fixing bootloader again but should work using nasm now

.vscode/settings.json

@@ -0,0 +1,7 @@
+{
+    "files.associations": {
+        ".fantomasignore": "ignore",
+        "stddef.h": "c",
+        "io.h": "c"
+    }
+}

README.md

@@ -48,4 +48,7 @@ Clone and build:
 git clone https://github.com/gbowne1/ClassicOS.git
 cd ClassicOS
 make
-```
+```
+
+build kernel
+for %f in (*.c) do gcc -m32 -O0 -Wall -Wextra -Werror -pedantic -ffreestanding -nostdlib -fno-pic -fno-stack-protector -fno-pie -march=i386 -mtune=i386 -c "%f" -o "%f.o"

bootloader/boot.asm

@@ -1,67 +1,292 @@
+; ==============================================================================
+; boot.asm - First Stage Bootloader (CHS Based)
+; ==============================================================================
+
 [BITS 16]
 [ORG 0x7C00]
 
 start:
-    cli
+    cli                         ; Disable interrupts
+
+    mov [bootdev], dl           ; Save boot device number (from BIOS in DL)
+
+    ; Setup stack safely below EBDA area (choose 0x0000:0x7A00)
+    xor ax, ax                  ; AX = 0
+    mov ss, ax                  ; Stack segment = 0x0000
+    mov sp, 0x7A00              ; Stack offset = 0x7A00
+
+    ; Initialize DS, ES for zero-based segments
     xor ax, ax
     mov ds, ax
     mov es, ax
-    mov ss, ax
-    mov sp, 0x7C00
 
+    ; Load second-stage bootloader (boot1.asm) to 0x7E00
+    mov ax, 1                   ; LBA of boot1.asm (starts at sector 1)
+    call lba_to_chs
+    mov si, 0x7E00
+    mov al, 4                   ; Number of sectors to read
+    call read_chs
+
+    ; Load kernel to 0x100000 (1 MB)
+    mov si, 0x0000              ; Destination offset
+    mov ax, 0x1000              ; ES = 0x1000 (0x1000:0x0000 = 1 MB)
+    mov es, ax
+    xor bx, bx
+    mov ax, 5                   ; LBA of kernel start (boot1 is 4 sectors: LBA 1–4 → kernel at LBA 5)
+    call lba_to_chs
+    mov al, 16                  ; Number of sectors for kernel
+    call read_chs
+    jc disk_error
+
+    ; Memory Validation: Verify checksum of second stage bootloader
+    mov si, 0x7E00             ; Start of second stage
+    mov cx, 512 * 4            ; Size in bytes (adjust if more sectors loaded)
+    call verify_checksum
+    jc disk_error              ; Jump if checksum fails
+
+    ; Enable A20 line
     call enable_a20
+    jc a20_error                ; Jump if A20 enable fails
+
+    ; Setup Global Descriptor Table
     call setup_gdt
+
+    ; Switch to protected mode and jump to second stage at 0x08:0x7E00
     call switch_to_pm
 
-; ----------------------
-; A20 Gate Enable (Fast method)
-enable_a20:
-    in al, 0x92
-    or al, 0x02
-    out 0x92, al
+disk_error:
+    mov si, disk_error_msg
+    call print_string_16
+    jmp halt
+
+a20_error:
+    mov si, a20_error_msg
+    call print_string_16
+    jmp halt
+
+; ----------------------------------------------------------------
+; Verify Checksum Routine
+; Uses SI = start address, CX = byte count
+; Simple XOR checksum over bytes, expects result 0
+
+verify_checksum:
+    push ax
+    push bx
+    push di
+    mov di, si
+    xor al, al
+    xor bx, bx
+
+.verify_loop:
+    lodsb
+    xor bl, al
+    loop .verify_loop
+
+    test bl, bl
+    jz .checksum_ok
+    stc                    ; Set carry on checksum error
+    jmp .done
+
+.checksum_ok:
+    clc                    ; Clear carry on success
+
+.done:
+    pop di
+    pop bx
+    pop ax
     ret
 
-; ----------------------
-; Set up a minimal GDT
+; ----------------------------------------------------------------
+; CHS Disk Read Routine
+; AL = number of sectors
+; CL = starting sector (1-based)
+; SI = destination offset (Segment:ES already set)
+; Inputs:
+; AL = sector count
+; CH = cylinder
+; DH = head
+; CL = sector (1–63, with top 2 bits as high cylinder bits)
+; SI = destination offset (segment ES must be set)
+
+; ----------------------------------------------------------------
+; Convert LBA to CHS
+; Inputs:
+;   AX = LBA sector number (0-based)
+; Outputs:
+;   CH = cylinder
+;   DH = head
+;   CL = sector (1-63, top 2 bits are upper cylinder bits)
+
+lba_to_chs:
+    pusha
+
+    xor dx, dx
+    mov bx, [sectors_per_track]
+    div bx                     ; AX = LBA / sectors_per_track, DX = remainder (sector number)
+    mov si, ax                 ; SI = temp quotient (track index)
+    mov cx, [heads_per_cylinder]
+    xor dx, dx
+    div cx                     ; AX = cylinder, DX = head
+    mov ch, al                 ; CH = cylinder low byte
+    mov dh, dl                 ; DH = head
+
+    ; Now take sector number from earlier remainder
+    mov cx, si                 ; Copy track index to CX to access CL
+    and cl, 0x3F               ; Mask to 6 bits (sector number)
+    inc cl                     ; Sector numbers are 1-based
+
+    ; Insert upper 2 bits of cylinder into CL
+    mov ah, al                 ; AH = cylinder again
+    and ah, 0xC0               ; Get top 2 bits of cylinder
+    or cl, ah                  ; OR them into sector byte
+
+    popa
+    ret
+
+read_chs:
+    pusha
+    push dx
+
+    mov cx, 5
+.retry:
+    mov ah, 0x02         ; BIOS: Read sectors
+    mov dl, [bootdev]    ; Boot device
+    ; Assume CH, DH, CL already set before this call
+    int 0x13
+    jc .error
+    pop dx
+    popa
+    ret
+
+.error:
+    dec cx
+    jz disk_error
+    xor ah, ah
+    int 0x13
+    jmp .retry
+
+; ----------------------------------------------------------------
+enable_a20:
+    ; Try fast A20 gate method
+    in al, 0x92
+    or al, 0x02
+    and al, 0xFE              ; Clear bit 0 to avoid fast A20 bugs
+    out 0x92, al
+
+    ; Verify A20
+    call check_a20
+    jnc .done                 ; Success
+
+    ; Fallback: use keyboard controller method
+    call .fallback
+
+.done:
+    ret
+
+.fallback:
+    mov al, 0xAD              ; Disable keyboard
+    out 0x64, al
+    call .wait_input_clear
+
+    mov al, 0xD0              ; Command: read output port
+    out 0x64, al
+    call .wait_output_full
+    in al, 0x60
+    or al, 0x02               ; Set A20 enable bit
+    mov bl, al
+
+    call .wait_input_clear
+    mov al, 0xD1              ; Command: write output port
+    out 0x64, al
+    call .wait_input_clear
+    mov al, bl
+    out 0x60, al
+
+    call .wait_input_clear
+    mov al, 0xAE              ; Enable keyboard
+    out 0x64, al
+    ret
+
+.wait_input_clear:
+    in al, 0x64
+    test al, 0x02
+    jnz .wait_input_clear
+    ret
+
+.wait_output_full:
+    in al, 0x64
+    test al, 0x01
+    jz .wait_output_full
+    ret
+
+check_a20:
+    in al, 0x64              ; Read keyboard controller status
+    test al, 0x02            ; Check if input buffer is full
+    jnz check_a20            ; Wait until empty
+
+    mov al, 0xD0             ; Command: read output port
+    out 0x64, al
+
+.wait_output:
+    in al, 0x60              ; Read output port value
+    test al, 0x02            ; Check A20 gate bit (bit 1)
+    jnz .a20_enabled         ; If set, A20 enabled
+
+    xor al, al               ; Clear carry to indicate failure
+    stc                      ; Set carry for failure, jc will jump
+
+    ret
+
+.a20_enabled:
+    clc                      ; Clear carry flag to indicate success
+    ret
+
+; ----------------------------------------------------------------
 gdt_start:
-    dq 0x0000000000000000          ; null descriptor
-    dq 0x00CF9A000000FFFF          ; code segment descriptor
-    dq 0x00CF92000000FFFF          ; data segment descriptor
+    dq 0x0000000000000000         ; Null descriptor
+    dq 0x00CF9A000000FFFF         ; 32-bit code segment (selector 0x08)
+    dq 0x00CF92000000FFFF         ; 32-bit data segment (selector 0x10)
+    dq 0x00009A000000FFFF         ; 16-bit code segment for real mode (selector 0x18)
 
 gdt_descriptor:
-    dw gdt_end - gdt_start - 1     ; size of GDT
-    dd gdt_start                   ; address of GDT
-
+    dw gdt_end - gdt_start - 1
+    dd gdt_start
 gdt_end:
 
 setup_gdt:
     lgdt [gdt_descriptor]
     ret
 
-; ----------------------
-; Switch to Protected Mode
+; ----------------------------------------------------------------
 switch_to_pm:
     cli
     mov eax, cr0
     or eax, 1
     mov cr0, eax
-    jmp 0x08:protected_mode_entry
-; ----------------------
-; 32-bit Protected Mode Entry Point
-[BITS 32]
-protected_mode_entry:
-    mov ax, 0x10       ; data segment selector
-    mov ds, ax
-    mov es, ax
-    mov fs, ax
-    mov gs, ax
-    mov ss, ax
-    mov esp, 0x90000
+    jmp 0x08:0x7E00
 
-    ; Kernel is assumed to be loaded at 0x100000
-    jmp 0x08:0x100000
+; ----------------------------------------------------------------
+print_string_16:
+.loop:
+    lodsb
+    or al, al
+    jz .done
+    mov ah, 0x0E
+    int 0x10
+    jmp .loop
+.done:
+    ret
+
+disk_error_msg db "Disk error!", 0
+a20_error_msg db "A20 error!", 0
+
+halt:
+    cli
+    hlt
+
+bootdev db 0
+sectors_per_track dw 63
+heads_per_cylinder dw 255
 
-; ----------------------
-; Boot signature
 times 510 - ($ - $$) db 0
 dw 0xAA55

