Merge pull request #74 from gbowne1/gbowne1-addpci

Adds PCI bus driver implementation

.clang-format

@@ -0,0 +1,24 @@
+BasedOnStyle: Google
+IndentWidth: 4
+TabWidth: 4
+UseTab: Never
+ColumnLimit: 80
+
+DerivePointerAlignment: false
+PointerAlignment: Right
+ReferenceAlignment: Right
+
+AlignConsecutiveMacros: Consecutive
+AlignTrailingComments:
+  Kind: Always
+  OverEmptyLines: 0
+
+IncludeBlocks: Regroup
+IncludeCategories:
+  # Std headers
+  - Regex: '<[[:alnum:]_.]+>'
+    Priority: 2
+
+  # Other headers
+  - Regex: '.*'
+    Priority: 1

.clangd

@@ -0,0 +1,6 @@
+CompileFlags:
+  CompilationDatabase: build
+
+Diagnostics:
+  UnusedIncludes: Strict
+  MissingIncludes: Strict

.editorconfig

@@ -0,0 +1,12 @@
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[Makefile]
+indent_style = tab
+indent_size = 8
+tab_width = 8

Makefile

@@ -18,9 +18,9 @@ KERNEL_OBJ += $(patsubst kernel/%.asm, $(BUILD_DIR)/asm_%.o, $(KERNEL_ASM_SRC))
 KLIBC_SRC = $(wildcard klibc/src/*.c)
 KLIBC_OBJ = $(patsubst klibc/src/%.c, $(BUILD_DIR)/klibc/%.o, $(KLIBC_SRC))
 
+.PHONY: all stage1 stage2 kernel compile-commands $(BUILD_DIR)/compile_commands.json run gdb clean clean-cross clean-all
 all: $(DISK_IMG)
 
-.PHONY: stage1 stage2 kernel run gdb clean
 stage1: $(BUILD_DIR)
 	$(AS) $(ASFLAGS) -o $(BUILD_DIR)/$@.o bootloader/$@.asm
 	$(LD) -Ttext=0x7c00 -melf_i386 -o $(BUILD_DIR)/$@.elf $(BUILD_DIR)/$@.o
@@ -57,6 +57,10 @@ $(BUILD_DIR):
 	mkdir -p $@
 	mkdir -p $(BUILD_DIR)/klibc
 
+compile-commands: $(BUILD_DIR)/compile_commands.json
+$(BUILD_DIR)/compile_commands.json: $(BUILD_DIR)
+	bear --output $@ -- make -B
+
 run:
 	qemu-system-i386 -s -S $(DISK_IMG)
 

