SHPI

The SHPI is a data structure used to pack together several bitmaps.

Each bitmap has 4-character identifier.

Header

The SHPI has a 16-byte header format

Offset	Length	Type	Data
0x00	4	String	"SHPI"
0x04	4	Number	Length of the file (bytes)
0x08	4	Number	Number of objects in the directory
0x0C	4	String	Directory identifier

Entries

This header is followed by the directory entries, each consisting of a 4-byte identifier string, and a 4-byte offset inside the SHPI structure pointing to the beginning of the corresponding data.

Each entry in the directory represents a bitmap or sometimes a color palette.

There may be gaps between the directory and the first bitmap, and between consecutive bitmaps (significance unknown).

Each directory entry points to a bitmap block with the following structure :

Offset	Length	Data
0x00	1	7Bh
0x01	3	Block size
0x04	2	Bitmap width (pixels)
0x06	2	Bitmap height (pixels)
0x08	4	Unknown
0x0C	2	X position to display the bitmap
0x0E	2	Y position to display the bitmap
0x10	w*h	Bitmap data

The block size is: width * length + 10h

Each pixel in the bitmap data is represented by 1 byte

The value 0xFF in the bitmaps stands for the background, which is useful when a bitmap has to be drawn on top of another one.