bootloader/boot1.asm

@@ -0,0 +1,203 @@
+; ==============================================================================
+; boot1.asm - Second Stage Bootloader (Fixed Real Mode Transition)
+; ==============================================================================
+
+[BITS 32]
+global _start
+extern kmain
+
+_start:
+    ; Set up segments
+    mov ax, 0x10
+    mov ds, ax
+    mov es, ax
+    mov fs, ax
+    mov gs, ax
+    mov ss, ax
+
+    ; Stack (must be identity-mapped)
+    mov esp, 0x90000
+
+    ; CPU Feature Detection: check CPUID support
+    pushfd                      ; Save flags
+    pop eax
+    mov ecx, eax
+    xor eax, 1 << 21            ; Flip ID bit
+    push eax
+    popfd
+    pushfd
+    pop eax
+    xor eax, ecx
+    jz .no_cpuid                ; CPUID unsupported if no change
+
+    ; CPUID supported, verify features
+    mov eax, 1
+    cpuid
+    ; Check for paging support (bit 31 of edx)
+    test edx, 1 << 31
+    jz .no_paging_support
+
+    ; Additional CPU feature checks could be added here
+
+    jmp .cpuid_check_done
+
+.no_cpuid:
+    mov si, no_cpuid_msg
+    call print_string_16
+    jmp halt
+
+.no_paging_support:
+    mov si, no_paging_msg
+    call print_string_16
+    jmp halt
+
+.cpuid_check_done:
+
+    ; Temporarily switch back to real mode
+    cli
+    mov eax, cr0
+    and eax, 0x7FFFFFFE        ; Clear PE & PG bits
+    mov cr0, eax
+    jmp 0x18:real_mode_entry
+
+; ----------------------------------------------------------------
+[BITS 16]
+real_mode_entry:
+    ; Real mode for BIOS access (E820, VESA)
+    xor ax, ax
+    mov es, ax
+
+    ; VESA call
+    mov di, VbeControllerInfo
+    mov ax, 0x4F00
+    int 0x10
+    jc vesa_error
+
+    ; E820 memory map
+    xor ebx, ebx
+    mov edx, 0x534D4150
+    mov di, MemoryMapBuffer
+    mov [MemoryMapEntries], dword 0
+
+.e820_loop:
+    mov eax, 0xE820
+    mov ecx, 24
+    int 0x15
+    jc e820_error
+    add di, 24
+    inc dword [MemoryMapEntries]
+    test ebx, ebx
+    jnz .e820_loop
+    jmp e820_done
+
+e820_error:
+    mov si, e820_error_msg
+    call print_string_16
+    jmp halt
+
+vesa_error:
+    mov si, vesa_error_msg
+    call print_string_16
+
+    ; Fallback: set VGA text mode 3 and continue
+    mov ah, 0x00           ; BIOS Set Video Mode function
+    mov al, 0x03           ; VGA 80x25 text mode
+    int 0x10
+
+    ; Clear screen
+    mov ah, 0x06           ; Scroll up function
+    mov al, 0              ; Clear entire screen
+    mov bh, 0x07           ; Text attribute (gray on black)
+    mov cx, 0              ; Upper-left corner
+    mov dx, 0x184F         ; Lower-right corner
+    int 0x10
+
+    jmp e820_done         ; Continue booting without VESA graphics
+
+e820_done:
+    ; Back to protected mode
+    cli
+    mov eax, cr0
+    or eax, 1
+    mov cr0, eax
+    jmp 0x08:protected_entry
+
+; ----------------------------------------------------------------
+[BITS 16]
+print_string_16:
+.loop:
+    lodsb
+    or al, al
+    jz .done
+    mov ah, 0x0E
+    int 0x10
+    jmp .loop
+.done:
+    ret
+
+e820_error_msg db "E820 Failed!", 0
+vesa_error_msg db "VESA Failed!", 0
+no_cpuid_msg db "No CPUID support detected!", 0
+no_paging_msg db "CPU lacks paging support!", 0
+
+; ----------------------------------------------------------------
+[BITS 32]
+protected_entry:
+    ; Paging setup
+    xor eax, eax
+    mov edi, page_directory
+    mov ecx, 1024
+    rep stosd
+    mov edi, page_table
+    rep stosd
+    mov eax, page_table
+    or eax, 0x3
+    mov [page_directory], eax
+    mov ecx, 1024
+    mov edi, page_table
+    mov eax, 0x00000003
+.fill_pages:
+    mov [edi], eax
+    add eax, 0x1000
+    add edi, 4
+    loop .fill_pages
+
+    mov eax, page_directory
+    mov cr3, eax
+    mov eax, cr0
+    or eax, 0x80000000
+    mov cr0, eax
+
+    jmp kmain
+
+halt:
+    cli
+
+.hang:
+    hlt
+    jmp .hang
+
+; ----------------------------------------------------------------
+; Data buffers and variables must be appropriately defined in your data section
+MemoryMapBuffer times 128 db 0          ; 128*24 bytes reserved for E820 memory map (adjust size as needed)
+MemoryMapEntries dd 0
+VbeControllerInfo times 512 db 0        ; Buffer for VESA controller info (adjust size as needed)
+
+; Define page directory and page table aligned as needed (in your data section)
+align 4096
+page_directory times 1024 dd 0
+align 4096
+page_table times 1024 dd 0
+
+%assign pad_size 4096
+%ifdef __SIZE__
+  %define size_current __SIZE__
+%else
+  %define size_current ($ - $$)
+%endif
+
+%if size_current < pad_size
+  times pad_size - size_current db 0
+%endif
+
+checksum_byte db 0

bootloader/linker.ld

@@ -1,10 +1,9 @@
-ENTRY(start)
+ENTRY(kmain)
 
 SECTIONS {
     . = 1M;
 
     .text : {
-        *(.multiboot)
         *(.text*)
     }
 
@@ -14,4 +13,14 @@ SECTIONS {
         *(.bss*)
         *(COMMON)
     }
+
+    .stack (NOLOAD) : {
+        . = ALIGN(4);
+        . = . + 0x1000;
+    }
+
+    .heap (NOLOAD) : {
+        . = ALIGN(4);
+        . = . + 0x10000;
+    }
 }

kernel/acpi.c

@@ -0,0 +1,54 @@
+#include "acpi.h"
+#include <stdint.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <string.h>
+
+// Function to find the RSDP (Root System Description Pointer)
+acpi_rsdp_t* acpi_find_rsdp() {
+    // Search memory from 0x000E0000 to 0x00100000 (BIOS)
+    for (uint32_t addr = 0x000E0000; addr < 0x00100000; addr += 16) {
+        acpi_rsdp_t* rsdp = (acpi_rsdp_t*)addr;
+        if (memcmp(rsdp->signature, "RSD PTR ", 8) == 0) {
+            uint8_t checksum = 0;
+            for (size_t i = 0; i < sizeof(acpi_rsdp_t); i++) { // Change int to size_t
+                checksum += ((uint8_t*)rsdp)[i];
+            }
+            if (checksum == 0) {
+                return rsdp;  // Valid RSDP found
+            }
+        }
+    }
+    return NULL;  // RSDP not found
+}
+
+// Function to get the RSDT or XSDT based on the RSDP revision
+void* acpi_get_rsdt_or_xsdt(acpi_rsdp_t* rsdp) {
+    if (rsdp->revision >= 2) {
+        return (void*)rsdp->xsdt_addr;  // ACPI 2.0+ uses XSDT
+    } else {
+        return (void*)rsdp->rsdt_addr;  // ACPI 1.0 uses RSDT
+    }
+}
+
+// Function to find the FADT table within the RSDT or XSDT
+acpi_fadt_t* acpi_find_fadt(void* rsdt_or_xsdt) {
+    acpi_rsdt_t* rsdt = (acpi_rsdt_t*)rsdt_or_xsdt;
+    uint32_t num_tables = (rsdt->length - sizeof(acpi_rsdt_t)) / sizeof(uint32_t);
+
+    for (size_t i = 0; i < num_tables; i++) {
+        uint32_t table_addr = rsdt->tables[i];
+        acpi_fadt_t* fadt = (acpi_fadt_t*)table_addr;
+        if (fadt->signature == 0x50434146) {
+            uint8_t checksum = 0;
+            for (size_t j = 0; j < fadt->length; j++) {
+                checksum += ((uint8_t*)fadt)[j];
+            }
+            if (checksum == 0) {
+                return fadt;
+            }
+        }
+    }
+    return NULL;
+}
+

kernel/acpi.h

@@ -0,0 +1,47 @@
+#ifndef ACPI_H
+#define ACPI_H
+
+#include <stdint.h>
+
+// ACPI base address (replace with actual value)
+#define ACPI_BASE 0xE0000000
+
+#ifndef NULL
+#define NULL ((void*)0)
+#endif
+
+// ACPI RSDP Structure (Root System Description Pointer)
+typedef struct {
+    uint8_t signature[8];      // Should be "RSD PTR "
+    uint8_t checksum;          // Checksum for the RSDP structure
+    uint8_t oem_id[6];         // OEM ID string
+    uint8_t revision;          // ACPI revision
+    uint32_t rsdt_addr;        // 32-bit RSDT address (ACPI 1.0)
+    uint32_t xsdt_addr;        // 64-bit XSDT address (ACPI 2.0+)
+} __attribute__((packed)) acpi_rsdp_t;
+
+// ACPI RSDT Structure (Root System Description Table)
+typedef struct {
+    uint32_t signature;    // Should be "RSDT"
+    uint32_t length;       // Length of the table
+    uint8_t revision;      // Revision of the RSDT table
+    uint8_t checksum;      // Checksum for the RSDT table
+    uint32_t tables[];     // Array of pointers to other tables (RSDT/XSDT entries)
+} __attribute__((packed)) acpi_rsdt_t;
+
+// ACPI FADT Structure (Fixed ACPI Description Table)
+typedef struct {
+    uint32_t signature;         // Should be "FACP"
+    uint32_t length;            // Length of the table
+    uint8_t revision;           // Revision of the FADT table
+    uint8_t checksum;           // Checksum for the FADT table
+    uint32_t pm_tmr_address;    // Power Management Timer Address
+    // ... other FADT fields
+} __attribute__((packed)) acpi_fadt_t;
+
+// Function prototypes
+acpi_rsdp_t* acpi_find_rsdp();
+void* acpi_get_rsdt_or_xsdt(acpi_rsdp_t* rsdp);
+acpi_fadt_t* acpi_find_fadt(void* rsdt_or_xsdt);
+
+#endif /* ACPI_H */

kernel/cpu.c

@@ -0,0 +1,37 @@
+#include "cpu.h"
+#include "serial.h"
+#include "terminal.h"
+#include "utils.h"
+#include "print.h"
+
+void cpuid(uint32_t function, uint32_t *eax, uint32_t *ebx, uint32_t *ecx, uint32_t *edx) {
+    asm volatile (
+        "cpuid"
+        : "=a"(*eax), "=b"(*ebx), "=c"(*ecx), "=d"(*edx)
+        : "a"(function)
+    );
+}
+
+void identify_cpu() {
+    uint32_t eax, ebx, ecx, edx;
+    char vendor[13];
+
+    cpuid(0, &eax, &ebx, &ecx, &edx);
+
+    *(uint32_t *)&vendor[0] = ebx;
+    *(uint32_t *)&vendor[4] = edx;
+    *(uint32_t *)&vendor[8] = ecx;
+    vendor[12] = '\0';
+
+    terminal_write("CPU Vendor: ");
+    terminal_write(vendor);
+    terminal_write("\n");
+
+    serial_write("CPU Vendor: ");
+    serial_write(vendor);
+    serial_write("\n");
+
+    terminal_write("CPUID max leaf: ");
+    print_hex(eax);  // You must implement this (see below)
+    terminal_write("\n");
+}

kernel/cpu.h

@@ -0,0 +1,9 @@
+#ifndef CPU_H
+#define CPU_H
+
+#include <stdint.h>
+
+void cpuid(uint32_t function, uint32_t *eax, uint32_t *ebx, uint32_t *ecx, uint32_t *edx);
+void identify_cpu(void);
+
+#endif // CPU_H

kernel/debug.c

@@ -0,0 +1,45 @@
+#include "debug.h"
+#include "vga.h"
+#include <stdint.h>
+
+#define VGA_WIDTH 80
+#define VGA_HEIGHT 25
+#define VGA_MEMORY 0xB8000
+
+// VGA text mode color attributes
+#define COLOR_WHITE 0x07
+
+// Pointer to the VGA memory
+volatile uint16_t* vga_buffer = (uint16_t*)VGA_MEMORY;
+
+// Function to print a string to the VGA text buffer
+void debug_print(const char *str) {
+    while (*str) {
+        if (*str == '\n') {
+            // Handle new line
+            // Move to the next line (not implemented here)
+            // You can implement line wrapping if needed
+            str++;
+            continue;
+        }
+
+        // Calculate the position in the VGA buffer
+        static int cursor_x = 0;
+        static int cursor_y = 0;
+
+        // Write the character and its attribute to the VGA buffer
+        vga_buffer[cursor_y * VGA_WIDTH + cursor_x] = (COLOR_WHITE << 8) | *str;
+
+        // Move the cursor to the right
+        cursor_x++;
+        if (cursor_x >= VGA_WIDTH) {
+            cursor_x = 0;
+            cursor_y++;
+            if (cursor_y >= VGA_HEIGHT) {
+                cursor_y = 0; // Scroll up (not implemented here)
+            }
+        }
+
+        str++;
+    }
+}

kernel/debug.h

@@ -0,0 +1,6 @@
+#ifndef DEBUG_H
+#define DEBUG_H
+
+void debug_print(const char *str);
+
+#endif // DEBUG_H

kernel/display.c

@@ -0,0 +1,36 @@
+#include "display.h"
+#include "io.h" // Include your I/O header for port access
+#include "vga.h"
+
+// Initialize the display
+void init_display(void) {
+    // Initialize VGA settings, if necessary
+    // This could involve setting up the VGA mode, etc.
+    set_display_mode(0x13); // Example: Set to 320x200 256-color mode
+}
+
+// Enumerate connected displays
+void enumerate_displays(void) {
+    // This is a simplified example. Actual enumeration may require
+    // reading from specific VGA registers or using BIOS interrupts.
+    
+    // For demonstration, we will just print a message
+    // In a real driver, you would check the VGA registers
+    // to determine connected displays.
+    clear_display();
+    // Here you would typically read from VGA registers to find connected displays
+    // For example, using inb() to read from VGA ports
+}
+
+// Set the display mode
+void set_display_mode(uint8_t mode) {
+    // Set the VGA mode by writing to the appropriate registers
+    outb(VGA_PORT, mode); // Example function to write to a port
+}
+
+// Clear the display
+void clear_display(void) {
+    // Clear the display by filling it with a color
+    // This is a placeholder for actual clearing logic
+    // You would typically write to video memory here
+}

kernel/display.h

@@ -0,0 +1,14 @@
+#ifndef DISPLAY_H
+#define DISPLAY_H
+
+#include <stdint.h>
+
+#define VGA_PORT 0x3C0  // Base port for VGA
+
+// Function prototypes
+void init_display(void);
+void enumerate_displays(void);
+void set_display_mode(uint8_t mode);
+void clear_display(void);
+
+#endif // DISPLAY_H

