Add centered mode to vga compatible text mode

2 files changed, 26 insertions, 10 deletions

diff --git a/kernel/src/io/vga_text.rs b/kernel/src/io/vga_text.rs
index 620aa32..281a40a 100644
--- a/kernel/src/io/vga_text.rs
+++ b/kernel/src/io/vga_text.rs
@@ -58,6 +58,7 @@ pub struct OStream {
     pos: (usize, usize),
     cursor: *mut VgaChar,
     state: CharState,
+    centered_mode: bool
 }
 
 impl OStream {
@@ -66,6 +67,7 @@ impl OStream {
             pos: (0, 0),
             cursor: Self::at(0),
             state: CharState::from_colors(Color::White, Color::Black),
+            centered_mode: false,
         }
     }
 
@@ -122,6 +124,10 @@ impl OStream {
         }
     }
 
+    pub fn set_centered(&mut self, b: bool) {
+        self.centered_mode = b
+    }
+
     pub fn new_line(&mut self) {
         if self.pos.1 >= HEIGHT - 1 {
             self.set_col(0);
@@ -137,20 +143,29 @@ impl OStream {
         self.state = state
     }
 
-    pub fn print(&mut self, s: &[u8]) {
+    pub fn put_bytes(&mut self, s: &[u8]) {
         for &b in s {
             self.put_byte(b)
         }
     }
 
+    pub fn print(&mut self, s: &[u8]) {
+        if self.centered_mode {
+            self.print_centered(s)
+        } else {
+            self.put_bytes(s)
+        }
+    }
+
     pub fn print_centered(&mut self, s: &[u8]) {
         let mut line = &s[..];
         let mut n = 0;
+        if s.len() == 0 { return; }
         let slast = s.len() - 1;
         for (i, &b) in s.iter().enumerate() {
             if n >= WIDTH {
                 self.set_col(0);
-                self.print(&line[..WIDTH]);
+                self.put_bytes(&line[..WIDTH]);
                 line = &line[WIDTH..];
                 n = 0;
             }
@@ -159,7 +174,7 @@ impl OStream {
                     n += 1
                 }
                 self.set_col(((WIDTH - n) / 2) as usize);
-                self.print(&line[..n]);
+                self.put_bytes(&line[..n]);
                 self.new_line();
                 if i == slast {
                     return;
diff --git a/kernel/src/lib.rs b/kernel/src/lib.rs
index d5a3e9e..cbc9915 100644
--- a/kernel/src/lib.rs
+++ b/kernel/src/lib.rs
@@ -1,6 +1,7 @@
 #![no_main]
 #![feature(compiler_builtins_lib)]
 #![feature(custom_test_frameworks)]
+#![feature(panic_info_message)]
 #![test_runner(crate::test_runner)]
 #![reexport_test_harness_main = "test_main"]
 #![no_std]
@@ -33,7 +34,7 @@ pub extern "C" fn _start() -> ! {
 
     let mut stdout = OStream::new();
     stdout.clear();
-    panic!("panic!");
+    panic!("panic! at the disco");
 
     core::iter::successors(Some(0), |n| Some(n + 1))
         .for_each(|n| write!(&mut stdout, "hello world {}!", n).unwrap());
@@ -43,7 +44,7 @@ pub extern "C" fn _start() -> ! {
 
 #[panic_handler]
 #[no_mangle]
-pub extern "C" fn panic_handler(_info: &core::panic::PanicInfo) -> ! {
+pub extern "C" fn panic_handler(info: &core::panic::PanicInfo) -> ! {
     let mut stderr = OStream::new();
     stderr.set_state(vga_text::CharState::from_colors(
         vga_text::Color::LightRed,
@@ -58,15 +59,15 @@ pub extern "C" fn panic_handler(_info: &core::panic::PanicInfo) -> ! {
     ));
     stderr.print_centered(b"<kernel panic>");
     stderr.set_row(14);
-    let text = _info
-        .payload()
-        .downcast_ref::<&str>()
-        .unwrap_or(&"no panic information is obtainable");
     stderr.set_state(vga_text::CharState::from_colors(
         vga_text::Color::Cyan,
         vga_text::Color::Red,
     ));
-    stderr.print_centered(text.as_bytes());
+    stderr.set_centered(true);
+    write!(&mut stderr, "{:?}", info.message()
+           .unwrap_or(&format_args!("no panic information obtainable")));
+    //loop{}
+    stderr.set_centered(false);
     if cfg!(test) {
         write!(serial::SerialStream::new(), "Testing failed\n").unwrap();
         qemu::exit_qemu(qemu::QemuExitCode::Failed);