kernel/ata.c

@@ -0,0 +1,119 @@
+#include "ata.h"
+#include "io.h"
+#include "print.h"
+
+#define ATA_TIMEOUT 100000
+
+static inline void ata_delay(void) {
+    /* 400ns delay by reading alternate status */
+    inb(ATA_PRIMARY_CTRL);
+    inb(ATA_PRIMARY_CTRL);
+    inb(ATA_PRIMARY_CTRL);
+    inb(ATA_PRIMARY_CTRL);
+}
+
+bool ata_wait_ready(void) {
+    for (int i = 0; i < ATA_TIMEOUT; i++) {
+        uint8_t status = inb(ATA_PRIMARY_IO + ATA_REG_STATUS);
+        /* Must NOT be busy AND must be ready */
+        if (!(status & ATA_SR_BSY) && (status & ATA_SR_DRDY))
+            return true;
+    }
+    return false;
+}
+
+static bool ata_wait(uint8_t mask) {
+    for (int i = 0; i < ATA_TIMEOUT; i++) {
+        uint8_t status = inb(ATA_PRIMARY_IO + ATA_REG_STATUS);
+        /* If ERR is set, stop waiting and return failure */
+        if (status & ATA_SR_ERR) return false;
+        
+        if (!(status & ATA_SR_BSY) && (status & mask))
+            return true;
+    }
+    return false;
+}
+
+bool ata_init(void) {
+    /* Select drive */
+    outb(ATA_PRIMARY_IO + ATA_REG_HDDEVSEL, ATA_MASTER);
+    ata_delay();
+
+    /* Check if drive exists */
+    uint8_t status = inb(ATA_PRIMARY_IO + ATA_REG_STATUS);
+    if (status == 0xFF || status == 0) return false;
+
+    outb(ATA_PRIMARY_IO + ATA_REG_COMMAND, ATA_CMD_IDENTIFY);
+    ata_delay();
+
+    if (!ata_wait(ATA_SR_DRQ))
+        return false;
+
+    uint16_t identify[256];
+    for (int i = 0; i < 256; i++)
+        identify[i] = inw(ATA_PRIMARY_IO);
+
+    print_string("[ATA] Primary master detected\n");
+    return true;
+}
+
+bool ata_read_sector(uint32_t lba, uint8_t* buffer) {
+    if (!buffer) return false;
+
+    /* 1. Wait for drive to be ready for command */
+    if (!ata_wait_ready()) return false;
+
+    /* 2. Setup Task File (LBA28) */
+    outb(ATA_PRIMARY_IO + ATA_REG_HDDEVSEL, 0xE0 | ((lba >> 24) & 0x0F));
+    outb(ATA_PRIMARY_IO + ATA_REG_SECCOUNT0, 1);
+    outb(ATA_PRIMARY_IO + ATA_REG_LBA0, (uint8_t)(lba));
+    outb(ATA_PRIMARY_IO + ATA_REG_LBA1, (uint8_t)(lba >> 8));
+    outb(ATA_PRIMARY_IO + ATA_REG_LBA2, (uint8_t)(lba >> 16));
+    
+    /* 3. Issue Read Command */
+    outb(ATA_PRIMARY_IO + ATA_REG_COMMAND, ATA_CMD_READ_PIO);
+
+    /* 4. Wait for Data Request (DRQ) */
+    if (!ata_wait(ATA_SR_DRQ))
+        return false;
+
+    /* 5. Transfer data */
+    for (int i = 0; i < 256; i++) {
+        uint16_t data = inw(ATA_PRIMARY_IO);
+        buffer[i * 2]     = data & 0xFF;
+        buffer[i * 2 + 1] = (data >> 8) & 0xFF;
+    }
+
+    ata_delay();
+    return true;
+}
+
+bool ata_write_sector(uint32_t lba, const uint8_t* buffer) {
+    if (!buffer) return false;
+
+    /* 1. Wait for drive to be ready for command */
+    if (!ata_wait_ready()) return false;
+
+    /* 2. Setup Task File */
+    outb(ATA_PRIMARY_IO + ATA_REG_HDDEVSEL, 0xE0 | ((lba >> 24) & 0x0F));
+    outb(ATA_PRIMARY_IO + ATA_REG_SECCOUNT0, 1);
+    outb(ATA_PRIMARY_IO + ATA_REG_LBA0, (uint8_t)(lba));
+    outb(ATA_PRIMARY_IO + ATA_REG_LBA1, (uint8_t)(lba >> 8));
+    outb(ATA_PRIMARY_IO + ATA_REG_LBA2, (uint8_t)(lba >> 16));
+    
+    /* 3. Issue Write Command */
+    outb(ATA_PRIMARY_IO + ATA_REG_COMMAND, ATA_CMD_WRITE_PIO);
+
+    /* 4. Wait for drive to request data */
+    if (!ata_wait(ATA_SR_DRQ))
+        return false;
+
+    /* 5. Transfer data */
+    for (int i = 0; i < 256; i++) {
+        uint16_t word = buffer[i * 2] | (buffer[i * 2 + 1] << 8);
+        outw(ATA_PRIMARY_IO, word);
+    }
+
+    ata_delay();
+    return true;
+}

kernel/ata.h

@@ -0,0 +1,44 @@
+#ifndef ATA_H
+#define ATA_H
+
+#include <stdint.h>
+#include <stdbool.h>
+
+/* ATA I/O ports */
+#define ATA_PRIMARY_IO     0x1F0
+#define ATA_PRIMARY_CTRL   0x3F6
+
+/* ATA registers */
+#define ATA_REG_DATA       0x00
+#define ATA_REG_ERROR      0x01
+#define ATA_REG_FEATURES   0x01
+#define ATA_REG_SECCOUNT0  0x02
+#define ATA_REG_LBA0       0x03
+#define ATA_REG_LBA1       0x04
+#define ATA_REG_LBA2       0x05
+#define ATA_REG_HDDEVSEL   0x06
+#define ATA_REG_COMMAND    0x07
+#define ATA_REG_STATUS     0x07
+
+/* ATA commands */
+#define ATA_CMD_READ_PIO   0x20
+#define ATA_CMD_WRITE_PIO  0x30
+#define ATA_CMD_IDENTIFY   0xEC
+
+/* Status flags */
+#define ATA_SR_BSY         0x80
+#define ATA_SR_DRDY        0x40
+#define ATA_SR_DRQ         0x08
+#define ATA_SR_ERR         0x01
+
+/* Drive select */
+#define ATA_MASTER         0xA0
+#define ATA_SLAVE          0xB0
+
+/* Public API */
+bool ata_init(void);
+bool ata_read_sector(uint32_t lba, uint8_t* buffer);
+bool ata_write_sector(uint32_t lba, const uint8_t* buffer);
+bool ata_wait_ready(void);
+
+#endif

kernel/display.c

@@ -1,36 +1,80 @@
+#include <string.h>
 #include "display.h"
-#include "io.h" // Include your I/O header for port access
+#include "io.h"
 #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
+    // Initialize the VGA driver. This typically sets up the 80x25 text mode,
+    // clears the screen, and sets the cursor.
+    vga_init();
 }
 
 // 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.
+    // This function is often a complex operation in a real driver.
+    // In this simplified kernel/VGA text mode environment, we use printf
+    // to output a message and rely on the fact that VGA is present.
     