kernel/elf.c

@@ -0,0 +1,50 @@
+#include "elf.h"
+#include <stddef.h>
+#include <string.h>
+
+// This assumes that the elf is ELF32 and little-endian Intel X86 architecture.
+
+// Check if a binary is a valid ELF executable.
+int elf_validate(const void* data) {
+    const Elf32_Ehdr* header = (const Elf32_Ehdr*)data;
+
+    if (*(uint32_t*)header->e_ident != ELF_MAGIC)
+        return 0;
+
+    if (header->e_type != ET_EXEC && header->e_type != ET_DYN)
+        return 0;
+
+    if (header->e_machine != EM_386)
+        return 0;
+
+    return 1;
+}
+
+// Load an ELF executable into memory.
+int elf_load(const void* data, void (*load_segment)(uint32_t vaddr, const void* src, uint32_t size)) {
+    const Elf32_Ehdr* header = (const Elf32_Ehdr*)data;
+    const Elf32_Phdr* ph = (const Elf32_Phdr*)((uint8_t*)data + header->e_phoff);
+
+    for (int i = 0; i < header->e_phnum; i++) {
+        if (ph[i].p_type != PT_LOAD)
+            continue;
+
+        const void* src = (uint8_t*)data + ph[i].p_offset;
+        uint32_t vaddr = ph[i].p_vaddr;
+        uint32_t filesz = ph[i].p_filesz;
+        uint32_t memsz = ph[i].p_memsz;
+
+        // Copy data segment
+        load_segment(vaddr, src, filesz);
+
+        // Zero remaining BSS (if any)
+        if (memsz > filesz) {
+            uint8_t* bss_start = (uint8_t*)(vaddr + filesz);
+            for (uint32_t j = 0; j < memsz - filesz; j++) {
+                bss_start[j] = 0;
+            }
+        }
+    }
+
+    return header->e_entry;
+}

kernel/elf.h

@@ -0,0 +1,52 @@
+#ifndef ELF_H
+#define ELF_H
+
+#include <stdint.h>
+
+#define ELF_MAGIC 0x464C457F  // "\x7FELF" in little-endian
+
+// ELF Types
+#define ET_EXEC 2
+#define ET_DYN  3
+
+// ELF Machine
+#define EM_386  3
+
+// ELF Ident indexes
+#define EI_NIDENT 16
+
+// Program header types
+#define PT_NULL    0
+#define PT_LOAD    1
+
+// ELF Header (32-bit)
+typedef struct {
+    uint8_t  e_ident[EI_NIDENT];
+    uint16_t e_type;
+    uint16_t e_machine;
+    uint32_t e_version;
+    uint32_t e_entry;     // Entry point
+    uint32_t e_phoff;     // Program header table offset
+    uint32_t e_shoff;     // Section header table offset
+    uint32_t e_flags;
+    uint16_t e_ehsize;
+    uint16_t e_phentsize;
+    uint16_t e_phnum;
+    uint16_t e_shentsize;
+    uint16_t e_shnum;
+    uint16_t e_shstrndx;
+} __attribute__((packed)) Elf32_Ehdr;
+
+// Program Header (32-bit)
+typedef struct {
+    uint32_t p_type;
+    uint32_t p_offset;
+    uint32_t p_vaddr;
+    uint32_t p_paddr;
+    uint32_t p_filesz;
+    uint32_t p_memsz;
+    uint32_t p_flags;
+    uint32_t p_align;
+} __attribute__((packed)) Elf32_Phdr;
+
+#endif // ELF_H

kernel/fat12.c

@@ -0,0 +1,5 @@
+#include "fat12.h"
+
+void fat12_init() {
+    // Filesystem initialization code
+}

kernel/fat12.h

@@ -0,0 +1,47 @@
+#ifndef FAT12_H
+#define FAT12_H
+
+#include <stdint.h> /* Include standard integer types */
+#include <stdio.h>  /* Include standard I/O library */
+#include <stdlib.h> /* Include standard library */
+
+#define FAT12_SECTOR_SIZE 512 /* Sector size for FAT12 */
+#define FAT12_MAX_FILES 128 /* Maximum number of files in root directory */
+#define FAT12_ROOT_DIR_SECTORS 1 /* Number of sectors for root directory */
+
+typedef struct {
+    uint8_t jump[3]; /* Jump instruction for boot */
+    char oem[8]; /* OEM name */
+    uint16_t bytes_per_sector; /* Bytes per sector */
+    uint8_t sectors_per_cluster; /* Sectors per cluster */
+    uint16_t reserved_sectors; /* Reserved sectors count */
+    uint8_t num_fats; /* Number of FATs */
+    uint16_t max_root_dir_entries; /* Max entries in root directory */
+    uint16_t total_sectors; /* Total sectors */
+    uint8_t media_descriptor; /* Media descriptor */
+    uint16_t fat_size; /* Size of each FAT */
+    uint16_t sectors_per_track; /* Sectors per track */
+    uint16_t num_heads; /* Number of heads */
+    uint32_t hidden_sectors; /* Hidden sectors count */
+    uint32_t total_sectors_large; /* Total sectors for large disks */
+} __attribute__((packed)) FAT12_BootSector; /* Packed structure for boot sector */
+
+typedef struct {
+    char name[11]; /* File name (8.3 format) */
+    uint8_t attr; /* File attributes */
+    uint16_t reserved; /* Reserved */
+    uint16_t time; /* Time of last write */
+    uint16_t date; /* Date of last write */
+    uint16_t start_cluster; /* Starting cluster number */
+    uint32_t file_size; /* File size in bytes */
+} __attribute__((packed)) FAT12_DirEntry; /* Directory entry structure */
+
+void initialize_fat12(const char *disk_image); /* Function to initialize FAT12 */
+void read_fat12(const char *disk_image); /* Function to read FAT12 */
+void write_fat12(const char *disk_image); /* Function to write FAT12 */
+void list_files(const char *disk_image); /* Function to list files in root directory */
+void read_file(const char *disk_image, const char *filename); /* Function to read a file */
+void write_file(const char *disk_image, const char *filename, const uint8_t *data, size_t size); /* Function to write a file */
+
+#endif 
+/* FAT12_H */

kernel/gdt.asm

@@ -0,0 +1,21 @@
+; gdt.asm
+; Assembler function to load the GDT and update segment registers
+
+global gdt_flush
+
+gdt_flush:
+    mov eax, [esp + 4]   ; Argument: pointer to GDT descriptor
+    lgdt [eax]           ; Load GDT
+
+    ; Reload segment registers
+    mov ax, 0x10         ; 0x10 = offset to kernel data segment (3rd entry)
+    mov ds, ax
+    mov es, ax
+    mov fs, ax
+    mov gs, ax
+    mov ss, ax
+
+    ; Jump to flush the instruction pipeline and load CS
+    jmp 0x08:.flush      ; 0x08 = offset to code segment (2nd entry)
+.flush:
+    ret

kernel/gdt.c

@@ -0,0 +1,48 @@
+#include "gdt.h"
+
+// Structure of a GDT entry (8 bytes)
+struct gdt_entry {
+    uint16_t limit_low;   // Limit bits 0–15
+    uint16_t base_low;    // Base bits 0–15
+    uint8_t  base_middle; // Base bits 16–23
+    uint8_t  access;      // Access flags
+    uint8_t  granularity; // Granularity + limit bits 16–19
+    uint8_t  base_high;   // Base bits 24–31
+} __attribute__((packed));
+
+// Structure of the GDT pointer
+struct gdt_ptr {
+    uint16_t limit;
+    uint32_t base;
+} __attribute__((packed));
+
+// Declare GDT with 3 entries
+static struct gdt_entry gdt[3];
+static struct gdt_ptr gp;
+
+// External ASM function to load GDT
+extern void gdt_flush(uint32_t);
+
+// Set an individual GDT entry
+static void gdt_set_gate(int num, uint32_t base, uint32_t limit, uint8_t access, uint8_t granularity) {
+    gdt[num].base_low    = (base & 0xFFFF);
+    gdt[num].base_middle = (base >> 16) & 0xFF;
+    gdt[num].base_high   = (base >> 24) & 0xFF;
+
+    gdt[num].limit_low   = (limit & 0xFFFF);
+    gdt[num].granularity = ((limit >> 16) & 0x0F) | (granularity & 0xF0);
+
+    gdt[num].access      = access;
+}
+
+// Initialize the GDT
+void gdt_init(void) {
+    gp.limit = (sizeof(struct gdt_entry) * 3) - 1;
+    gp.base  = (uint32_t)&gdt;
+
+    gdt_set_gate(0, 0, 0, 0, 0);                // Null segment
+    gdt_set_gate(1, 0, 0xFFFFFFFF, 0x9A, 0xCF); // Code segment
+    gdt_set_gate(2, 0, 0xFFFFFFFF, 0x92, 0xCF); // Data segment
+
+    gdt_flush((uint32_t)&gp);
+}

kernel/gdt.h

@@ -0,0 +1,8 @@
+#ifndef GDT_H
+#define GDT_H
+
+#include <stdint.h>
+
+void gdt_init(void);
+
+#endif

kernel/heap.c

@@ -0,0 +1,63 @@
+#include "heap.h"
+#include <stdint.h>
+
+typedef struct heap_block {
+    size_t size;
+    struct heap_block *next;
+    int is_free;
+} heap_block_t;
+
+static heap_block_t *free_list = NULL;
+static void *heap_start_ptr = NULL;
+static void *heap_end_ptr = NULL;
+
+void heap_init(void *heap_start, void *heap_end) {
+    heap_start_ptr = heap_start;
+    heap_end_ptr = heap_end;
+
+    free_list = (heap_block_t *)heap_start;
+    free_list->size = (uintptr_t)heap_end - (uintptr_t)heap_start - sizeof(heap_block_t);
+    free_list->next = NULL;
+    free_list->is_free = 1;
+}
+
+void *heap_alloc(size_t size) {
+    heap_block_t *current = free_list;
+
+    while (current != NULL) {
+        if (current->is_free && current->size >= size) {
+            // If it's a large block, split it
+            if (current->size > size + sizeof(heap_block_t)) {
+                heap_block_t *new_block = (heap_block_t *)((uintptr_t)current + sizeof(heap_block_t) + size);
+                new_block->size = current->size - size - sizeof(heap_block_t);
+                new_block->next = current->next;
+                new_block->is_free = 1;
+
+                current->next = new_block;
+                current->size = size;
+            }
+
+            current->is_free = 0;
+            return (void *)((uintptr_t)current + sizeof(heap_block_t));
+        }
+
+        current = current->next;
+    }
+
+    return NULL; // Out of memory
+}
+
+void heap_free(void *ptr) {
+    if (ptr == NULL) return;
+
+    heap_block_t *block = (heap_block_t *)((uintptr_t)ptr - sizeof(heap_block_t));
+    block->is_free = 1;
+
+    // Coalesce with next block
+    if (block->next && block->next->is_free) {
+        block->size += block->next->size + sizeof(heap_block_t);
+        block->next = block->next->next;
+    }
+
+    // TODO: Coalesce with previous block for better compaction
+}

kernel/heap.h

@@ -0,0 +1,11 @@
+#ifndef HEAP_H
+#define HEAP_H
+
+#include <stddef.h>
+
+void heap_init(void *heap_start, void *heap_end);
+
+void *heap_alloc(size_t size);
+void heap_free(void *ptr);
+
+#endif // HEAP_H

kernel/idt.c

@@ -8,7 +8,37 @@ idt_ptr_t idt_ptr;
 
 // External assembly stubs for ISRs (provided below)
 extern void isr0();
+extern void isr1();
+extern void isr2();
+extern void isr3();
+extern void isr4();
+extern void isr5();
+extern void isr6();
+extern void isr7();
+extern void isr8();
+extern void isr9();
+extern void isr10();
+extern void isr11();
+extern void isr12();
 extern void isr13();
+extern void isr14();
+extern void isr15();
+extern void isr16();
+extern void isr17();
+extern void isr18();
+extern void isr19();
+extern void isr20();
+extern void isr21();
+extern void isr22();
+extern void isr23();
+extern void isr24();
+extern void isr25();
+extern void isr26();
+extern void isr27();
+extern void isr28();
+extern void isr29();
+extern void isr30();
+extern void isr31();
 extern void isr_default();
 
