[fpc-pascal] Problem with c header conversion

[gabor]

Hello,

I'm trying to convert c header code from "Windows Mobile API 5" to 
pascal and I'm getting wrong size of converted record:

original c header:

typedef struct _DDPIXELFORMAT
{
     DWORD	dwSize;
     DWORD	dwFlags;
     DWORD	dwFourCC;
     union
     {
	DWORD	dwRGBBitCount;
	DWORD	dwYUVBitCount;
	DWORD	dwAlphaBitDepth;
     };
     union
     {
	DWORD	dwRBitMask;
	DWORD	dwYBitMask;
     };
     union
     {
	DWORD	dwGBitMask;
	DWORD	dwUBitMask;
     };
     union
     {
	DWORD	dwBBitMask;
	DWORD	dwVBitMask;
	};
     union
     {
	DWORD	dwRGBAlphaBitMask;
     };

} DDPIXELFORMAT, * LPDDPIXELFORMAT;

and my pascal conversion:

PDDPixelFormat = ^TDDPixelFormat;
   _DDPIXELFORMAT = record
     dwSize: DWORD;
     dwFlags: DWORD;
     dwFourCC: DWORD;
     case Integer of
       0: (
           dwRGBBitCount : DWORD;
           dwYUVBitCount : DWORD;
           dwAlphaBitDepth : DWORD;
           );
       1: (
           dwRBitMask : DWORD;
           dwYBitMask : DWORD;
           );
       2: (
           dwGBitMask : DWORD;
           dwUBitMask : DWORD;
           );
       3: (
           dwBBitMask : DWORD;
           dwVBitMask : DWORD;
           );
       4: (
           dwRGBAlphaBitMask: DWORD;
          );
   end;
   DDPIXELFORMAT = _DDPIXELFORMAT;
   TDDPixelFormat = _DDPIXELFORMAT;


embedded visual c++ 4 returns sizeof(_DDPIXELFORMAT) = 32

free pascal 2.2.2 arm/wince target returns sizeof(_DDPIXELFORMAT) = 24

When I retrive these structure from Windows, field dwSize = 32

Where is problem? Maybe I shuld use special compiler directive or switch?

Michal

p.s. sorry for my bad english