-    // 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
+    // Clear the display before printing a message
+    vga_clear(vga_entry_color(VGA_COLOR_LIGHT_GREY, VGA_COLOR_BLACK));
+    
+    // Output a simplified enumeration message
+    vga_printf("Display: Standard VGA Text Mode (80x25) Detected.\n");
+    
+    // In a real driver, you would use inb() and outb() with specific VGA ports
+    // to read information (e.g., from the CRTC registers 0x3D4/0x3D5)
+    // to check for display presence or configuration.
 }
 
 // Set the display mode
+// NOTE: Setting arbitrary VGA modes (like 0x13 for 320x200) is very complex
+// and requires writing hundreds of register values, often done via BIOS in
+// real mode. Since we are in protected mode and have a simple text driver,
+// this function is kept simple or treated as a placeholder for full mode changes.
 void set_display_mode(uint8_t mode) {
-    // Set the VGA mode by writing to the appropriate registers
+    // Check if the requested mode is a known mode (e.g., VGA Text Mode 3)
+    // For this example, we simply acknowledge the call.
+    // A true mode set would involve complex register sequencing.
+    
+    // The provided vga.c is a Text Mode driver, so a graphical mode set
+    // like 0x13 (320x200 256-color) would break the existing vga_printf functionality.
+    
+    // A simplified text-mode-specific response:
+    if (mode == 0x03) { // Mode 3 is standard 80x25 text mode
+        vga_printf("Display mode set to 80x25 Text Mode (Mode 0x03).\n");
+        vga_init(); // Re-initialize the text mode
+    } else {
+        // Simple I/O example based on the original structure (Caution: Incomplete for full mode set)
         outb(VGA_PORT, mode); // Example function to write to a port
+        vga_printf("Attempting to set display mode to 0x%x. (Warning: May break current display)\n", mode);
+    }
 }
 
 // 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
+    // Use the VGA driver's clear function, typically clearing to black on light grey
+    // or black on black. We'll use the black on light grey from vga_init for consistency.
+    vga_clear(vga_entry_color(VGA_COLOR_BLACK, VGA_COLOR_LIGHT_GREY));
+    // Reset cursor to 0, 0
+    vga_set_cursor_position(0, 0);
+}
+
+// Helper function to write a string
+void display_write_string(const char* str) {
+    // Use the VGA driver's string writing function
+    vga_write_string(str, strlen(str));
+}
+
+// Helper function to print a formatted string
+void display_printf(const char* format, ...) {
+    // Use the VGA driver's printf function
+    va_list args;
+    va_start(args, format);
+    
+    // The vga_printf function already handles the va_list internally,
+    // so we can just call it directly.
+    vga_printf(format, args);
+    
+    va_end(args);
 }

kernel/display.h

@@ -2,13 +2,21 @@
 #define DISPLAY_H
 
 #include <stdint.h>
+#include "vga.h" // Include VGA functions
 
-#define VGA_PORT 0x3C0  // Base port for VGA
+#define VGA_PORT 0x3C0  // Base port for VGA (Often used for general control, though 0x3D4/0x3D5 are used for cursor)
 
 // Function prototypes
 void init_display(void);
 void enumerate_displays(void);
-void set_display_mode(uint8_t mode);
+void set_display_mode(uint8_t mode); // In this context, modes are typically BIOS or VESA modes, which are complex.
+                                      // We'll treat this as a placeholder/simple mode call.
 void clear_display(void);
 
+// New function to write a string using the VGA driver
+void display_write_string(const char* str);
+
+// New function to print a formatted string using the VGA driver
+void display_printf(const char* format, ...);
+
 #endif // DISPLAY_H

kernel/hid.c

@@ -0,0 +1,65 @@
+#include "hid.h"
+#include "usb.h"
+#include "mouse.h"
+#include "keyboard.h"
+#include "print.h"
+#include <stdint.h>
+#include <stdbool.h>
+
+// Global variables
+static bool hid_initialized = false;
+
+void hid_init(void) {
+    if (hid_initialized) return;
+    hid_initialized = true;
+
+    // Initialize keyboard and mouse HID handling
+    keyboard_init();
+    // Assume USB mouse has been initialized and is connected.
+    usb_hid_init(); // Initializes USB HID for both keyboard and mouse
+}
+
+void hid_process_report(uint8_t* report, uint8_t length) {
+    // Process the HID report based on its type
+    if (length == 8) {  // Assuming a standard 8-byte report for HID keyboard
+        keyboard_hid_report_t* k_report = (keyboard_hid_report_t*) report;
+        hid_process_keyboard_report(k_report);
+    } else if (length == 3) {  // Assuming a standard 3-byte report for HID mouse
+        mouse_hid_report_t* m_report = (mouse_hid_report_t*) report;
+        hid_process_mouse_report(m_report);
+    }
+}
+
+// Handle HID keyboard report
+void hid_process_keyboard_report(const keyboard_hid_report_t* report) {
+    // Iterate over the keycodes and process key presses
+    for (int i = 0; i < 6; i++) {
+        uint8_t keycode = report->keycodes[i];
+        if (keycode != 0) {
+            char key = scancode_map[keycode];
+            if (key) {
+                keyboard_buffer_add(key);
+            }
+        }
+    }
+}
+
+// Handle HID mouse report
+void hid_process_mouse_report(const mouse_hid_report_t* report) {
+    // Process mouse movement and button clicks
+    mouse_data.x += report->x;
+    mouse_data.y += report->y;
+    mouse_data.left_button = (report->buttons & 0x01) != 0;
+    mouse_data.right_button = (report->buttons & 0x02) != 0;
+
+    print_hex((uint32_t)mouse_data.x, 1, 1);
+    print_hex((uint32_t)mouse_data.y, 1, 1);
+    print_hex((uint32_t)report->buttons, 1, 1);
+}
+
+// Parse the HID descriptor (for parsing USB HID device descriptors)
+bool hid_parse_descriptor(uint8_t* descriptor, uint32_t length) {
+    // HID descriptors are defined in the USB HID specification, we'll need to parse them here.
+    // For now, just return true assuming we have a valid descriptor.
+    return true;
+}

