Add TTY and VGA interface

Line endings


Removed redundant files


Line ending

build.zig

@@ -53,6 +53,7 @@ fn buildTest(b: *Builder, src_path: []const u8) void {
         var file_src = concat(b.allocator, src_path2.toSlice(), file) catch unreachable;
         file_src.append(".zig") catch unreachable;
         const tst = b.addTest(file_src.toSlice());
+        tst.setMainPkgPath(".");
         step.dependOn(&tst.step);
     }
 }

src/kernel/arch.zig

@@ -1,2 +1,32 @@
+// Zig version: 0.4.0
+
+///
 /// Initialise the architecture
+///
 pub extern fn init() void;
+
+///
+/// Inline assembly to write to a given port with a byte of data.
+///
+/// Arguments:
+///     IN port: u16 - The port to write to.
+///     IN data: u8  - The byte of data that will be sent.
+///
+pub extern fn outb(port: u16, data: u8) void;
+
+///
+/// Inline assembly that reads data from a given port and returns its value.
+///
+/// Arguments:
+///     IN port: u16 - The port to read data from.
+///
+/// Return:
+///     The data that the port returns.
+///
+pub extern fn inb(port: u16) u8;
+
+///
+/// A simple way of waiting for I/O event to happen by doing an I/O event to flush the I/O
+/// event being waited.
+///
+pub extern fn ioWait() void;

src/kernel/arch/x86/arch.zig

@@ -1,3 +1,17 @@
+// Zig version: 0.4.0
+
+const is_test = @import("builtin").is_test;
+
+const ALIGN = 1 << 0;
+const MEMINFO = 1 << 1;
+const MAGIC = 0x1BADB002;
+const FLAGS = ALIGN | MEMINFO;
+
+const KERNEL_ADDR_OFFSET = 0xC0000000;
+const KERNEL_PAGE_NUMBER = KERNEL_ADDR_OFFSET >> 22;
+// The number of pages occupied by the kernel, will need to be increased as we add a heap etc.
+const KERNEL_NUM_PAGES = 1;
+
 extern fn kmain() void;
 
 const MultiBoot = packed struct {
@@ -6,22 +20,12 @@ const MultiBoot = packed struct {
     checksum: i32,
 };
 
-const ALIGN = 1 << 0;
+export var multiboot align(4) linksection(".rodata.boot") = MultiBoot {
-const MEMINFO = 1 << 1;
-const MAGIC = 0x1BADB002;
-const FLAGS = ALIGN | MEMINFO;
-
-export var multiboot align(4) linksection(".rodata.boot") = MultiBoot{
     .magic = MAGIC,
     .flags = FLAGS,
     .checksum = -(MAGIC + FLAGS),
 };
 
-const KERNEL_ADDR_OFFSET = 0xC0000000;
-const KERNEL_PAGE_NUMBER = KERNEL_ADDR_OFFSET >> 22;
-// The number of pages occupied by the kernel, will need to be increased as we add a heap etc.
-const KERNEL_NUM_PAGES = 1;
-
 // The initial page directory used for booting into the higher half. Should be overwritten later
 export var boot_page_directory: [1024]u32 align(4096) linksection(".rodata.boot") = init: {
     // Increase max number of branches done by comptime evaluator
@@ -35,7 +39,7 @@ export var boot_page_directory: [1024]u32 align(4096) linksection(".rodata.boot"
     var i = 0;
     var idx = 1;
 
-    // Fill preceding pages with zeroes. May be unecessary but incurs no runtime cost
+    // Fill preceding pages with zeroes. May be unnecessary but incurs no runtime cost
     while (i < KERNEL_PAGE_NUMBER - 1) : ({
         i += 1;
         idx += 1;
@@ -51,7 +55,7 @@ export var boot_page_directory: [1024]u32 align(4096) linksection(".rodata.boot"
     }) {
         dir[idx] = 0x00000083 | (i << 22);
     }
-    // Fill suceeding pages with zeroes. May be unecessary but incurs no runtime cost
+    // Fill succeeding pages with zeroes. May be unnecessary but incurs no runtime cost
     i = 0;
     while (i < 1024 - KERNEL_PAGE_NUMBER - KERNEL_NUM_PAGES) : ({
         i += 1;
@@ -107,4 +111,43 @@ export nakedcc fn start_higher_half() noreturn {
     while (true) {}
 }
 