 // Helper to set an IDT gate
@@ -36,8 +66,40 @@ void idt_init() {
     }
 
     // Set specific handlers
-    idt_set_gate(0, (uint32_t)isr0);   // Divide by zero
-    idt_set_gate(13, (uint32_t)isr13); // General protection fault
+    // Assign CPU exception handlers
+    idt_set_gate(0, (uint32_t)isr0);
+    idt_set_gate(1, (uint32_t)isr1);
+    idt_set_gate(2, (uint32_t)isr2);
+    idt_set_gate(3, (uint32_t)isr3);
+    idt_set_gate(4, (uint32_t)isr4);
+    idt_set_gate(5, (uint32_t)isr5);
+    idt_set_gate(6, (uint32_t)isr6);
+    idt_set_gate(7, (uint32_t)isr7);
+    idt_set_gate(8, (uint32_t)isr8);
+    idt_set_gate(9, (uint32_t)isr9);
+    idt_set_gate(10, (uint32_t)isr10);
+    idt_set_gate(11, (uint32_t)isr11);
+    idt_set_gate(12, (uint32_t)isr12);
+    idt_set_gate(13, (uint32_t)isr13);
+    idt_set_gate(14, (uint32_t)isr14);
+    idt_set_gate(15, (uint32_t)isr15);
+    idt_set_gate(16, (uint32_t)isr16);
+    idt_set_gate(17, (uint32_t)isr17);
+    idt_set_gate(18, (uint32_t)isr18);
+    idt_set_gate(19, (uint32_t)isr19);
+    idt_set_gate(20, (uint32_t)isr20);
+    idt_set_gate(21, (uint32_t)isr21);
+    idt_set_gate(22, (uint32_t)isr22);
+    idt_set_gate(23, (uint32_t)isr23);
+    idt_set_gate(24, (uint32_t)isr24);
+    idt_set_gate(25, (uint32_t)isr25);
+    idt_set_gate(26, (uint32_t)isr26);
+    idt_set_gate(27, (uint32_t)isr27);
+    idt_set_gate(28, (uint32_t)isr28);
+    idt_set_gate(29, (uint32_t)isr29);
+    idt_set_gate(30, (uint32_t)isr30);
+    idt_set_gate(31, (uint32_t)isr31);
+
 
     idt_load();
 }

kernel/io.h

@@ -1,6 +1,8 @@
 #ifndef IO_H
 #define IO_H
 
+#include <stdint.h>
+
 static inline void outb(uint16_t port, uint8_t val) {
     asm volatile ("outb %0, %1" : : "a"(val), "Nd"(port));
 }

kernel/irq.c

@@ -0,0 +1,5 @@
+#include "irq.h"
+
+void irq_init() {
+    // IRQ initialization code
+}

kernel/irq.h

@@ -0,0 +1,6 @@
+#ifndef IRQ_H
+#define IRQ_H
+
+void irq_init();
+
+#endif // IRQ_H

kernel/isr.asm

@@ -1,29 +1,79 @@
-; isr.asm
 [BITS 32]
-[GLOBAL isr0, isr13, isr_default]
+[GLOBAL isr0, isr1, isr2, isr3, isr4, isr5, isr6, isr7, isr8, isr9]
+[GLOBAL isr10, isr11, isr12, isr13, isr14, isr15, isr16, isr17, isr18, isr19]
+[GLOBAL isr20, isr21, isr22, isr23, isr24, isr25, isr26, isr27, isr28, isr29]
+[GLOBAL isr30, isr31, isr_default]
 
-isr0:
+[EXTERN isr_handler]
+
+%macro ISR_NOERR 1
+isr%1:
     cli
-    push byte 0
-    push byte 0
+    push dword 0         ; Dummy error code
+    push dword %1        ; Interrupt number
     call isr_handler
     add esp, 8
     sti
     iret
+%endmacro
 
-isr13:
+%macro ISR_ERR 1
+isr%1:
     cli
-    push byte 13
-    push byte 0
+    push dword %1        ; Interrupt number
     call isr_handler
     add esp, 8
     sti
     iret
+%endmacro
 
+; ISR 0–7: No error code
+ISR_NOERR 0
+ISR_NOERR 1
+ISR_NOERR 2
+ISR_NOERR 3
+ISR_NOERR 4
+ISR_NOERR 5
+ISR_NOERR 6
+ISR_NOERR 7
+
+; ISR 8–14: Error code pushed automatically
+ISR_ERR 8
+ISR_NOERR 9           ; Coprocessor Segment Overrun (obsolete, no error code)
+ISR_ERR 10
+ISR_ERR 11
+ISR_ERR 12
+ISR_ERR 13
+ISR_ERR 14
+
+; ISR 15 is reserved
+ISR_NOERR 15
+
+; ISR 16–19 (FPU, Alignment Check, etc.)
+ISR_NOERR 16
+ISR_ERR 17
+ISR_NOERR 18
+ISR_NOERR 19
+
+; ISR 20–31 (reserved or future use)
+ISR_NOERR 20
+ISR_NOERR 21
+ISR_NOERR 22
+ISR_NOERR 23
+ISR_NOERR 24
+ISR_NOERR 25
+ISR_NOERR 26
+ISR_NOERR 27
+ISR_NOERR 28
+ISR_NOERR 29
+ISR_NOERR 30
+ISR_NOERR 31
+
+; Fallback handler
 isr_default:
     cli
-    push byte 255
-    push byte 0
+    push dword 255
+    push dword 0
     call isr_handler
     add esp, 8
     sti

kernel/isr.c

@@ -1,21 +1,53 @@
 #include "terminal.h"
 #include "serial.h"
+#include "isr.h"
+#include "io.h"
+#include "utils.h"
+
+static isr_callback_t interrupt_handlers[MAX_INTERRUPTS] = { 0 };
 
 void isr_handler(uint32_t int_num, uint32_t err_code) {
     terminal_write("Interrupt occurred: ");
-    // Add simple int-to-string printing here
+
+    print_hex(int_num);
+    terminal_write("\n");
+
     serial_write("INT triggered\n");
 
-    if (int_num == 0) {
-        terminal_write(" -> Divide by zero error!\n");
-    } else if (int_num == 13) {
-        terminal_write(" -> General Protection Fault!\n");
+    terminal_write("Error code: ");
+    print_hex(err_code);
+    terminal_write("\n");
+
+    if (interrupt_handlers[int_num]) {
+        interrupt_handlers[int_num]();  // Call registered handler
     } else {
-        terminal_write(" -> Unknown interrupt\n");
+        terminal_write(" -> No handler registered\n");
+
+        if (int_num == 0) {
+            terminal_write(" -> Divide by zero error!\n");
+        } else if (int_num == 13) {
+            terminal_write(" -> General Protection Fault!\n");
+        } else {
+            terminal_write(" -> Unknown interrupt\n");
+        }
+
+        // Halt CPU
+        while (1) {
+            asm volatile ("hlt");
+        }
     }
 
-    // Halt CPU
-    while (1) {
-        asm volatile ("hlt");
+    // === Send End Of Interrupt to PIC(s) ===
+    if (int_num >= 40) {
+        // Send reset signal to slave PIC
+        outb(0xA0, 0x20);
+    }
+    if (int_num >= 32) {
+        // Send reset signal to master PIC
+        outb(0x20, 0x20);
     }
 }
+
+void register_interrupt_handler(uint8_t n, isr_callback_t handler) {
+    interrupt_handlers[n] = handler;
+}

kernel/isr.h

@@ -0,0 +1,13 @@
+#ifndef ISR_H
+#define ISR_H
+
+#include <stdint.h>
+
+#define MAX_INTERRUPTS 256
+
+typedef void (*isr_callback_t)(void);
+
+void isr_handler(uint32_t int_num, uint32_t err_code);
+void register_interrupt_handler(uint8_t n, isr_callback_t handler);
+
+#endif

kernel/keyboard.c

@@ -0,0 +1,59 @@
+#include "keyboard.h"
+#include "io.h"
+#include "isr.h"
+#include "terminal.h"
+
+#define KEYBOARD_DATA_PORT 0x60
+
+static char key_buffer[256];
+static uint8_t buffer_index = 0;
+
+// Basic US QWERTY keymap (scancode to ASCII)
+static const char scancode_map[128] = {
+    0,  27, '1', '2', '3', '4', '5', '6', '7', '8', // 0x00 - 0x09
+   '9', '0', '-', '=', '\b', '\t', 'q', 'w', 'e', 'r', // 0x0A - 0x13
+   't', 'y', 'z', 'u', 'i', 'o', 'p', '[', ']', '\n', // 0x14 - 0x1D
+    0, 'a', 's', 'd', 'f', 'g', 'h', 'j', 'k', 'l', // 0x1E - 0x27
+   ';', '\'', '`', 0, '\\', 'x', 'c', 'v', 'b', // 0x28 - 0x31
+   'n', 'm', ',', '.', '/', 0, '*', 0, ' ', 0,      // 0x32 - 0x3B
+    // rest can be filled as needed
+};
+
+// Interrupt handler for IRQ1
+void keyboard_callback(void) {
+    uint8_t scancode = inb(0x60);
+
+    // Only handle key press (ignore key release)
+    if (!(scancode & 0x80)) {
+        char c = scancode_map[scancode];
+        if (c && buffer_index < sizeof(key_buffer) - 1) {
+            key_buffer[buffer_index++] = c;
+            terminal_putchar(c);
+        }
+    }
+
+    // Send End of Interrupt (EOI) to the PIC
+    outb(0x20, 0x20);
+}
+
+
+void keyboard_init() {
+    register_interrupt_handler(33, keyboard_callback); // IRQ1 = int 33 (0x21)
+}
+
+// Blocking read (returns one char)
+char keyboard_get_char() {
+    while (buffer_index == 0); // Busy wait
+
+    char c;
+    __asm__ __volatile__("cli");
+    c = key_buffer[0];
+    for (uint8_t i = 1; i < buffer_index; i++) {
+        key_buffer[i - 1] = key_buffer[i];
+    }
+    buffer_index--;
+    __asm__ __volatile__("sti");
+
+    return c;
+}
+

kernel/keyboard.h

@@ -0,0 +1,7 @@
+#ifndef KEYBOARD_H
+#define KEYBOARD_H
+
+void keyboard_init(void);
+char keyboard_get_char(void);  // Blocking read from buffer
+
+#endif

kernel/kmain.c

@@ -6,6 +6,12 @@
 #include "idt.h"
 #include "paging.h"
 #include "memmap.h"
+#include "gdt.h"
+#include "cpu.h"
+#include "kmalloc.h"
+#include "timer.h"
+#include "utils.h"
+#include "keyboard.h"
 
 #define LPT1 0x378
 
@@ -21,8 +27,16 @@ void kmain(void) {
     serial_init();
     serial_write("Serial port initialized.\n");
 
+    terminal_write("Identifying CPU...\n");
+    identify_cpu();
+    serial_write("CPU identification complete.\n");
+
     lpt_write('L'); // Send 'L' to LPT1 to test
 
+    terminal_write("Initializing GDT...\n");
+    gdt_init();
+    serial_write("GDT initialized.\n");
+
     terminal_write("Initializing IDT...\n");
     idt_init();
     serial_write("IDT initialized.\n");
@@ -31,17 +45,37 @@ void kmain(void) {
     paging_init();
     serial_write("Paging initialized.\n");
 
+    terminal_write("Initializing memory allocator...\n");
+    kmalloc_init(0xC0100000);  // Virtual heap start address (must be mapped!)
+    serial_write("kmalloc initialized.\n");
+
+    serial_write("Allocated 128 bytes.\n");
+
+    terminal_write("Initializing timer...\n");
+    timer_init(100);  // 100 Hz (10 ms interval)
+    serial_write("Timer initialized.\n");
+
+    terminal_write("Initializing keyboard...\n");
+    keyboard_init();
+    serial_write("Keyboard initialized.\n");
+
     terminal_write("Getting memory map...\n");
     memory_map_entry_t mmap[32];
     uint32_t mmap_size = get_memory_map(mmap, 32);
     serial_write("Memory map retrieved.\n");
 
     terminal_write("Memory Regions:\n");
+
+    char buf[32];
     for (uint32_t i = 0; i < mmap_size; i++) {
-        terminal_write(" - Region: ");
-        // You would format and print base/length/type here
-        // (e.g., with a basic itoa and print_hex helper)
-        serial_write("Memory region entry\n");
+        terminal_write(" - Base: ");
+        print_hex((uint32_t)(mmap[i].base_addr & 0xFFFFFFFF));  // Lower 32 bits
+        terminal_write(", Length: ");
+        print_hex((uint32_t)(mmap[i].length & 0xFFFFFFFF));     // Lower 32 bits
+        terminal_write(", Type: ");
+        itoa(mmap[i].type, buf, 10);
+        terminal_write(buf);
+        terminal_write("\n");
     }
 
     terminal_write("System initialized. Halting.\n");

kernel/kmalloc.c

@@ -0,0 +1,51 @@
+#include "kmalloc.h"
+#include "terminal.h"  // Optional: for debug output
+
+#define HEAP_END 0xC0100000
+
+static uint32_t current_heap = 0;
+
+// Initialize the allocator with a starting heap address
+void kmalloc_init(uint32_t heap_start) {
+    current_heap = heap_start;
+}
+
+// Simple bump allocator
+void* kmalloc(size_t size) {
+    if (current_heap == 0) {
+        terminal_write("kmalloc used before initialization!\n");
+        return 0;
+    }
+
+    void* addr = (void*)current_heap;
+    current_heap += size;
+    return addr;
+}
+
+// Allocate memory aligned to a power-of-two boundary (e.g., 0x1000)
+void* kmalloc_aligned(size_t size, uint32_t alignment) {
+    if (current_heap == 0) {
+        terminal_write("kmalloc_aligned used before initialization!\n");
+        return 0;
+    }
+
+    // Align the current_heap pointer
+    if ((current_heap & (alignment - 1)) != 0) {
+        current_heap = (current_heap + alignment) & ~(alignment - 1);
+    }
+
+    if (current_heap + size > HEAP_END) {
+        terminal_write("kmalloc_aligned: Out of memory!\n");
+        return 0;
+    }
+
+    void* addr = (void*)current_heap;
+    current_heap += size;
+    return addr;
+}
+
+void kfree(void* ptr) {
+    // In a bump allocator, we cannot free individual blocks.
+    // We can reset the allocator to the initial state.
+    current_heap = 0; // Reset the heap pointer
+}