kernel/hid.h

@@ -0,0 +1,46 @@
+#ifndef HID_H
+#define HID_H
+
+#include <stdint.h>
+#include <stdbool.h>
+
+// HID Report types
+#define HID_REPORT_INPUT  0x01
+#define HID_REPORT_OUTPUT 0x02
+#define HID_REPORT_FEATURE 0x03
+
+// HID usage page constants (USB HID)
+#define HID_USAGE_PAGE_GENERIC 0x01
+#define HID_USAGE_KEYBOARD 0x06
+#define HID_USAGE_MOUSE 0x02
+
+// HID keyboard and mouse data
+typedef struct {
+    uint8_t modifier;    // Modifier keys (shift, ctrl, alt, etc.)
+    uint8_t reserved;    // Reserved byte
+    uint8_t keycodes[6]; // Keycodes for keys pressed
+} keyboard_hid_report_t;
+
+typedef struct {
+    uint8_t buttons;     // Mouse buttons (bitwise: 0x01 = left, 0x02 = right, 0x04 = middle)
+    int8_t x;            // X axis movement
+    int8_t y;            // Y axis movement
+    int8_t wheel;        // Mouse wheel
+} mouse_hid_report_t;
+
+// Initialize the HID subsystem
+void hid_init(void);
+
+// Process an incoming HID report
+void hid_process_report(uint8_t* report, uint8_t length);
+
+// Process HID keyboard report
+void hid_process_keyboard_report(const keyboard_hid_report_t* report);
+
+// Process HID mouse report
+void hid_process_mouse_report(const mouse_hid_report_t* report);
+
+// USB HID report descriptor parsing
+bool hid_parse_descriptor(uint8_t* descriptor, uint32_t length);
+
+#endif // HID_H

kernel/keyboard.c

@@ -2,64 +2,91 @@
 #include "io.h"
 #include "isr.h"
 #include "terminal.h"
+#include <stddef.h>
 
 #define KEYBOARD_DATA_PORT 0x60
 #define KEY_BUFFER_SIZE 256
 
-static char key_buffer[KEY_BUFFER_SIZE];
-static uint8_t buffer_head = 0;  // Write position (interrupt)
-static uint8_t buffer_tail = 0;  // Read position (get_char)
-static uint8_t buffer_count = 0;
-static uint8_t buffer_index = 0;
+// Use volatile so the compiler knows these change inside interrupts
+static volatile char key_buffer[KEY_BUFFER_SIZE];
+static volatile uint8_t buffer_head = 0;
+static volatile uint8_t buffer_tail = 0;
+static volatile uint8_t buffer_count = 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
+// Exported map: Removed 'static' so hid.c can reference it if needed
+const char scancode_map[128] = {
+    0,  27, '1', '2', '3', '4', '5', '6', '7', '8',
+    '9', '0', '-', '=', '\b', '\t', 'q', 'w', 'e', 'r',
+    't', 'y', 'u', 'i', 'o', 'p', '[', ']', '\n', 0,
+    'a', 's', 'd', 'f', 'g', 'h', 'j', 'k', 'l', ';',
+    '\'', '`', 0, '\\', 'z', 'x', 'c', 'v', 'b', 'n',
+    'm', ',', '.', '/', 0, '*', 0, ' ', 0
 };
 
-// Interrupt handler for IRQ1
-void keyboard_callback(void) {
-    uint8_t scancode = inb(KEYBOARD_DATA_PORT);
-
-    if (scancode & 0x80) return;  // Ignore key release
-
-    char c = scancode_map[scancode];
+/**
+ * Shared function used by both PS/2 (callback) and USB (hid.c)
+ * This fixes the "undefined reference to keyboard_buffer_add" error.
+ */
+void keyboard_buffer_add(char c) {
     if (!c) return;
 
     uint8_t next_head = (buffer_head + 1) % KEY_BUFFER_SIZE;
 
-    // Drop key if buffer full
-    if (next_head == buffer_tail) return;
+    // If buffer is full, we must drop the key
+    if (next_head == buffer_tail) {
+        return; 
+    }
 
     key_buffer[buffer_head] = c;
     buffer_head = next_head;
     buffer_count++;
 
