Initial commit. Still a lot to do

.clang-format

@@ -0,0 +1,149 @@
+---
+Language:        Cpp
+# BasedOnStyle:  GNU
+AccessModifierOffset: -2
+AlignAfterOpenBracket: Align
+AlignConsecutiveMacros: false
+AlignConsecutiveAssignments: false
+AlignConsecutiveBitFields: false
+AlignConsecutiveDeclarations: false
+AlignEscapedNewlines: Right
+AlignOperands:   Align
+AlignTrailingComments: true
+AllowAllArgumentsOnNextLine: true
+AllowAllConstructorInitializersOnNextLine: true
+AllowAllParametersOfDeclarationOnNextLine: true
+AllowShortEnumsOnASingleLine: true
+AllowShortBlocksOnASingleLine: Never
+AllowShortCaseLabelsOnASingleLine: false
+AllowShortFunctionsOnASingleLine: All
+AllowShortLambdasOnASingleLine: All
+AllowShortIfStatementsOnASingleLine: Never
+AllowShortLoopsOnASingleLine: false
+AlwaysBreakAfterDefinitionReturnType: All
+AlwaysBreakAfterReturnType: AllDefinitions
+AlwaysBreakBeforeMultilineStrings: false
+AlwaysBreakTemplateDeclarations: MultiLine
+BinPackArguments: true
+BinPackParameters: true
+BraceWrapping:
+  AfterCaseLabel:  true
+  AfterClass:      true
+  AfterControlStatement: Always
+  AfterEnum:       true
+  AfterFunction:   true
+  AfterNamespace:  true
+  AfterObjCDeclaration: true
+  AfterStruct:     true
+  AfterUnion:      true
+  AfterExternBlock: true
+  BeforeCatch:     true
+  BeforeElse:      true
+  BeforeLambdaBody: false
+  BeforeWhile:     true
+  IndentBraces:    true
+  SplitEmptyFunction: true
+  SplitEmptyRecord: true
+  SplitEmptyNamespace: true
+BreakBeforeBinaryOperators: All
+BreakBeforeBraces: GNU
+BreakBeforeInheritanceComma: false
+BreakInheritanceList: BeforeColon
+BreakBeforeTernaryOperators: true
+BreakConstructorInitializersBeforeComma: false
+BreakConstructorInitializers: BeforeColon
+BreakAfterJavaFieldAnnotations: false
+BreakStringLiterals: true
+ColumnLimit:     79
+CommentPragmas:  '^ IWYU pragma:'
+CompactNamespaces: false
+ConstructorInitializerAllOnOneLineOrOnePerLine: false
+ConstructorInitializerIndentWidth: 4
+ContinuationIndentWidth: 4
+Cpp11BracedListStyle: false
+DeriveLineEnding: true
+DerivePointerAlignment: false
+DisableFormat:   false
+ExperimentalAutoDetectBinPacking: false
+FixNamespaceComments: false
+ForEachMacros:
+  - foreach
+  - Q_FOREACH
+  - BOOST_FOREACH
+IncludeBlocks:   Preserve
+IncludeCategories:
+  - Regex:           '^"(llvm|llvm-c|clang|clang-c)/'
+    Priority:        2
+    SortPriority:    0
+  - Regex:           '^(<|"(gtest|gmock|isl|json)/)'
+    Priority:        3
+    SortPriority:    0
+  - Regex:           '.*'
+    Priority:        1
+    SortPriority:    0
+IncludeIsMainRegex: '(Test)?$'
+IncludeIsMainSourceRegex: ''
+IndentCaseLabels: false
+IndentCaseBlocks: false
+IndentGotoLabels: true
+IndentPPDirectives: None
+IndentExternBlock: AfterExternBlock
+IndentWidth:     2
+IndentWrappedFunctionNames: false
+InsertTrailingCommas: None
+JavaScriptQuotes: Leave
+JavaScriptWrapImports: true
+KeepEmptyLinesAtTheStartOfBlocks: true
+MacroBlockBegin: ''
+MacroBlockEnd:   ''
+MaxEmptyLinesToKeep: 1
+NamespaceIndentation: None
+ObjCBinPackProtocolList: Auto
+ObjCBlockIndentWidth: 2
+ObjCBreakBeforeNestedBlockParam: true
+ObjCSpaceAfterProperty: false
+ObjCSpaceBeforeProtocolList: true
+PenaltyBreakAssignment: 2
+PenaltyBreakBeforeFirstCallParameter: 19
+PenaltyBreakComment: 300
+PenaltyBreakFirstLessLess: 120
+PenaltyBreakString: 1000
+PenaltyBreakTemplateDeclaration: 10
+PenaltyExcessCharacter: 1000000
+PenaltyReturnTypeOnItsOwnLine: 60
+PointerAlignment: Right
+ReflowComments:  true
+SortIncludes:    true
+SortUsingDeclarations: true
+SpaceAfterCStyleCast: false
+SpaceAfterLogicalNot: false
+SpaceAfterTemplateKeyword: true
+SpaceBeforeAssignmentOperators: true
+SpaceBeforeCpp11BracedList: false
+SpaceBeforeCtorInitializerColon: true
+SpaceBeforeInheritanceColon: true
+SpaceBeforeParens: Always
+SpaceBeforeRangeBasedForLoopColon: true
+SpaceInEmptyBlock: false
+SpaceInEmptyParentheses: false
+SpacesBeforeTrailingComments: 1
+SpacesInAngles:  false
+SpacesInConditionalStatement: false
+SpacesInContainerLiterals: true
+SpacesInCStyleCastParentheses: false
+SpacesInParentheses: false
+SpacesInSquareBrackets: false
+SpaceBeforeSquareBrackets: false
+Standard:        c++03
+StatementMacros:
+  - Q_UNUSED
+  - QT_REQUIRE_VERSION
+TabWidth:        8
+UseCRLF:         false
+UseTab:          Never
+WhitespaceSensitiveMacros:
+  - STRINGIZE
+  - PP_STRINGIZE
+  - BOOST_PP_STRINGIZE
+...
+

