Add basic commands

src/shell.rs

@@ -1,14 +1,42 @@
 use crate::println;
 use crate::print;
+use crate::vga_buffer::{change_color, Color};
 
 pub fn evaluate(command: &str) {
     if let Some(stripped) = command.strip_prefix(">>> ") {
         let res = stripped.trim();
         if res != "" {
             println!();
-            println!();
-            println!("[ {} ]", res);
+            let selected = match res {
+                "help" => help,
+                "info" => info,
+                _ => default 
+            };
+            selected();
             print!(">>> ");
         }
     }
 }
+
+fn default() {
+    println!("Error: unknown command.");
+}
+
+fn help() {
+    change_color(Color::LightBlue, Color::Black);
+    print!("KarxShell help menu\n\n");
+    println!("[help] This message");
+    change_color(Color::White, Color::Black);
+}
+
+fn info() {
+    print!("KarxOS by ");
+    change_color(Color::Blue, Color::Black);
+    println!("karx (karx1 on GitHub)");
+    change_color(Color::White, Color::Black);
+    print!("Developed for a science project in the ");
+    change_color(Color::Red, Color::Black);
+    println!("Rust language.");
+    change_color(Color::White, Color::Black);
+    println!("If you're having input problems, switch to a US keyboard layout.");
+}