+///
+/// Initialise the architecture
+///
 export fn init() void {}
+
+///
+/// Inline assembly to write to a given port with a byte of data.
+///
+/// Arguments:
+///     IN port: u16 - The port to write to.
+///     IN data: u8  - The byte of data that will be sent.
+///
+export fn outb(port: u16, data: u8) void {
+    asm volatile ("outb %[data], %[port]"
+        :
+        : [port] "{dx}" (port), [data] "{al}" (data));
+}
+
+///
+/// Inline assembly that reads data from a given port and returns its value.
+///
+/// Arguments:
+///     IN port: u16 - The port to read data from.
+///
+/// Return:
+///     The data that the port returns.
+///
+export fn inb(port: u16) u8 {
+    return asm volatile ("inb %[port], %[result]"
+        : [result] "={al}" (-> u8)
+        : [port] "N{dx}" (port));
+}
+
+///
+/// A simple way of waiting for I/O event to happen by doing an I/O event to flush the I/O
+/// event being waited.
+///
+export fn ioWait() void {
+    outb(0x80, 0);
+}

src/kernel/kmain.zig

@@ -1,17 +1,14 @@
-//
+// Zig version: 0.4.0
-// kmain
+
-// Zig version:
-// Author: DrDeano
-// Date: 2019-03-30
-//
 const builtin = @import("builtin");
-const arch = @import("arch.zig");
+const arch = if (builtin.is_test) @import("../../test/kernel/arch_mock.zig") else @import("arch.zig");
 const multiboot = @import("multiboot.zig");
+const tty = @import("tty.zig");
+const vga = @import("vga.zig");
 
 pub fn panic(msg: []const u8, error_return_trace: ?*builtin.StackTrace) noreturn {
     @setCold(true);
-    terminal.write("KERNEL PANIC: ");
+    tty.print("\nKERNEL PANIC: {}\n", msg);
-    terminal.write(msg);
     while (true) {}
 }
 
@@ -19,81 +16,8 @@ pub export fn kmain(mb_info: *multiboot.multiboot_info_t, mb_magic: u32) void {
     if (mb_magic == multiboot.MULTIBOOT_BOOTLOADER_MAGIC) {
         // Booted with compatible bootloader
         arch.init();
-        terminal.initialize();
+        vga.init();
-        terminal.write("Hello, kernel World!");
+        tty.init();
+        tty.print("\nHello Pluto from kernel :)\n");
     }
 }
-
-// Hardware text mode color constants
-const VGA_COLOUR = enum(u8) {
-    VGA_COLOUR_BLACK,
-    VGA_COLOUR_BLUE,
-    VGA_COLOUR_GREEN,
-    VGA_COLOUR_CYAN,
-    VGA_COLOUR_RED,
-    VGA_COLOUR_MAGENTA,
-    VGA_COLOUR_BROWN,
-    VGA_COLOUR_LIGHT_GREY,
-    VGA_COLOUR_DARK_GREY,
-    VGA_COLOUR_LIGHT_BLUE,
-    VGA_COLOUR_LIGHT_GREEN,
-    VGA_COLOUR_LIGHT_CYAN,
-    VGA_COLOUR_LIGHT_RED,
-    VGA_COLOUR_LIGHT_MAGENTA,
-    VGA_COLOUR_LIGHT_BROWN,
-    VGA_COLOUR_WHITE,
-};
-
-fn vga_entry_colour(fg: VGA_COLOUR, bg: VGA_COLOUR) u8 {
-    return @enumToInt(fg) | (@enumToInt(bg) << 4);
-}
-
-fn vga_entry(uc: u8, colour: u8) u16 {
-    return u16(uc) | (u16(colour) << 8);
-}
-
-const VGA_WIDTH = 80;
-const VGA_HEIGHT = 25;
-
-const terminal = struct {
-    var row = usize(0);
-    var column = usize(0);
-    var colour = vga_entry_colour(VGA_COLOUR.VGA_COLOUR_LIGHT_GREY, VGA_COLOUR.VGA_COLOUR_BLACK);
-
-    const buffer = @intToPtr([*]volatile u16, 0xC00B8000);
-
-    fn initialize() void {
-        var y = usize(0);
-        while (y < VGA_HEIGHT) : (y += 1) {
-            var x = usize(0);
-            while (x < VGA_WIDTH) : (x += 1) {
-                putCharAt(' ', colour, x, y);
-            }
-        }
-    }
-
-    fn setColour(new_colour: u8) void {
-        colour = new_colour;
-    }
-
-    fn putCharAt(c: u8, new_colour: u8, x: usize, y: usize) void {
-        const index = y * VGA_WIDTH + x;
-        buffer[index] = vga_entry(c, new_colour);
-    }
-
-    fn putChar(c: u8) void {
-        putCharAt(c, colour, column, row);
-        column += 1;
-        if (column == VGA_WIDTH) {
-            column = 0;
-            row += 1;
-            if (row == VGA_HEIGHT)
-                row = 0;
-        }
-    }
-
-    fn write(data: []const u8) void {
-        for (data) |c|
-            putChar(c);
-    }
-};

