wasm4fun-graphics 0.1.0

Graphics primitives and subsystems for WASM-4 fantasy console
Documentation 
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// Copyright Claudio Mattera 2022.
//
// Distributed under the MIT License or the Apache 2.0 License at your option.
// See the accompanying files License-MIT.txt and License-Apache-2.0.txt, or
// online at
// https://opensource.org/licenses/MIT
// https://opensource.org/licenses/Apache-2.0

use wasm4fun_core::DRAW_COLORS;

/// Set colour for a specific palette index
pub fn set_one_drawing_color(index: usize, value: u8) {
    let drawcolorsimpl = unsafe { &mut *(DRAW_COLORS as *mut DrawColorsImpl) };
    drawcolorsimpl.set_one(index, value);
}

/// Set all colours
pub fn set_drawing_colors(value: u16) {
    let drawcolorsimpl = unsafe { &mut *(DRAW_COLORS as *mut DrawColorsImpl) };
    drawcolorsimpl.set(value);
}

/// Get all colours
pub fn get_drawing_colors() -> u16 {
    let drawcolorsimpl = unsafe { &mut *(DRAW_COLORS as *mut DrawColorsImpl) };
    drawcolorsimpl.get()
}

#[derive(Clone, Copy)]
struct DrawColorsImpl(pub u16);

impl DrawColorsImpl {
    pub fn set_one(&mut self, index: usize, value: u8) -> &mut Self {
        if value < 5 {
            let value = value as u16;
            let mask_shift = (index) * 4;
            let mask: u16 = 0xf000 >> mask_shift;
            let rest = self.0 & !mask;
            let new_shift = (3 - index) * 4;
            let new = value << new_shift;
            self.0 = rest | new;
        }
        self
    }

    pub fn set(&mut self, value: u16) {
        self.0 = value;
    }

    pub fn get(&self) -> u16 {
        self.0
    }
}

#[cfg(test)]
mod tests {
    use super::DrawColorsImpl;

    #[test]
    fn get() {
        let draw_colors = DrawColorsImpl(0x3102);
        let actual = draw_colors.get();
        let expected = 0x3102;
        assert_eq!(actual, expected);
    }

    #[test]
    fn set() {
        let mut draw_colors = DrawColorsImpl(0);
        draw_colors.set(0x3102);
        let actual = draw_colors.get();
        let expected = 0x3102;
        assert_eq!(actual, expected);
    }

    #[test]
    fn set_one_first() {
        let mut draw_colors = DrawColorsImpl(0);
        draw_colors.set_one(0, 3);
        let actual = draw_colors.get();
        let expected = 0x3000;
        assert_eq!(actual, expected);
    }

    #[test]
    fn set_one_second() {
        let mut draw_colors = DrawColorsImpl(0);
        draw_colors.set_one(1, 3);
        let actual = draw_colors.get();
        let expected = 0x0300;
        assert_eq!(actual, expected);
    }

    #[test]
    fn set_one_third() {
        let mut draw_colors = DrawColorsImpl(0);
        draw_colors.set_one(2, 3);
        let actual = draw_colors.get();
        let expected = 0x0030;
        assert_eq!(actual, expected);
    }

    #[test]
    fn set_one_fourth() {
        let mut draw_colors = DrawColorsImpl(0);
        draw_colors.set_one(3, 3);
        let actual = draw_colors.get();
        let expected = 0x0003;
        assert_eq!(actual, expected);
    }

    #[test]
    fn set_one_first_existing() {
        let mut draw_colors = DrawColorsImpl(0x1111);
        draw_colors.set_one(0, 3);
        let actual = draw_colors.get();
        let expected = 0x3111;
        assert_eq!(actual, expected);
    }

    #[test]
    fn set_one_second_existing() {
        let mut draw_colors = DrawColorsImpl(0x1111);
        draw_colors.set_one(1, 3);
        let actual = draw_colors.get();
        let expected = 0x1311;
        assert_eq!(actual, expected);
    }

    #[test]
    fn set_one_third_existing() {
        let mut draw_colors = DrawColorsImpl(0x1111);
        draw_colors.set_one(2, 3);
        let actual = draw_colors.get();
        let expected = 0x1131;
        assert_eq!(actual, expected);
    }

    #[test]
    fn set_one_fourth_existing() {
        let mut draw_colors = DrawColorsImpl(0x1111);
        draw_colors.set_one(3, 3);
        let actual = draw_colors.get();
        let expected = 0x1113;
        assert_eq!(actual, expected);
    }

    #[test]
    fn set_one_all() {
        let mut draw_colors = DrawColorsImpl(0);
        draw_colors.set_one(0, 3);
        draw_colors.set_one(1, 1);
        draw_colors.set_one(2, 0);
        draw_colors.set_one(3, 2);
        let actual = draw_colors.get();
        let expected = 0x3102;
        assert_eq!(actual, expected);
    }

    #[test]
    fn set_one_chained() {
        let mut draw_colors = DrawColorsImpl(0);
        draw_colors
            .set_one(0, 3)
            .set_one(1, 1)
            .set_one(2, 0)
            .set_one(3, 2);
        let actual = draw_colors.get();
        let expected = 0x3102;
        assert_eq!(actual, expected);
    }
}