x86_64/vga: extract buffer type

1 files changed, 101 insertions, 0 deletions

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