x86_64/vga: extract buffer type

7 files changed, 268 insertions, 216 deletions

diff --git a/arch/x86_64/CMakeLists.txt b/arch/x86_64/CMakeLists.txt
index 54f04cb..2505bb6 100644
--- a/arch/x86_64/CMakeLists.txt
+++ b/arch/x86_64/CMakeLists.txt
@@ -32,7 +32,8 @@ target_sources("x86_64" PRIVATE
     "src/memory/scoped_mapping.cpp"
 
     # VGA text mode
-    "src/vga/text.cpp"
+    "src/vga/text/buffer.cpp"
+    "src/vga/text/device.cpp"
 )
 
 file(GLOB_RECURSE ARCH_HEADERS RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} "include/**.hpp")
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
diff --git a/arch/x86_64/src/vga/text.cpp b/arch/x86_64/src/vga/text.cpp
deleted file mode 100644
index 1ee69f6..0000000
--- a/arch/x86_64/src/vga/text.cpp
+++ /dev/null
@@ -1,148 +0,0 @@
-#include "x86_64/vga/text.hpp"
-
-#include "kapi/boot.hpp"
-#include "kapi/cio.hpp"
-
-#include "x86_64/boot/boot.hpp"
-#include "x86_64/boot/ld.hpp"
-#include "x86_64/vga/crtc.hpp"
-
-#include <algorithm>
-#include <bit>
-#include <cstddef>
-#include <cstdint>
-#include <span>
-#include <string_view>
-#include <utility>
-
-namespace teachos::vga::x86_64::text
-{
-  namespace
-  {
-    constexpr auto default_buffer_address = std::uintptr_t{0xb8000};
-    constexpr auto default_buffer_width = 80z;
-    constexpr auto default_buffer_height = 25z;
-
-    constexpr auto bit_cursor_enabled = 5U;
-
-    [[maybe_unused]] constexpr auto black_on_black = attribute{.foreground_color = color::black,
-                                                               .foreground_flag = foreground_flag::none,
-                                                               .background_color = color::black,
-                                                               .background_flag = background_flag::none};
-  }  // namespace
-
-  device::device()
-      : m_width{default_buffer_width}
-      , m_height{default_buffer_height}
-      , m_buffer{std::bit_cast<device::cell *>(default_buffer_address +
-                                               std::bit_cast<std::uintptr_t>(&teachos::boot::x86_64::TEACHOS_VMA)),
-                 m_width * m_height}
-      , m_position{boot::bootstrap_information.vga_buffer_index}
-  {
-    clear();
-  }
-
-  auto device::clear() -> void
-  {
-    m_position = 0;
-    std::ranges::fill(m_buffer, std::pair{' ', std::bit_cast<std::byte>(black_on_black)});
-  }
-
-  auto device::cursor(bool enabled) -> void
-  {
-    auto cursor_disable_byte = std::byte{!enabled} << bit_cursor_enabled;
-
-    crtc::address::write(crtc::registers::cursor_start);
-    crtc::data::write(crtc::data::read() | cursor_disable_byte);
-  }
-
-  [[nodiscard]] auto device::column() const noexcept -> std::ptrdiff_t
-  {
-    return m_position % m_width;
-  }
-
-  [[nodiscard]] auto device::line() const noexcept -> std::ptrdiff_t
-  {
-    return m_position / m_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
-  {
-    m_buffer[m_position++] = std::pair{code_point, std::bit_cast<std::byte>(attribute)};
-  }
-
-  auto device::newline() -> void
-  {
-    auto free_glyphs_in_line = m_width - column();
-    m_position += free_glyphs_in_line;
-  }
-
-  auto device::scroll(std::size_t nof_lines) -> void
-  {
-    auto scroll_count = std::min(nof_lines, m_height);
-
-    auto scroll_start = m_buffer.begin() + (scroll_count * m_width);
-    std::ranges::move(scroll_start, m_buffer.end(), m_buffer.begin());
-
-    auto clear_start = m_buffer.begin() + (m_height - scroll_count) * m_width;
-    std::ranges::fill(clear_start, m_buffer.end(), cell{});
-
-    m_position = (line() - scroll_count) * m_width;
-  }
-
-  auto device::write(cio::output_stream stream, std::string_view text) -> void
-  {
-    auto attributes = [&] -> attribute {
-      switch (stream)
-      {
-        case cio::output_stream::stderr:
-          return red_on_black;
-        default:
-          return green_on_black;
-      }
-    }();
-    write(text, attributes);
-  }
-
-  auto device::write(std::string_view code_points, attribute attribute) -> void
-  {
-    std::ranges::for_each(code_points, [&](auto code_point) -> void { write(code_point, attribute); });
-  }
-
-  auto device::write(char code_point, attribute attribute) -> void
-  {
-    if (m_position + 1 > static_cast<std::ptrdiff_t>(m_height * m_width))
-    {
-      scroll();
-    }
-
-    if (!handle_special_code_point(code_point, attribute))
-    {
-      put(code_point, attribute);
-    }
-  };
-
-}  // namespace teachos::vga::x86_64::text