.gitignore

@@ -0,0 +1,6 @@
+*.o
+*.bin
+*~
+\#*\#
+.\#*
+*.out

Makefile

@@ -0,0 +1,92 @@
+CROSS_PATH=$(HOME)/opt/cross/bin
+
+LD=$(CROSS_PATH)/i686-elf-ld
+CC=$(CROSS_PATH)/i686-elf-gcc
+
+ASM=nasm
+ECHO=echo -e
+QEMU=qemu-system-i386
+GDB=gdb
+
+CFLAGS=-g -ffreestanding -falign-jumps -falign-functions -falign-labels \
+	-falign-loops -fstrength-reduce -fomit-frame-pointer \
+	-finline-functions -Wno-unused-function -fno-builtin -Werror \
+	-Wno-unused-label -Wno-cpp -Wno-unused-parameter -nostdlib \
+	-nostartfiles -nodefaultlibs -Wall -O0
+INCLUDES=-I.
+
+NO_SECTORS=100
+
+OBJS=build/kernel.asm.o build/kernel.o build/idt/idt.asm.o build/idt/idt.o \
+	build/mm/mem.o build/io/io.asm.o build/string/string.o
+
+# VESA Driver
+OBJS+=build/drivers/vesa/vesa.o build/drivers/vesa/terminal.o \
+	build/drivers/vesa/fonts/vga.o
+
+all: build/boot/boot.bin build/kernel.out
+	@dd if=build/boot/boot.bin > kinl.bin
+	@dd if=build/kernel.out >> kinl.bin
+	@dd if=/dev/zero bs=512 count=$(NO_SECTORS) >> kinl.bin
+
+build/kernel.out: $(OBJS)
+	@$(LD) -g -relocatable $(OBJS) -o build/kernelfull.o
+	@$(CC) $(CFLAGS) -T linker.ld -o $@ -ffreestanding -O0 -nostdlib \
+		build/kernelfull.o
+
+build/boot/boot.bin: boot/bios.asm
+	@$(ECHO) "ASM\t\t"$<
+	@$(ASM) -f bin $< -o $@
+
+build/kernel.asm.o: sys/kernel.asm
+	@$(ECHO) "ASM\t\t"$<
+	@$(ASM) -f elf -g $< -o $@
+
+build/kernel.o: sys/kernel.c
+	@$(ECHO) "CC\t\t"$<
+	@$(CC) $(CFLAGS) $(INCLUDES) -std=gnu99 -c $< -o $@
+
+build/idt/idt.asm.o: sys/idt/idt.asm
+	@$(ECHO) "ASM\t\t"$<
+	@$(ASM) -f elf -g $< -o $@
+
+build/idt/idt.o: sys/idt/idt.c
+	@$(ECHO) "CC\t\t"$<
+	@$(CC) $(CFLAGS) $(INCLUDES) -std=gnu99 -c $< -o $@
+
+build/mm/mem.o: sys/mm/mem.c
+	@$(ECHO) "CC\t\t"$<
+	@$(CC) $(CFLAGS) $(INCLUDES) -std=gnu99 -c $< -o $@
+
+build/io/io.asm.o: sys/io/io.asm
+	@$(ECHO) "ASM\t\t"$<
+	@$(ASM) -f elf -g $< -o $@
+
+build/string/string.o: sys/string/string.c
+	@$(ECHO) "CC\t\t"$<
+	@$(CC) $(CFLAGS) $(INCLUDES) -std=gnu99 -c $< -o $@
+
+# VESA Driver
+build/drivers/vesa/vesa.o: drivers/vesa/vesa.c
+	@$(ECHO) "CC\t\t"$<
+	@$(CC) $(CFLAGS) $(INCLUDES) -std=gnu99 -c $< -o $@
+
+build/drivers/vesa/terminal.o: drivers/vesa/terminal.c
+	@$(ECHO) "CC\t\t"$<
+	@$(CC) $(CFLAGS) $(INCLUDES) -std=gnu99 -c $< -o $@
+
+build/drivers/vesa/fonts/vga.o: drivers/vesa/fonts/vga.c
+	@$(ECHO) "CC\t\t"$<
+	@$(CC) $(CFLAGS) $(INCLUDES) -std=gnu99 -c $< -o $@
+
+gdb: all
+	@$(GDB) -ex "set confirm off" \
+			-ex "add-symbol-file build/kernelfull.o 0x0100000" \
+			-ex "target remote | qemu-system-i386 -hda kinl.bin -S -gdb stdio"
+
+run: all
+	@$(QEMU) -hda kinl.bin
+
+clean:
+	@rm -Rf build/boot/boot.bin build/kernel.out \
+		build/kernelfull.o $(OBJS)

