Kernel: Add support for text mode terminal

This probably won't be used at all but it was so simple and made me do
really nice refactorings so i decided to add it :)

kernel/CMakeLists.txt

@@ -90,6 +90,7 @@ set(KERNEL_SOURCES
 	kernel/Terminal/PseudoTerminal.cpp
 	kernel/Terminal/Serial.cpp
 	kernel/Terminal/TerminalDriver.cpp
+	kernel/Terminal/TextModeTerminal.cpp
 	kernel/Terminal/TTY.cpp
 	kernel/Terminal/VirtualTTY.cpp
 	kernel/Thread.cpp

kernel/include/kernel/BananBootloader.h

@@ -4,6 +4,7 @@
 
 #define BANAN_BOOTLOADER_MAGIC	0xD3C60CFF
 #define BANAN_BOOTLOADER_FB_RGB		1
+#define BANAN_BOOTLOADER_FB_TEXT	2
 
 struct BananBootFramebufferInfo
 {

kernel/include/kernel/BootInfo.h

@@ -15,6 +15,7 @@ namespace Kernel
 			None,
 			Unknown,
 			RGB,
+			Text,
 		};
 
 		paddr_t  address;

kernel/include/kernel/Terminal/TextModeTerminal.h

@@ -0,0 +1,42 @@
+#pragma once
+
+#include <kernel/Terminal/TerminalDriver.h>
+
+namespace Kernel
+{
+
+	class TextModeTerminalDriver final : public TerminalDriver
+	{
+	public:
+		static BAN::ErrorOr<BAN::RefPtr<TextModeTerminalDriver>> create_from_boot_info();
+		~TextModeTerminalDriver();
+
+		uint32_t width() const override { return m_width; }
+		uint32_t height() const override { return m_height; }
+
+		void putchar_at(uint16_t, uint32_t, uint32_t, Color, Color) override;
+		void clear(Color) override;
+
+		void set_cursor_shown(bool) override;
+		void set_cursor_position(uint32_t, uint32_t) override;
+
+	private:
+		TextModeTerminalDriver(paddr_t paddr, uint32_t width, uint32_t height, uint32_t pitch)
+			: m_paddr(paddr)
+			, m_width(width)
+			, m_height(height)
+			, m_pitch(pitch)
+		{}
+
+		BAN::ErrorOr<void> initialize();
+
+	private:
+		const paddr_t m_paddr;
+		const uint32_t m_width;
+		const uint32_t m_height;
+		const uint32_t m_pitch;
+		vaddr_t m_vaddr { 0 };
+		static constexpr Color s_cursor_color = TerminalColor::BRIGHT_WHITE;
+	};
+
+}

kernel/include/kernel/multiboot2.h

@@ -12,6 +12,7 @@
 #define MULTIBOOT2_TAG_NEW_RSDP		15
 
 #define MULTIBOOT2_FRAMEBUFFER_TYPE_RGB		1
+#define MULTIBOOT2_FRAMEBUFFER_TYPE_TEXT	2
 
 #define MULTIBOOT2_MAGIC 0x36d76289
 

kernel/kernel/BootInfo.cpp

@@ -41,6 +41,8 @@ namespace Kernel
 				g_boot_info.framebuffer.bpp		= framebuffer_tag.framebuffer_bpp;
 				if (framebuffer_tag.framebuffer_type == MULTIBOOT2_FRAMEBUFFER_TYPE_RGB)
 					g_boot_info.framebuffer.type = FramebufferInfo::Type::RGB;
+				else if (framebuffer_tag.framebuffer_type == MULTIBOOT2_FRAMEBUFFER_TYPE_TEXT)
+					g_boot_info.framebuffer.type = FramebufferInfo::Type::Text;
 				else
 					g_boot_info.framebuffer.type = FramebufferInfo::Type::Unknown;
 			}
@@ -107,6 +109,8 @@ namespace Kernel
 		g_boot_info.framebuffer.bpp		= framebuffer.bpp;
 		if (framebuffer.type == BANAN_BOOTLOADER_FB_RGB)
 			g_boot_info.framebuffer.type = FramebufferInfo::Type::RGB;
+		else if (framebuffer.type == BANAN_BOOTLOADER_FB_TEXT)
+			g_boot_info.framebuffer.type = FramebufferInfo::Type::Text;
 		else
 			g_boot_info.framebuffer.type = FramebufferInfo::Type::Unknown;
 

kernel/kernel/Terminal/TerminalDriver.cpp

@@ -1,5 +1,6 @@
 #include <kernel/BootInfo.h>
 #include <kernel/Terminal/FramebufferTerminal.h>
+#include <kernel/Terminal/TextModeTerminal.h>
 
 namespace Kernel
 {
@@ -18,6 +19,9 @@ namespace Kernel
 					TRY(FramebufferDevice::create_from_boot_framebuffer())
 				));
 				break;
+			case FramebufferInfo::Type::Text:
+				g_terminal_driver = TRY(TextModeTerminalDriver::create_from_boot_info());
+				break;
 		}
 		return {};
 	}