kernel/kmalloc.h

@@ -0,0 +1,11 @@
+#ifndef KMALLOC_H
+#define KMALLOC_H
+
+#include <stdint.h>
+#include <stddef.h> // for size_t
+
+void kmalloc_init(uint32_t heap_start);
+void* kmalloc(size_t size);
+void* kmalloc_aligned(size_t size, uint32_t alignment);
+
+#endif

kernel/linker.ld

@@ -0,0 +1,31 @@
+ENTRY(_start)
+
+SECTIONS {
+    . = 1M;
+
+    .multiboot : {
+        *(.multiboot)
+    }
+
+    .text : {
+        *(.text)
+    }
+
+    .rodata : {
+        *(.rodata)
+    }
+
+    .data : {
+        *(.data)
+    }
+
+    .bss : {
+        *(.bss)
+        *(COMMON)
+    }
+
+    . = ALIGN(4096);
+    __stack_top = .;
+    . += 128K;
+    __stack_bottom = .;
+}

kernel/malloc.c

@@ -0,0 +1,105 @@
+#include "malloc.h"
+#include <stdint.h>
+
+static void *heap_start; // Start of the heap
+static void *heap_end;   // End of the heap
+static struct memory_block *free_blocks; // List of free blocks
+
+void init_heap(void *start, void *end)
+{
+    heap_start = start;
+    heap_end = end;
+
+    // Initialize the heap with a single large free block
+    free_blocks = (struct memory_block *)start;
+    free_blocks->size = (uintptr_t)end - (uintptr_t)start - sizeof(struct memory_block);
+    free_blocks->next = NULL;
+    free_blocks->is_free = 1;
+}
+
+void *find_free_block(size_t size) {
+    struct memory_block *current = free_blocks;
+    while (current != NULL) {
+        if (current->is_free && current->size >= size) {
+            return current;
+        }
+        current = current->next;
+    }
+    // No suitable block found
+    return NULL;
+}
+
+void mark_as_used(void *ptr, size_t size) {
+    struct memory_block *block = (struct memory_block *)ptr;
+    block->is_free = 0;
+
+    // If the block is larger than needed, split it
+    if (block->size > size + sizeof(struct memory_block)) {
+        struct memory_block *new_block = (struct memory_block *)((uintptr_t)ptr + size + sizeof(struct memory_block));
+        new_block->size = block->size - size - sizeof(struct memory_block);
+        new_block->next = block->next;
+        new_block->is_free = 1;
+
+        block->size = size;
+        block->next = new_block;
+    }
+}
+
+void mark_as_free(void *ptr) {
+    struct memory_block *block = (struct memory_block *)ptr;
+    block->is_free = 1;
+
+    // Coalesce with next block if it's free
+    if (block->next && block->next->is_free) {
+        block->size += block->next->size + sizeof(struct memory_block);
+        block->next = block->next->next;
+    }
+
+    // Coalesce with previous block if it's free
+    struct memory_block *prev = free_blocks;
+    while (prev && prev->next != block) {
+        prev = prev->next;
+    }
+    if (prev && prev->is_free) {
+        prev->size += block->size + sizeof(struct memory_block);
+        prev->next = block->next;
+    }
+}
+
+void *malloc(size_t size)
+{
+    if (heap_start == NULL || heap_end == NULL)
+    {
+        // Heap not initialized, cannot allocate
+        return NULL;
+    }
+
+    // Align the size to the word size for efficiency
+    size = (size + sizeof(size_t) - 1) & ~(sizeof(size_t) - 1);
+
+    // Search for a free block of sufficient size
+    void *block = find_free_block(size);
+    if (block != NULL)
+    {
+        // Mark the block as used
+        mark_as_used(block, size);
+        return (void *)((uintptr_t)block + sizeof(struct memory_block));
+    }
+
+    // No suitable block found, out of memory
+    return NULL;
+}
+
+void free(void *ptr)
+{
+    if (ptr == NULL)
+    {
+        return;
+    }
+
+    // Adjust pointer to the start of the memory block
+    struct memory_block *block = (struct memory_block *)((uintptr_t)ptr - sizeof(struct memory_block));
+
+    // Mark the block as free
+    mark_as_free(block);
+}

kernel/malloc.h

@@ -0,0 +1,27 @@
+#ifndef MALLOC_H
+#define MALLOC_H
+
+#include <stddef.h> // For size_t
+
+// Define the memory block structure
+struct memory_block {
+    size_t size;
+    struct memory_block *next;
+    int is_free;
+};
+
+// Function prototypes
+void init_heap(void *start, void *end);
+void *malloc(size_t size);
+void free(void *ptr);
+
+// Helper function prototypes
+void *find_free_block(size_t size);
+void mark_as_used(void *ptr, size_t size);
+void mark_as_free(void *ptr);
+
+// External heap boundaries
+extern void *user_heap_start;
+extern void *user_heap_end;
+
+#endif // MALLOC_H

kernel/memmap.c

@@ -1,14 +1,21 @@
 #include "memmap.h"
 
 uint32_t get_memory_map(memory_map_entry_t *map, uint32_t max_entries) {
-    // Fill with dummy values for now
-    map[0].base_addr = 0x00000000;
-    map[0].length = 0x0009FC00;
-    map[0].type = 1;
+    uint32_t count = 0;
 
-    map[1].base_addr = 0x00100000;
-    map[1].length = 0x1FF00000;
-    map[1].type = 1;
+    if (max_entries >= 1) {
+        map[count].base_addr = 0x00000000;
+        map[count].length = 0x0009FC00;
+        map[count].type = 1;
+        count++;
+    }
 
-    return 2; // 2 regions
-}
+    if (max_entries >= 2) {
+        map[count].base_addr = 0x00100000;
+        map[count].length = 0x1FF00000;
+        map[count].type = 1;
+        count++;
+    }
+
+    return count;
+}

kernel/mouse.c

@@ -0,0 +1,27 @@
+// mouse.c
+#include "mouse.h"
+#include "usb.h"
+#include <stdint.h>
+#include <stdbool.h>
+
+// Mouse buffer
+static mouse_data_t mouse_data;
+
+// Read USB mouse data
+mouse_data_t usb_read_mouse(void) {
+    uint8_t buffer[3]; // USB HID Mouse reports typically use 3 bytes
+    if (usb_interrupt_transfer(buffer, sizeof(buffer))) { // Ensure buffer is filled
+        // Process the received data
+        mouse_data.x += buffer[1]; // X movement
+        mouse_data.y += buffer[2]; // Y movement
+        mouse_data.left_button = buffer[0] & 0x01;
+        mouse_data.right_button = buffer[0] & 0x02;
+    } else {
+        // Handle the case where no data was received
+        // You can choose to reset mouse_data or leave it unchanged
+        // For example, you might want to set movement to zero if no data is received
+        // mouse_data.x = 0;
+        // mouse_data.y = 0;
+    }
+    return mouse_data;
+}

kernel/mouse.h

@@ -0,0 +1,26 @@
+#ifndef MOUSE_H
+#define MOUSE_H
+
+#include <stdint.h>
+#include <stdbool.h>
+
+// Mouse data structure
+typedef struct {
+    int x;
+    int y;
+    bool left_button;
+    bool right_button;
+} mouse_data_t;
+
+// Function declarations for USB 1.x HID mouse support
+bool usb_mouse_init(void);
+bool usb_mouse_detected(void);
+bool usb_mouse_received(void);
+mouse_data_t usb_read_mouse(void);
+
+// USB Host Controller Interface functions (USB 1.x support)
+bool uhci_init(void);
+bool ohci_init(void);
+
+#endif // MOUSE_H
+

kernel/paging.c

@@ -1,21 +1,21 @@
 #include "paging.h"
 #include "io.h"
+#include <stdint.h>
+#include <stddef.h>
 
 page_directory_entry_t *page_directory = (page_directory_entry_t *)0x100000;
-page_table_entry_t *page_table = (page_table_entry_t *)0x101000; // Located right after the page directory
+page_table_entry_t *page_table = (page_table_entry_t *)0x101000;
+page_table_entry_t *heap_page_table = (page_table_entry_t *)0x102000; // Located right after the page directory
 
 // Helper function to set up the page directory entry
 void set_page_directory(page_directory_entry_t *dir) {
     for (int i = 0; i < PAGE_DIRECTORY_SIZE; i++) {
-        // Set up a page directory entry with identity mapping
-        dir[i].present = 1;
-        dir[i].rw = 1;           // Read/Write
-        dir[i].user = 0;         // Kernel mode
-        dir[i].write_through = 0;
-        dir[i].cache_disabled = 0;
-        dir[i].accessed = 0;
-        dir[i].frame = (uint32_t)&page_table[i] >> 12;  // Page table frame address
+        dir[i].present = 0;
     }
+    dir[0].present = 1;
+    dir[0].rw = 1;
+    dir[0].user = 0;
+    dir[0].frame = (uint32_t)page_table >> 12;
 }
 
 // Helper function to set up the page table entry
@@ -47,10 +47,26 @@ void enable_paging() {
 
 // Initialize paging: set up the page directory and enable paging
 void paging_init() {
-    // Set up the page directory and page tables
+    // Set up identity-mapped page directory + table
     set_page_directory(page_directory);
     set_page_table(page_table);
 
-    // Enable paging
+    // === Set up heap mapping at 0xC0100000 ===
+    for (int i = 0; i < PAGE_TABLE_SIZE; i++) {
+        heap_page_table[i].present = 1;
+        heap_page_table[i].rw = 1;
+        heap_page_table[i].user = 0;
+        heap_page_table[i].write_through = 0;
+        heap_page_table[i].cache_disabled = 0;
+        heap_page_table[i].accessed = 0;
+        heap_page_table[i].frame = (256 + i); // Start physical heap at 1MB (256*4KB = 1MB)
+    }
+
+    // Index 772 = 0xC0100000 / 4MB
+    page_directory[772].present = 1;
+    page_directory[772].rw = 1;
+    page_directory[772].user = 0;
+    page_directory[772].frame = (uint32_t)heap_page_table >> 12;
+
     enable_paging();
 }

kernel/paging.h

@@ -6,6 +6,7 @@
 #define PAGE_SIZE 4096                // Page size in bytes
 #define PAGE_DIRECTORY_SIZE 1024      // 1024 entries in page directory
 #define PAGE_TABLE_SIZE 1024          // 1024 entries in a page table
+#define KERNEL_HEAP_START 0xC0100000
 
