1 files changed, 63 insertions, 0 deletions
diff --git a/src/vgaterminal.cpp b/src/vgaterminal.cpp
new file mode 100644
index 0000000..5f86081
--- /dev/null
+++ b/src/vgaterminal.cpp
@@ -0,0 +1,63 @@
+#include "portio.hpp"
+#include "vgaterminal.hpp"
+
+#include <algorithm>
+#include <cstddef>
+#include <cstdint>
+#include <utility>
+
+void VGATerminal::write(char c) noexcept
+{
+    checkpos();
+
+    switch (c) {
+    case '\b':
+        if (offset % Width) {
+            --offset;
+            put(' ');
+            --offset;
+        }
+        break;
+    case '\n':
+        offset += Width;
+        [[fallthrough]];
+    case '\r':
+        offset -= offset % Width;
+        break;
+    default:
+        put(c);
+        break;
+    }
+
+    updatecursor();
+}
+
+void VGATerminal::put(char c) noexcept
+{
+    std::uint16_t cell = c
+        | (std::to_underlying(foreground) << 8)
+        | (std::to_underlying(background) << 12);
+
+    auto ptr = reinterpret_cast<std::uint16_t *>(Videoram);
+    ptr[offset++] = cell;
+}
+
+void VGATerminal::checkpos() noexcept
+{
+    if (offset >= Width * Height) {
+        auto ptr = reinterpret_cast<std::uint16_t *>(Videoram);
+        const auto end = ptr + Width * Height;
+        std::copy(ptr + Width, end, ptr);
+        std::fill(end - Width, end, 0);
+        offset = Width * Height - Width;
+    }
+}
+
+void VGATerminal::updatecursor() const noexcept
+{
+    outb(0x03d4, 0x0f);
+    outb(0x03d5, static_cast<std::uint8_t>(offset));
+    outb(0x03d4, 0x0e);
+    outb(0x03d5, static_cast<std::uint8_t>(offset >> 8));
+}
+