...

makefile

@@ -4,6 +4,13 @@ LD = x86_64-elf-ld
 CFLAGS 	= -m64 -ffreestanding -fno-builtin -Wall -Wextra -Wshadow -std=c23
 LDFLAGS = 
 
+SRC_C   := src/kernel.c src/vga.c src/idt.c src/string.c
+SRC_ASM := src/boot.asm src/idt_stub.asm
+
+OBJ_C   := $(SRC_C:src/%.c=.build/%.o)
+OBJ_ASM := $(SRC_ASM:src/%.asm=.build/%.o)
+OBJS    := $(OBJ_C) $(OBJ_ASM)
+
 all: .build/nub-os.iso
 
 clean:
@@ -12,26 +19,17 @@ clean:
 build-dir:
 	mkdir .build 2>/dev/null || true
 
-.build/nub-os.iso: build-dir .build/kernel
+.build/nub-os.iso: .build/kernel
 	mkdir -p .build/iso/boot/grub
 	cp grub.cfg .build/iso/boot/grub
 	cp .build/kernel .build/iso/boot/
 	grub-mkrescue -o .build/nub-os.iso .build/iso/
 
-.build/kernel: build-dir .build/boot.o .build/kernel.o .build/vga.o .build/idt.o .build/idt_stub.o
+.build/kernel: $(OBJS)
-	$(LD) $(LDFLAGS) -T src/boot.ld -o .build/kernel .build/boot.o .build/kernel.o .build/vga.o .build/idt.o .build/idt_stub.o
+	$(LD) $(LDFLAGS) -T src/boot.ld -o $@ $^
 
-.build/kernel.o: build-dir src/kernel.c
+.build/%.o: src/%.c | build-dir
-	$(CC) $(CFLAGS) -c -o .build/kernel.o src/kernel.c
+	$(CC) $(CFLAGS) -c -o $@ $<
 
-.build/vga.o: build-dir src/vga.c
+.build/%.o: src/%.asm | build-dir
-	$(CC) $(CFLAGS) -c -o .build/vga.o src/vga.c
+	nasm -f elf64 -o $@ $<
-
-.build/idt.o: build-dir src/idt.c
-	$(CC) $(CFLAGS) -c -o .build/idt.o src/idt.c
-
-.build/idt_stub.o: build-dir src/idt_stub.asm
-	nasm -f elf64 -o .build/idt_stub.o src/idt_stub.asm
-
-.build/boot.o: build-dir src/boot.asm
-	nasm -f elf64 -o .build/boot.o src/boot.asm

src/idt.c

@@ -52,10 +52,10 @@ void idt_set_descriptor(uint8_t vector, void* handler, uint8_t dpl)
 void exception_handler(isr_frame_t* frame)
 {
     vga_print("Interrupt\n");
-    vga_print("    int_no:");
+    vga_print("    int_no: ");
     vga_print_uint(frame->int_no);
     vga_print("\n");
-    vga_print("    err_code:");
+    vga_print("    err_code: ");
     vga_print_uint(frame->err_code);
     vga_print("\n");
     __asm__ volatile("cli; hlt");
@@ -71,5 +71,4 @@ void idt_init(void)
     idtr_t idtr = { .base = (uintptr_t)&idt[0], .limit = (uint16_t)sizeof(interrupt_descriptor) * IDT_SIZE - 1 };
 
     __asm__ volatile("lidt %0" : : "m"(idtr));
-    __asm__ volatile("sti");
 }

src/kernel.c

@@ -4,11 +4,15 @@
 void kernel_main(void)
 {
     vga_clear();
+    vga_print_success();
+    vga_print(" VGA intialzied\n");
 
     idt_init();
-    vga_print_success("IDT intialzied\n");
+    vga_print_success();
+    vga_print(" IDT intialzied\n");
 
-    vga_print("Welcome to nub OS\n");
+    vga_print("\nWelcome to nub OS\n");
+    vga_print(">");
 
