001

Best Wishes,
-David Delaune

Re: How to inverse a variable in bit level?

toxcct8-Jan-09 23:49

toxcct

8-Jan-09 23:49

definitely marvelous... with your accordance, may I quote you in my article which talks about bits twiddling ?

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Re: How to inverse a variable in bit level?

Randor 8-Jan-09 23:55

Randor

8-Jan-09 23:55

toxcct wrote:
may I quote you

Hi toxcct,

Absolutely. Smile | :)

Best Wishes,
-David Delaune

Re: How to inverse a variable in bit level?

toxcct9-Jan-09 0:00

toxcct

9-Jan-09 0:00

shame on me, it was already (partially) there
check the article[^], at the Links chapter (down the end) ^^

there it is in the "Reversing bit sequences" chapter of this page[^]...

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Re: How to inverse a variable in bit level?

Randor 9-Jan-09 0:09

Randor

9-Jan-09 0:09

Hi,
That is an excellent link to an awesome collection of bit manipulation codes. I have used many of them in various projects over the years. Smile | :)

Best Wishes,
-David Delaune

Re: How to inverse a variable in bit level?

toxcct10-Jan-09 22:57

toxcct

10-Jan-09 22:57

done... the article[^] has been updated Smile | :)

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Re: A plain approach

CPallini8-Jan-09 22:44

CPallini

8-Jan-09 22:44

Inefficient, sure, but maybe easier to grasp.

BYTE b = 139;
BYTE r = 0;

for (int i=0; i<8; i++)
{
  r = r << 1;
  r |= b & 0x1;
  b = b >> 1;
}

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

Re: A plain approach

Iain Clarke, Warrior Programmer9-Jan-09 0:16

Iain Clarke, Warrior Programmer

9-Jan-09 0:16

I'm not sure it's much less efficient - all those multiplies will quite a high cost.

If it's just a BYTE, you could cut it down more by not even bothering with a loop:

BYTE b = 139;
BYTE r;
r = ((b & 1) << 7) | ((b & 2) << 5) | ((b & 4) << 3)  | ((b & 8) << 1)  | ((b & 16) >> 1)  | ((b & 32) >> 3)  | ((b & 64) << 5)  | ((b & 128) >> 7) )

This would not extend well for unsigned __int64...

Iain.

Codeproject MVP for C++, I can't believe it's for my lounge posts...

Re: A plain approach

CPallini9-Jan-09 0:28

CPallini

9-Jan-09 0:28

Uhm...loop unrolling: the oldie-goldie game-hacker Iain!
Big Grin | :-D

Re: A plain approach

Randor 9-Jan-09 1:05

Randor

9-Jan-09 1:05

Your version should be slightly faster. In theory on the Pentium 4 instruction cycle count should be as follows:

Bit masking technique:
3 MUL * 16 cycles
1 OR * 0.5 cycle
2 AND * 0.5 cycle
1 SHR * 4 cycles
===============
53.5 cycles

 
Your unrolled shifting:
8 AND * 0.5 cycles
7 OR * 0.5 cycles
5 SHL * 4 cycles
3 SHR * 4 cycles
================
39.5

It would be interesting to have MSVC output an .asm file with the /FA option. It would be interesting to see what the 2005/2008 compiler optimizer does to all of our codes!

Best Wishes,
-David Delaune

Re: A plain approach

CPallini9-Jan-09 1:43

CPallini

9-Jan-09 1:43

I think you may drop off a pair of ANDs in Iain expression.

BTW: very good job, I like soo much your posts.
Smile | :)

Re: How to inverse a variable in bit level?

Luc Pattyn9-Jan-09 2:51

Luc Pattyn

9-Jan-09 2:51

Hi,

if you need it once, the answers given to you are fine.
if you need to bit-swap an entire file or large memory buffer, I suggest you create a 256-byte lookup table, which you initialize by running one of the given code snippets for all possible byte values.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

Love, happiness and fewer bugs for 2009!

Potential problem with 'typedef redefinition'

6Qing888-Jan-09 20:27

6Qing88

8-Jan-09 20:27

hi, everyone
recently I started a new project which needs to be written in plain C,
and I got problem with different compilers that:

I want the declaration of public APIs along with data types required to
be in some separate files, and the definition of the types in some others,
for example:

interface.h
struct _VECTOR;
/**
* there's a problem with the absence of 'struct' in function
* declaration at least in mingw2.95, but that's not the point
* of my post.
*/
void _InitVector(struct _VECTOR* pVector);

implementation.h
#include "interface.h"

/* my point is here */
typedef struct _tagVECTOR {
int a;
} _VECTOR, *_PVECTOR;

implementation.c
#include "implementation.h"

void _InitVector(struct _VECTOR* pVector)
{
pVector->a = 1; /* derefferencing pointer to imcomplete type. */
}

It seems that the compiler cannot recognize the fact that _VECTOR is a typedef
name of the struct _tagVECTOR;

By the definition of 'typedef', I know that _VECTOR declared in "interface.h"
is exactly the same entity to that in "implementation.h", although it turned
out to be a typedef name of _tagVECTOR, but it won't compile in mingw2.95 with
the error mentioned in the code above.

Revised version can solve the problem:
typedef struct _VECTOR {
int a;
} *_PVECTOR;

But I want it to be consistent with the general idea, so I revised further:
typedef struct _VECTOR {
int a;
} _VECTOR, *_PVECTOR;

It compiled with no problem, but I'm not sure if I'm lucky enough with other
compilers holding the potential issue of "typedef redefinition".

Thanks in advance.

Smile | :)

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