+    // Echo to terminal
     terminal_putchar(c);
 }
 
-void keyboard_init() {
-    register_interrupt_handler(33, keyboard_callback); // IRQ1 = int 33 (0x21)
+/**
+ * Hardware Interrupt Handler for PS/2
+ */
+void keyboard_callback(void) {
+    uint8_t scancode = inb(KEYBOARD_DATA_PORT);
+
+    // Ignore break codes (key release)
+    if (scancode & 0x80) return; 
+
+    char c = scancode_map[scancode];
+    keyboard_buffer_add(c);
 }
 
-// Blocking read (returns one char)
-char keyboard_get_char(void) {
-    while (buffer_count == 0) {
-        __asm__ __volatile__("hlt");  // Better than busy loop
-    }
+void keyboard_init(void) {
+    buffer_head = 0;
+    buffer_tail = 0;
+    buffer_count = 0;
+    // IRQ1 is usually mapped to IDT entry 33
+    register_interrupt_handler(33, keyboard_callback); 
+}
 
+/**
+ * Blocking read with a safe HLT to prevent CPU 100% usage
+ */
+char keyboard_get_char(void) {
     char c;
-    __asm__ __volatile__("cli");
+
+    while (1) {
+        __asm__ __volatile__("cli"); // Disable interrupts to check buffer_count safely
+        
+        if (buffer_count > 0) {
             c = key_buffer[buffer_tail];
             buffer_tail = (buffer_tail + 1) % KEY_BUFFER_SIZE;
             buffer_count--;
-    __asm__ __volatile__("sti");
-
+            __asm__ __volatile__("sti"); // Re-enable interrupts after reading
             return c;
+        }
+
+        /* * IMPORTANT: 'sti' followed by 'hlt' is guaranteed by x86 
+         * to execute 'hlt' BEFORE the next interrupt can trigger.
+         * This prevents the race condition hang.
+         */
+        __asm__ __volatile__("sti; hlt"); 
+    }
 }

kernel/keyboard.h

@@ -1,7 +1,12 @@
 #ifndef KEYBOARD_H
 #define KEYBOARD_H
 
+#include <stdint.h>
+
 void keyboard_init(void);
-char keyboard_get_char(void);  // Blocking read from buffer
+void keyboard_buffer_add(char c);
+char keyboard_get_char(void);  
+
+extern const char scancode_map[128]; 
 
 #endif

kernel/mouse.c

@@ -5,7 +5,7 @@
 #include <stdbool.h>
 
 // Mouse buffer
-static mouse_data_t mouse_data;
+mouse_data_t mouse_data;
 
 // Read USB mouse data
 mouse_data_t usb_read_mouse(void) {

kernel/mouse.h

@@ -12,6 +12,8 @@ typedef struct {
     bool right_button;
 } mouse_data_t;
 
+extern mouse_data_t mouse_data;
+
 // Function declarations for USB 1.x HID mouse support
 bool usb_mouse_init(void);
 bool usb_mouse_detected(void);

