GsMAP

Background composition map

struct GsMAP {
        u_char cellw, cellh;
        u_short ncellw, ncellh;
        GsCELL *base;
        u_short *index;
};

Members

cellw, cellh	Cell size (0 is the same as 256)
ncellw, ncellh	Size of the background (BG) in cells
base	Pointer to the GsCELL structure array
index	Pointer to cell information

Explanation

The GsMAP structure contains map data that is used to create a background from GsCELL data.
Map data is managed by cell index array information.
cellw, cellh specify the size of one cell in pixels. Note that one BG is made up of cells of the same size.
ncellw and ncellh specify the size of the BG map in units of cells.
base specifies the starting address of the GsCELL array.
index specifies the starting address of the cell data table.
Cell data is a list of index values whose size is equivalent to (ncellw * ncellh) for the array specified by base. If a cell value is 0xFFFF it indicates a NULL (transparent) cell.