...

grub.cfg

@@ -1,3 +1,4 @@
 menuentry "nub-os" {
-    multiboot2 /boot/kernel.bin
+    multiboot2 /boot/kernel
+    boot
 }

makefile

@@ -1,7 +1,7 @@
 CC = i386-elf-gcc
 LD = i386-elf-ld
 
-CFLAGS = -ffreestanding -m32
+CFLAGS = -Werror -Wall -pedantic -std=c23 -ffreestanding -m32
 
 all: .build/nub-os.iso
 
@@ -11,20 +11,20 @@ clean:
 build-dir:
 	mkdir .build 2>/dev/null || true
 
-.build/nub-os.iso: build-dir .build/kernel.bin
+.build/nub-os.iso: build-dir .build/kernel
 	mkdir -p .build/iso/boot/grub
 	cp grub.cfg .build/iso/boot/grub
-	cp .build/kernel.bin .build/iso/boot/
+	cp .build/kernel .build/iso/boot/
 	grub-mkrescue -o .build/nub-os.iso .build/iso/
 
-.build/kernel.bin: build-dir .build/boot.o .build/kernel.o .build/print.o
-	$(LD) -Ttext 0x100000 -o .build/kernel.bin .build/boot.o .build/kernel.o .build/print.o
+.build/kernel: build-dir .build/boot.o .build/kernel.o .build/vga.o
+	$(LD) -Ttext 0x100000 -o .build/kernel .build/boot.o .build/kernel.o .build/vga.o
 
 .build/kernel.o: build-dir src/kernel.c
 	$(CC) $(CFLAGS) -c -o .build/kernel.o src/kernel.c
 
-.build/print.o: build-dir src/print.c
-	$(CC) $(CFLAGS) -c -o .build/print.o src/print.c
+.build/vga.o: build-dir src/vga.c
+	$(CC) $(CFLAGS) -c -o .build/vga.o src/vga.c
 
 .build/boot.o: build-dir src/boot.asm
 	nasm -f elf32 -o .build/boot.o src/boot.asm

src/kernel.c

@@ -1,6 +1,7 @@
-#include "print.h"
+#include "vga.h"
 
 void kernel_main(void)
 {
-    print("Welcome to nub OS\n");
+    vga_reset();
+    vga_print("Welcome to nub OS\n");
 }

src/print.c

@@ -1,97 +0,0 @@
-#include "print.h"
-#include <stdint.h>
-
-#define ROWS 25
-#define COLUMNS 80
-#define BUF_SIZE ((ROWS * COLUMNS) * 2)
-
-#define BUF_START 0xb8000
-#define BUF_END (BUF_START + BUF_SIZE)
-
-typedef struct
-{
-    uint8_t character;
-    uint8_t color;
-} vga_char;
-
-static vga_char* vga_buffer = (vga_char*)BUF_START;
-static int cursor_row = 0;
-static int cursor_col = 0;
-
-void scroll(void)
-{
-    for (int row = 1; row < ROWS; row++)
-    {
-        for (int col = 0; col < COLUMNS; col++)
-        {
-            vga_buffer[(row - 1) * COLUMNS + col] = vga_buffer[row * COLUMNS + col];
-        }
-    }
-
-    for (int col = 0; col < COLUMNS; col++)
-    {
-        vga_buffer[(ROWS - 1) * COLUMNS + col] = (vga_char){ ' ', FG_WHITE | BG_BLACK << 4 };
-    }
-}
-
-void put_char(char c, FG_COLOR fg_color, BG_COLOR bg_color)
-{
-    if (c == '\n')
-    {
-        cursor_col = 0;
-        cursor_row++;
-    }
-    else
-    {
-        uint8_t color = fg_color | bg_color << 4;
-        vga_buffer[cursor_row * COLUMNS + cursor_col] = (vga_char){ c, color };
-        cursor_col++;
-    }
-
-    if (cursor_col >= COLUMNS)
-    {
-        cursor_col = 0;
-        cursor_row++;
-    }
-
-    if (cursor_row >= ROWS)
-    {
-        scroll();
-        cursor_row = ROWS - 1;
-    }
-}
-
-void print(const char* string)
-{
-    print_clr(string, FG_WHITE, BG_BLACK);
-}
-
-void print_clr(const char* string, FG_COLOR fg_color, BG_COLOR bg_color)
-{
-    for (int i = 0; string[i]; i++)
-    {
-        put_char(string[i], fg_color, bg_color);
-    }
-}
-
-void clear_screen(void)
-{
-    uint8_t color = FG_WHITE | BG_BLACK << 4;
-
-    for (int i = 0; i < ROWS * COLUMNS; i++)
-    {
-        vga_buffer[i] = (vga_char){ ' ', color };
-    }
-
-    cursor_row = 0;
-    cursor_col = 0;
-}
-
-void set_cursor_position(int row, int col)
-{
-    if (row >= 0 && row < ROWS && col >= 0 && col < COLUMNS)
-    {
-        cursor_row = row;
-        cursor_col = col;
-    }
-}