kernel/pci.c

@@ -0,0 +1,109 @@
+#include "pci.h"
+#include "io.h"
+
+/* --- Configuration Access Functions --- */
+
+uint32_t pci_config_read_dword(uint8_t bus, uint8_t slot, uint8_t func, uint8_t offset) {
+    uint32_t address = (uint32_t)((uint32_t)1 << 31) | 
+                       ((uint32_t)bus << 16) | 
+                       ((uint32_t)slot << 11) | 
+                       ((uint32_t)func << 8) | 
+                       (offset & 0xFC);
+    outl(PCI_CONFIG_ADDRESS, address);
+    return inl(PCI_CONFIG_DATA);
+}
+
+void pci_config_write_dword(uint8_t bus, uint8_t slot, uint8_t func, uint8_t offset, uint32_t data) {
+    uint32_t address = (uint32_t)((uint32_t)1 << 31) | 
+                       ((uint32_t)bus << 16) | 
+                       ((uint32_t)slot << 11) | 
+                       ((uint32_t)func << 8) | 
+                       (offset & 0xFC);
+    outl(PCI_CONFIG_ADDRESS, address);
+    outl(PCI_CONFIG_DATA, data);
+}
+
+/* To read a word or byte, we read the Dword and shift/mask */
+uint16_t pci_config_read_word(uint8_t bus, uint8_t slot, uint8_t func, uint8_t offset) {
+    uint32_t dword = pci_config_read_dword(bus, slot, func, offset);
+    return (uint16_t)((dword >> ((offset & 2) * 8)) & 0xFFFF);
+}
+
+uint8_t pci_config_read_byte(uint8_t bus, uint8_t slot, uint8_t func, uint8_t offset) {
+    uint32_t dword = pci_config_read_dword(bus, slot, func, offset);
+    return (uint8_t)((dword >> ((offset & 3) * 8)) & 0xFF);
+}
+
+/* --- BAR Decoding Logic --- */
+
+pci_bar_t pci_get_bar(uint8_t bus, uint8_t slot, uint8_t func, uint8_t bar_index) {
+    pci_bar_t bar = {0};
+    uint8_t offset = PCI_REG_BAR0 + (bar_index * 4);
+    
+    uint32_t initial_val = pci_config_read_dword(bus, slot, func, offset);
+    
+    // The Size Masking Trick
+    pci_config_write_dword(bus, slot, func, offset, 0xFFFFFFFF);
+    uint32_t mask = pci_config_read_dword(bus, slot, func, offset);
+    pci_config_write_dword(bus, slot, func, offset, initial_val); // Restore
+    
+    if (initial_val & 0x1) {
+        // I/O Space BAR
+        bar.is_io = true;
+        bar.base_address = initial_val & 0xFFFFFFFC;
+        bar.size = ~(mask & 0xFFFFFFFC) + 1;
+    } else {
+        // Memory Space BAR
+        bar.is_io = false;
+        bar.base_address = initial_val & 0xFFFFFFF0;
+        bar.is_prefetchable = (initial_val & 0x8) != 0;
+        bar.size = ~(mask & 0xFFFFFFF0) + 1;
+    }
+    
+    return bar;
+}
+
+/* --- Enumeration and Discovery --- */
+
+void pci_check_function(uint8_t bus, uint8_t slot, uint8_t func) {
+    uint16_t vendor_id = pci_config_read_word(bus, slot, func, PCI_REG_VENDOR_ID);
+    if (vendor_id == 0xFFFF) return; 
+
+    uint16_t device_id = pci_config_read_word(bus, slot, func, PCI_REG_DEVICE_ID);
+    uint8_t class_code = pci_config_read_byte(bus, slot, func, PCI_REG_CLASS);
+    
+    /* Optional: Set Master Latency Timer if it is 0. 
+       A value of 32 (0x20) or 64 (0x40) is typical. 
+    */
+    uint8_t latency = pci_config_read_byte(bus, slot, func, PCI_REG_LATENCY_TIMER);
+    if (latency == 0) {
+        // pci_config_write_byte would be needed here, or write a dword with the byte modified
+        uint32_t reg_0c = pci_config_read_dword(bus, slot, func, 0x0C);
+        reg_0c |= (0x20 << 8); // Set latency to 32
+        pci_config_write_dword(bus, slot, func, 0x0C, reg_0c);
+    }
+
+    // Replace with your kernel's print/logging function
+    // printf("Found PCI Device: %x:%x Class: %x at %d:%d:%d\n", vendor_id, device_id, class_code, bus, slot, func);
+}
+
+void pci_init(void) {
+    for (uint16_t bus = 0; bus < 256; bus++) {
+        for (uint8_t slot = 0; slot < 32; slot++) {
+            // Check Function 0 first
+            uint16_t vendor = pci_config_read_word(bus, slot, 0, PCI_REG_VENDOR_ID);
+            if (vendor == 0xFFFF) continue;
+
+            pci_check_function(bus, slot, 0);
+
+            // Check if this is a multi-function device
+            uint8_t header_type = pci_config_read_byte(bus, slot, 0, PCI_REG_HEADER_TYPE);
+            if (header_type & 0x80) {
+                // Check functions 1-7
+                for (uint8_t func = 1; func < 8; func++) {
+                    pci_check_function(bus, slot, func);
+                }
+            }
+        }
+    }
+}

kernel/pci.h

@@ -0,0 +1,60 @@
+#ifndef PCI_H
+#define PCI_H
+
+#include <stdint.h>
+#include <stdbool.h>
+
+/* I/O Ports for PCI Configuration Mechanism #1 */
+#define PCI_CONFIG_ADDRESS 0xCF8
+#define PCI_CONFIG_DATA    0xCFC
+
+/* Common PCI Configuration Register Offsets */
+#define PCI_REG_VENDOR_ID       0x00
+#define PCI_REG_DEVICE_ID       0x02
+#define PCI_REG_COMMAND         0x04
+#define PCI_REG_STATUS          0x06
+#define PCI_REG_REVISION_ID     0x08
+#define PCI_REG_PROG_IF         0x09
+#define PCI_REG_SUBCLASS        0x0A
+#define PCI_REG_CLASS           0x0B
+#define PCI_REG_CACHE_LINE_SIZE 0x0C
+#define PCI_REG_LATENCY_TIMER   0x0D
+#define PCI_REG_HEADER_TYPE     0x0E
+#define PCI_REG_BIST            0x0F
+#define PCI_REG_BAR0            0x10
+#define PCI_REG_BAR1            0x14
+#define PCI_REG_BAR2            0x18
+#define PCI_REG_BAR3            0x1C
+#define PCI_REG_BAR4            0x20
+#define PCI_REG_BAR5            0x24
+#define PCI_REG_INTERRUPT_LINE  0x3C
+
+typedef struct {
+    uint32_t base_address;
+    uint32_t size;
+    bool     is_io;
+    bool     is_prefetchable; // Only for Memory BARs
+} pci_bar_t;
+
+typedef struct {
+    uint8_t  bus;
+    uint8_t  device;
+    uint8_t  function;
+    uint16_t vendor_id;
+    uint16_t device_id;
+    uint8_t  class_code;
+    uint8_t  subclass;
+    uint8_t  interrupt_line;
+} pci_dev_t;
+
+/* Function Prototypes */
+uint32_t pci_config_read_dword(uint8_t bus, uint8_t slot, uint8_t func, uint8_t offset);
+void     pci_config_write_dword(uint8_t bus, uint8_t slot, uint8_t func, uint8_t offset, uint32_t data);
+
+uint16_t pci_config_read_word(uint8_t bus, uint8_t slot, uint8_t func, uint8_t offset);
+uint8_t  pci_config_read_byte(uint8_t bus, uint8_t slot, uint8_t func, uint8_t offset);
+
+pci_bar_t pci_get_bar(uint8_t bus, uint8_t slot, uint8_t func, uint8_t bar_index);
+void      pci_init(void);
+
+#endif

