gb-emu/src/processor/gpu/tile_window.rs

use minifb::Window;

use crate::{
    processor::{
        get_bit,
        gpu::{
            bits_to_mapped_colour, scale_buffer, Palette, TiledataArea, TILE_WINDOW_HEIGHT,
            TILE_WINDOW_HEIGHT_SCALED, TILE_WINDOW_WIDTH, TILE_WINDOW_WIDTH_SCALED,
        },
        memory::Memory,
    },
    FACTOR,
};

pub(super) struct TileWindow {
    sprite_buffer: Vec<u32>,
    sprite_buffer_scaled: Vec<u32>,
    sprite_window: Window,
}

impl TileWindow {
    pub(super) fn new(window: Window) -> Self {
        Self {
            sprite_buffer: vec![0; TILE_WINDOW_WIDTH * TILE_WINDOW_HEIGHT],
            sprite_buffer_scaled: vec![0; TILE_WINDOW_WIDTH_SCALED * TILE_WINDOW_HEIGHT_SCALED],
            sprite_window: window,
        }
    }
}

impl TileWindow {
    pub(super) fn draw_sprite_window(&mut self, palette: Palette, memory: &Memory) {
        for tile_y in 0..16 {
            self.draw_row(
                tile_y,
                tile_y as usize,
                TiledataArea::D8000,
                palette,
                memory,
            );
        }
        for tile_y in 0..8 {
            self.draw_row(
                tile_y,
                (tile_y as usize) + 16,
                TiledataArea::D9000,
                palette,
                memory,
            );
        }

        self.sprite_buffer_scaled = scale_buffer(
            &self.sprite_buffer,
            TILE_WINDOW_WIDTH,
            TILE_WINDOW_HEIGHT,
            FACTOR,
        );
        self.sprite_window
            .update_with_buffer(
                &self.sprite_buffer_scaled,
                TILE_WINDOW_WIDTH_SCALED,
                TILE_WINDOW_HEIGHT_SCALED,
            )
            .unwrap();
    }

    fn draw_row(
        &mut self,
        tile_y: u8,
        display_y: usize,
        area: TiledataArea,
        palette: Palette,
        memory: &Memory,
    ) {
        for tile_x in 0..16 {
            let tile_num = (tile_y * 16) + tile_x;
            let data_begin = area.get_addr(tile_num);
            for px_y in 0..8 {
                let lsbs = memory.get((px_y * 2) + data_begin);
                let msbs = memory.get((px_y * 2) + data_begin + 1);
                for px_x in 0..8 {
                    let real_px_y = (display_y * 8) + px_y as usize;
                    let real_px_x = (tile_x as usize * 8) + px_x as usize;
                    let lsb = get_bit(lsbs, 7 - px_x);
                    let msb = get_bit(msbs, 7 - px_x);
                    let colour = bits_to_mapped_colour(lsb, msb, palette);

                    self.sprite_buffer[real_px_x + (real_px_y * TILE_WINDOW_WIDTH)] =
                        colour.to_rgb();
                }
            }
        }
    }
}