Create fat16.c

Add implementation for fat16 filesystem

.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/fat16.c

@@ -0,0 +1,107 @@
+#include "fat16.h"
+#include "ata.h"   // Use ata_read_sector and ata_write_sector
+#include "print.h" // For debugging
+#include <string.h> // For string manipulation
+
+// Global variables
+static fat16_boot_sector_t boot_sector;
+static uint32_t root_dir_sector = FAT16_ROOT_DIR_SECTOR;
+
+// Read a sector from the disk using ATA
+bool read_sector(uint32_t lba, uint8_t* buffer) {
+    return ata_read_sector(lba, buffer);
+}
+
+// Write a sector to the disk using ATA
+bool write_sector(uint32_t lba, const uint8_t* buffer) {
+    return ata_write_sector(lba, buffer);
+}
+
+// Parse the boot sector to retrieve basic file system info
+bool parse_fat16_boot_sector(void) {
+    uint8_t sector_buffer[FAT16_SECTOR_SIZE];
+
+    // Read the boot sector
+    if (!read_sector(FAT16_BOOT_SECTOR, sector_buffer)) {
+        print_string("[FAT16] Failed to read boot sector\n");
+        return false;
+    }
+
+    // Cast to boot sector structure
+    memcpy(&boot_sector, sector_buffer, sizeof(fat16_boot_sector_t));
+
+    // Check for FAT16 signature
+    if (boot_sector.oem_name[0] != 'F' || boot_sector.oem_name[1] != 'A' || boot_sector.oem_name[2] != 'T') {
+        print_string("[FAT16] Invalid FAT16 boot sector signature\n");
+        return false;
+    }
+
+    print_string("[FAT16] FAT16 boot sector parsed successfully\n");
+    return true;
+}
+
+// Parse the root directory
+bool parse_fat16_root_dir(void) {
+    uint8_t sector_buffer[FAT16_SECTOR_SIZE];
+
+    for (int i = 0; i < (boot_sector.max_root_entries / (FAT16_SECTOR_SIZE / sizeof(fat16_dir_entry_t))); i++) {
+        // Read root directory sector
+        if (!read_sector(root_dir_sector + i, sector_buffer)) {
+            print_string("[FAT16] Failed to read root directory sector\n");
+            return false;
+        }
+
+        // Parse the root directory entries
+        for (int j = 0; j < (FAT16_SECTOR_SIZE / sizeof(fat16_dir_entry_t)); j++) {
+            fat16_dir_entry_t* entry = (fat16_dir_entry_t*)&sector_buffer[j * sizeof(fat16_dir_entry_t)];
+            if (entry->name[0] == 0x00) {
+                // End of directory entries
+                return true;
+            }
+            if (entry->name[0] != 0xE5) {
+                // Print file name (8.3 format)
+                char filename[12];
+                strncpy(filename, (char*)entry->name, 8);
+                filename[8] = '.';
+                strncpy(&filename[9], (char*)entry->ext, 3);
+                filename[11] = '\0';
+                print_string(filename);
+                print_string("\n");
+            }
+        }
+    }
+    return true;
+}
+
+// Read a specific directory entry from the FAT16 root directory
+bool read_fat16_entry(uint16_t entry_index, fat16_dir_entry_t* entry) {
+    uint8_t sector_buffer[FAT16_SECTOR_SIZE];
+    uint32_t sector_num = FAT16_ROOT_DIR_SECTOR + (entry_index / (FAT16_SECTOR_SIZE / sizeof(fat16_dir_entry_t)));
+    uint16_t entry_offset = entry_index % (FAT16_SECTOR_SIZE / sizeof(fat16_dir_entry_t));
+
+    // Read the sector
+    if (!read_sector(sector_num, sector_buffer)) {
+        print_string("[FAT16] Failed to read root directory sector\n");
+        return false;
+    }
+
+    // Get the entry
+    memcpy(entry, &sector_buffer[entry_offset * sizeof(fat16_dir_entry_t)], sizeof(fat16_dir_entry_t));
+    return true;
+}
+
+// Mount the FAT16 filesystem
+bool mount_fat16(void) {
+    // Parse the boot sector
+    if (!parse_fat16_boot_sector()) {
+        return false;
+    }
+
+    // Parse the root directory
+    if (!parse_fat16_root_dir()) {
+        return false;
+    }
+
+    print_string("[FAT16] Filesystem mounted successfully\n");
+    return true;
+}