kernel/ps2.c

@@ -0,0 +1,107 @@
+#include "ps2.h"
+#include "io.h"
+
+/* --- Controller Synchronization --- */
+
+// Wait until the controller is ready to receive a byte
+static void ps2_wait_write() {
+    while (inb(PS2_STATUS_REG) & PS2_STATUS_INPUT);
+}
+
+// Wait until the controller has a byte for us to read
+static void ps2_wait_read() {
+    while (!(inb(PS2_STATUS_REG) & PS2_STATUS_OUTPUT));
+}
+
+/* --- Initialization --- */
+
+void ps2_write_device(uint8_t command) {
+    ps2_wait_write();
+    outb(PS2_DATA_PORT, command);
+}
+
+void ps2_write_mouse(uint8_t data) {
+    ps2_wait_write();
+    outb(PS2_COMMAND_REG, PS2_CMD_WRITE_MOUSE); // "Next byte goes to mouse"
+    ps2_wait_write();
+    outb(PS2_DATA_PORT, data);
+}
+
+void ps2_init(void) {
+    // 1. Disable Devices
+    ps2_wait_write();
+    outb(PS2_COMMAND_REG, PS2_CMD_DISABLE_KB);
+    ps2_wait_write();
+    outb(PS2_COMMAND_REG, PS2_CMD_DISABLE_MS);
+
+    // 2. Flush Output Buffer
+    while (inb(PS2_STATUS_REG) & PS2_STATUS_OUTPUT) {
+        inb(PS2_DATA_PORT);
+    }
+
+    // 3. Set Controller Configuration Byte
+    // Bit 0: KB Interrupt, Bit 1: Mouse Interrupt, Bit 6: Translation
+    ps2_wait_write();
+    outb(PS2_COMMAND_REG, PS2_CMD_READ_CONFIG);
+    ps2_wait_read();
+    uint8_t status = inb(PS2_DATA_PORT);
+    status |= (1 << 0) | (1 << 1); // Enable IRQ 1 and IRQ 12
+    
+    ps2_wait_write();
+    outb(PS2_COMMAND_REG, PS2_CMD_WRITE_CONFIG);
+    ps2_wait_write();
+    outb(PS2_DATA_PORT, status);
+
+    // 4. Enable Devices
+    ps2_wait_write();
+    outb(PS2_COMMAND_REG, PS2_CMD_ENABLE_KB);
+    ps2_wait_write();
+    outb(PS2_COMMAND_REG, PS2_CMD_ENABLE_MS);
+
+    // 5. Initialize Mouse (The mouse won't send IRQs until you tell it to)
+    ps2_write_mouse(MOUSE_CMD_SET_DEFAULTS);
+    ps2_wait_read(); inb(PS2_DATA_PORT); // Read ACK (0xFA)
+    
+    ps2_write_mouse(MOUSE_CMD_ENABLE_SCAN);
+    ps2_wait_read(); inb(PS2_DATA_PORT); // Read ACK (0xFA)
+}
+
+/* --- IRQ Handlers --- */
+
+// Called from IRQ 1 (Keyboard)
+void ps2_keyboard_handler(void) {
+    uint8_t scancode = inb(PS2_DATA_PORT);
+    // Process scancode (e.g., put it into a circular buffer)
+}
+
+// Called from IRQ 12 (Mouse)
+static uint8_t mouse_cycle = 0;
+static uint8_t mouse_bytes[3];
+
+void ps2_mouse_handler(void) {
+    uint8_t status = inb(PS2_STATUS_REG);
+    
+    // Ensure this is actually mouse data
+    if (!(status & PS2_STATUS_MOUSE)) return;
+
+    mouse_bytes[mouse_cycle++] = inb(PS2_DATA_PORT);
+
+    if (mouse_cycle == 3) {
+        mouse_cycle = 0;
+        
+        // Byte 0: Flags (Buttons, Signs)
+        // Byte 1: X Delta
+        // Byte 2: Y Delta
+        
+        mouse_state_t state;
+        state.left_button   = (mouse_bytes[0] & 0x01);
+        state.right_button  = (mouse_bytes[0] & 0x02);
+        state.middle_button = (mouse_bytes[0] & 0x04);
+
+        // Handle negative deltas (signed 9-bit logic)
+        state.x_delta = (int8_t)mouse_bytes[1];
+        state.y_delta = (int8_t)mouse_bytes[2];
+
+        // Update your kernel's internal mouse position here
+    }
+}

