new OS

kernel/idt.c

@@ -0,0 +1,43 @@
+#include "idt.h"
+#include "io.h"
+
+#define KERNEL_CS 0x08  // Kernel code segment selector
+
+idt_entry_t idt[IDT_ENTRIES];
+idt_ptr_t idt_ptr;
+
+// External assembly stubs for ISRs (provided below)
+extern void isr0();
+extern void isr13();
+extern void isr_default();
+
+// Helper to set an IDT gate
+void idt_set_gate(int n, uint32_t handler) {
+    idt[n].offset_low = handler & 0xFFFF;
+    idt[n].selector = KERNEL_CS;
+    idt[n].zero = 0;
+    idt[n].type_attr = 0x8E;  // Present, ring 0, 32-bit interrupt gate
+    idt[n].offset_high = (handler >> 16) & 0xFFFF;
+}
+
+// Load IDT via lidt
+static void idt_load() {
+    asm volatile("lidt (%0)" : : "r" (&idt_ptr));
+}
+
+// IDT initialization
+void idt_init() {
+    idt_ptr.limit = sizeof(idt_entry_t) * IDT_ENTRIES - 1;
+    idt_ptr.base = (uint32_t)&idt;
+
+    // Clear all entries
+    for (int i = 0; i < IDT_ENTRIES; i++) {
+        idt_set_gate(i, (uint32_t)isr_default);
+    }
+
+    // Set specific handlers
+    idt_set_gate(0, (uint32_t)isr0);   // Divide by zero
+    idt_set_gate(13, (uint32_t)isr13); // General protection fault
+
+    idt_load();
+}

kernel/idt.h

@@ -0,0 +1,24 @@
+#ifndef IDT_H
+#define IDT_H
+
+#include <stdint.h>
+
+#define IDT_ENTRIES 256
+
+typedef struct {
+    uint16_t offset_low;
+    uint16_t selector;
+    uint8_t zero;
+    uint8_t type_attr;
+    uint16_t offset_high;
+} __attribute__((packed)) idt_entry_t;
+
+typedef struct {
+    uint16_t limit;
+    uint32_t base;
+} __attribute__((packed)) idt_ptr_t;
+
+void idt_set_gate(int n, uint32_t handler);
+void idt_init(void);
+
+#endif

kernel/io.h

@@ -0,0 +1,14 @@
+#ifndef IO_H
+#define IO_H
+
+static inline void outb(uint16_t port, uint8_t val) {
+    asm volatile ("outb %0, %1" : : "a"(val), "Nd"(port));
+}
+
+static inline uint8_t inb(uint16_t port) {
+    uint8_t ret;
+    asm volatile ("inb %1, %0" : "=a"(ret) : "Nd"(port));
+    return ret;
+}
+
+#endif

kernel/isr.asm

@@ -0,0 +1,30 @@
+; isr.asm
+[BITS 32]
+[GLOBAL isr0, isr13, isr_default]
+
+isr0:
+    cli
+    push byte 0
+    push byte 0
+    call isr_handler
+    add esp, 8
+    sti
+    iret
+
+isr13:
+    cli
+    push byte 13
+    push byte 0
+    call isr_handler
+    add esp, 8
+    sti
+    iret
+
+isr_default:
+    cli
+    push byte 255
+    push byte 0
+    call isr_handler
+    add esp, 8
+    sti
+    iret

kernel/isr.c

@@ -0,0 +1,21 @@
+#include "terminal.h"
+#include "serial.h"
+
+void isr_handler(uint32_t int_num, uint32_t err_code) {
+    terminal_write("Interrupt occurred: ");
+    // Add simple int-to-string printing here
+    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");
+    } else {
+        terminal_write(" -> Unknown interrupt\n");
+    }
+
+    // Halt CPU
+    while (1) {
+        asm volatile ("hlt");
+    }
+}

kernel/kmain.c

@@ -0,0 +1,53 @@
+#include <stdint.h>
+#include <stdbool.h>
+#include "io.h"
+#include "serial.h"
+#include "terminal.h"
+#include "idt.h"
+#include "paging.h"
+#include "memmap.h"
+
+#define LPT1 0x378
+
+void lpt_write(char c) {
+    while ((inb(LPT1 + 1) & 0x80) == 0); // Wait for ready
+    outb(LPT1, c);
+}
+
+void kmain(void) {
+    terminal_initialize();
+    terminal_write("Welcome to ClassicOS\n");
+
+    serial_init();
+    serial_write("Serial port initialized.\n");
+
+    lpt_write('L'); // Send 'L' to LPT1 to test
+
+    terminal_write("Initializing IDT...\n");
+    idt_init();
+    serial_write("IDT initialized.\n");
+
+    terminal_write("Enabling paging...\n");
+    paging_init();
+    serial_write("Paging 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");
+    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("System initialized. Halting.\n");
+
+    // Halt CPU in loop
+    while (1) {
+        asm volatile("hlt");
+    }
+}

kernel/memmap.c

@@ -0,0 +1,14 @@
+#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;
+
+    map[1].base_addr = 0x00100000;
+    map[1].length = 0x1FF00000;
+    map[1].type = 1;
+
+    return 2; // 2 regions
+}

kernel/memmap.h

@@ -0,0 +1,14 @@
+#ifndef MEMMAP_H
+#define MEMMAP_H
+
+#include <stdint.h>
+
+typedef struct {
+    uint64_t base_addr;
+    uint64_t length;
+    uint32_t type;
+} __attribute__((packed)) memory_map_entry_t;
+
+uint32_t get_memory_map(memory_map_entry_t *map, uint32_t max_entries);
+
+#endif

