ableos/shadeable/src/pixel_format.rs

use core::ops::{BitAnd, BitOr, Shr};

use vga::colors::Color16;
pub type Rgba64 = u64;

pub fn get_r(rgba: Rgba64) -> u8 {
    rgba.bitand(0xff_00_00_00).shr(0o30) as u8
}
pub fn get_g(rgba: Rgba64) -> u8 {
    rgba.bitand(0xff_00_00).shr(0o20) as u8
}

pub fn get_b(rgba: Rgba64) -> u8 {
    rgba.bitand(0xff_00).shr(0o10) as u8
}

pub fn get_a(rgba: Rgba64) -> u8 {
    (rgba & 0xff) as u8
}

pub fn set_r(rgba: Rgba64, r: u8) -> Rgba64 {
    rgba.bitand(0xffffffff_00_ff_ff_ff)
        .bitor((r as Rgba64).shr(0o30))
}

pub fn set_g(rgba: Rgba64, g: u8) -> Rgba64 {
    rgba.bitand(0xffffffff_ff_00_ff_ff)
        .bitor((g as Rgba64).shr(0o20))
}

pub fn set_b(rgba: Rgba64, b: u8) -> Rgba64 {
    rgba.bitand(0xffffffff_ff_ff_00_ff)
        .bitor((b as Rgba64).shr(0o10))
}

pub fn set_a(rgba: Rgba64, a: u8) -> Rgba64 {
    rgba.bitand(0xffffffff_ff_ff_ff_00).bitor(a as Rgba64)
}

pub fn rgba_div(a: Rgba64, b: Rgba64) -> Rgba64 {
    set_r(0, get_r(a) / get_r(b))
        | set_g(0, get_g(a) / get_g(b))
        | set_g(0, get_b(a) / get_b(b))
        | set_g(0, get_a(a) / get_a(b))
}

pub fn new_rgba64(r: u8, g: u8, b: u8, a: u8) -> Rgba64 {
    set_r(0, r) | set_g(0, g) | set_b(0, b) | set_a(0, a)
}

enum ChannelValue {
    Dark,
    Low,
    Mid,
    High,
}

impl From<u8> for ChannelValue {
    fn from(b: u8) -> Self {
        use ChannelValue::*;
        match b {
            0x00..=0x3f => Dark,
            0x40..=0x7f => Low,
            0x80..=0xbf => Mid,
            0xc0..=0xff => High,
        }
    }
}

pub fn into_vga_16(rgba_64: Rgba64) -> Color16 {
    use ChannelValue::*;
    use Color16::*;
    match (
        get_r(rgba_64).into(),
        get_g(rgba_64).into(),
        get_b(rgba_64).into(),
    ) {
        (Dark, Dark, Dark) => Black,
        (Dark, Dark, Low) => Black,
        (Dark, Dark, Mid) => Blue,
        (Dark, Dark, High) => Blue,
        (Dark, Low, Dark) => Black,
        (Dark, Low, Low) => Black,
        (Dark, Low, Mid) => Blue,
        (Dark, Low, High) => Blue,
        (Dark, Mid, Dark) => Green,
        (Dark, Mid, Low) => Green,
        (Dark, Mid, Mid) => Cyan,
        (Dark, Mid, High) => Cyan,
        (Dark, High, Dark) => Green,
        (Dark, High, Low) => Green,
        (Dark, High, Mid) => Green,
        (Dark, High, High) => Cyan,
        (Low, Dark, Dark) => Black,
        (Low, Dark, Low) => Black,
        (Low, Dark, Mid) => Blue,
        (Low, Dark, High) => Blue,
        (Low, Low, Dark) => Black,
        (Low, Low, Low) => DarkGrey,
        (Low, Low, Mid) => LightGrey,
        (Low, Low, High) => Blue,
        (Low, Mid, Dark) => DarkGrey,
        (Low, Mid, Low) => LightGrey,
        (Low, Mid, Mid) => Cyan,
        (Low, Mid, High) => Cyan,
        (Low, High, Dark) => Green,
        (Low, High, Low) => Green,
        (Low, High, Mid) => Cyan,
        (Low, High, High) => Cyan,
        (Mid, Dark, Dark) => Red,
        (Mid, Dark, Low) => Red,
        (Mid, Dark, Mid) => Magenta,
        (Mid, Dark, High) => Magenta,
        (Mid, Low, Dark) => Brown,
        (Mid, Low, Low) => Red,
        (Mid, Low, Mid) => DarkGrey,
        (Mid, Low, High) => LightBlue,
        (Mid, Mid, Dark) => Brown,
        (Mid, Mid, Low) => Brown,
        (Mid, Mid, Mid) => LightGrey,
        (Mid, Mid, High) => LightBlue,
        (Mid, High, Dark) => Green,
        (Mid, High, Low) => Green,
        (Mid, High, Mid) => LightGreen,
        (Mid, High, High) => LightCyan,
        (High, Dark, Dark) => Red,
        (High, Dark, _) => Magenta,
        (High, Low, Dark) => Red,
        (High, Low, Low) => LightRed,
        (High, Low, Mid) => Pink,
        (High, Low, High) => Magenta,
        (High, Mid, Dark) => Yellow,
        (High, Mid, Low) => Yellow,
        (High, Mid, Mid) => LightRed,
        (High, Mid, High) => Pink,
        (High, High, Dark) => Yellow,
        (High, High, Low) => White,
        (High, High, Mid) => White,
        (High, High, High) => White,
    }
}

pub fn from_vga_16(color: Color16) -> Rgba64 {
    use Color16::*;
    match color {
        Black => new_rgba64(0, 0, 0, 0),
        DarkGrey => new_rgba64(105, 105, 105, 0),
        LightGrey => new_rgba64(211, 211, 211, 0),
        //
        Blue => new_rgba64(0, 0, 0xff, 0),
        Green => new_rgba64(0, 0xff, 0, 0),
        Red => new_rgba64(0xff, 0, 0, 0),
        //
        Yellow => new_rgba64(0xff, 0xff, 0, 0),
        Cyan => new_rgba64(0, 0xff, 0xff, 0),
        Magenta => new_rgba64(0xff, 0, 0xff, 0),

        Brown => new_rgba64(165, 42, 42, 0),
        Pink => new_rgba64(0xff, 105, 180, 0),
        White => new_rgba64(0xff, 0xff, 0xff, 0),

        LightBlue => new_rgba64(173, 216, 230, 0),
        LightGreen => new_rgba64(144, 238, 144, 0),
        LightCyan => new_rgba64(88, 100, 100, 0),
        LightRed => new_rgba64(0xff, 204, 203, 0),
    }
}