src/kernel/vga.zig

@@ -0,0 +1,413 @@
+// Zig version: 0.4.0
+
+const builtin = @import("builtin");
+const arch = if (builtin.is_test) @import("../../test/kernel/arch_mock.zig")
+             else @import("arch.zig");
+
+const expectEqual = @import("std").testing.expectEqual;
+const warn = @import("std").debug.warn;
+
+/// The port address for the VGA register selection.
+const PORT_ADDRESS: u16 = 0x03D4;
+
+/// The port address for the VGA data.
+const PORT_DATA: u16 = 0x03D5;
+
+// The indexes that is passed to the address port to select the register for the data to be
+// read or written to.
+
+const REG_HORIZONTAL_TOTAL: u8                = 0x00;
+const REG_HORIZONTAL_DISPLAY_ENABLE_END: u8   = 0x01;
+const REG_START_HORIZONTAL_BLINKING: u8       = 0x02;
+const REG_END_HORIZONTAL_BLINKING: u8         = 0x03;
+const REG_START_HORIZONTAL_RETRACE_PULSE: u8  = 0x04;
+const REG_END_HORIZONTAL_RETRACE_PULSE: u8    = 0x05;
+const REG_VERTICAL_TOTAL: u8                  = 0x06;
+const REG_OVERFLOW: u8                        = 0x07;
+const REG_PRESET_ROW_SCAN: u8                 = 0x08;
+const REG_MAXIMUM_SCAN_LINE: u8               = 0x09;
+
+/// The command for setting the start of the cursor scan line.
+const REG_CURSOR_START: u8                    = 0x0A;
+
+/// The command for setting the end of the cursor scan line.
+const REG_CURSOR_END: u8                      = 0x0B;
+const REG_START_ADDRESS_HIGH: u8              = 0x0C;
+const REG_START_ADDRESS_LOW: u8               = 0x0D;
+
+/// The command for setting the upper byte of the cursor's linear location.
+const REG_CURSOR_LOCATION_HIGH: u8            = 0x0E;
+
+/// The command for setting the lower byte of the cursor's linear location.
+const REG_CURSOR_LOCATION_LOW: u8             = 0x0F;
+const REG_VERTICAL_RETRACE_START: u8          = 0x10;
+const REG_VERTICAL_RETRACE_END: u8            = 0x11;
+const REG_VERTICAL_DISPLAY_ENABLE_END: u8     = 0x12;
+const REG_OFFSET: u8                          = 0x13;
+const REG_UNDERLINE_LOCATION: u8              = 0x14;
+const REG_START_VERTICAL_BLINKING: u8         = 0x15;
+const REG_END_VERTICAL_BLINKING: u8           = 0x16;
+const REG_CRT_MODE_CONTROL: u8                = 0x17;
+const REG_LINE_COMPARE: u8                    = 0x18;
+
+
+///The start of the cursor scan line, the very beginning.
+const CURSOR_SCANLINE_START: u8   = 0x0;
+
+///The scan line for use in the underline cursor shape.
+const CURSOR_SCANLINE_MIDDLE: u8  = 0xE;
+
+///The end of the cursor scan line, the very end.
+const CURSOR_SCANLINE_END: u8     = 0xF;
+
+/// If set, disables the cursor.
+const CURSOR_DISABLE: u8    = 0x20;
+
+pub const WIDTH: u16        = 80;
+pub const HEIGHT: u16       = 25;
+
+// The set of colours that VGA supports and can display for the foreground and background.
+pub const COLOUR_BLACK: u4            = 0x00;
+pub const COLOUR_BLUE: u4             = 0x01;
+pub const COLOUR_GREEN: u4            = 0x02;
+pub const COLOUR_CYAN: u4             = 0x03;
+pub const COLOUR_RED: u4              = 0x04;
+pub const COLOUR_MAGENTA: u4          = 0x05;
+pub const COLOUR_BROWN: u4            = 0x06;
+pub const COLOUR_LIGHT_GREY: u4       = 0x07;
+pub const COLOUR_DARK_GREY: u4        = 0x08;
