D3DFORMAT ist defined in d3d9.h as long variable:

Code:
#define D3DFORMAT long


and D3DFORMAT is defined in the MSDN as the following enum:

Code:
typedef enum _D3DFORMAT {
    D3DFMT_UNKNOWN              =  0,

    D3DFMT_R8G8B8               = 20,
    D3DFMT_A8R8G8B8             = 21,
    D3DFMT_X8R8G8B8             = 22,
    D3DFMT_R5G6B5               = 23,
    D3DFMT_X1R5G5B5             = 24,
    D3DFMT_A1R5G5B5             = 25,
    D3DFMT_A4R4G4B4             = 26,
    D3DFMT_R3G3B2               = 27,
    D3DFMT_A8                   = 28,
    D3DFMT_A8R3G3B2             = 29,
    D3DFMT_X4R4G4B4             = 30,
    D3DFMT_A2B10G10R10          = 31,
    D3DFMT_A8B8G8R8             = 32,
    D3DFMT_X8B8G8R8             = 33,
    D3DFMT_G16R16               = 34,
    D3DFMT_A2R10G10B10          = 35,
    D3DFMT_A16B16G16R16         = 36,

    D3DFMT_A8P8                 = 40,
    D3DFMT_P8                   = 41,

    D3DFMT_L8                   = 50,
    D3DFMT_A8L8                 = 51,
    D3DFMT_A4L4                 = 52,

    D3DFMT_V8U8                 = 60,
    D3DFMT_L6V5U5               = 61,
    D3DFMT_X8L8V8U8             = 62,
    D3DFMT_Q8W8V8U8             = 63,
    D3DFMT_V16U16               = 64,
    D3DFMT_A2W10V10U10          = 67,

    D3DFMT_UYVY                 = MAKEFOURCC('U', 'Y', 'V', 'Y'),
    D3DFMT_R8G8_B8G8            = MAKEFOURCC('R', 'G', 'B', 'G'),
    D3DFMT_YUY2                 = MAKEFOURCC('Y', 'U', 'Y', '2'),
    D3DFMT_G8R8_G8B8            = MAKEFOURCC('G', 'R', 'G', 'B'),
    D3DFMT_DXT1                 = MAKEFOURCC('D', 'X', 'T', '1'),
    D3DFMT_DXT2                 = MAKEFOURCC('D', 'X', 'T', '2'),
    D3DFMT_DXT3                 = MAKEFOURCC('D', 'X', 'T', '3'),
    D3DFMT_DXT4                 = MAKEFOURCC('D', 'X', 'T', '4'),
    D3DFMT_DXT5                 = MAKEFOURCC('D', 'X', 'T', '5'),

    D3DFMT_D16_LOCKABLE         = 70,
    D3DFMT_D32                  = 71,
    D3DFMT_D15S1                = 73,
    D3DFMT_D24S8                = 75,
    D3DFMT_D24X8                = 77,
    D3DFMT_D24X4S4              = 79,
    D3DFMT_D16                  = 80,

    D3DFMT_D32F_LOCKABLE        = 82,
    D3DFMT_D24FS8               = 83,

#if !defined(D3D_DISABLE_9EX)
    D3DFMT_D32_LOCKABLE         = 84,
    D3DFMT_S8_LOCKABLE          = 85,
#endif // !D3D_DISABLE_9EX

    D3DFMT_L16                  = 81,

    D3DFMT_VERTEXDATA           =100,
    D3DFMT_INDEX16              =101,
    D3DFMT_INDEX32              =102,

    D3DFMT_Q16W16V16U16         =110,

    D3DFMT_MULTI2_ARGB8         = MAKEFOURCC('M','E','T','1'),

    D3DFMT_R16F                 = 111,
    D3DFMT_G16R16F              = 112,
    D3DFMT_A16B16G16R16F        = 113,

    D3DFMT_R32F                 = 114,
    D3DFMT_G32R32F              = 115,
    D3DFMT_A32B32G32R32F        = 116,

    D3DFMT_CxV8U8               = 117,

#if !defined(D3D_DISABLE_9EX)
    D3DFMT_A1                   = 118,
    D3DFMT_A2B10G10R10_XR_BIAS  = 119,
    D3DFMT_BINARYBUFFER         = 199,
#endif // !D3D_DISABLE_9EX

    D3DFMT_FORCE_DWORD          =0x7fffffff
} D3DFORMAT;


So, just choose a number and pass it.

In your case, the parameter format is described as:

Quote:
Allowable pixel formats. See Remarks.


and under remarks it is said:

Quote:
An application supplies a display mode and a format to EnumAdapterModes which returns a display mode. This method could be used in a loop to enumerate all available display modes.
The application specifies a format and the enumeration is restricted to those display modes that exactly match the format (alpha is ignored). Allowed formats (which are members of D3DFORMAT) are as follows:

D3DFMT_A1R5G5B5
D3DFMT_A2R10G10B10
D3DFMT_A8R8G8B8
D3DFMT_R5G6B5
D3DFMT_X1R5G5B5
D3DFMT_X8R8G8B8

In addition, EnumAdapterModes treats pixel formats 565 and 555 as equivalent, and returns the correct version. The difference comes into play only when the application locks the back buffer and there is an explicit flag that the application must set in order to accomplish this.


Thus, I would try D3DFMT_A8R8G8B8 first, which is = 21 according to the above mentioned enum.