boot/bios.asm

@@ -0,0 +1,142 @@
+	ORG 0x7c00
+	BITS 16
+
+	CODE_SEG equ gdt_code - gdt_start
+	DATA_SEG equ gdt_data - gdt_start
+
+_start:
+	jmp short start
+	nop
+
+	times 33 db 0
+
+start:
+	jmp 0:step2
+
+step2:
+	cli			; Disable interrupts
+	mov ax, 0x00
+	mov ds, ax
+	mov es, ax
+
+	mov ss, ax
+	mov sp, 0x7c00
+	sti			; Enable interrupts
+
+  mov ax, 0x4F01
+  mov cx, 0x118
+  mov di, 0x500
+  int 0x10
+
+  mov ax, 0x4F02
+  mov bx, 0x118
+  int 0x10
+
+	.load_protected:
+	cli
+	lgdt [gdt_descriptor]
+	mov eax, cr0
+	or eax, 1
+	mov cr0, eax
+	jmp CODE_SEG:load32
+
+	;; GDT
+gdt_start:
+gdt_null:
+	dd 0x0
+	dd 0x0
+
+	;; offset 0x8
+gdt_code:			; CS Should point to this
+	dw 0xffff		; Segment limit first 0-15 bits
+	dw 0			; Base first 0-15 bits
+	db 0			; Base 16-23 bits
+	db 0x9a			; Access bytes
+	db 11001111b		; High 4 bit flags and the low 4 bit flags
+	db 0			; Base 24-31 bits
+
+	;; offset 0x10
+gdt_data:			; DS, SS, ES, FS, GS
+	dw 0xffff		; Segment limit, first  0-15 bits
+	dw 0			; Base first 0-15 bits
+	db 0			; Base 16-23 bits
+	db 0x92			; Access byte
+	db 11001111b		; High 4 bit flags and the low 4 bit flags
+	db 0			; Base 24-31 bits
+gdt_end:
+gdt_descriptor:
+	dw gdt_end - gdt_start - 1
+	dd gdt_start
+
+	[BITS 32]
+load32:
+	mov eax, 1
+	mov ecx, 100
+	mov edi, 0x0100000
+	call ata_lba_read
+	jmp CODE_SEG:0x0100000
+
+	
+ata_lba_read:
+	mov ebx, eax		; Backup the LBA
+
+	;; Send the highest 8 bits of the LBA to the hard disk controller
+	shr eax, 24
+	or eax, 0xE0
+	mov dx, 0x1F6
+	out dx, al
+	;; Finished sending the highest 8 bits of the LBA
+
+	;; Send the total sectors to read
+	mov eax, ecx
+	mov dx, 0x1F2
+	out dx, al
+	;; Finished sending the total sectors to read
+
+	;; Send more bits of the LBA
+	mov eax, ebx	      ; Restore the backup LBA
+	mov dx, 0x1F3
+	out dx, al
+	;; Finished sending more bits of the LBA
+
+	;; Send more bits of the LBA
+	mov dx, 0x1F4
+	mov eax, ebx		; Restore the backup LBA
+	shr eax, 8
+	out dx, al
+	;; Finished sending more bits of the LBA
+
+	;; Send upper 16 bits of the LBA
+	mov dx, 0x1F5
+	mov eax, ebx	  ; Restore the backup LBA
+	shr eax, 16
+	out dx, al
+	;; Finished sending upper 16 bits of the LBA
+
+	mov dx, 0x1F7
+	mov al, 0x20
+	out dx, al
+
+	;; Read all sectors into memory