+pub const COLOUR_LIGHT_BLUE: u4       = 0x09;
+pub const COLOUR_LIGHT_GREEN: u4      = 0x0A;
+pub const COLOUR_LIGHT_CYAN: u4       = 0x0B;
+pub const COLOUR_LIGHT_RED: u4        = 0x0C;
+pub const COLOUR_LIGHT_MAGENTA: u4    = 0x0D;
+pub const COLOUR_LIGHT_BROWN: u4      = 0x0E;
+pub const COLOUR_WHITE: u4            = 0x0F;
+
+/// The set of shapes that can be displayed.
+pub const CursorShape = enum(u1) {
+    /// The cursor has the underline shape.
+    UNDERLINE,
+
+    /// The cursor has the block shape.
+    BLOCK,
+};
+
+/// The cursor scan line start so to know whether is in block or underline mode.
+var cursor_scanline_start: u8 = undefined;
+
+/// The cursor scan line end so to know whether is in block or underline mode.
+var cursor_scanline_end: u8 = undefined;
+
+///
+/// Takes two 4 bit values that represent the foreground and background colour of the text and
+/// returns a 8 bit value that gives both to be displayed.
+///
+/// Arguments:
+///     IN fg: u4 - The foreground colour.
+///     IN bg: u4 - The background colour.
+///
+/// Return:
+///     Both combined into 1 byte for the colour to be displayed.
+///
+pub fn entryColour(fg: u4, bg: u4) u8 {
+    return u8(fg) | u8(bg) << 4;
+}
+
+///
+/// Create the 2 bytes entry that the VGA used to display a character with a foreground and
+/// background colour.
+///
+/// Arguments:
+///     IN uc: u8     - The character.
+///     IN colour: u8 - The foreground and background colour.
+///
+/// Return:
+///     The VGA entry.
+///
+pub fn entry(uc: u8, colour: u8) u16 {
+    return u16(uc) | u16(colour) << 8;
+}
+
+///
+/// Update the hardware on screen cursor.
+///
+/// Arguments:
+///     IN x: u16 - The horizontal position of the cursor.
+///     IN y: u16 - The vertical position of the cursor.
+///
+/// Return:
+///     The VGA entry.
+///
+pub fn updateCursor(x: u16, y: u16) void {
+    var pos: u16 = undefined;
+    var pos_upper: u16 = undefined;
+    var pos_lower: u16 = undefined;
+
+    // Make sure new cursor position is within the screen
+    if (x < HEIGHT and y < WIDTH) {
+        pos = y * WIDTH + x;
+    } else {
+        // If not within the screen, then just put the cursor at the very end
+        pos = (HEIGHT - 1) * WIDTH + (WIDTH - 1);
+    }
+
+    pos_upper = (pos >> 8) & 0x00FF;
+    pos_lower = pos & 0x00FF;
+
+    // Set the cursor position
+    arch.outb(PORT_ADDRESS, REG_CURSOR_LOCATION_LOW);
+    arch.outb(PORT_DATA, @truncate(u8, pos_lower));
+
+    arch.outb(PORT_ADDRESS, REG_CURSOR_LOCATION_HIGH);
+    arch.outb(PORT_DATA, @truncate(u8, pos_upper));
+}
+
+///
+/// Get the hardware cursor position.
+///
+/// Return:
+///     The linear cursor position.
+///
+pub fn getCursor() u16 {
+    var cursor: u16 = 0;
+
+    arch.outb(PORT_ADDRESS, REG_CURSOR_LOCATION_LOW);
+    cursor |= u16(arch.inb(PORT_DATA));
+
+    arch.outb(PORT_ADDRESS, REG_CURSOR_LOCATION_HIGH);
+    cursor |= u16(arch.inb(PORT_DATA)) << 8;
+
+    return cursor;
+}
+
+///
+/// Enables the blinking cursor to that is is visible.
+///
+pub fn enableCursor() void {
+    arch.outb(PORT_ADDRESS, REG_CURSOR_START);
+    arch.outb(PORT_DATA, cursor_scanline_start);
+
+    arch.outb(PORT_ADDRESS, REG_CURSOR_END);