 // Page Directory and Page Table structure
 typedef struct {
@@ -38,6 +39,7 @@ typedef struct {
 
 extern page_directory_entry_t *page_directory;
 extern page_table_entry_t *page_table;
+extern page_table_entry_t *heap_page_table;
 
 void paging_init(void);
 void set_page_directory(page_directory_entry_t *dir);

kernel/panic.c

@@ -0,0 +1,19 @@
+#include "panic.h"
+#include "terminal.h"
+#include "serial.h"
+#include <stdbool.h>
+
+void panic(const char *message) {
+    terminal_write("KERNEL PANIC: ");
+    terminal_write(message);
+    terminal_write("\nSystem halted.\n");
+
+    serial_write("KERNEL PANIC: ");
+    serial_write(message);
+    serial_write("\nSystem halted.\n");
+
+    // Halt the system
+    while (true) {
+        asm volatile ("cli; hlt");
+    }
+}

kernel/panic.h

@@ -0,0 +1,6 @@
+#ifndef PANIC_H
+#define PANIC_H
+
+void panic(const char *message);
+
+#endif // PANIC_H

kernel/print.c

@@ -0,0 +1,84 @@
+#include <stdio.h>
+#include <stdarg.h>
+#include "print.h"
+
+void my_putchar(char ch) {
+    // Write a single character to standard output
+    // In a freestanding environment, you might need to implement this differently
+    // For now, we will use the standard putchar for demonstration
+    // Replace this with your own implementation if needed
+    putchar(ch);
+}
+
+void print_string(const char *str) {
+    // Simple implementation to print a string
+    while (*str) {
+        my_putchar(*str++);
+    }
+}
+
+void my_printf(const char *format, ...) {
+    va_list args;
+    va_start(args, format);
+
+    while (*format) {
+        if (*format == '%') {
+            format++; // Move to the next character after '%'
+            switch (*format) {
+                case 's': { // String
+                    char *str = va_arg(args, char *);
+                    print_string(str);
+                    break;
+                }
+                case 'd': { // Integer
+                    int num = va_arg(args, int);
+                    char buffer[20]; // Buffer to hold the string representation
+                    snprintf(buffer, sizeof(buffer), "%d", num);
+                    print_string(buffer);
+                    break;
+                }
+                case 'c': { // Character
+                    char ch = (char)va_arg(args, int); // Promote char to int
+                    my_putchar(ch);
+                    break;
+                }
+                default:
+                    my_putchar('%'); // Print the '%' if no valid format specifier
+                    my_putchar(*format);
+                    break;
+            }
+        } else {
+            my_putchar(*format);
+        }
+        format++;
+    }
+
+    va_end(args);
+}
+
+
+void print_hex(unsigned int num) {
+    // Buffer to hold the hexadecimal representation
+    char buffer[9]; // 8 hex digits + null terminator
+    buffer[8] = '\0'; // Null-terminate the string
+
+    for (int i = 7; i >= 0; i--) {
+        int digit = num & 0xF; // Get the last 4 bits
+        buffer[i] = (digit < 10) ? (digit + '0') : (digit - 10 + 'A'); // Convert to hex character
+        num >>= 4; // Shift right by 4 bits
+    }
+
+    // Print the buffer, skipping leading zeros
+    int leading_zero = 1;
+    for (int i = 0; i < 8; i++) {
+        if (buffer[i] != '0') {
+            leading_zero = 0; // Found a non-zero digit
+        }
+        if (!leading_zero) {
+            my_putchar(buffer[i]);
+        }
+    }
+    if (leading_zero) {
+        my_putchar('0'); // If all were zeros, print a single '0'
+    }
+}

kernel/print.h

@@ -0,0 +1,9 @@
+#ifndef PRINT_H
+#define PRINT_H
+
+void print_string(const char *str);
+void my_printf(const char *format, ...);
+void print_hex(unsigned int num);
+void my_putchar(char ch);
+
+#endif

kernel/scheduler.c

@@ -0,0 +1,62 @@
+#include "scheduler.h"
+#include <stddef.h>
+
+static task_t tasks[MAX_TASKS];
+static uint32_t task_stacks[MAX_TASKS][STACK_SIZE / sizeof(uint32_t)];
+
+static int task_count = 0;
+static task_t *task_list = NULL;
+static task_t *current_task = NULL;
+
+void scheduler_init() {
+    // Initialize task list, etc.
+    task_list = NULL;
+    current_task = NULL;
+    task_count = 0;
+}
+
+void scheduler_add_task(void (*entry)(void)) {
+    if (task_count >= MAX_TASKS || entry == NULL) return;
+
+    task_t *new_task = &tasks[task_count];
+    new_task->id = task_count;
+    new_task->entry = entry;
+
+    // Simulate a stack pointer pointing to the "top" of the stack
+    new_task->stack_ptr = &task_stacks[task_count][STACK_SIZE / sizeof(uint32_t) - 1];
+
+    new_task->next = NULL;
+
+    // Add to task list
+    if (task_list == NULL) {
+        task_list = new_task;
+    } else {
+        task_t *tail = task_list;
+        while (tail->next) {
+            tail = tail->next;
+        }
+        tail->next = new_task;
+    }
+
+    task_count++;
+}
+
+void scheduler_schedule() {
+    // Very basic round-robin switch
+    if (current_task && current_task->next) {
+        current_task = current_task->next;
+    } else {
+        current_task = task_list; // Loop back
+    }
+
+    // Call context switch or simulate yielding to current_task
+    // In real system: context_switch_to(current_task)
+    if (current_task && current_task->entry) {
+        current_task->entry();  // Simulate switching by calling
+    }
+}
+
+void scheduler_yield() {
+    // Stub: manually call schedule for cooperative multitasking
+    scheduler_schedule();
+}

kernel/scheduler.h

@@ -0,0 +1,21 @@
+#ifndef SCHEDULER_H
+#define SCHEDULER_H
+
+#include <stdint.h>
+
+#define MAX_TASKS 8
+#define STACK_SIZE 1024
+
+typedef struct task {
+    uint32_t id;
+    void (*entry)(void);
+    uint32_t *stack_ptr;
+    struct task *next;
+} task_t;
+
+void scheduler_init();
+void scheduler_add_task(void (*entry)(void));
+void scheduler_schedule();
+void scheduler_yield();  // Optional for cooperative scheduling
+
+#endif // SCHEDULER_H

kernel/serial.c

@@ -1,20 +1,40 @@
 #include "io.h"
+#include "serial.h"
+#include <stdint.h>
 
 #define COM1 0x3F8
+#define COM2 0x2F8
+#define COM3 0x3E8
+#define COM4 0x2E8
+
+void serial_init_port(uint16_t port) {
+    outb(port + 1, 0x00);
+    outb(port + 3, 0x80);
+    outb(port + 0, 0x03);
+    outb(port + 1, 0x00);
+    outb(port + 3, 0x03);
+    outb(port + 2, 0xC7);
+    outb(port + 4, 0x0B);
+}
 
 void serial_init(void) {
-    outb(COM1 + 1, 0x00); // Disable interrupts
-    outb(COM1 + 3, 0x80); // Enable DLAB
-    outb(COM1 + 0, 0x03); // Set baud rate to 38400
-    outb(COM1 + 1, 0x00);
-    outb(COM1 + 3, 0x03); // 8 bits, no parity, one stop bit
-    outb(COM1 + 2, 0xC7); // Enable FIFO, clear, 14-byte threshold
-    outb(COM1 + 4, 0x0B); // IRQs enabled, RTS/DSR set
+    serial_init_port(COM1);
+    serial_init_port(COM2);
+    serial_init_port(COM3);
+    serial_init_port(COM4);
+}
+
+void serial_write_char(char c) {
+    while (!(inb(COM1 + 5) & 0x20));
+    outb(COM1, c);
 }
 
 void serial_write(const char *str) {
     while (*str) {
-        while (!(inb(COM1 + 5) & 0x20)); // Wait for the transmitter holding register to be empty
-        outb(COM1, *str++);
+        serial_write_char(*str++);
     }
 }
+
+void serial_write_string(const char* str) {
+    serial_write(str);
+}

kernel/serial.h

@@ -4,7 +4,9 @@
 #include <stdint.h>
 
 void serial_init(void);
-void serial_write(char c);
+void serial_init_port(uint16_t port);
+void serial_write_char(char c);
+void serial_write(const char *str);
 void serial_write_string(const char *str);
 
-#endif
+#endif

kernel/shell.c

@@ -0,0 +1,62 @@
+#include "shell.h"
+#include "keyboard.h"
+#include "terminal.h"
+#include "print.h"
+#include <stdio.h>
+#include <string.h>
+#include "string_utils.h"
+
+void execute(char *input) {
+    if (my_strcmp(input, "help") == 0) {
+        my_printf("Available commands: help, clear, exit\n");
+    } else if (my_strcmp(input, "clear") == 0) {
+        terminal_clear();
+    } else {
+        my_printf("Unknown command: %s\n", input);
+    }
+}
+
+void shell_loop()
+{
+    char input[256];
+    size_t index = 0;
+    char c;
+
+    while (1)
+    {
+        my_printf("> ");
+        index = 0;
+
+        while (1)
+        {
+            c = keyboard_get_char(); // Waits for input
+
+            if (c == '\n' || c == '\r')  // Enter key
+            {
+                input[index] = '\0';
+                my_printf("\n");
+                break;
+            }
+            else if (c == '\b' || c == 127) // Backspace
+            {
+                if (index > 0)
+                {
+                    index--;
+                    my_printf("\b \b"); // Erase last char on screen
+                }
+            }
+            else
+            {
+                if (index < sizeof(input) - 1) {
+                    input[index++] = c;
+                    putchar(c);
+                }
+            }
+        }
+
+        if (my_strcmp(input, "exit") == 0)
+            break;
+
+        execute(input);
+    }
+}

kernel/shell.h

@@ -0,0 +1,7 @@
+#ifndef SHELL_H
+#define SHELL_H
+
+void shell_loop(void);
+void execute(char *input);
+
+#endif

kernel/string_utils.c

@@ -0,0 +1,80 @@
+#include "string_utils.h"
+#include <stddef.h>
+#include <stdarg.h>
+
+size_t my_strlen(const char *str) {
+    const char *s = str;
+    while (*s) s++;
+    return s - str;
+}
+
+// Forward declaration of my_itoa
+static size_t my_itoa(int value, char *str, size_t size);
+
+int my_vsnprintf(char *str, size_t size, const char *format, ...) {
+    va_list args;
+    va_start(args, format);
+    size_t written = 0; // Change to size_t
+
+    for (const char *p = format; *p != '\0' && written < size - 1; p++) {
+        if (*p == '%') {
+            p++;
+            if (*p == 's') {
+                const char *s = va_arg(args, const char *);
+                while (*s && written < size - 1) {
+                    str[written++] = *s++;
+                }
+            } else if (*p == 'd') {
+                // Handle integer formatting
+                written += my_itoa(va_arg(args, int), str + written, size - written);
+            } else {
+                // Handle other formats as needed
+                str[written++] = *p; // Just copy the character
+            }
+        } else {
+            str[written++] = *p;
+        }
+    }
+    str[written] = '\0'; // Null-terminate the string
+    va_end(args);
+    return written;
+}
+
+static size_t my_itoa(int value, char *str, size_t size) {
+    size_t written = 0; // Change to size_t
+    if (value < 0) {
+        if (written < size - 1) {
+            str[written++] = '-';
+        }
+        value = -value;
+    }
+    // Convert integer to string
+    int temp = value;
+    int digits = 0;
+    do {
+        digits++;
+        temp /= 10;
+    } while (temp);
+    
+    if (written + digits >= size) {
+        digits = size - written - 1; // Prevent overflow
+    }
+    
+    str += written + digits; // Move pointer to the end
+    *str-- = '\0'; // Null-terminate the string
+
+    do {
+        *str-- = (value % 10) + '0';
+        value /= 10;
+    } while (value && str >= str - digits);
+    
+    return written + digits; // Return total written characters
+}
+
+int my_strcmp(const char *str1, const char *str2) {
+    while (*str1 && (*str1 == *str2)) {
+        str1++;
+        str2++;
+    }
+    return *(unsigned char *)str1 - *(unsigned char *)str2;
+}

kernel/string_utils.h

@@ -0,0 +1,11 @@
+#ifndef STRING_UTILS_H
+#define STRING_UTILS_H
+
+#include <stddef.h>
+#include <stdarg.h> // Include for va_list and related macros
+
+size_t my_strlen(const char *str); // Renamed to avoid conflict
+int my_vsnprintf(char *str, size_t size, const char *format, ...); // Renamed to avoid conflict
+int my_strcmp(const char *str1, const char *str2);
+
+#endif // STRING_UTILS_H

kernel/syscalls.c

@@ -0,0 +1,29 @@
+#include "syscalls.h"
+#include "scheduler.h"
+#include <stdarg.h>
+
+void syscall_handler(int code, va_list args) {
+    switch (code) {
+        case SYSCALL_INIT:
+            scheduler_init();
+            break;
+        case SYSCALL_SPAWN: {
+            void (*entry)(void) = va_arg(args, void (*)(void));
+            scheduler_add_task(entry);
+            break;
+        }
+        case SYSCALL_YIELD:
+            scheduler_yield();
+            break;
+        default:
+            // Unknown syscall
+            break;
+    }
+}
+
+void syscall(int code, ...) {
+    va_list args;
+    va_start(args, code);
+    syscall_handler(code, args);
+    va_end(args);
+}

kernel/syscalls.h

@@ -0,0 +1,17 @@
+#ifndef SYSCALLS_H
+#define SYSCALLS_H
+
+#include <stdarg.h>
+// Syscall numbers
+typedef enum {
+    SYSCALL_INIT = 0,
+    SYSCALL_SPAWN,
+    SYSCALL_YIELD
+} syscall_code_t;
+
+// Syscall dispatcher
+void syscall_handler(int code, va_list args);
+// Syscall interface
+void syscall(int code, ...);
+
+#endif // SYSCALLS_H

kernel/terminal.c

@@ -1,5 +1,7 @@
 #include <stdint.h>
 #include "io.h"
+#include "terminal.h"
+#include "vga.h"
 
