* Made the kernel higher half

* Implemented Physical memory manager
* Implemented a dynamic memory allocator
* Implemented Paging
* Implemented Virtual filesystem
* Implemented PCI
* Added two new data structures list_t and gentere_t
* Added 32bit and 16bit varients of inb and outb
* Updated link.ld
* Splitted loader.s into multiboot.s and loader.asm
* Updated Makefile
* Added a new header for math operations
* Updated exception handler
* Added new function printE
* Updated string.c
* Added a function to PANIC the kernel
* Updated vga.h
* Updated sysfetch function to include info about paging and kheap
* Bumped kernel version to 2.0.0

Author: Arun007coder

docs/Readme.md

@@ -9,13 +9,18 @@ Second rewrite of the SectorOS project. Written in C and assembly.
 * string stdlib
 * Vga color changing
 * IDT and GDT functional
+* Paging
+* malloc
+* A basic shell
+* Virtual filesystem
 
 ## TODO
 
-* Implement driver for serial port, keyboard, mouse and other devices
-* Implement VFS
-* Implement memory management
-* Implement paging
+* Implement driver for ata, mouse and other devices
+* Implement Tasking
+* Implement Networking
+* Implement EXT2 filesystem
+* Implement ELF loader
 * etc...
 
 ## Build
@@ -33,4 +38,14 @@ make -f src/Makefile iso
 To run the project, run the following command:
 ```bash
 make -f src/Makefile run
-```
+```
+
+## Resources
+
+The resources used in this project are:
+
+* [osdev wiki](https://wiki.osdev.org)
+* [osdev forums](https://forum.osdev.org)
+* [JamesM's kernel development tutorials](http://www.jamesmolloy.co.uk/tutorial_html/)
+* [szhou42/osdev](https://github.com/szhou42/osdev)
+* [SectorOS](https://github.com/arun007coder/SectorOS)

src/Include/gentree.h

@@ -0,0 +1,32 @@
+#ifndef __GENTREE_H_
+#define __GENTREE_H_
+
+#include "list.h"
+#include "kheap.h"
+#include "system.h"
+
+typedef struct gentree_node
+{
+    list_t *children;
+    void *data;
+}gentree_node_t;
+
+typedef struct gentree
+{
+    gentree_node_t *root;
+}gentree_t;
+
+gentree_t* gentree_create();
+
+gentree_node_t* gentree_node_create(void *data);
+gentree_node_t* gentree_insert(gentree_t *tree, gentree_node_t *subroot, void *data);
+gentree_node_t* gentree_findParent(gentree_t *tree, gentree_node_t *remove_node, int* child_index);
+gentree_node_t* gentree_findParent_recur(gentree_t *tree, gentree_node_t *remove_node, gentree_node_t *subroot, int *child_index);
+
+void gentree_remove(gentree_t *tree, gentree_node_t *remove_node);
+void tree2list_recur(gentree_node_t *subroot, list_t *list);
+void tree2list(gentree_t *tree, list_t *list);
+void tree2array(gentree_t *tree, void **array, int *size);
+void tree2array_recur(gentree_node_t *subroot, void **array, int *size);
+
+#endif

src/Include/kheap.h

@@ -0,0 +1,112 @@
+// Based on code from http://www.jamesmolloy.co.uk/tutorial_html/4.-The%20Heap.html
+#ifndef _KHEAP_H_
+#define _KHEAP_H_
+
+#include "system.h"
+#include "printf.h"
+#include "string.h"
+#include "vga.h"
+#include "paging.h"
+
+#define KHEAP_START (void*)0xC0400000
+#define KHEAP_INITIAL_SIZE 48 * MB
+#define KHEAP_MAX_ADDRESS (void*)0xCFFFFFFF
+#define HEAP_MIN_SIZE 4 * MB
+
+#define PAGE_SIZE 4096
+#define OVERHEAD (sizeof(struct memory_block) + sizeof(uint32_t))
+
+typedef struct memory_block
+{
+    struct memory_block* next;
+    struct memory_block* prev;
+    uint32_t size;
+} memory_block_t;
+
+extern bool Kheap_enabled;
+
+/*
+* if heap is initialized then uss the dynamic memory allocator else use the placement memory allocator