+	.next_sector:
+	push ecx
+
+	;; Checking if we need to read
+	.try_again:
+	mov dx, 0x1F7
+	in al, dx
+	test al, 8
+	jz .try_again
+
+	;; We need to read 256 words at a time
+	mov ecx, 256
+	mov dx, 0x1F0
+	rep insw
+	pop ecx
+	loop .next_sector
+	;; End of reading sectors into memory
+
+	ret
+
+	times 510-($-$$) db 0
+	dw 0xAA55

compile_flags.txt

@@ -0,0 +1,8 @@
+-Wno-unused-function
+-Wno-unused-label
+-Wno-cpp
+-Wno-unused-parameter
+-nostdlib
+-nodefaultlibs
+-Wall
+-I.

drivers/vesa/fonts/fonts.h

@@ -0,0 +1,9 @@
+#ifndef __VESA_FONTS_H
+#define __VESA_FONTS_H
+
+#define FONT_VGA_WIDTH 12
+#define FONT_VGA_HEIGHT 18
+
+int font_vga (int index, int y);
+
+#endif

drivers/vesa/terminal.c

@@ -0,0 +1,71 @@
+#include "vesa.h"
+
+#include "fonts/fonts.h"
+
+#include <sys/kernel.h>
+#include <sys/string/string.h>
+
+#define TERMINAL_DEFAULT_FONT font_vga
+
+u16 _row = 0;
+u16 _col = 0;
+
+static void
+terminal_putchar (char c, u32 col)
+{
+  if (c == '\n')
+    {
+      _row += 1;
+      _col = 0;
+      return;
+    }
+
+  vesa_putchar (TERMINAL_DEFAULT_FONT, FONT_VGA_WIDTH, FONT_VGA_HEIGHT, c,
+                _col * (FONT_VGA_WIDTH / 1.5), _row * FONT_VGA_HEIGHT, col);
+
+  _col += 1;
+  if (_col * (FONT_VGA_WIDTH / 1.5) >= vesa_get_width ())
+    {
+      _col = 0;
+      _row += 1;
+    }
+}
+
+void
+terminal_print (const char *str)
+{
+  int len = strlen (str);
+  for (int i = 0; i < len; i++)
+    {
+      terminal_putchar (str[i], vesa_make_colour (255, 255, 255));
+    }
+}
+
+void
+terminal_print_ext (const char *str, u32 col)
+{
+  int len = strlen (str);
+
+  for (int i = 0; i < len; i++)
+    {
+      terminal_putchar (str[i], col);
+    }
+}
+
+// This is a function that will write "* PENDING `task'" to the screen
+void
+terminal_print_pending (const char *task)
+{
+  terminal_print_ext ("\n*", vesa_make_colour (255, 105, 147));
+  terminal_print_ext (" PENDING ", vesa_make_colour (255, 20, 147));
+  terminal_print (task);
+}
+
+// This is a function that will write "* DONE `task'" to the screen
+void
+terminal_print_done (const char *task)
+{
+  terminal_print_ext ("\n*", vesa_make_colour (0, 255, 0));
+  terminal_print_ext (" DONE ", vesa_make_colour (34, 139, 34));
+  terminal_print (task);
+}