-    int i = 2 / 0;
+    int x = 1 / 0;
 }

src/string.c

@@ -1,4 +1,5 @@
 #include "string.h"
+#include <stdbool.h>
 
 int strcmp(const char* a, const char* b)
 {
@@ -10,3 +11,79 @@ int strcmp(const char* a, const char* b)
 
     return (*a == *b) ? 0 : (*a > *b) ? 1 : -1;
 }
+
+void reverse(char* str, size_t length)
+{
+    int start = 0;
+    int end = length - 1;
+    while (start < end)
+    {
+        char temp = str[start];
+        str[start] = str[end];
+        str[end] = temp;
+        start++;
+        end--;
+    }
+}
+
+int uitoa(uint64_t value, char* buffer)
+{
+    int i = 0;
+    if (value == 0)
+    {
+        buffer[i++] = '0';
+        buffer[i] = '\0';
+        return i;
+    }
+
+    while (value > 0)
+    {
+        buffer[i++] = (value % 10) + '0';
+        value /= 10;
+    }
+
+    buffer[i] = '\0';
+    reverse(buffer, i);
+    return i;
+}
+
+int itoa(int64_t value, char* buffer)
+{
+    int i = 0;
+
+    if (value == 0)
+    {
+        buffer[i++] = '0';
+        buffer[i] = '\0';
+        return i;
+    }
+
+    bool negative = false;
+    uint64_t v;
+
+    if (value < 0)
+    {
+        negative = true;
+        v = (uint64_t)(-value);
+    }
+    else
+    {
+        v = (uint64_t)value;
+    }
+
+    while (v > 0)
+    {
+        buffer[i++] = (v % 10) + '0';
+        v /= 10;
+    }
+
+    if (negative)
+    {
+        buffer[i++] = '-';
+    }
+
+    buffer[i] = '\0';
+    reverse(buffer, i);
+
+    return i;
+}

src/string.h

@@ -1,3 +1,9 @@
 #pragma once
 
+#include <stddef.h>
+#include <stdint.h>
+
 int strcmp(const char* a, const char* b);
+void reverse(char* str, size_t length);
+int uitoa(uint64_t value, char* buffer);
+int itoa(int64_t value, char* buffer);

src/vga.c

@@ -1,4 +1,8 @@
 #include "vga.h"
+#include "string.h"
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
 
 #define ROWS 25
 #define COLUMNS 80
@@ -110,78 +114,30 @@ void vga_print(const char* string)
     vga_print_colored(string, vga_default_color());
 }
 
-void vga_print_success(const char* message)
+void vga_print_success(void)
 {
     vga_print("[ ");
     vga_print_colored("success", VGA_GREEN);
-    vga_print(" ] ");
+    vga_print(" ]");
-    vga_print(message);
 }
 
-void vga_print_error(const char* message)
+void vga_print_error(void)
 {
     vga_print("[ ");
     vga_print_colored("error", VGA_RED);
-    vga_print(" ] ");
+    vga_print(" ]");
-    vga_print(message);
 }
 
-static void reverse(char* str, int length)
+void vga_print_uint(uint64_t value)
-{
-    int start = 0;
-    int end = length - 1;
-    while (start < end)
-    {
-        char temp = str[start];
-        str[start] = str[end];
-        str[end] = temp;
-        start++;
-        end--;
-    }
-}
-
-static int uitoa(unsigned int value, char* buffer)
-{
-    int i = 0;
-    if (value == 0)
-    {
-        buffer[i++] = '0';
-        buffer[i] = '\0';
-        return i;
-    }
-
-    while (value > 0)
-    {
-        buffer[i++] = (value % 10) + '0';
-        value /= 10;
-    }
-
-    buffer[i] = '\0';
-    reverse(buffer, i);
-    return i;
-}
-
-void vga_print_uint(unsigned int value)
 {
     char buffer[11];
     uitoa(value, buffer);
     vga_print(buffer);
 }
 
-void vga_print_int(int value)
+void vga_print_int(int64_t value)
 {
     char buffer[12];
-
+    itoa(value, buffer);
-    if (value < 0)
-    {
-        vga_print("-");
-        unsigned int abs_val = (unsigned int)(-value);
-        uitoa(abs_val, buffer);
-    }
-    else
-    {
-        uitoa((unsigned int)value, buffer);
-    }
-
     vga_print(buffer);
 }

src/vga.h

@@ -27,11 +27,11 @@ 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);
 
-void vga_print_success(const char* message);
+void vga_print_success(void);
-void vga_print_error(const char* message);
+void vga_print_error(void);
 
-void vga_print_uint(unsigned int value);
+void vga_print_uint(uint64_t value);
-void vga_print_int(int value);
+void vga_print_int(int64_t value);
 
 static inline vga_color_t vga_color(vga_color_t fg_color, vga_color_t bg_color)
 {