From 62cce51eff15b648179a3ad8c77a0885e9394a10 Mon Sep 17 00:00:00 2001
From: natrixaeria <upezu@student.kit.edu>
Date: Sat, 26 Oct 2019 00:54:05 +0200
Subject: Create a kernel panic screen

---
 kernel/build.sh        |  4 +++-
 kernel/src/lib.rs      | 18 ++++++++++++++++++
 kernel/src/vga_text.rs | 35 +++++++++++++++++++++++++++++++----
 3 files changed, 52 insertions(+), 5 deletions(-)

diff --git a/kernel/build.sh b/kernel/build.sh
index a162d57..d8086b6 100755
--- a/kernel/build.sh
+++ b/kernel/build.sh
@@ -69,8 +69,10 @@ build_clean() {
 }
 
 build_build() {
-    build_clean
     cargo xbuild
+    rm -rf $TARGET_PATH/sysroot
+    rm -rf $TARGET_PATH/kernel.bin
+    rm -rf $TARGET_PATH/uff.iso
     build_run
 }
 
diff --git a/kernel/src/lib.rs b/kernel/src/lib.rs
index 48cb93d..8d2eee2 100644
--- a/kernel/src/lib.rs
+++ b/kernel/src/lib.rs
@@ -16,6 +16,8 @@ pub extern "C" fn _start() -> ! {
 
     write!(&mut stdout, "hello world!");
 
+    panic!("i has panicing");
+
     core::iter::successors(Some(0), |n| Some(n + 1))
         .for_each(|n|
             write!(&mut stdout, "hello world {}!", n).unwrap()
@@ -27,5 +29,21 @@ pub extern "C" fn _start() -> ! {
 #[panic_handler]
 #[no_mangle]
 pub extern "C" fn panic_handler(_info: &core::panic::PanicInfo) -> ! {
+    let mut stderr = vga_text::OStream::new();
+    stderr.set_state(vga_text::CharState::from_colors(
+            vga_text::Color::LightRed, vga_text::Color::Red));
+    stderr.clear();
+    stderr.print(b"uff-os");
+    stderr.set_row(10);
+    stderr.set_state(vga_text::CharState::from_colors(
+            vga_text::Color::White, vga_text::Color::Red));
+    stderr.print_centered(b"<kernel panic>");
+    stderr.set_row(14);
+    let text = _info.payload()
+        .downcast_ref::<&str>()
+        .unwrap_or(&"no panic informations are obtainable");
+    stderr.set_state(vga_text::CharState::from_colors(
+            vga_text::Color::Cyan, vga_text::Color::Red));
+    stderr.print_centered(text.as_bytes());
     loop {}
 }
diff --git a/kernel/src/vga_text.rs b/kernel/src/vga_text.rs
index 5298da7..a292c8c 100644
--- a/kernel/src/vga_text.rs
+++ b/kernel/src/vga_text.rs
@@ -128,13 +128,40 @@ impl OStream {
     pub fn set_state(&mut self, state: CharState) {
         self.state = state
     }
+
+    pub fn print(&mut self, s: &[u8]) {
+        for &b in s {
+            self.put_byte(b)
+        }
+    }
+
+    pub fn print_centered(&mut self, s: &[u8]) {
+        let mut line = &s[..];
+        let mut n = 0;
+        let slast = s.len() - 1;
+        for (i, &b) in s.iter().enumerate() {
+            if n >= 80 {
+                self.set_col(0);
+                self.print(&line[..80]);
+                line = &line[80..];
+                n = 0;
+            }
+            if b == b'\n' || i == slast {
+                if b != b'\n' { n += 1 }
+                self.set_col(((80 - n) / 2) as u8);
+                self.print(&line[..n]);
+                self.new_line();
+                if i == slast { return; }
+                line = &line[(n+1)..];
+                n = 0;
+            }
+            n += 1;
+        }
+    }
 }
 
 impl core::fmt::Write for OStream {
     fn write_str(&mut self, s: &str) -> core::fmt::Result {
-        for &b in s.as_bytes() {
-            self.put_byte(b)
-        }
-        Ok(())
+        Ok(self.print(s.as_bytes()))
     }
 }
-- 
cgit v1.2.3-54-g00ecf