Add print macro to kernel

kernel/src/main.rs

@@ -4,35 +4,20 @@
 use core::arch::asm;
 use core::panic::PanicInfo;
 
-#[panic_handler]
-fn panic(_info: &PanicInfo) -> ! {
-    loop {}
-}
+mod print;
+
+const VERSION: &str = env!("CARGO_PKG_VERSION");
 
 #[no_mangle]
 #[link_section = ".start"]
 pub extern "C" fn _start() -> ! {
-    print("Hello from kernel\0");
+    print!("Welcome to Felix {}!", VERSION);
 
     loop {}
 }
 
-fn print(message: &str) {
-    unsafe {
-        asm!("mov esi, {0:e}",
-            "mov edi, 0x000b8000",
-            "cld",
-            "2:",
-            "lodsb",
-            "or al, al",
-            "jz 1f",
-
-            "mov [edi], al",
-            "inc edi",
-            "inc edi",
-
-            "jmp 2b",
-            "1:",
-            in(reg) message.as_ptr());
-    }
+#[panic_handler]
+fn panic(_info: &PanicInfo) -> ! {
+    loop {}
 }
+

kernel/src/print.rs

@@ -0,0 +1,82 @@
+use core::arch::asm;
+use core::fmt;
+
+pub struct Printer {
+    vga_pointer: u32,
+}
+
+//core lib needs to know how to print a string to implement its print formatted func
+impl fmt::Write for Printer {
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        self.prints(s);
+        Ok(())
+    }
+}
+
+impl Printer {
+    //copy given char to memory pointed to vga_pointer
+    pub fn printc(&mut self, c: char) {
+        unsafe {
+            asm!(
+                "mov [{0}], {1}",
+                in(reg) self.vga_pointer,
+                in(reg_byte) c as u8,
+            );
+            self.vga_pointer += 2;
+        }
+    }
+
+    //print a string by printing one char at the time
+    pub fn prints(&mut self, s: &str) {
+        for c in s.chars() {
+            self.printc(c);
+        }
+    }
+
+}
+
+//macro for print!
+#[macro_export]
+macro_rules! print {
+    ($($arg:tt)*) => ($crate::print::_print(format_args!($($arg)*)));
+}
+
+//macro for println!
+/*#[macro_export]
+macro_rules! println {
+    () => ($crate::print!("\r\n"));
+    ($($arg:tt)*) => ($crate::print!("{}\r\n", format_args!($($arg)*)));
+}*/
+
+//global printer
+pub static mut PRINTER: Printer = Printer {
+    vga_pointer: 0x000b8000
+};
+
+#[doc(hidden)]
+pub fn _print(args: fmt::Arguments) {
+    use core::fmt::Write;
+    unsafe {
+        PRINTER.write_fmt(args).unwrap();
+    }
+}
+
+/*fn print(message: &str) {
+    unsafe {
+        asm!("mov esi, {0:e}",
+            "mov edi, 0x000b8000",
+            "cld",
+            "2:",
+            "lodsb",
+            "or al, al",
+            "jz 1f",
+
+            "mov [edi], al",
+            "inc edi",
+            "inc edi",
+
+            "jmp 2b",
+            "1:",
+            in(reg) message.as_ptr());
+    }
+}*/