kernel/kernel/Terminal/TextModeTerminal.cpp

@@ -0,0 +1,146 @@
+#include <kernel/BootInfo.h>
+#include <kernel/IO.h>
+#include <kernel/Memory/PageTable.h>
+#include <kernel/MMIO.h>
+#include <kernel/Terminal/TextModeTerminal.h>
+
+namespace Kernel
+{
+
+	static constexpr TerminalDriver::Color s_palette[] {
+		TerminalColor::BLACK,
+		TerminalColor::BLUE,
+		TerminalColor::GREEN,
+		TerminalColor::CYAN,
+		TerminalColor::RED,
+		TerminalColor::MAGENTA,
+		TerminalColor::YELLOW,
+		TerminalColor::WHITE,
+		TerminalColor::BRIGHT_BLACK,
+		TerminalColor::BRIGHT_BLUE,
+		TerminalColor::BRIGHT_GREEN,
+		TerminalColor::BRIGHT_CYAN,
+		TerminalColor::BRIGHT_RED,
+		TerminalColor::BRIGHT_MAGENTA,
+		TerminalColor::BRIGHT_YELLOW,
+		TerminalColor::BRIGHT_WHITE,
+	};
+
+	static constexpr uint8_t color_to_text_mode_color(TerminalDriver::Color color)
+	{
+		uint32_t min_diff = BAN::numeric_limits<uint32_t>::max();
+		uint8_t closest = 0;
+
+		static_assert(sizeof(s_palette) / sizeof(*s_palette) == 16);
+		for (size_t i = 0; i < 16; i++)
+		{
+			const auto rdiff = color.red()   - s_palette[i].red();
+			const auto gdiff = color.green() - s_palette[i].green();
+			const auto bdiff = color.blue()  - s_palette[i].blue();
+			const uint32_t diff = rdiff*rdiff + gdiff*gdiff + bdiff*bdiff;
+			if (diff >= min_diff)
+				continue;
+			min_diff = diff;
+			closest = i;
+		}
+
+		return closest;
+	}
+
+	BAN::ErrorOr<BAN::RefPtr<TextModeTerminalDriver>> TextModeTerminalDriver::create_from_boot_info()
+	{
+		ASSERT(g_boot_info.framebuffer.type == FramebufferInfo::Type::Text);
+		if (g_boot_info.framebuffer.bpp != 16)
+			return BAN::Error::from_errno(ENOTSUP);
+		auto* driver_ptr = new TextModeTerminalDriver(
+			g_boot_info.framebuffer.address,
+			g_boot_info.framebuffer.width,
+			g_boot_info.framebuffer.height,
+			g_boot_info.framebuffer.pitch
+		);
+		if (driver_ptr == nullptr)
+			return BAN::Error::from_errno(ENOMEM);
+		auto driver = BAN::RefPtr<TextModeTerminalDriver>::adopt(driver_ptr);
+		TRY(driver->initialize());
+		return driver;
+	}
+
+	BAN::ErrorOr<void> TextModeTerminalDriver::initialize()
+	{
+		const size_t page_count = range_page_count(m_paddr, m_height * m_pitch);
+		const vaddr_t vaddr = PageTable::kernel().reserve_free_contiguous_pages(page_count, KERNEL_OFFSET);
+		if (vaddr == 0)
+			return BAN::Error::from_errno(ENOMEM);
+
+		PageTable::kernel().map_range_at(
+			m_paddr & PAGE_ADDR_MASK,
+			vaddr,
+			page_count * PAGE_SIZE,
+			PageTable::Flags::ReadWrite | PageTable::Flags::Present,
+			PageTable::MemoryType::WriteCombining
+		);
+
+		m_vaddr = vaddr + (m_paddr % PAGE_SIZE);
+
+		set_cursor_position(0, 0);
+		clear(TerminalColor::BLACK);
+
+		return {};
+	}
+
+	TextModeTerminalDriver::~TextModeTerminalDriver()
+	{
+		if (m_vaddr == 0)
+			return;
+		const size_t page_count = range_page_count(m_paddr, m_height * m_pitch);
+		PageTable::kernel().unmap_range(m_vaddr & PAGE_ADDR_MASK, page_count * PAGE_SIZE);
+	}
+
+	void TextModeTerminalDriver::putchar_at(uint16_t ch, uint32_t x, uint32_t y, Color fg, Color bg)
+	{
+		if (x >= m_width || y >= m_height)
+			return;
+
+		if (ch >= 0x100)
+			ch = '?';
+
+		const uint8_t color =
+			(color_to_text_mode_color(bg) << 4) |
+			(color_to_text_mode_color(fg) << 0);
+		MMIO::write16(m_vaddr + y * m_pitch + 2 * x, ch | (color << 8));
+	}
+
+	void TextModeTerminalDriver::clear(Color color)
+	{
+		for (uint32_t y = 0; y < m_height; y++)
+			for (uint32_t x = 0; x < m_width; x++)
+				putchar_at(' ', x, y, TerminalColor::BRIGHT_WHITE, color);
+	}
+
+	void TextModeTerminalDriver::set_cursor_shown(bool shown)
+	{
+		if (shown)
+		{
+			IO::outb(0x3D4, 0x0A);
+			IO::outb(0x3D5, (IO::inb(0x3D5) & 0xC0) | 14);
+
+			IO::outb(0x3D4, 0x0B);
+			IO::outb(0x3D5, (IO::inb(0x3D5) & 0xE0) | 15);
+		}
+		else
+		{
+			IO::outb(0x3D4, 0x0A);
+			IO::outb(0x3D5, 0x20);
+		}
+	}
+
+	void TextModeTerminalDriver::set_cursor_position(uint32_t x, uint32_t y)
+	{
+		const uint16_t pos = y * m_width + x;
+		IO::outb(0x3D4, 0x0F);
+		IO::outb(0x3D5, pos & 0xFF);
+		IO::outb(0x3D4, 0x0E);
+		IO::outb(0x3D5, pos >> 8);
+	}
+
+}