+    arch.outb(PORT_DATA, cursor_scanline_end);
+}
+
+///
+/// Disables the blinking cursor to that is is visible.
+///
+pub fn disableCursor() void {
+    arch.outb(PORT_ADDRESS, REG_CURSOR_START);
+    arch.outb(PORT_DATA, CURSOR_DISABLE);
+}
+
+///
+/// Set the shape of the cursor. This can be and underline or block shape.
+///
+/// Arguments:
+///     IN shape: CURSOR_SHAPE - The enum CURSOR_SHAPE that selects which shape to use.
+///
+pub fn setCursorShape(shape: CursorShape) void {
+    switch(shape) {
+        CursorShape.UNDERLINE => {
+            arch.outb(PORT_ADDRESS, REG_CURSOR_START);
+            arch.outb(PORT_DATA, CURSOR_SCANLINE_MIDDLE);
+
+            arch.outb(PORT_ADDRESS, REG_CURSOR_END);
+            arch.outb(PORT_DATA, CURSOR_SCANLINE_END);
+
+            cursor_scanline_start = CURSOR_SCANLINE_MIDDLE;
+            cursor_scanline_end = CURSOR_SCANLINE_END;
+        },
+        CursorShape.BLOCK => {
+            arch.outb(PORT_ADDRESS, REG_CURSOR_START);
+            arch.outb(PORT_DATA, CURSOR_SCANLINE_START);
+
+            arch.outb(PORT_ADDRESS, REG_CURSOR_END);
+            arch.outb(PORT_DATA, CURSOR_SCANLINE_END);
+
+            cursor_scanline_start = CURSOR_SCANLINE_START;
+            cursor_scanline_end = CURSOR_SCANLINE_END;
+        },
+    }
+}
+
+///
+/// Initialise the VGA text mode. This sets the cursor and underline shape.
+///
+pub fn init() void {
+    // Set the maximum scan line to 0x0F
+    arch.outb(PORT_ADDRESS, REG_MAXIMUM_SCAN_LINE);
+    arch.outb(PORT_DATA, CURSOR_SCANLINE_END);
+
+    // Set by default the underline cursor
+    setCursorShape(CursorShape.UNDERLINE);
+    cursor_scanline_start = CURSOR_SCANLINE_MIDDLE;
+    cursor_scanline_end = CURSOR_SCANLINE_END;
+}
+
+test "entryColour" {
+    var fg: u4 = COLOUR_BLACK;
+    var bg: u4 = COLOUR_BLACK;
+    var res: u8 = entryColour(fg, bg);
+    expectEqual(u8(0x00), res);
+
+    fg = COLOUR_LIGHT_GREEN;
+    bg = COLOUR_BLACK;
+    res = entryColour(fg, bg);
+    expectEqual(u8(0x0A), res);
+
+    fg = COLOUR_BLACK;
+    bg = COLOUR_LIGHT_GREEN;
+    res = entryColour(fg, bg);
+    expectEqual(u8(0xA0), res);
+
+    fg = COLOUR_BROWN;
+    bg = COLOUR_LIGHT_GREEN;
+    res = entryColour(fg, bg);
+    expectEqual(u8(0xA6), res);
+}
+
+test "entry" {
+    var colour: u8 = entryColour(COLOUR_BROWN, COLOUR_LIGHT_GREEN);
+    expectEqual(u8(0xA6), colour);
+
+    // Character '0' is 0x30
+    var video_entry: u16 = entry('0', colour);
+    expectEqual(u16(0xA630), video_entry);
+
+    video_entry = entry(0x55, colour);
+    expectEqual(u16(0xA655), video_entry);
+}
+
+fn testOutOfBounds(x: u16, y: u16) bool {
+    if(x < HEIGHT and y < WIDTH) {
+        return true;
+    }
+    return false;
+}
+
+fn testUpperVal(x: u16, y: u16) u16 {
+    const pos: u16 = x * WIDTH + y;
+    const pos_upper: u16 = (pos >> 8) & 0x00FF;
+    return pos_upper;
+}
+
+fn testLowerVal(x: u16, y: u16) u16 {
+    const pos: u16 = x * WIDTH + y;
+    const pos_lower: u16 = pos & 0x00FF;
+    return pos_lower;
+}
+
+test "updateCursor out of bounds" {
+    var x: u16 = 0;
+    var y: u16 = 0;
+    var res: bool = testOutOfBounds(x, y);
+    expectEqual(true, res);
+
+    x = HEIGHT - 1;
