chore: comparison of instr_timing image

Also added support for image saving.

frontends/sdl/src/test.rs

-use image::io::Reader as ImageReader;
+use image::{io::Reader as ImageReader, ImageBuffer, Rgb};
 
 pub fn compare_images(source_pixels: &[u8], target_path: &str) -> bool {
     let image_buffer = ImageReader::open(target_path)
@@ -23,6 +23,19 @@ pub fn compare_images(source_pixels: &[u8], target_path: &str) -> bool {
     true
 }
 
+pub fn save_image(pixels: &[u8], width: u32, height: u32, file_path: &str) {
+    let mut image_buffer: ImageBuffer<Rgb<u8>, Vec<u8>> = ImageBuffer::new(width, height);
+
+    for (x, y, pixel) in image_buffer.enumerate_pixels_mut() {
+        let base = ((y * width + x) * 3) as usize;
+        *pixel = Rgb([pixels[base], pixels[base + 1], pixels[base + 2]]);
+    }
+
+    image_buffer
+        .save_with_format(file_path, image::ImageFormat::Png)
+        .unwrap();
+}
+
 #[cfg(test)]
 mod tests {
     use boytacean::{
@@ -31,7 +44,7 @@ mod tests {
         test::{run_image_test, TestOptions},
     };
 
-    use super::compare_images;
+    use super::{compare_images, save_image};
 
     #[test]
     fn test_blargg_cpu_instrs() {
@@ -44,6 +57,18 @@ mod tests {
         assert_eq!(image_result, true);
     }
 
+    #[test]
+    fn test_blargg_instr_timing() {
+        let result: [u8; FRAME_BUFFER_SIZE] = run_image_test(
+            "../../res/roms/test/blargg/instr_timing/instr_timing.gb",
+            Some(50000000),
+            TestOptions::default(),
+        );
+        compare_images(&result, "res/test/blargg/instr_timing/instr_timing.png");
+        let image_result = compare_images(&result, "res/test/blargg/instr_timing/instr_timing.png");
+        assert_eq!(image_result, true);
+    }
+
     #[test]
     fn test_dmg_acid2() {
         let result: [u8; FRAME_BUFFER_SIZE] = run_image_test(