x86_64/vga: extract buffer type

3 files changed, 105 insertions, 67 deletions

diff --git a/arch/x86_64/include/x86_64/boot/boot.hpp b/arch/x86_64/include/x86_64/boot/boot.hpp
index 0db2396..2c44659 100644
--- a/arch/x86_64/include/x86_64/boot/boot.hpp
+++ b/arch/x86_64/include/x86_64/boot/boot.hpp
@@ -60,7 +60,7 @@ namespace teachos::boot
     multiboot2::information_view const * mbi;
 
     //! The index of the next character to be written in the VGA text buffer after handoff.
-    std::ptrdiff_t vga_buffer_index;
+    std::size_t vga_buffer_index;
   };
 
 }  // namespace teachos::boot
diff --git a/arch/x86_64/include/x86_64/vga/text/buffer.hpp b/arch/x86_64/include/x86_64/vga/text/buffer.hpp
new file mode 100644
index 0000000..9e93af3
--- /dev/null
+++ b/arch/x86_64/include/x86_64/vga/text/buffer.hpp
@@ -0,0 +1,101 @@
+#ifndef TEACHOS_X86_64_VGA_TEXT_BUFFER_HPP
+#define TEACHOS_X86_64_VGA_TEXT_BUFFER_HPP
+
+// IWYU pragma: private, include "x86_64/vga/text.hpp"
+
+#include "x86_64/vga/text/attribute.hpp"
+
+#include <cstddef>
+#include <span>
+#include <string_view>
+#include <utility>
+
+namespace teachos::vga::x86_64::text
+{
+  //! A VGA text buffer.
+  //!
+  //! VGA text mode presents a linear buffer of so-called cells. Each cell consists of a single code point and a
+  //! rendering attribute. The codepoint determines the character being rendered in a specific cell, while the attribute
+  //! determines the visual style of that cell.
+  //!
+  //! @see text::attribute
+  struct buffer
+  {
+    using cell = std::pair<char, std::byte>;
+
+    //! Create a new buffer.
+    //!
+    //! @param width The width of the buffer
+    //! @param height The height of the buffer
+    //! @param start A pointer to the first byte of the buffer.
+    //! @param position The starting position for the first write to the buffer
+    buffer(std::size_t width, std::size_t height, cell * start, std::size_t position = 0);
+
+    //! Clear the buffer.
+    //!
+    //! Clearing the buffer ensures it is filled with zeroes, effectively erasing all data and resetting the output
+    //! position to the start of the buffer.
+    auto clear() -> void;
+
+    //! Write a string of formatted code points to the buffer.
+    //!
+    //! @param code_points A string of (8-bit) code points to write to the buffer.
+    //! @param attribute The formatting to apply to the written sequence of code points.
+    auto write(std::string_view code_points, attribute attribute) -> void;
+
+    //! Write a single, formatted code point to the buffer.
+    //!
+    //! @param code_point A single (8-bit) code point
+    //! @param attribute The formatting to apply to the code point.
+    auto write(char code_point, attribute attribute) -> void;
+
+    //! Move the output position to a new line and scroll the buffer if necessary.
+    auto newline() -> void;
+
+    //! Scroll the buffer contents.
+    //!
+    //! @param nof_lines The number of lines to scroll up.
+    auto scroll(std::size_t nof_lines = 1) -> void;
+
+  private:
+    //! Get column number of the current cell.
+    [[nodiscard]] auto column() const noexcept -> std::ptrdiff_t;
+
+    //! Get the line number of the current cell.
+    [[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 do_write(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 do_write(char code_point, attribute attribute) -> void;
+
+    //! The width, in cells, of the buffer.
+    std::size_t m_width{};
+
+    //! The height, in cells, of the buffer.
+    std::size_t m_height{};
+
+    //! The text mode data buffer.
+    std::span<cell> m_buffer;
+
+    //! The position of the next cell to be written to.
+    std::size_t m_position{};
+  };
+
+}  // namespace teachos::vga::x86_64::text
+
+#endif
\ No newline at end of file
diff --git a/arch/x86_64/include/x86_64/vga/text/device.hpp b/arch/x86_64/include/x86_64/vga/text/device.hpp
index 6cb7a45..f5c69a1 100644
--- a/arch/x86_64/include/x86_64/vga/text/device.hpp
+++ b/arch/x86_64/include/x86_64/vga/text/device.hpp
@@ -5,12 +5,9 @@
 
 #include "kapi/cio.hpp"
 
-#include "x86_64/vga/text/attribute.hpp"
+#include "x86_64/vga/text/buffer.hpp"
 
-#include <cstddef>
-#include <span>
 #include <string_view>
-#include <utility>
 
 namespace teachos::vga::x86_64::text
 {
@@ -25,7 +22,7 @@ namespace teachos::vga::x86_64::text
   {
     device();
 
-    //! Clear the buffer.
+    //! Clear the screen.
     //!
     //! Clearing the screen ensures the text mode buffer is filled with zeroes, effectively erasing all displayed data
     //! and resetting the output position to the start of the buffer.
@@ -40,67 +37,7 @@ namespace teachos::vga::x86_64::text
     auto write(cio::output_stream stream, std::string_view text) -> void override;
 
   private:
-    using cell = std::pair<char, std::byte>;
-
-    //! Get column number of the current cell.
-    [[nodiscard]] auto column() const noexcept -> std::ptrdiff_t;
-
-    //! Get the line number of the current cell.
-    [[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;
-
-    //! Move the cursor to a new line and scroll the buffer if necessary.
-    auto newline() -> void;
-
-    //! Scroll the screen.
-    //!
-    //! @param nof_lines The number of lines to scroll up.
-    auto scroll(std::size_t nof_lines = 1) -> void;
-
-    //! Write a string of code points to the text buffer.
-    //!
-    //! @note This function also updates the text mode buffer pointer.
-    //!
-    //! @param code_points A string of (8-bit) code points to write to the VGA text mode buffer.
-    //! @param attribute The attribute to apply to the written sequence of code points.
-    //! @see vga::text::attribute
-    auto write(std::string_view code_points, attribute attribute) -> void;
-
-    //! Write a single code point to the VGA text buffer.
-    //!
-    //! @param code_point A single (8-bit) code point
-    //! @param attribute The #attribute to apply to the code point.
-    auto write(char code_point, attribute attribute) -> void;
-
-    //! The width, in cells, of the buffer.
-    std::size_t m_width{};
-
-    //! The height, in cells, of the buffer.
-    std::size_t m_height{};
-
-    //! The text mode data buffer.
-    std::span<cell> m_buffer;
-
-    //! The position of the next cell to be written to.
-    std::ptrdiff_t m_position{};
+    buffer m_buffer;
   };
 
 }  // namespace teachos::vga::x86_64::text