trevors_chip8_toy/gemma/src/chip8/video.rs

use crate::chip8::video::Chip8VideoModes::{HighRes, LowRes};
use crate::constants::{
    CHIP8_VIDEO_HEIGHT, CHIP8_VIDEO_MEMORY, CHIP8_VIDEO_WIDTH, SCHIP_VIDEO_HEIGHT,
    SCHIP_VIDEO_WIDTH, SCHIP_VIDE_MEMORY,
};
use log::debug;
use serde::{Deserialize, Serialize};

#[derive(Clone, Copy, Serialize, Deserialize, Debug, PartialEq)]
pub enum Chip8VideoModes {
    LowRes,
    HighRes,
}

#[derive(Clone, Serialize, Deserialize, Debug, PartialEq)]
pub struct Chip8Video {
    memory: Vec<bool>,
    pub has_frame_changed: bool,
    current_res: Chip8VideoModes,
}

impl Chip8Video {
    pub fn reset(&mut self) {
        self.cls();
        self.set_lowres();
        self.start_frame();
    }

    pub fn is_highres(&self) -> bool {
        matches!(self.current_res, HighRes)
    }

    pub fn set_highres(&mut self) {
        self.current_res = HighRes;
        self.cls();
    }

    pub fn set_lowres(&mut self) {
        self.current_res = LowRes;
        self.cls();
    }

    pub fn get_screen_resolution(&mut self) -> Chip8VideoModes {
        self.current_res
    }

    pub fn cls(&mut self) {
        self.memory.clear();
        let num_loops = match self.current_res {
            LowRes => CHIP8_VIDEO_MEMORY,
            HighRes => SCHIP_VIDE_MEMORY,
        };
        for i in 0..num_loops {
            self.memory.push(false);
        }
    }

    pub fn start_frame(&mut self) {
        self.has_frame_changed = false;
    }

    pub fn new(initial_configuration: Box<Vec<bool>>) -> Self {
        Self {
            memory: *initial_configuration,
            has_frame_changed: false,
            current_res: Chip8VideoModes::LowRes,
        }
    }

    pub fn peek(&self, address: u16) -> bool {
        let loop_value: u16 = if self.is_highres() {
            SCHIP_VIDE_MEMORY as u16
        } else {
            CHIP8_VIDEO_MEMORY as u16
        };
        let effective_address = if address >= loop_value {
            address % loop_value
        } else {
            address
        };
        self.memory[effective_address as usize]
    }

    pub fn poke(&mut self, address: u16, new_value: bool) {
        let loop_value: u16 = self.get_memory_size() as u16;
        // Loop the address
        let effective_address = address % loop_value;

        let old_value = self.memory[effective_address as usize];
        let xored_value = new_value ^ old_value; // XOR of the video
                                                 // if the frame has already changed we dont care if it changed again.
        if !self.has_frame_changed && old_value != xored_value {
            self.has_frame_changed = true
        }

        //     println!("VIDEO POKE COMPLETE WITH {effective_address} SET TO {xored_value}");
        self.memory[effective_address as usize] = xored_value;
    }

    pub fn poke_byte(&mut self, first_address: u16, to_write: u8) {
        for i in (0..8).rev() {
            self.poke(first_address + (7 - i), (to_write & (1 << i)) != 0);
        }
    }

    pub fn poke_2byte(&mut self, first_address: u16, to_write: [u8; 2]) {
        for (idx, _) in to_write.iter().enumerate() {
            for i in (0..8).rev() {
                self.poke(
                    first_address + (idx * 8) as u16 + (7 - i),
                    (to_write[idx] & (1 << i)) != 0,
                );
            }
        }
    }

    pub fn format_as_string(&self) -> String {
        let (width, height) = self.get_resolution();
        println!("FORMATTING {width}x{height}");
        let mut output = String::new();
        for row in 0..height {
            for column in 0..width {
                let data_offset = row * width + column;
                debug!(
                    "Rendering {data_offset} with value {}",
                    self.memory[data_offset as usize]
                );
                if self.memory[data_offset as usize] {
                    output += "*"
                } else {
                    output += " "
                }
            }
            output += "\n";
        }
        output
    }

    pub fn get_resolution(&self) -> (i32, i32) {
        if self.is_highres() {
            (SCHIP_VIDEO_WIDTH, SCHIP_VIDEO_HEIGHT)
        } else {
            (CHIP8_VIDEO_WIDTH, CHIP8_VIDEO_HEIGHT)
        }
    }
    fn get_memory_size(&self) -> i32 {
        let (width, height) = self.get_resolution();
        width * height
    }

    pub fn tick(&mut self) {
        self.has_frame_changed = false;
    }

    pub fn scroll_right(&mut self) {
        let (width, height) = self.get_resolution();

        for current_row in 0..height {
            let row_offset: usize = (current_row * width) as usize;

            // Shift pixels to the right by 4 in the current row
            for current_column in (0..(width - 4)).rev() {
                let source_address = row_offset + current_column as usize;
                let target_address = source_address + 4;
                self.memory[target_address] = self.memory[source_address];
            }

            // Clear the first 4 pixels in the current row
            self.memory[row_offset..row_offset + 4].fill(false);
        }
    }

    pub fn scroll_left(&mut self) {
        let (width, height) = self.get_resolution();

        for current_row in 0..height {
            let row_offset = current_row * width;
            for current_column in (0..width - 4) {
                let target: usize = (row_offset + current_column) as usize;
                let source: usize = target + 4;
                self.memory[target] = self.memory[source];
            }

            let clear_start: usize = (row_offset + width - 4) as usize;
            let clear_end: usize = clear_start + 4;

            self.memory[clear_start..clear_end].fill(false);
        }
    }

    pub fn scroll_up(&mut self, how_far: &u8) {
        let how_far = *how_far as i32;
        let (width, height) = self.get_resolution();
        let row_shift = how_far * width;

        for current_source_row in how_far..height {
            let current_source_offset = current_source_row * width;
            for current_source_column in 0..width {
                let base_offset: usize = (current_source_offset + current_source_column) as usize;
                let shifted_offset: usize = base_offset - row_shift as usize;
                self.memory[shifted_offset] = self.memory[base_offset];
            }
        }

        // Clear the new bottom rows after shifting
        let clear_start = ((height - how_far) * width) as usize;
        self.memory[clear_start..].fill(false);
    }

    pub fn scroll_down(&mut self, how_far: i32) {
        let (width, height) = self.get_resolution();
        let row_shift = how_far * width;

        let max_source_row = height - how_far;
        for current_source_row in (0..max_source_row).rev() {
            let current_source_offset = current_source_row * width;
            for current_source_column in 0..width {
                let base_offset: usize = (current_source_offset + current_source_column) as usize;
                let extended_offset: usize = base_offset + row_shift as usize;
                self.memory[extended_offset] = self.memory[base_offset];
            }
        }

        // Clear the new top rows after shifting
        let clear_end = (how_far * width) as usize;
        self.memory[0..clear_end].fill(false);
    }
}

impl Default for Chip8Video {
    fn default() -> Self {
        let mut mem = vec![];
        for _ in 0..CHIP8_VIDEO_MEMORY {
            mem.push(false);
        }
        Chip8Video {
            memory: mem,
            has_frame_changed: false,
            current_res: LowRes,
        }
    }
}