From dff78de795a89c181e9c94b26db2f16988e8f4d6 Mon Sep 17 00:00:00 2001
From: Fabian Imhof <fabian.imhof@ost.ch>
Date: Thu, 10 Apr 2025 12:11:55 +0000
Subject: move context_switch function and environment into different directory

---
 .../segment_selector.hpp                           |  7 ++++++-
 .../x86_64/include/arch/context_switching/main.hpp | 24 ++++++++++++++++++++++
 .../include/arch/kernel/cpu/segment_register.hpp   |  9 +++++++-
 3 files changed, 38 insertions(+), 2 deletions(-)

(limited to 'arch/x86_64/include')

diff --git a/arch/x86_64/include/arch/context_switching/interrupt_descriptor_table/segment_selector.hpp b/arch/x86_64/include/arch/context_switching/interrupt_descriptor_table/segment_selector.hpp
index b31f9e8..e8854f9 100644
--- a/arch/x86_64/include/arch/context_switching/interrupt_descriptor_table/segment_selector.hpp
+++ b/arch/x86_64/include/arch/context_switching/interrupt_descriptor_table/segment_selector.hpp
@@ -52,7 +52,12 @@ namespace teachos::arch::context_switching::interrupt_descriptor_table
      * @param flags Allows to set flags for the flags field using the unscoped enum contained in this class, used to
      * allow for direct integer conversion.
      */
-    segment_selector(uint16_t index, uint8_t flags);
+    constexpr segment_selector(uint16_t index, uint8_t flags)
+        : _flags(flags)
+        , _index(index * 2U)
+    {
+      // Nothing to do.
+    }
 
     /**
      * @brief Checks if the given std::bitset is a subset or equivalent to the underlying data.
diff --git a/arch/x86_64/include/arch/context_switching/main.hpp b/arch/x86_64/include/arch/context_switching/main.hpp
index d2243ed..e296457 100644
--- a/arch/x86_64/include/arch/context_switching/main.hpp
+++ b/arch/x86_64/include/arch/context_switching/main.hpp
@@ -15,8 +15,32 @@ namespace teachos::arch::context_switching
     interrupt_descriptor_table::interrupt_descriptor_table & idt;  ///< Reference to the interrupt descriptor table.
   };
 
+  /**
+   * @brief Setup GDT and IDT TODO
+   *
+   * @return descriptor_tables
+   */
   auto initialize_descriptor_tables() -> descriptor_tables;
 
+  /**
+   * @brief TODO
+   *
+   * @param data_segment
+   * @param code_segment
+   * @param return_function
+   */
+  auto switch_to_user_mode() -> void;
+
+  /**
+   * @brief TODO
+   *
+   * @param data_segment
+   * @param code_segment
+   * @param return_function
+   */
+  auto switch_context(interrupt_descriptor_table::segment_selector data_segment,
+                      interrupt_descriptor_table::segment_selector code_segment, void (*return_function)()) -> void;
+
 }  // namespace teachos::arch::context_switching
 
 #endif  // TEACHOS_ARCH_X86_64_CONTEXT_SWITCHING_MAIN_HPP
diff --git a/arch/x86_64/include/arch/kernel/cpu/segment_register.hpp b/arch/x86_64/include/arch/kernel/cpu/segment_register.hpp
index bd244fd..fd5a972 100644
--- a/arch/x86_64/include/arch/kernel/cpu/segment_register.hpp
+++ b/arch/x86_64/include/arch/kernel/cpu/segment_register.hpp
@@ -12,12 +12,19 @@ namespace teachos::arch::kernel::cpu
   auto reload_segment_registers() -> void;
 
   /**
-   * @brief Set the value of all segment registers.
+   * @brief Set the value of all segment registers. TODO
    *
    * @param segment_selector
    */
   auto set_segment_registers(context_switching::interrupt_descriptor_table::segment_selector segment_selector) -> void;
 
+  /**
+   * @brief Returns the segment_selector in the code segment (cs) register. TODO
+   *
+   * @return segment_selector in the cs register
+   */
+  auto read_code_segment_register() -> context_switching::interrupt_descriptor_table::segment_selector;
+
 }  // namespace teachos::arch::kernel::cpu
 
 #endif  // TEACHOS_ARCH_X86_64_KERNEL_CPU_SEGMENT_REGISTER_HPP
-- 
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