kernel/fat16.h

@@ -0,0 +1,60 @@
+#ifndef FAT16_H
+#define FAT16_H
+
+#include <stdint.h>
+#include <stdbool.h>
+
+/* FAT16 Constants */
+#define FAT16_SECTOR_SIZE        512
+#define FAT16_CLUSTER_SIZE       1
+#define FAT16_MAX_FILENAME_LEN   11   // 8.3 format
+#define FAT16_ROOT_DIR_ENTRIES   224  // Fat16 root directory entries (typically 512 bytes per entry)
+
+#define FAT16_BOOT_SECTOR        0
+#define FAT16_FAT1_SECTOR        1
+#define FAT16_FAT2_SECTOR        2
+#define FAT16_ROOT_DIR_SECTOR    19  // First sector of root directory
+
+/* Boot Sector */
+typedef struct {
+    uint8_t jmp[3];               // Jump instruction to code
+    uint8_t oem_name[8];          // OEM Name
+    uint16_t bytes_per_sector;    // Bytes per sector (512)
+    uint8_t sectors_per_cluster;  // Sectors per cluster
+    uint16_t reserved_sectors;    // Reserved sectors
+    uint8_t num_fats;             // Number of FAT tables
+    uint16_t max_root_entries;    // Max number of root directory entries
+    uint16_t total_sectors_16;    // Total sectors in FAT16
+    uint8_t media_type;           // Media type (0xF8 = fixed drive)
+    uint16_t sectors_per_fat;    // Sectors per FAT table
+    uint16_t sectors_per_track;  // Sectors per track (for CHS addressing)
+    uint16_t num_heads;          // Number of heads (for CHS addressing)
+    uint32_t hidden_sectors;     // Hidden sectors (before the partition)
+    uint32_t total_sectors_32;   // Total sectors in FAT16 (extended)
+} __attribute__((packed)) fat16_boot_sector_t;
+
+/* FAT16 Directory Entry */
+typedef struct {
+    uint8_t name[8];   // File name (8 chars)
+    uint8_t ext[3];    // File extension (3 chars)
+    uint8_t attributes; // File attributes (e.g., directory, read-only)
+    uint8_t reserved;   // Reserved
+    uint8_t creation_time[2]; // Creation time
+    uint8_t creation_date[2]; // Creation date
+    uint8_t last_access_date[2]; // Last access date
+    uint8_t first_cluster_high[2]; // High part of first cluster number
+    uint8_t last_mod_time[2];  // Last modification time
+    uint8_t last_mod_date[2];  // Last modification date
+    uint8_t first_cluster_low[2];  // Low part of first cluster number
+    uint32_t file_size;         // File size in bytes
+} __attribute__((packed)) fat16_dir_entry_t;
+
+/* Function Prototypes */
+bool mount_fat16(void);
+bool read_sector(uint32_t lba, uint8_t* buffer);
+bool write_sector(uint32_t lba, const uint8_t* buffer);
+bool parse_fat16_boot_sector(void);
+bool parse_fat16_root_dir(void);
+bool read_fat16_entry(uint16_t entry_index, fat16_dir_entry_t* entry);
+
+#endif // FAT16_H

kernel/hid.c

@@ -1,66 +0,0 @@
-#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 mouse movement for debugging
-    print_hex(mouse_data.x, 1, 1);
-    print_hex(mouse_data.y, 1, 1);
-    print_hex(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

@@ -1,46 +0,0 @@
-#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