drivers/vesa/vesa.c

@@ -0,0 +1,105 @@
+#include "vesa.h"
+
+struct vbe_info *info = (struct vbe_info *)VBE_INFO_ADDR;
+
+u32
+vesa_make_colour (u8 r, u8 g, u8 b)
+{
+  return r << info->red_position | g << info->green_position
+         | b << info->blue_position;
+}
+
+void
+vesa_putpixel (u16 x, u16 y, u32 col)
+{
+  void *framebuffer = (void *)(unsigned long)info->framebuffer;
+
+  switch (info->bpp)
+    {
+    case 8:
+      {
+        u8 *pixel = framebuffer + info->pitch * y + x;
+        *pixel = col;
+      }
+      break;
+
+    case 15:
+    case 16:
+      {
+        u16 *pixel = framebuffer + info->pitch * y + 2 * x;
+        *pixel = col;
+      }
+      break;
+
+    case 24:
+      {
+        u32 *pixel = framebuffer + info->pitch * y + 3 * x;
+        *pixel = (col & 0xffffff) | (*pixel & 0xff000000);
+      }
+      break;
+
+    case 32:
+      {
+        u32 *pixel = framebuffer + info->pitch * y + 4 * x;
+        *pixel = col;
+      }
+      break;
+    }
+}
+
+void
+vesa_cls (u32 col)
+{
+  for (u16 y = 0; y < info->height; y++)
+    {
+      for (u16 x = 0; x < info->width; x++)
+        {
+          vesa_putpixel (x, y, col);
+        }
+    }
+}
+
+void
+vesa_draw_rect (u16 x, u16 y, u16 w, u16 h, u32 col)
+{
+  for (u16 j = y; j < (y + h); j++)
+    {
+      for (u16 i = x; i < (x + w); i++)
+        {
+          vesa_putpixel (i, j, col);
+        }
+    }
+}
+
+u16
+vesa_get_width ()
+{
+  return info->width;
+}
+
+u16
+vesa_get_height ()
+{
+  return info->height;
+}
+
+void
+vesa_putchar (int (*font) (int, int), u8 font_width, u8 font_height, char c,
+              u16 x, u16 y, u32 col)
+{
+  for (u8 j = 0; j < font_height; j++)
+    {
+      u32 row = (*font) ((i32)c, j);
+      i32 shift = font_width - 1;
+      i32 bit_val = 0;
+
+      for (u8 i = 0; i < font_width; i++)
+        {
+          bit_val = (row >> shift) & 1;
+          if (bit_val)
+            vesa_putpixel (x + i, y + j, col);
+
+          shift -= 1;
+        }
+    }
+}

drivers/vesa/vesa.h

@@ -0,0 +1,66 @@
+#ifndef __VESA_H
+#define __VESA_H
+
+#include <sys/kernel.h>
+
+#define VBE_INFO_ADDR 0x500
+
+struct vbe_info
+{
+  u16 attributes;
+  u8 window_a;
+  u8 window_b;
+  u16 granularity;
+  u16 window_size;
+  u16 segment_a;
+  u16 segment_b;
+  u32 win_func_ptr;
+  u16 pitch;
+  u16 width;
+  u16 height;
+  u8 w_char;
+  u8 y_char;
+  u8 planes;
+  u8 bpp;
+  u8 banks;
+  u8 memory_model;
+  u8 bank_size;
+  u8 image_pages;
+  u8 reserved0;
+
+  u8 red_mask;
+  u8 red_position;
+  u8 green_mask;
+  u8 green_position;
+  u8 blue_mask;
+  u8 blue_position;
+  u8 reserved_mask;
+  u8 reserved_position;
+  u8 direct_colour_attributes;
+
+  u32 framebuffer;
+
+  u32 off_screen_mem_off;
+  u16 off_screen_mem_size;
+
+  u8 reserved1[206];
+} __attribute__ ((packed));
+
+u32 vesa_make_colour (u8 r, u8 g, u8 b);
+void vesa_putpixel (u16 x, u16 y, u32 col);
+void vesa_cls (u32 col);
+void vesa_draw_rect (u16 x, u16 y, u16 w, u16 h, u32 col);
+void vesa_putchar (int (*font) (int, int), u8 font_width, u8 font_height,
+                   char c, u16 x, u16 y, u32 col);
+
+// "terminal"
+void terminal_print (const char *str);
+void terminal_print_ext (const char *str, u32 col);
+
+void terminal_print_pending (const char *task);
+void terminal_print_done (const char *task);
+
+u16 vesa_get_width ();
+u16 vesa_get_height ();
+
+#endif