src/print.h

@@ -1,40 +0,0 @@
-#pragma once
-#include <stdint.h>
-
-typedef enum
-{
-    FG_BLACK = 0x0,
-    FG_BLUE = 0x1,
-    FG_GREEN = 0x2,
-    FG_CYAN = 0x3,
-    FG_RED = 0x4,
-    FG_MAGENTA = 0x5,
-    FG_BROWN = 0x6,
-    FG_LIGHT_GRAY = 0x7,
-    FG_DARK_GRAY = 0x8,
-    FG_LIGHT_BLUE = 0x9,
-    FG_LIGHT_GREEN = 0xA,
-    FG_LIGHT_CYAN = 0xB,
-    FG_LIGHT_RED = 0xC,
-    FG_LIGHT_MAGENTA = 0xD,
-    FG_YELLOW = 0xE,
-    FG_WHITE = 0xF,
-} FG_COLOR;
-
-typedef enum
-{
-    BG_BLACK = 0x0,
-    BG_BLUE = 0x1,
-    BG_GREEN = 0x2,
-    BG_CYAN = 0x3,
-    BG_RED = 0x4,
-    BG_MAGENTA = 0x5,
-    BG_BROWN = 0x6,
-    BG_LIGHT_GRAY = 0x7,
-} BG_COLOR;
-
-void put_char(char c, FG_COLOR fg_color, BG_COLOR bg_color);
-void print(const char* string);
-void print_clr(const char* string, FG_COLOR fg_color, BG_COLOR bg_color);
-void clear_screen(void);
-void set_cursor_position(int row, int col);

src/stdint.h

@@ -0,0 +1,17 @@
+#pragma once
+
+typedef signed char int8_t;
+typedef unsigned char uint8_t;
+
+typedef signed short int16_t;
+typedef unsigned short uint16_t;
+
+typedef signed long int int32_t;
+typedef unsigned long int uin32_t;
+
+typedef signed long long int int64_t;
+typedef unsigned long long int uin64_t;
+
+#define bool uint8_t;
+#define true 1
+#define false 0

src/vga.c

@@ -0,0 +1,111 @@
+#include "vga.h"
+
+#define ROWS 25
+#define COLUMNS 80
+
+typedef struct
+{
+    uint8_t character;
+    uint8_t color;
+} vga_char;
+
+vga_char* vga_buffer = (vga_char*)0xb8000;
+uint8_t cursor_row = 0;
+uint8_t cursor_col = 0;
+
+void vga_set_char(uint8_t row, uint8_t col, vga_char character)
+{
+    vga_buffer[COLUMNS * row + col] = character;
+}
+
+vga_char vga_char_at(uint8_t row, uint8_t col)
+{
+    return vga_buffer[COLUMNS * row + col];
+}
+
+void vga_reset(void)
+{
+    for (uint8_t row = 0; row < ROWS; row++)
+    {
+        for (uint8_t col = 0; col < COLUMNS; col++)
+        {
+            vga_char character = { .character = ' ', .color = vga_default_color() };
+            vga_set_char(row, col, character);
+        }
+    }
+
+    cursor_row = 0;
+    cursor_col = 0;
+}
+
+void vga_set_cursor_position(uint8_t row, uint8_t col)
+{
+    if (row < ROWS && col < COLUMNS)
+    {
+        cursor_row = row;
+        cursor_col = col;
+    }
+}
+
+void vga_print_char(char character, vga_color_t color)
+{
+    switch (character)
+    {
+    case '\n':
+    {
+        cursor_row += 1;
+        cursor_col = 0;
+        break;
+    }
+    case '\r':
+    {
+        cursor_col = 0;
+        break;
+    }
+    default:
+    {
+        vga_char c = { .character = character, .color = color };
+        vga_set_char(cursor_row, cursor_col, c);
+        cursor_col += 1;
+        break;
+    }
+    }
+
+    if (cursor_col >= COLUMNS)
+    {
+        cursor_col = 0;
+        cursor_row += 1;
+    }
+
+    if (cursor_row >= ROWS)
+    {
+        for (uint8_t row = 1; row < ROWS; row++)
+        {
+            for (uint8_t col = 0; col < COLUMNS; col++)
+            {
+                vga_set_char(row, col, vga_char_at(row - 1, col));
+            }
+        }
+
+        for (uint8_t col = 0; col < COLUMNS; col++)
+        {
+            vga_char character = { .character = ' ', .color = vga_default_color() };
+            vga_set_char(ROWS - 1, col, character);
+        };
+
+        cursor_row = ROWS - 1;
+    }
+}
+
+void vga_print_colored(const char* string, vga_color_t color)
+{
+    for (uint8_t i = 0; string[i] != '\0'; i++)
+    {
+        vga_print_char(string[i], color);
+    }
+}
+
+void vga_print(const char* string)
+{
+    vga_print_colored(string, vga_default_color());
+}

src/vga.h

@@ -0,0 +1,38 @@
+#pragma once
+
+#include "stdint.h"
+
+#define VGA_BLACK 0
+#define VGA_BLUE 1
+#define VGA_GREEN 2
+#define VGA_CYAN 3
+#define VGA_RED 4
+#define VGA_MAGENTA 5
+#define VGA_BROWN 6
+#define VGA_LIGHT_GRAY 7
+#define VGA_DARK_GRAY 8
+#define VGA_LIGHT_BLUE 9
+#define VGA_LIGHT_GREEN 10
+#define VGA_LIGHT_CYAN 11
+#define VGA_LIGHT_RED 12
+#define VGA_LIGHT_MAGENTA 13
+#define VGA_YELLOW 14
+#define VGA_WHITE 15
+
+typedef uint8_t vga_color_t;
+
+void vga_reset(void);
+void vga_set_cursor_position(uint8_t row, uint8_t col);
+
+void vga_print_colored(const char* string, vga_color_t color);
+void vga_print(const char* string);
+
+static inline vga_color_t vga_color(vga_color_t fg_color, vga_color_t bg_color)
+{
+    return fg_color | bg_color << 4;
+}
+
+static inline vga_color_t vga_default_color()
+{
+    return vga_color(VGA_LIGHT_GRAY, VGA_BLACK);
+}