ableos/shadeable/src/pixel_format.rs

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

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

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

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

pub fn set_r(rgba: Rgba64, r: u8) -> Rgba64 {
   rgba & 0xffffffff_00_ff_ff_ff | (r as Rgba64) << 0o30
}

pub fn set_g(rgba: Rgba64, g: u8) -> Rgba64 {
   rgba & 0xffffffff_ff_00_ff_ff | (g as Rgba64) << 0o20
}

pub fn set_b(rgba: Rgba64, b: u8) -> Rgba64 {
   rgba & 0xffffffff_ff_ff_00_ff | (b as Rgba64) << 0o10
}

pub fn set_a(rgba: Rgba64, a: u8) -> Rgba64 {
   rgba & 0xffffffff_ff_ff_ff_00 | (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),
   }
}