gudt/docs/D8_fbptr.md

Framebuffer Pointer

Node format

Offset	Size	Description
0	1	type = 0xd8
1	1	flags = 0
2	2	parent node
4	4	packed pixel size and format
8	8	framebuffer address

This node should not appear in GUDT blobs on disk, rather it is added by the boot loader before it passes the GUDT to a kernel. Usually a node of type 0xd9 follows. Since byte order is swapped on big endian machines, you must use bitshift and mask to get the data from the size field:

• size & 0xff: size of one pixel in bits (implicitly bits per channel: 15=5 bits, 16=rb:5,g:6, 24,32=8 bits)
• (size >> 8) & 31: red channel's position in bits
• (size >> 16) & 31: green channel's position in bits
• (size >> 24) & 31: blue channel's position in bits

JSON format

{
    "type": "FBPTR",
    "parent": 0,
    "size": (number) pixel size and format,
    "base": (number) framebuffer address
}