more sample roms.

more coverage.

gemma/src/bin/speedtest.rs

@@ -0,0 +1,42 @@
+use std::fs::File;
+use std::io::Read;
+use std::ops::Add;
+use std::path::Path;
+use std::time::{Duration, Instant};
+use gemma::chip8::computer::Chip8Computer;
+use gemma::chip8::computer_manager::Chip8ComputerManager;
+
+const ROM_ROOT: &str = "resources/roms";
+
+fn main() {
+    let mut x = Chip8ComputerManager::new();
+
+    let mut buffer = Vec::new();
+    let mut input_file = File::open(Path::new(&(ROM_ROOT.to_string() + "/mandelbrot_bench.ch8"))).expect("derp");
+    input_file.read_to_end(&mut buffer).expect("unable to read file");
+    x.load_new_program_to_system_memory((&*buffer).into());
+
+    for _ in 0..10 {
+        let start_time = Instant::now();
+        let mut num_cycles = 0;
+        // how many instructions in 10s.
+        let end_time = start_time.add(Duration::from_secs(10));
+        while (Instant::now().le(&end_time)) {
+            num_cycles += 1;
+            x.step();
+        }
+
+        let num = num_cycles.to_string()
+            .as_bytes()
+            .rchunks(3)
+            .rev()
+            .map(std::str::from_utf8)
+            .collect::<Result<Vec<&str>, _>>()
+            .unwrap()
+            .join(",");  // separator
+
+
+        let num_ips = num_cycles / 1000000;
+        println!("Completed at {num_ips} Mips.");
+    }
+}

gemma/src/chip8/system_memory.rs

@@ -35,7 +35,8 @@ impl Chip8SystemMemory {
 
     pub fn peek(&self, address: u16) -> u8 {
         trace!("PEEK: {} / {}", address, self.memory[address as usize].clone());
-        self.memory[address as usize]
+        let effective = address as i32 % CHIP8_MEMORY_SIZE;
+        self.memory[effective as usize]
     }
 
     pub fn poke(&mut self, address: u16, value: u8)  {

gemma/src/chip8/video.rs

@@ -3,7 +3,7 @@ use crate::chip8::video::Chip8VideoModes::{HighRes, LowRes};
 use crate::constants::{CHIP8_VIDEO_HEIGHT, CHIP8_VIDEO_MEMORY, CHIP8_VIDEO_WIDTH, SCHIP_VIDE_MEMORY, SCHIP_VIDEO_HEIGHT, SCHIP_VIDEO_WIDTH};
 
 #[derive(Clone, Copy)]
-enum Chip8VideoModes {
+pub enum Chip8VideoModes {
     LowRes,
     HighRes,
 }
@@ -15,15 +15,10 @@ pub struct Chip8Video {
     current_res: Chip8VideoModes,
 }
 
-impl Chip8Video {
-    pub fn scroll_up(&self, how_far: &u8) {
-        println!("Scrolling up {how_far} rows.");
-    }
-}
-
 impl Chip8Video {
     pub fn reset(&mut self) {
         self.cls();
+        self.set_lowres();
         self.start_frame();
     }
 
@@ -186,6 +181,26 @@ impl Chip8Video {
         }
     }
 
+    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;