 #define VGA_ADDRESS 0xB8000
 #define VGA_WIDTH 80
@@ -9,29 +11,41 @@
 static uint16_t* const vga_buffer = (uint16_t*) VGA_ADDRESS;
 static uint8_t cursor_x = 0;
 static uint8_t cursor_y = 0;
-
-static uint16_t vga_entry(char c, uint8_t color) {
-    return (uint16_t) color << 8 | (uint8_t) c;
-}
+static uint8_t current_color = WHITE_ON_BLACK;
 
 void terminal_initialize(void) {
     for (uint16_t y = 0; y < VGA_HEIGHT; y++) {
         for (uint16_t x = 0; x < VGA_WIDTH; x++) {
             const size_t index = y * VGA_WIDTH + x;
-            vga_buffer[index] = vga_entry(' ', WHITE_ON_BLACK);
+            vga_buffer[index] = vga_entry(' ', current_color);
         }
     }
     cursor_x = 0;
     cursor_y = 0;
+    update_cursor(); // Optional: good idea to reset position
 }
 
 void terminal_putchar(char c) {
+    // Handle backspace
+    if (c == '\b') {
+        if (cursor_x > 0) {
+            cursor_x--;
+        } else if (cursor_y > 0) {
+            cursor_y--;
+            cursor_x = VGA_WIDTH - 1;
+        }
+        vga_buffer[cursor_y * VGA_WIDTH + cursor_x] = vga_entry(' ', current_color);
+        update_cursor(); // Optional, if you add cursor updating
+        return;
+    }
+
+    // Handle newline
     if (c == '\n') {
         cursor_x = 0;
         cursor_y++;
     } else {
         const size_t index = cursor_y * VGA_WIDTH + cursor_x;
-        vga_buffer[index] = vga_entry(c, WHITE_ON_BLACK);
+        vga_buffer[index] = vga_entry(c, current_color);
         cursor_x++;
         if (cursor_x >= VGA_WIDTH) {
             cursor_x = 0;
@@ -49,15 +63,44 @@ void terminal_putchar(char c) {
 
         // Clear the last line
         for (uint16_t x = 0; x < VGA_WIDTH; x++) {
-            vga_buffer[(VGA_HEIGHT - 1) * VGA_WIDTH + x] = vga_entry(' ', WHITE_ON_BLACK);
+            vga_buffer[(VGA_HEIGHT - 1) * VGA_WIDTH + x] = vga_entry(' ', current_color);
         }
 
         cursor_y = VGA_HEIGHT - 1;
     }
+
+    update_cursor(); // Optional, if you want the hardware cursor to follow
 }
 
+
 void terminal_write(const char* str) {
     for (size_t i = 0; str[i] != '\0'; i++) {
         terminal_putchar(str[i]);
     }
 }
+
+void terminal_setcolor(uint8_t color)
+{
+    current_color = color;
+}
+
+void terminal_clear(void) {
+    for (uint16_t y = 0; y < VGA_HEIGHT; y++) {
+        for (uint16_t x = 0; x < VGA_WIDTH; x++) {
+            const size_t index = y * VGA_WIDTH + x;
+            vga_buffer[index] = vga_entry(' ', current_color);
+        }
+    }
+    cursor_x = 0;
+    cursor_y = 0;
+    update_cursor();
+}
+
+void update_cursor() {
+    uint16_t pos = cursor_y * VGA_WIDTH + cursor_x;
+
+    outb(0x3D4, 0x0F);
+    outb(0x3D5, (uint8_t)(pos & 0xFF));
+    outb(0x3D4, 0x0E);
+    outb(0x3D5, (uint8_t)((pos >> 8) & 0xFF));
+}

kernel/terminal.h

@@ -7,5 +7,7 @@ void terminal_initialize(void);
 void terminal_putchar(char c);
 void terminal_write(const char *str);
 void terminal_setcolor(uint8_t color);
+void terminal_clear(void);
+void update_cursor(void);
 
 #endif

kernel/threading.c

@@ -0,0 +1,118 @@
+#include "threading.h"
+#include <stdlib.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+
+#define MAX_THREADS 16           // Maximum number of threads
+#define THREAD_STACK_SIZE 8192   // Stack size for each thread
+
+// The thread table stores information about all threads
+static Thread thread_table[MAX_THREADS];
+static uint32_t current_thread = 0;  // Index of the currently running thread
+static uint32_t num_threads = 0;     // Number of active threads
+
+// A simple mutex spinlock
+static volatile int mutex_locked = 0;
+
+// Function declaration for context_switch
+void context_switch(Thread *next);
+
+// Initialize the threading system
+void thread_init(void) {
+    memset(thread_table, 0, sizeof(thread_table));
+    num_threads = 0;
+}
+
+// Create a new thread
+void thread_create(Thread *thread __attribute__((unused)), void (*start_routine)(void *), void *arg) {
+    if (num_threads >= MAX_THREADS) {
+        printf("Error: Maximum thread count reached.\n");
+        return;
+    }
+
+    // Find an empty slot for the new thread
+    int index = num_threads++;
+    thread_table[index] = (Thread){0};
+    
+    // Set up the new thread
+    thread_table[index].start_routine = start_routine;
+    thread_table[index].arg = arg;
+    thread_table[index].stack_size = THREAD_STACK_SIZE;
+    thread_table[index].stack = (uint32_t*)malloc(THREAD_STACK_SIZE);
+    thread_table[index].stack_top = thread_table[index].stack + THREAD_STACK_SIZE / sizeof(uint32_t);
+
+    // Initialize the stack (simulate pushing the function's return address)
+    uint32_t *stack_top = thread_table[index].stack_top;
+    *(--stack_top) = (uint32_t)start_routine;  // Return address (the thread's entry point)
+    *(--stack_top) = (uint32_t)arg;            // Argument to pass to the thread
+
+    // Set the thread's state to ready
+    thread_table[index].state = THREAD_READY;
+
+    // If this is the first thread, switch to it
+    if (index == 0) {
+        scheduler();
+    }
+}
+
+// Yield the CPU to another thread
+void thread_yield(void) {
+    // Find the next thread in a round-robin manner
+    uint32_t next_thread = (current_thread + 1) % num_threads;
+    while (next_thread != current_thread && thread_table[next_thread].state != THREAD_READY) {
+        next_thread = (next_thread + 1) % num_threads;
+    }
+
+    if (next_thread != current_thread) {
+        current_thread = next_thread;
+        scheduler();
+    }
+}
+
+// Exit the current thread
+void thread_exit(void) {
+    thread_table[current_thread].state = THREAD_BLOCKED;  // Mark the thread as blocked (finished)
+    free(thread_table[current_thread].stack);             // Free the thread's stack
+    num_threads--;                                       // Decrease thread count
+
+    // Yield to the next thread
+    thread_yield();
+}
+
+// Scheduler: This function selects the next thread to run
+void scheduler(void) {
+    // Find the next ready thread
+    uint32_t next_thread = (current_thread + 1) % num_threads;
+    while (thread_table[next_thread].state != THREAD_READY) {
+        next_thread = (next_thread + 1) % num_threads;
+    }
+
+    if (next_thread != current_thread) {
+        current_thread = next_thread;
+        context_switch(&thread_table[current_thread]);
+    }
+}
+
+// Context switch to the next thread (assembly would go here to save/load registers)
+void context_switch(Thread *next) {
+    // For simplicity, context switching in this example would involve saving/restoring registers.
+    // In a real system, you would need to save the CPU state (registers) and restore the next thread's state.
+    printf("Switching to thread...\n");
+    next->start_routine(next->arg);  // Start running the next thread
+}
+
+// Simple mutex functions (spinlock)
+void mutex_init(void) {
+    mutex_locked = 0;
+}
+
+void mutex_lock(void) {
+    while (__sync_lock_test_and_set(&mutex_locked, 1)) {
+        // Busy wait (spinlock)
+    }
+}
+
+void mutex_unlock(void) {
+    __sync_lock_release(&mutex_locked);
+}

kernel/threading.h

@@ -0,0 +1,36 @@
+#ifndef THREADING_H
+#define THREADING_H
+
+#include <stdint.h>
+#include <stddef.h>
+
+// Define a basic thread structure (Thread Control Block - TCB)
+typedef struct Thread {
+    void (*start_routine)(void *);   // Function pointer to the thread function
+    void *arg;                       // Argument to be passed to the thread function
+    uint32_t *stack;                 // Pointer to the thread's stack
+    uint32_t *stack_top;             // Top of the stack (where the thread will start)
+    uint32_t stack_size;             // Size of the stack
+    uint32_t state;                  // Thread state (running, ready, blocked)
+} Thread;
+
+// Thread states
+#define THREAD_RUNNING 0
+#define THREAD_READY   1
+#define THREAD_BLOCKED 2
+
+// Thread management functions
+void thread_init(void);
+void thread_create(Thread *thread, void (*start_routine)(void *), void *arg);
+void thread_yield(void);
+void thread_exit(void);
+
+// Scheduler function
+void scheduler(void);
+
+// Synchronization functions (mutex spinlocks)
+void mutex_init(void);
+void mutex_lock(void);
+void mutex_unlock(void);
+
+#endif // THREADING_H

kernel/timer.c

@@ -0,0 +1,35 @@
+#include "timer.h"
+#include "io.h"
+#include "isr.h"
+#include "terminal.h"
+#include "stdio.h"
+
+static volatile uint32_t tick = 0;
+
+void timer_callback(void) {
+    tick++;
+
+    if (tick % 100 == 0) {
+        char buf[16];
+        itoa(tick, buf, 10);
+        terminal_write("Tick count: ");
+        terminal_write(buf);
+        terminal_write("\n");
+    }
+
+    outb(0x20, 0x20); // EOI to PIC
+}
+
+void timer_init(uint32_t frequency) {
+    register_interrupt_handler(32, timer_callback); // IRQ0 = Interrupt 32
+
+    uint32_t divisor = 1193180 / frequency;
+
+    outb(0x43, 0x36);             // Command byte
+    outb(0x40, divisor & 0xFF);   // Low byte
+    outb(0x40, (divisor >> 8));   // High byte
+}
+
+uint32_t timer_get_ticks(void) {
+    return tick;
+}

kernel/timer.h

@@ -0,0 +1,9 @@
+#ifndef TIMER_H
+#define TIMER_H
+
+#include <stdint.h>
+
+void timer_init(uint32_t frequency);
+uint32_t timer_get_ticks(void);
+
+#endif

kernel/types.c

@@ -0,0 +1,9 @@
+#include "types.h"
+
+// Example: Basic memory helper (unnecessary if libc exists)
+void *memset(void *dest, int value, size_t len) {
+    unsigned char *ptr = (unsigned char *)dest;
+    while (len-- > 0)
+        *ptr++ = (unsigned char)value;
+    return dest;
+}

kernel/types.h

@@ -0,0 +1,62 @@
+#ifndef TYPES_H
+#define TYPES_H
+
+// ----------------------------
+// Fixed-width integer types
+// ----------------------------
+typedef unsigned char      uint8_t;
+typedef signed char        int8_t;
+typedef unsigned short     uint16_t;
+typedef signed short       int16_t;
+typedef unsigned int       uint32_t;
+typedef signed int         int32_t;
+typedef unsigned long long uint64_t;
+typedef signed long long   int64_t;
+
+// ----------------------------
+// Boolean & NULL definitions
+// ----------------------------
+#ifndef __cplusplus
+typedef enum { false = 0, true = 1 } bool;
+#endif
+
+#ifndef NULL
+#define NULL ((void*)0)
+#endif
+
+// ----------------------------
+// OS subsystem types
+// ----------------------------
+typedef uint32_t size_t;
+typedef int32_t  ssize_t;
+
+typedef uint32_t phys_addr_t; // Physical address
+typedef uint32_t virt_addr_t; // Virtual address
+
+typedef uint32_t pid_t;       // Process ID
+typedef uint32_t tid_t;       // Thread ID
+
+// ----------------------------
+// Bitfield & utility macros
+// ----------------------------
+#define BIT(n) (1U << (n))
+#define BITS(m, n) (((1U << ((n) - (m) + 1)) - 1) << (m))
+
+// Align value to next multiple of alignment
+#define ALIGN_UP(val, align) (((val) + ((align)-1)) & ~((align)-1))
+#define ALIGN_DOWN(val, align) ((val) & ~((align)-1))
+
+// ----------------------------
+// Attributes for structures
+// ----------------------------
+#define PACKED      __attribute__((packed))
+#define ALIGN(x)    __attribute__((aligned(x)))
+
+// ----------------------------
+// Likely/unlikely branch hints
+// (for future optimization use)
+// ----------------------------
+#define likely(x)   __builtin_expect(!!(x), 1)
+#define unlikely(x) __builtin_expect(!!(x), 0)
+
+#endif // TYPES_H