kernel/ps2.h

@@ -0,0 +1,45 @@
+#ifndef PS2_H
+#define PS2_H
+
+#include <stdint.h>
+#include <stdbool.h>
+
+/* I/O Ports */
+#define PS2_DATA_PORT       0x60
+#define PS2_STATUS_REG      0x64
+#define PS2_COMMAND_REG     0x64
+
+/* Status Register Bits */
+#define PS2_STATUS_OUTPUT   0x01 // 1 = Data ready to be read
+#define PS2_STATUS_INPUT    0x02 // 1 = Controller busy, don't write yet
+#define PS2_STATUS_SYS      0x04 // System flag
+#define PS2_STATUS_CMD_DATA 0x08 // 0 = Data written to 0x60, 1 = Cmd to 0x64
+#define PS2_STATUS_MOUSE    0x20 // 1 = Mouse data, 0 = Keyboard data
+
+/* Controller Commands */
+#define PS2_CMD_READ_CONFIG  0x20
+#define PS2_CMD_WRITE_CONFIG 0x60
+#define PS2_CMD_DISABLE_MS   0xA7
+#define PS2_CMD_ENABLE_MS    0xA8
+#define PS2_CMD_DISABLE_KB   0xAD
+#define PS2_CMD_ENABLE_KB    0xAE
+#define PS2_CMD_WRITE_MOUSE  0xD4
+
+/* Mouse Commands */
+#define MOUSE_CMD_SET_DEFAULTS 0xF6
+#define MOUSE_CMD_ENABLE_SCAN  0xF4
+
+typedef struct {
+    int8_t  x_delta;
+    int8_t  y_delta;
+    bool    left_button;
+    bool    right_button;
+    bool    middle_button;
+} mouse_state_t;
+
+/* Public API */
+void ps2_init(void);
+void ps2_keyboard_handler(void);
+void ps2_mouse_handler(void);
+
+#endif

kernel/threading.c

@@ -16,7 +16,7 @@ static uint32_t num_threads = 0;     // Number of active threads
 static volatile int mutex_locked = 0;
 
 // Function declaration for context_switch
-void context_switch(Thread *next);
+void context_switch(Thread* next);
 
 // Initialize the threading system
 void thread_init(void) {
@@ -25,7 +25,8 @@ void thread_init(void) {
 }
 
 // Create a new thread
-void thread_create(Thread *thread __attribute__((unused)), void (*start_routine)(void *), void *arg) {
+void thread_create(Thread* thread __attribute__((unused)),
+                   void (*start_routine)(void*), void* arg) {
   if (num_threads >= MAX_THREADS) {
     my_printf("Error: Maximum thread count reached.\n");
     return;
@@ -40,11 +41,13 @@ void thread_create(Thread *thread __attribute__((unused)), void (*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);
+  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)
+  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
@@ -60,7 +63,8 @@ void thread_create(Thread *thread __attribute__((unused)), void (*start_routine)
 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) {
+  while (next_thread != current_thread &&
+         thread_table[next_thread].state != THREAD_READY) {
     next_thread = (next_thread + 1) % num_threads;
   }
 
@@ -72,7 +76,8 @@ void thread_yield(void) {
 
 // Exit the current thread
 void thread_exit(void) {
-    thread_table[current_thread].state = THREAD_BLOCKED;  // Mark the thread as blocked (finished)
+  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
 
@@ -94,18 +99,18 @@ void scheduler(void) {
   }
 }
 
-// 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.
+// 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.
   my_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_init(void) { mutex_locked = 0; }
 
 void mutex_lock(void) {
   while (__sync_lock_test_and_set(&mutex_locked, 1)) {
@@ -113,6 +118,4 @@ void mutex_lock(void) {
   }
 }
 
-void mutex_unlock(void) {
-    __sync_lock_release(&mutex_locked);
-}
+void mutex_unlock(void) { __sync_lock_release(&mutex_locked); }

kernel/vga.c

@@ -1,9 +1,9 @@
-#include "vga.h"
 #include <stddef.h>
 #include <stdbool.h>
 #include <string.h>
 #include <stdarg.h>
 #include "string_utils.h"
+#include "vga.h"
 
 void outb(uint16_t port, uint8_t value) {
     __asm__ volatile("outb %0, %1" : : "a"(value), "Nd"(port));
@@ -134,7 +134,7 @@ void vga_printf(const char* format, ...) {
     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
+    vga_write_string(buffer, strlen(buffer)); // Use my_strlen instead of strlen
 }
 
 void vga_init(void) {

kernel/vga.h

@@ -35,6 +35,7 @@ typedef enum {
 // 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_init(void);
 
 void vga_put_entry_at(char c, uint8_t color, size_t x, size_t y);
 void vga_clear(uint8_t color);