Memory Form Definition Block

The MFDB is roughly equivalent to a BITMAP structure in MS-Windows; it describes the location and format of an area of memory containing a raster image.

typedef struct memform
{
    LPVOID      mp;

/* Pointer to the bitmap data. If this pointer is zero, the MFDB describes the screen and all other members are ignored; if not, it describes an off-screen bitmap. In GEM/3, it may also be 0xFFFFFFFFL (-1) to indicate a buffer in the graphics card's memory, outside conventional RAM. This is only valid if the vq_extnd() call has indicated that such a buffer is present. */

    WORD        fwp;

/* Width of area in pixels */

    WORD        fh;

/* Height of area in pixels */

    WORD        fww;

/* Width of area in words */

    WORD        ff;

/* Format of data (0 = device-dependent, 1 = device-independent) */

    WORD        np;

/* No. of planes */

    WORD        r1;
    WORD        r2;
    WORD        r3;

/* Reserved */

} MFDB;