1 files changed, 30 insertions, 12 deletions
diff --git a/arch/x86_64/src/video/vga/text.cpp b/arch/x86_64/src/video/vga/text.cpp
index f1e7412..0137ddb 100644
--- a/arch/x86_64/src/video/vga/text.cpp
+++ b/arch/x86_64/src/video/vga/text.cpp
@@ -1,6 +1,5 @@
 #include "arch/video/vga/text.hpp"
 
-#include "arch/boot/pointers.hpp"
 #include "arch/video/vga/io.hpp"
 #include "memory/asm_pointer.hpp"
 
@@ -10,24 +9,18 @@
 
 namespace teachos::arch::video::vga::text
 {
-
   namespace
   {
-    auto constexpr default_text_buffer_address = 0xb8000;
+    auto constexpr DEFAULT_TEXT_BUFFER_WIDTH = 80U;
+    auto constexpr DEFAULT_TEXT_BUFFER_HEIGHT = 25U;
 
     extern "C" std::pair<char, attribute> * vga_buffer_pointer;
     auto constinit text_buffer = teachos::memory::asm_pointer{vga_buffer_pointer};
-
-    auto write(char code_point, attribute attribute) -> void
-    {
-      auto & p = *text_buffer;
-      (*p++) = std::pair{code_point, attribute};
-    };
   }  // namespace
 
   auto clear(attribute attribute) -> void
   {
-    *text_buffer = reinterpret_cast<decltype(text_buffer)::pointer>(default_text_buffer_address);
+    *text_buffer = reinterpret_cast<decltype(text_buffer)::pointer>(DEFAULT_VGA_TEXT_BUFFER_ADDRESS);
     std::ranges::fill_n(*text_buffer, 2000, std::pair{' ', attribute});
   }
 
@@ -39,9 +32,34 @@ namespace teachos::arch::video::vga::text
     crtc::data_port::write(vga::crtc::data_port::read() | cursor_disable_byte);
   }
 
-  auto write(std::string_view code_points, attribute attribute) -> void
+  auto newline() -> void
   {
-    std::ranges::for_each(code_points, [&](auto code_point) { write(code_point, attribute); });
+    auto base = reinterpret_cast<decltype(text_buffer)::pointer>(DEFAULT_VGA_TEXT_BUFFER_ADDRESS);
+    auto & raw_buffer = *text_buffer;
+    auto current_line = (raw_buffer - base) / DEFAULT_TEXT_BUFFER_WIDTH;
+    auto next_line = current_line + 1;
+
+    if (next_line >= DEFAULT_TEXT_BUFFER_HEIGHT)
+    {
+      auto begin = base + DEFAULT_TEXT_BUFFER_WIDTH;
+      auto end = base + DEFAULT_TEXT_BUFFER_WIDTH * DEFAULT_TEXT_BUFFER_HEIGHT;
+      std::ranges::move(begin, end, base);
+      raw_buffer = base + current_line * DEFAULT_TEXT_BUFFER_WIDTH;
+    }
+    else
+    {
+      raw_buffer = base + next_line * DEFAULT_TEXT_BUFFER_WIDTH;
+    }
   }
 
+  auto write_char(char code_point, attribute attribute) -> void
+  {
+    auto & p = *text_buffer;
+    (*p++) = std::pair{code_point, attribute};
+  };
+
+  auto write(std::string_view code_points, attribute attribute) -> void
+  {
+    std::ranges::for_each(code_points, [&](auto code_point) { write_char(code_point, attribute); });
+  }
 }  // namespace teachos::arch::video::vga::text