x86_64/vga: extract special character handling

2 files changed, 49 insertions, 8 deletions

diff --git a/arch/x86_64/include/x86_64/vga/text.hpp b/arch/x86_64/include/x86_64/vga/text.hpp
index fcda67f..64cb2b9 100644
--- a/arch/x86_64/include/x86_64/vga/text.hpp
+++ b/arch/x86_64/include/x86_64/vga/text.hpp
@@ -129,6 +129,25 @@ namespace teachos::vga::x86_64::text
     [[nodiscard]] auto column() const noexcept -> std::ptrdiff_t;
     [[nodiscard]] auto line() const noexcept -> std::ptrdiff_t;
 
+    //! Process the semantics of special code points, for example newlines and carriage returns.
+    //!
+    //! @param code_point The code point to process.
+    //! @param attribute The attribute to use when writing to the text buffer.
+    //! @return @p true iff. the code point was handled, @p false otherwise.
+    auto handle_special_code_point(char code_point, attribute attribute) -> bool;
+
+    //! Perform the actual output to the buffer.
+    //!
+    //! @param code_points The code points to output..
+    //! @param attribute The attribute to use when writing to the text buffer.
+    auto put(std::string_view code_points, attribute attribute) -> void;
+
+    //! Perform the actual output to the buffer.
+    //!
+    //! @param code_point The code point to output.
+    //! @param attribute The attribute to use when writing to the text buffer.
+    auto put(char code_point, attribute attribute) -> void;
+
     /**
      * @brief Move the cursor to a new line, scrolling the buffer if necessary.
      */
diff --git a/arch/x86_64/src/vga/text.cpp b/arch/x86_64/src/vga/text.cpp
index 8f6214e..1249cc3 100644
--- a/arch/x86_64/src/vga/text.cpp
+++ b/arch/x86_64/src/vga/text.cpp
@@ -58,6 +58,34 @@ namespace teachos::vga::x86_64::text
     return m_position / DEFAULT_TEXT_BUFFER_WIDTH;
   }
 
+  auto device::handle_special_code_point(char code_point, attribute attribute) -> bool
+  {
+    switch (code_point)
+    {
+      case '\n':
+        newline();
+        return true;
+      case '\r':
+        m_position -= column();
+        return true;
+      case '\t':
+        put("  ", attribute);
+        return true;
+      default:
+        return false;
+    }
+  }
+
+  auto device::put(std::string_view code_points, attribute attribute) -> void
+  {
+    std::ranges::for_each(code_points, [&](auto code_point) -> void { put(code_point, attribute); });
+  }
+
+  auto device::put(char code_point, attribute attribute) -> void
+  {
+    buffer[m_position++] = std::pair{code_point, std::bit_cast<std::byte>(attribute)};
+  }
+
   auto device::newline() -> void
   {
     auto free_glyphs_in_line = DEFAULT_TEXT_BUFFER_WIDTH - column();
@@ -103,16 +131,10 @@ namespace teachos::vga::x86_64::text
       scroll();
     }
 
-    if (code_point == '\n')
+    if (!handle_special_code_point(code_point, attribute))
     {
-      if (column())
-      {
-        newline();
-      }
-      return;
+      put(code_point, attribute);
     }
-
-    buffer[m_position++] = std::pair{code_point, std::bit_cast<std::byte>(attribute)};
   };
 
 }  // namespace teachos::vga::x86_64::text