linker.ld

@@ -0,0 +1,31 @@
+ENTRY (_start)
+OUTPUT_FORMAT(binary)
+SECTIONS
+{
+	. = 1M;
+	.text : ALIGN (4096)
+	{
+		*(.text)
+	}
+
+	.rodata : ALIGN (4096)
+	{
+		*(.rodata)
+	}
+
+	.data : ALIGN (4096)
+	{
+		*(.data)
+	}
+
+	.bss : ALIGN (4096)
+	{
+		*(COMMON)
+		*(.bss)
+	}
+
+	.asm :
+	{
+		*(.asm)
+	}
+}

sys/config.h

@@ -0,0 +1,9 @@
+#ifndef __CONFIG_H
+#define __CONFIG_H
+
+#define KERNEL_CODE_SELECTOR 0x08
+#define KERNEL_DATA_SELECTOR 0x10
+
+#define KINL_TOTAL_INTERRUPTS 512
+
+#endif

sys/idt/idt.asm

@@ -0,0 +1,13 @@
+  section .asm
+
+  global idt_load
+
+idt_load: 
+  push ebp
+  mov ebp, esp
+
+  mov ebx, [ebp + 8]
+  lidt [ebx]
+
+  pop ebp
+  ret

sys/idt/idt.c

@@ -0,0 +1,41 @@
+#include "idt.h"
+#include <sys/config.h>
+
+#include <sys/mm/mem.h>
+
+#include <drivers/vesa/vesa.h>
+
+struct idt_desc idt_descriptors[KINL_TOTAL_INTERRUPTS];
+struct idtr_desc idtr_descriptor;
+
+extern void idt_load (void *ptr);
+
+void
+idt_zero ()
+{
+  terminal_print ("Divide by zero error\n");
+}
+
+void
+idt_set (int interrupt_no, void *address)
+{
+  struct idt_desc *desc = &idt_descriptors[interrupt_no];
+  desc->offset_1 = (u32)address & 0x0000ffff;
+  desc->selector = KERNEL_CODE_SELECTOR;
+  desc->zero = 0x00;
+  desc->type_attribute = 0xee;
+  desc->offset_2 = (u32)address >> 16;
+}
+
+void
+idt_init ()
+{
+  memset (idt_descriptors, 0, sizeof (idt_descriptors));
+  idtr_descriptor.limit = sizeof (idt_descriptors) - 1;
+  idtr_descriptor.base = (u32)idt_descriptors;
+
+  idt_set (0, idt_zero);
+
+  // Load the interrupt descriptor table
+  idt_load (&idtr_descriptor);
+}

sys/idt/idt.h

@@ -0,0 +1,24 @@
+#ifndef __IDT_H
+#define __IDT_H
+
+#include <sys/kernel.h>
+
+struct idt_desc
+{
+  u16 offset_1; // Offset bits  0 - 16
+  u16 selector; // Selector that's in our GDT
+  u8 zero;
+  u8 type_attribute; // Descriptor type attribute
+  u16 offset_2;      // Offset bits 16-31
+} __attribute__ ((packed));
+
+struct idtr_desc
+{
+  u16 limit; // Size of descriptor tabe
+  u32 base;  // Base address of the start of the interrupt table
+} __attribute__ ((packed));
+
+void idt_init ();
+void idt_set (int interrupt_no, void *address);
+
+#endif