kernel/paging.c

@@ -0,0 +1,56 @@
+#include "paging.h"
+#include "io.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
+
+// 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
+    }
+}
+
+// Helper function to set up the page table entry
+void set_page_table(page_table_entry_t *table) {
+    for (int i = 0; i < PAGE_TABLE_SIZE; i++) {
+        // Set up page table entries with identity mapping
+        table[i].present = 1;
+        table[i].rw = 1;          // Read/Write
+        table[i].user = 0;        // Kernel mode
+        table[i].write_through = 0;
+        table[i].cache_disabled = 0;
+        table[i].accessed = 0;
+        table[i].frame = i;       // Identity mapping
+    }
+}
+
+// Enable paging by loading the page directory into CR3 and setting the PG bit in CR0
+void enable_paging() {
+    uint32_t cr0;
+
+    // Load page directory into CR3
+    asm volatile("mov %0, %%cr3" : : "r"(page_directory));
+
+    // Enable paging (set the PG bit in CR0)
+    asm volatile("mov %%cr0, %0" : "=r"(cr0));
+    cr0 |= 0x80000000;  // Set the PG (paging) bit
+    asm volatile("mov %0, %%cr0" : : "r"(cr0));
+}
+
+// Initialize paging: set up the page directory and enable paging
+void paging_init() {
+    // Set up the page directory and page tables
+    set_page_directory(page_directory);
+    set_page_table(page_table);
+
+    // Enable paging
+    enable_paging();
+}

kernel/paging.h

@@ -0,0 +1,47 @@
+#ifndef PAGING_H
+#define PAGING_H
+
+#include <stdint.h>
+
+#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
+
+// Page Directory and Page Table structure
+typedef struct {
+    uint32_t present : 1;  // Present bit (1: page is present in memory)
+    uint32_t rw : 1;       // Read-Write bit (1: page is read-write)
+    uint32_t user : 1;     // User-supervisor bit (1: user mode access)
+    uint32_t write_through : 1;  // Write-through cache
+    uint32_t cache_disabled : 1; // Cache disabled
+    uint32_t accessed : 1;        // Accessed bit
+    uint32_t reserved : 1;        // Reserved bit
+    uint32_t page_size : 1;       // Page size (0: 4KB, 1: 4MB)
+    uint32_t global : 1;           // Global page (can be used across different processes)
+    uint32_t available : 3;        // Available bits for the system
+    uint32_t frame : 20;           // Frame address (physical address)
+} __attribute__((packed)) page_table_entry_t;
+
+// Define page directory entry
+typedef struct {
+    uint32_t present : 1;
+    uint32_t rw : 1;
+    uint32_t user : 1;
+    uint32_t write_through : 1;
+    uint32_t cache_disabled : 1;
+    uint32_t accessed : 1;
+    uint32_t reserved : 1;
+    uint32_t zero : 5;           // Must be zero for page directory
+    uint32_t reserved_2 : 7;     // Reserved bits
+    uint32_t frame : 20;         // Frame address of the page table
+} __attribute__((packed)) page_directory_entry_t;
+
+extern page_directory_entry_t *page_directory;
+extern page_table_entry_t *page_table;
+
+void paging_init(void);
+void set_page_directory(page_directory_entry_t *dir);
+void set_page_table(page_table_entry_t *table);
+void enable_paging(void);
+
+#endif

kernel/serial.c

@@ -0,0 +1,20 @@
+#include "io.h"
+
+#define COM1 0x3F8
+
+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
+}
+
+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++);
+    }
+}

kernel/serial.h

@@ -0,0 +1,10 @@
+#ifndef SERIAL_H
+#define SERIAL_H
+
+#include <stdint.h>
+
+void serial_init(void);
+void serial_write(char c);
+void serial_write_string(const char *str);
+
+#endif

kernel/terminal.c

@@ -0,0 +1,63 @@
+#include <stdint.h>
+#include "io.h"
+
+#define VGA_ADDRESS 0xB8000
+#define VGA_WIDTH 80
+#define VGA_HEIGHT 25
+#define WHITE_ON_BLACK 0x0F
+
+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;
+}
+
+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);
+        }
+    }
+    cursor_x = 0;
+    cursor_y = 0;
+}
+
+void terminal_putchar(char c) {
+    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);
+        cursor_x++;
+        if (cursor_x >= VGA_WIDTH) {
+            cursor_x = 0;
+            cursor_y++;
+        }
+    }
+
+    // Scroll if needed
+    if (cursor_y >= VGA_HEIGHT) {
+        for (uint16_t y = 1; y < VGA_HEIGHT; y++) {
+            for (uint16_t x = 0; x < VGA_WIDTH; x++) {
+                vga_buffer[(y - 1) * VGA_WIDTH + x] = vga_buffer[y * VGA_WIDTH + x];
+            }
+        }
+
+        // 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);
+        }
+
+        cursor_y = VGA_HEIGHT - 1;
+    }
+}
+
+void terminal_write(const char* str) {
+    for (size_t i = 0; str[i] != '\0'; i++) {
+        terminal_putchar(str[i]);
+    }
+}

kernel/terminal.h

@@ -0,0 +1,11 @@
+#ifndef TERMINAL_H
+#define TERMINAL_H
+
+#include <stdint.h>
+
+void terminal_initialize(void);
+void terminal_putchar(char c);
+void terminal_write(const char *str);
+void terminal_setcolor(uint8_t color);
+
+#endif