os: rework kernel architecture

Rework the code structure and architecture of the kernel by separating
platform-dependent and platform-independent code more cleanly. As of
this patchset, full feature parity has not been achieved. Nonetheless, a
sufficient subset of functionality has been ported to the new
architecture to demonstrate the feasibility of the new structure.

4 files changed, 64 insertions, 0 deletions

diff --git a/arch/x86_64/pre/src/exception_handling/abort.cpp b/arch/x86_64/pre/src/exception_handling/abort.cpp
new file mode 100644
index 0000000..5dc6869
--- /dev/null
+++ b/arch/x86_64/pre/src/exception_handling/abort.cpp
@@ -0,0 +1,18 @@
+#include "arch/exception_handling/panic.hpp"
+
+#include <cstdlib>
+
+namespace teachos::arch::exception_handling
+{
+  /**
+   * @brief Override for the newlib abort function.
+   *
+   * @note newlib defines @p ::abort as a weak symbol, thus allowing implementations to override it by simply providing
+   * a matching implementation. Since the default implemenatation calls a number of functions the kernel does not
+   * currently implement, @p ::abort gets overridden to simply panic.
+   */
+  extern "C" auto abort() -> void
+  {
+    panic("Terminate was called, possibly due to an unhandled exception");
+  }
+}  // namespace teachos::arch::exception_handling
diff --git a/arch/x86_64/pre/src/exception_handling/assert.cpp b/arch/x86_64/pre/src/exception_handling/assert.cpp
new file mode 100644
index 0000000..b2963de
--- /dev/null
+++ b/arch/x86_64/pre/src/exception_handling/assert.cpp
@@ -0,0 +1,15 @@
+#include "arch/exception_handling/assert.hpp"
+
+#include "arch/exception_handling/panic.hpp"
+
+namespace teachos::arch::exception_handling
+{
+  auto assert(bool condition, char const * message) -> void
+  {
+    if (condition)
+    {
+      return;
+    }
+    panic("Assertion Violation: ", message);
+  }
+}  // namespace teachos::arch::exception_handling
diff --git a/arch/x86_64/pre/src/exception_handling/panic.cpp b/arch/x86_64/pre/src/exception_handling/panic.cpp
new file mode 100644
index 0000000..9511a9a
--- /dev/null
+++ b/arch/x86_64/pre/src/exception_handling/panic.cpp
@@ -0,0 +1,25 @@
+#include "arch/exception_handling/panic.hpp"
+
+#include "arch/kernel/halt.hpp"
+#include "arch/video/vga/text.hpp"
+
+namespace teachos::arch::exception_handling
+{
+  extern "C" char const message_prefix_panic[];
+
+  auto panic(char const * reason) -> void
+  {
+    panic(message_prefix_panic, reason);
+  }
+
+  auto panic(char const * prefix, char const * reason) -> void
+  {
+    using video::vga::text::common_attributes::white_on_red;
+
+    video::vga::text::newline();
+    video::vga::text::write(prefix, white_on_red);
+    video::vga::text::write(reason, white_on_red);
+
+    kernel::halt();
+  };
+}  // namespace teachos::arch::exception_handling
diff --git a/arch/x86_64/pre/src/exception_handling/pure_virtual.cpp b/arch/x86_64/pre/src/exception_handling/pure_virtual.cpp
new file mode 100644
index 0000000..67772f7
--- /dev/null
+++ b/arch/x86_64/pre/src/exception_handling/pure_virtual.cpp
@@ -0,0 +1,6 @@
+#include "arch/exception_handling/panic.hpp"
+
+extern "C" auto __cxa_pure_virtual() -> void
+{
+  teachos::arch::exception_handling::panic("Runtime", "Tried to call a pure virtual function!");
+}