sys/io/io.asm

@@ -0,0 +1,51 @@
+  section .asm
+
+  global insb
+  global insw
+
+  global outb
+  global outw
+
+insb:
+  push ebp
+  mov ebp, esp
+
+  xor eax, eax
+  mov edx, [ebp + 8]
+  in al, dx
+
+  pop ebp
+  ret
+
+insw:
+  push ebp
+  mov ebp, esp
+
+  xor eax, eax
+  mov edx, [ebp + 8]
+  in ax, dx
+
+  pop ebp
+  ret
+
+outb:
+  push ebp
+  mov ebp, esp
+
+  mov eax, [ebp + 12]
+  mov edx, [ebp + 8]
+  out dx, al
+
+  pop ebp
+  ret
+
+outw: 
+  push ebp
+  mov ebp, esp
+
+  mov eax, [ebp + 12]
+  mov edx, [ebp + 8]
+  out dx, ax
+
+  pop ebp
+  ret

sys/io/io.h

@@ -0,0 +1,12 @@
+#ifndef __IO_H
+#define __IO_H
+
+#include <sys/kernel.h>
+
+u8 insb (u16 port);
+u16 insw (u16 port);
+
+void outb (u16 port, u8 val);
+void outw (u16 port, u16 val);
+
+#endif

sys/kernel.asm

@@ -0,0 +1,29 @@
+	[BITS 32]
+
+	extern kmain
+
+	global _start
+
+	CODE_SEG equ 0x08
+	DATA_SEG equ 0x10
+
+_start:
+	mov ax, DATA_SEG
+	mov ds, ax
+	mov es, ax
+	mov fs, ax
+	mov gs, ax
+	mov ss, ax
+	mov ebp, 0x00200000
+	mov esp, ebp
+
+	;; Enable A20 line
+	in al, 0x92
+	or al, 2
+	out 0x92, al
+
+	call kmain
+
+	jmp $
+
+	times 512-($-$$) db 0

sys/kernel.c

@@ -0,0 +1,17 @@
+#include <sys/kernel.h>
+
+#include <drivers/vesa/vesa.h>
+
+#include <sys/idt/idt.h>
+#include <sys/io/io.h>
+
+void
+kmain ()
+{
+  terminal_print ("Welcome to the Kinl operating system!\n");
+
+  // Initialise the IDT
+  terminal_print_pending ("Initialise IDT");
+  idt_init ();
+  terminal_print_done ("Initialised IDT");
+}

sys/kernel.h

@@ -0,0 +1,16 @@
+#ifndef __KERNEL_H
+#define __KERNEL_H
+
+typedef unsigned char u8;
+typedef unsigned short u16;
+typedef unsigned int u32;
+typedef unsigned long long u64;
+
+typedef char i8;
+typedef short i16;
+typedef int i32;
+typedef long long i64;
+
+void kmain ();
+
+#endif

sys/mm/mem.c

@@ -0,0 +1,14 @@
+#include "mem.h"
+
+void *
+memset (void *ptr, int c, u32 size)
+{
+  char *c_ptr = (char *)ptr;
+
+  for (u32 i = 0; i < size; i++)
+    {
+      c_ptr[i] = (char)c;
+    }
+
+  return ptr;
+}

sys/mm/mem.h

@@ -0,0 +1,8 @@
+#ifndef __MEM_H_
+#define __MEM_H
+
+#include <sys/kernel.h>
+
+void *memset (void *ptr, int c, u32 size);
+
+#endif

sys/string/string.c

@@ -0,0 +1,36 @@
+#include "string.h"
+
+char
+tolower (char s1)
+{
+  if (s1 >= 65 && s1 <= 90)
+    s1 += 32;
+
+  return s1;
+}
+
+int
+strlen (const char *str)
+{
+  int i = 0;
+  while (*str != 0)
+    {
+      i++;
+      str += 1;
+    }
+
+  return i;
+}
+
+int
+strnlen (const char *str, int max)
+{
+  int i = 0;
+  for (int i = 0; i < max; i++)
+    {
+      if (str[i] == 0)
+        break;
+    }
+
+  return i;
+}

sys/string/string.h

@@ -0,0 +1,8 @@
+#ifndef __STRING_H
+#define __STRING_H
+
+char tolower (char s1);
+int strlen (const char *str);
+int strnlen (const char *str, int max);
+
+#endif