kernel/usb.c

@@ -0,0 +1,64 @@
+#include "usb.h"
+#include <stdint.h>
+#include <stdbool.h>
+
+// USB version detection
+bool usb_detect_version(uint16_t *version) {
+    if (!version) return false;
+    *version = 0x0110; // Example: USB 1.1
+    return true;
+}
+
+// USB initialization for 1.x
+bool usb_init(void) {
+    // Detect controller type (UHCI or OHCI)
+    bool uhci_supported = uhci_init();
+    bool ohci_supported = ohci_init();
+    
+    if (!uhci_supported && !ohci_supported) {
+        return false; // No supported controllers found
+    }
+    
+    return true;
+}
+
+// USB device enumeration (1.x)
+bool usb_enumerate_devices(void) {
+    // Implementation for detecting devices on USB 1.x ports
+    return true;
+}
+
+// HID initialization for USB 1.x
+bool usb_hid_init(void) {
+    // Ensure USB is initialized
+    if (!usb_init()) return false;
+    
+    return usb_enumerate_devices();
+}
+
+// USB transfers (stubs for 1.x)
+bool usb_control_transfer(/* parameters */) {
+    // Implement control transfer for USB 1.x
+    return true;
+}
+
+bool usb_interrupt_transfer(/* parameters */) {
+    // Implement interrupt transfer for USB 1.x
+    return true;
+}
+
+bool usb_bulk_transfer(/* parameters */) {
+    // Implement bulk transfer for USB 1.x
+    return true;
+}
+
+// USB host controller initialization (UHCI & OHCI)
+bool uhci_init(void) {
+    // Initialize UHCI controller (USB 1.x)
+    return true;
+}
+
+bool ohci_init(void) {
+    // Initialize OHCI controller (USB 1.x)
+    return true;
+}

kernel/usb.h

@@ -0,0 +1,24 @@
+#ifndef USB_H
+#define USB_H
+
+#include <stdint.h>
+#include <stdbool.h>
+
+// USB initialization and management functions
+bool usb_init(void);
+bool usb_detect_version(uint16_t *version);
+bool usb_enumerate_devices(void);
+
+// HID-specific functions
+bool usb_hid_init(void);
+
+// USB transfer functions
+bool usb_control_transfer(/* parameters */);
+bool usb_interrupt_transfer(/* parameters */);
+bool usb_bulk_transfer(/* parameters */);
+
+// USB host controller initialization (USB 1.x only)
+bool uhci_init(void); // UHCI support
+bool ohci_init(void); // OHCI support
+
+#endif // USB_H

kernel/utils.c

@@ -0,0 +1,91 @@
+#include "utils.h"
+#include "serial.h"
+#include "terminal.h"
+
+static void reverse(char* str, int len) {
+    int start = 0;
+    int end = len - 1;
+    while (start < end) {
+        char temp = str[start];
+        str[start++] = str[end];
+        str[end--] = temp;
+    }
+}
+
+// Integer to ASCII for signed ints
+char* itoa(int value, char* str, int base) {
+    int i = 0;
+    int isNegative = 0;
+    unsigned int uval;
+
+    if (base < 2 || base > 36) {
+        str[0] = '\0';
+        return str;
+    }
+
+    // Handle zero explicitly
+    if (value == 0) {
+        str[i++] = '0';
+        str[i] = '\0';
+        return str;
+    }
+
+    // Handle negative numbers (only for base 10)
+    if (value < 0 && base == 10) {
+        isNegative = 1;
+        uval = (unsigned int)(-value);
+    } else {
+        uval = (unsigned int)value;
+    }
+
+    while (uval != 0) {
+        int rem = uval % base;
+        str[i++] = (rem > 9) ? (rem - 10) + 'a' : rem + '0';
+        uval /= base;
+    }
+
+    if (isNegative) {
+        str[i++] = '-';
+    }
+
+    str[i] = '\0';
+    reverse(str, i);
+    return str;
+}
+
+// Integer to ASCII for unsigned ints
+char* utoa(unsigned int value, char* str, int base) {
+    int i = 0;
+
+    if (base < 2 || base > 36) {
+        str[0] = '\0';
+        return str;
+    }
+
+    if (value == 0) {
+        str[i++] = '0';
+        str[i] = '\0';
+        return str;
+    }
+
+    while (value != 0) {
+        int rem = value % base;
+        str[i++] = (rem > 9) ? (rem - 10) + 'a' : rem + '0';
+        value /= base;
+    }
+
+    str[i] = '\0';
+    reverse(str, i);
+    return str;
+}
+
+void print_hex(uint32_t val) {
+    char hex_chars[] = "0123456789ABCDEF";
+    char buf[11] = "0x00000000";
+    for (int i = 9; i >= 2; i--) {
+        buf[i] = hex_chars[val & 0xF];
+        val >>= 4;
+    }
+    terminal_write(buf);
+    serial_write(buf);
+}

kernel/utils.h

@@ -0,0 +1,14 @@
+#ifndef UTILS_H
+#define UTILS_H
+#include <stdint.h>
+
+
+// Convert integer to string (base is typically 10, 16, etc.)
+char* itoa(int value, char* str, int base);
+
+// Convert unsigned integer to string (base is typically 10, 16, etc.)
+char* utoa(unsigned int value, char* str, int base);
+
+void print_hex(uint32_t val);
+
+#endif // UTILS_H

kernel/vga.c

@@ -0,0 +1,151 @@
+#include "vga.h"
+#include <stddef.h>
+#include <stdbool.h>
+#include <string.h>
+#include <stdarg.h>
+#include "string_utils.h"
+
+void outb(uint16_t port, uint8_t value) {
+    __asm__ volatile("outb %0, %1" : : "a"(value), "Nd"(port));
+}
+
+// Read a byte from the specified port
+uint8_t inb(uint16_t port) {
+    uint8_t value;
+    __asm__ volatile("inb %1, %0" : "=a"(value) : "Nd"(port));
+    return value;
+}
+
+uint8_t vga_entry_color(vga_color fg, vga_color bg) {
+    return fg | bg << 4;
+}
+
+uint16_t vga_entry(unsigned char uc, uint8_t color) {
+    return (uint16_t)uc | (uint16_t)color << 8;
+}
+
+void vga_put_entry_at(char c, uint8_t color, size_t x, size_t y) {
+    const size_t index = y * 80 + x;
+    ((uint16_t*) 0xB8000)[index] = vga_entry(c, color);
+}
+
+void vga_clear(uint8_t color) {
+    uint16_t blank = vga_entry(' ', color);
+    for (size_t i = 0; i < 80 * 25; ++i) {
+        ((uint16_t*) 0xB8000)[i] = blank;
+    }
+}
+
+void vga_write_string(const char* data, size_t size) {
+    size_t x = 0;
+    size_t y = 0;
+    for (size_t i = 0; i < size; ++i) {
+        if (x >= 80) {  // If we reach the end of a line, move to the next line
+            x = 0;
+            y++;
+        }
+        
+        if (y >= 25) {  // If we reach the bottom of the screen, scroll
+            vga_scroll();
+            y = 24;  // Reset to the last row
+        }
+        
+        vga_put_entry_at(data[i], vga_entry_color(VGA_COLOR_LIGHT_GREY, VGA_COLOR_BLACK), x, y);
+        x++;  // Move to the next column
+    }
+}
+
+void vga_scroll(void) {
+    uint16_t* video_memory = (uint16_t*)0xB8000;
+    // Shift all lines up by one row (80 columns per row)
+    for (size_t i = 0; i < 24 * 80; ++i) {
+        video_memory[i] = video_memory[i + 80];  // Move one row up
+    }
+
+    // Clear the last row (bottom row)
+    for (size_t i = 24 * 80; i < 25 * 80; ++i) {
+        video_memory[i] = vga_entry(' ', vga_entry_color(VGA_COLOR_BLACK, VGA_COLOR_WHITE));
+    }
+}
+
+void vga_set_cursor_position(size_t x, size_t y) {
+    uint16_t position = y * 80 + x;  // Calculate linear index (y * 80 + x)
+
+    // Set the high byte of the cursor position
+    outb(VGA_PORT_INDEX, 0x0E);        // Cursor high byte register
+    outb(VGA_PORT_DATA, position >> 8);
+
+    // Set the low byte of the cursor position
+    outb(VGA_PORT_INDEX, 0x0F);        // Cursor low byte register
+    outb(VGA_PORT_DATA, position & 0xFF);
+}
+
+size_t vga_get_cursor_position(void) {
+    outb(VGA_PORT_INDEX, 0x0E);         // Cursor high byte register
+    uint8_t high = inb(VGA_PORT_DATA);  // Read high byte
+
+    outb(VGA_PORT_INDEX, 0x0F);         // Cursor low byte register
+    uint8_t low = inb(VGA_PORT_DATA);   // Read low byte
+
+    return (high << 8) | low;  // Combine the high and low bytes
+}
+
+void vga_set_cursor_blinking(bool enable) {
+    outb(VGA_PORT_INDEX, 0x0A);        // Cursor control register
+    uint8_t cursor = inb(VGA_PORT_DATA);
+    if (enable) {
+        cursor |= 0x01;  // Enable blinking
+    } else {
+        cursor &= ~0x01; // Disable blinking
+    }
+    outb(VGA_PORT_INDEX, 0x0A);        // Cursor control register
+    outb(VGA_PORT_DATA, cursor);
+}
+
+void vga_set_cursor_shape(uint8_t start, uint8_t end) {
+    outb(VGA_PORT_INDEX, 0x0A);        // Cursor control register
+    uint8_t cursor = inb(VGA_PORT_DATA);
+    cursor = (cursor & 0xC0) | (start & 0x3F);  // Set start of cursor shape
+    outb(VGA_PORT_DATA, cursor);
+
+    outb(VGA_PORT_INDEX, 0x0B);        // Cursor start register
+    outb(VGA_PORT_DATA, end & 0x3F);   // Set end of cursor shape
+}
+
+void vga_set_cursor_color(uint8_t color) {
+    outb(VGA_PORT_INDEX, 0x0A);        // Cursor control register
+    uint8_t cursor = inb(VGA_PORT_DATA);
+    cursor = (cursor & 0xC0) | (color & 0x3F);  // Set cursor color
+    outb(VGA_PORT_DATA, cursor);
+}
+
+void vga_set_cursor_blink_rate(uint8_t rate) {
+    outb(VGA_PORT_INDEX, 0x0A);        // Cursor control register
+    uint8_t cursor = inb(VGA_PORT_DATA);
+    cursor = (cursor & 0xC0) | (rate & 0x3F);  // Set cursor blink rate
+    outb(VGA_PORT_DATA, cursor);
+}
+
+void vga_printf(const char* format, ...) {
+    char buffer[256];  // Buffer to store the formatted string
+    va_list args;
+    va_start(args, format);
+    my_vsnprintf(buffer, sizeof(buffer), format, args); // Use my_vsnprintf instead of vsnprintf
+    va_end(args);
+    
+    // Now you can use the buffer with vga_write_string
+    vga_write_string(buffer, my_strlen(buffer)); // Use my_strlen instead of strlen
+}
+
+void vga_init(void) {
+    // Clear the screen
+    vga_clear(vga_entry_color(VGA_COLOR_BLACK, VGA_COLOR_LIGHT_GREY));
+    
+    // Set the cursor to the top-left corner
+    vga_set_cursor_position(0, 0);
+    
+    // Optionally, set cursor blinking and shape
+    vga_set_cursor_blinking(true);
+    vga_set_cursor_shape(0x20, 0x3F);  // Default shape
+}
+

kernel/vga.h

@@ -0,0 +1,53 @@
+#ifndef VGA_H
+#define VGA_H
+
+#include <stdint.h>
+#include <stddef.h>
+#include <stdbool.h>
+#include <stdarg.h>  // For va_list, va_start, etc.
+
+// VGA color definitions
+typedef enum {
+    VGA_COLOR_BLACK = 0,
+    VGA_COLOR_BLUE = 1,
+    VGA_COLOR_GREEN = 2,
+    VGA_COLOR_CYAN = 3,
+    VGA_COLOR_RED = 4,
+    VGA_COLOR_MAGENTA = 5,
+    VGA_COLOR_BROWN = 6,
+    VGA_COLOR_LIGHT_GREY = 7,
+    VGA_COLOR_DARK_GREY = 8,
+    VGA_COLOR_LIGHT_BLUE = 9,
+    VGA_COLOR_LIGHT_GREEN = 10,
+    VGA_COLOR_LIGHT_CYAN = 11,
+    VGA_COLOR_LIGHT_RED = 12,
+    VGA_COLOR_LIGHT_MAGENTA = 13,
+    VGA_COLOR_LIGHT_BROWN = 14,
+    VGA_COLOR_WHITE = 15,
+} vga_color;
+
+// VGA port addresses
+typedef enum {
+    VGA_PORT_INDEX = 0x3D4,  // Index register for VGA
+    VGA_PORT_DATA  = 0x3D5   // Data register for VGA
+} vga_io_port_t;
+
+// Function prototypes
+uint8_t vga_entry_color(vga_color fg, vga_color bg);
+uint16_t vga_entry(unsigned char uc, uint8_t color);
+
+void vga_put_entry_at(char c, uint8_t color, size_t x, size_t y);
+void vga_clear(uint8_t color);
+void vga_write_string(const char* data, size_t size);
+void vga_scroll(void);
+void vga_set_cursor_position(size_t x, size_t y);
+size_t vga_get_cursor_position(void);
+
+void vga_set_cursor_blinking(bool enable);
+void vga_set_cursor_shape(uint8_t start, uint8_t end);
+void vga_set_cursor_color(uint8_t color);
+void vga_set_cursor_blink_rate(uint8_t rate);
+
+void vga_printf(const char* format, ...);
+
+#endif