diff --git a/arch/x86_64/src/vga/text/buffer.cpp b/arch/x86_64/src/vga/text/buffer.cpp
new file mode 100644
index 0000000..2dcf084
--- /dev/null
+++ b/arch/x86_64/src/vga/text/buffer.cpp
@@ -0,0 +1,101 @@
+#include "x86_64/vga/text/buffer.hpp"
+
+#include "x86_64/vga/text/attribute.hpp"
+
+#include <algorithm>
+#include <bit>
+#include <cstddef>
+#include <span>
+#include <string_view>
+#include <utility>
+
+namespace teachos::vga::x86_64::text
+{
+  buffer::buffer(std::size_t width, std::size_t height, cell * start, std::size_t position)
+      : m_width{width}
+      , m_height{height}
+      , m_buffer{start, m_width * m_height}
+      , m_position{position}
+  {}
+
+  auto buffer::clear() -> void
+  {
+    m_position = 0;
+    std::ranges::fill(m_buffer, std::pair{'\0', static_cast<std::byte>(0x00)});
+  }
+
+  auto buffer::write(std::string_view code_points, attribute attribute) -> void
+  {
+    std::ranges::for_each(code_points, [&](auto code_point) -> void { write(code_point, attribute); });
+  }
+
+  auto buffer::write(char code_point, attribute attribute) -> void
+  {
+    if (m_position + 1 > m_height * m_width)
+    {
+      scroll();
+    }
+
+    if (!handle_special_code_point(code_point, attribute))
+    {
+      do_write(code_point, attribute);
+    }
+  };
+
+  auto buffer::newline() -> void
+  {
+    auto free_glyphs_in_line = m_width - column();
+    m_position += free_glyphs_in_line;
+  }
+
+  auto buffer::scroll(std::size_t nof_lines) -> void
+  {
+    auto scroll_count = std::min(nof_lines, m_height);
+
+    auto scroll_start = m_buffer.begin() + (scroll_count * m_width);
+    std::ranges::move(scroll_start, m_buffer.end(), m_buffer.begin());
+
+    auto clear_start = m_buffer.begin() + (m_height - scroll_count) * m_width;
+    std::ranges::fill(clear_start, m_buffer.end(), cell{});
+
+    m_position = (line() - scroll_count) * m_width;
+  }
+
+  auto buffer::column() const noexcept -> std::ptrdiff_t
+  {
+    return m_position % m_width;
+  }
+
+  auto buffer::line() const noexcept -> std::ptrdiff_t
+  {
+    return m_position / m_width;
+  }
+  auto buffer::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':
+        do_write("  ", attribute);
+        return true;
+      default:
+        return false;
+    }
+  }
+
+  auto buffer::do_write(std::string_view code_points, attribute attribute) -> void
+  {
+    std::ranges::for_each(code_points, [&](auto code_point) -> void { do_write(code_point, attribute); });
+  }
+
+  auto buffer::do_write(char code_point, attribute attribute) -> void
+  {
+    m_buffer[m_position++] = std::pair{code_point, std::bit_cast<std::byte>(attribute)};
+  }
+
+}  // namespace teachos::vga::x86_64::text
diff --git a/arch/x86_64/src/vga/text/device.cpp b/arch/x86_64/src/vga/text/device.cpp
new file mode 100644
index 0000000..2da9e06
--- /dev/null
+++ b/arch/x86_64/src/vga/text/device.cpp
@@ -0,0 +1,60 @@
+#include "kapi/cio.hpp"
+
+#include "x86_64/boot/boot.hpp"
+#include "x86_64/boot/ld.hpp"
+#include "x86_64/vga/crtc.hpp"
+#include "x86_64/vga/text.hpp"
+
+#include <bit>
+#include <cstddef>
+#include <cstdint>
+#include <string_view>
+
+namespace teachos::vga::x86_64::text
+{
+  namespace
+  {
+    constexpr auto default_buffer_address = std::uintptr_t{0xb8000};
+    constexpr auto default_buffer_width = 80z;
+    constexpr auto default_buffer_height = 25z;
+
+    constexpr auto bit_cursor_enabled = 5U;
+  }  // namespace
+
+  device::device()
+      : m_buffer{default_buffer_width, default_buffer_height,
+                 std::bit_cast<buffer::cell *>(default_buffer_address +
+                                               std::bit_cast<std::uintptr_t>(&teachos::boot::x86_64::TEACHOS_VMA)),
+                 boot::bootstrap_information.vga_buffer_index}
+  {
+    clear();
+  }
+
+  auto device::clear() -> void
+  {
+    m_buffer.clear();
+  }
+
+  auto device::cursor(bool enabled) -> void
+  {
+    auto cursor_disable_byte = std::byte{!enabled} << bit_cursor_enabled;
+
+    crtc::address::write(crtc::registers::cursor_start);
+    crtc::data::write(crtc::data::read() | cursor_disable_byte);
+  }
+
+  auto device::write(cio::output_stream stream, std::string_view text) -> void
+  {
+    auto attributes = [&] -> attribute {
+      switch (stream)
+      {
+        case cio::output_stream::stderr:
+          return red_on_black;
+        default:
+          return green_on_black;
+      }
+    }();
+    m_buffer.write(text, attributes);
+  }
+
+}  // namespace teachos::vga::x86_64::text