Constant libnotcurses_sys::NCALPHA_FG_ALPHA_MASK

pub const NCALPHA_FG_ALPHA_MASK: u64 = crate::bindings::ffi::NC_FG_ALPHA_MASK; // 0x3000_0000_0000_0000u64

Extract these bits to get the foreground alpha mask (NcAlphaBits)

See the detailed diagram at NcChannels

Note: When working with a single NcChannel use NCALPHA_BG_ALPHA_MASK;