Function ioc 

pub const fn ioc(dir: u32, type_: u8, nr: u32, size: usize) -> u32

The number of an ioctl request in the encoding most architectures use (x86, ARM, RISC-V): two bits of direction, fourteen of size, eight of type and eight of number. The request numbers of the reference (FBIO_WAITFORVSYNC, FBIOGET_VBLANK) are in this encoding too.