+    res = testOutOfBounds(x, y);
+    expectEqual(true, res);
+
+    y = WIDTH - 1;
+    res = testOutOfBounds(x, y);
+    expectEqual(true, res);
+
+    x = HEIGHT;
+    y = WIDTH;
+    res = testOutOfBounds(x, y);
+    expectEqual(false, res);
+
+    x = HEIGHT - 1;
+    y = WIDTH;
+    res = testOutOfBounds(x, y);
+    expectEqual(false, res);
+
+    x = HEIGHT;
+    y = WIDTH - 1;
+    res = testOutOfBounds(x, y);
+    expectEqual(false, res);
+}
+
+test "updateCursor lower values" {
+    var x: u16 = 0x0000;
+    var y: u16 = 0x0000;
+    var res: u16 = testLowerVal(x, y);
+    var expected: u16 = 0x0000;
+    expectEqual(expected, res);
+
+    x = 0x0000;
+    y = 0x000A;
+    res = testLowerVal(x, y);
+    expected = 0x000A;
+    expectEqual(expected, res);
+
+    x = 0x000A;
+    y = 0x0000;
+    res = testLowerVal(x, y);
+    expected = 0x0020;
+    expectEqual(expected, res);
+
+    x = 0x000A;
+    y = 0x000A;
+    res = testLowerVal(x, y);
+    expected = 0x002A;
+    expectEqual(expected, res);
+}
+
+test "updateCursor upper values" {
+    var x: u16 = 0x0000;
+    var y: u16 = 0x0000;
+    var res: u16 = testUpperVal(x, y);
+    var expected: u16 = 0x0000;
+    expectEqual(expected, res);
+
+    x = 0x0000;
+    y = 0x000A;
+    res = testUpperVal(x, y);
+    expected = 0x0000;
+    expectEqual(expected, res);
+
+    x = 0x000A;
+    y = 0x0000;
+    res = testUpperVal(x, y);
+    expected = 0x0003;
+    expectEqual(expected, res);
+
+    x = 0x000A;
+    y = 0x000A;
+    res = testUpperVal(x, y);
+    expected = 0x0003;
+    expectEqual(expected, res);
+}
+
+test "getCursor all" {
+    warn(" Waiting for mocking ");
+    var res = getCursor();
+}
+
+test "enableCursor all" {
+    warn(" Waiting for mocking ");
+    enableCursor();
+}
+
+test "disableCursor all" {
+    warn(" Waiting for mocking ");
+    disableCursor();
+}
+
+test "setCursorShape all" {
+    setCursorShape(CursorShape.UNDERLINE);
+    expectEqual(CURSOR_SCANLINE_MIDDLE, cursor_scanline_start);
+    expectEqual(CURSOR_SCANLINE_END, cursor_scanline_end);
+
+    setCursorShape(CursorShape.BLOCK);
+    expectEqual(CURSOR_SCANLINE_START, cursor_scanline_start);
+    expectEqual(CURSOR_SCANLINE_END, cursor_scanline_end);
+}
+
+test "init all" {
+    warn(" Waiting for mocking ");
+    init();
+    expectEqual(CURSOR_SCANLINE_MIDDLE, cursor_scanline_start);
+    expectEqual(CURSOR_SCANLINE_END, cursor_scanline_end);
+}

test/kernel/arch_mock.zig

@@ -0,0 +1,32 @@
+// Zig version: 0.4.0
+
+///
+/// Initialise the architecture
+///
+pub fn init() void {}
+
+///
+/// Inline assembly to write to a given port with a byte of data.
+///
+/// Arguments:
+///     IN port: u16 - The port to write to.
+///     IN data: u8  - The byte of data that will be sent.
+///
+pub fn outb(port: u16, data: u8) void {}
+
+///
+/// Inline assembly that reads data from a given port and returns its value.
+///
+/// Arguments:
+///     IN port: u16 - The port to read data from.
+///
+/// Return:
+///     The data that the port returns.
+///
+pub fn inb(port: u16) u8 {return 0;}
+
+///
+/// A simple way of waiting for I/O event to happen by doing an I/O event to flush the I/O
+/// event being waited.
+///
+pub fn ioWait() void {}