+* @param size The size of the memory to be allocated
+* @param align Should the memory be aligned?
+* @param paddr Should the allocated memory be given a physical address?
+*/
+uint32_t kmalloc_int(uint32_t size, int align, uint32_t* paddr);
+
+/*
+* continuous kmalloc which can be used before the heap is initialised
+* @param size The size of the memory to be allocated
+* @param align Should the memory be aligned?
+* @param paddr Should the allocated memory be given a physical address?
+*/
+void* kmalloc_c(uint32_t size, int align, uint32_t* paddr);
+
+/*
+* Wrapper for kmalloc_int with align = 1
+* @param size The size of the memory to be allocated
+*/
+void* kmalloc_a(uint32_t size);
+
+/*
+* Wrapper for kmalloc_int with align = 0 and paddr = paddr
+* @param size The size of the memory to be allocated
+* @param paddr Should the allocated memory be given a physical address?
+*/
+uint32_t kmalloc_p(uint32_t size, uint32_t* paddr);
+
+/*
+* Wrapper for kmalloc_int with align = 1 and paddr = paddr
+* @param size The size of the memory to be allocated
+* @param paddr Should the allocated memory be given a physical address?
+*/
+uint32_t kmalloc_ap(uint32_t size, uint32_t* paddr);
+
+/*
+* Wrapper for kmalloc_int with align = 0 and paddr = 0
+* @param size The size of the memory to be allocated
+*/
+void *kmalloc(uint32_t size);
+
+/*
+* A function to free a block of memory previously allocated with kmalloc
+* @param ptr The pointer to the memory to be freed
+*/
+void kfree(void* ptr);
+
+/*
+* A function to reallocate a block of memory previously allocated with kmalloc
+* @param ptr The pointer to the memory to be reallocated
+* @param size The size of the memory to be reallocated
+*/
+void* krealloc(void* ptr, uint32_t size);
+
+void* kcalloc(uint32_t size, uint32_t num);
+
+void print_db();
+
+int doesItFit(memory_block_t* block, uint32_t size);
+
+void setFree(uint32_t *size, int x);
+
+void removeFromList(memory_block_t* block);
+void addToList(memory_block_t* block);
+
+int isBetter(memory_block_t* block1, memory_block_t* block2);
+memory_block_t* bestFit(uint32_t size);
+memory_block_t* getPrevBlock(memory_block_t* block);
+memory_block_t* getNextBlock(memory_block_t* block);
+
+uint32_t getRealSize(uint32_t size);
+uint32_t getSbrkSize(uint32_t size);
+
+int isFree(memory_block_t* block);
+int isEnd(memory_block_t* block);
+
+void init_kheap(void* start, void* end, void* max);
+
+void* malloc(uint32_t size);
+void* realloc(void* ptr, uint32_t size);
+void* calloc(uint32_t size, uint32_t num);
+
+void free(void* ptr);
+#endif

src/Include/list.h

@@ -0,0 +1,50 @@
+#ifndef __LIST_H__
+#define __LIST_H__
+
+#include "system.h"
+
+typedef struct listnode
+{
+    void *val;
+    struct listnode *next;
+    struct listnode *prev;
+} listnode_t;
+
+typedef struct list
+{
+    listnode_t *head;
+    listnode_t *tail;
+    uint32_t size;
+} list_t;
+
+#define foreach(t, list) for(listnode_t * t = list->head; t != NULL; t = t->next)
+
+list_t *list_create();
+uint32_t list_size(list_t *list);
+
+listnode_t* list_insert_front(list_t *list, void *val);
+void list_insert_back(list_t *list, void *val);
+
+void * list_remove_node(list_t * list, listnode_t * node);
+void * list_remove_front(list_t * list);
+void * list_remove_back(list_t * list);
+
+void list_push(list_t * list, void * val);
+listnode_t * list_pop(list_t * list);
+
+void list_enqueue(list_t * list, void * val);
+listnode_t * list_dequeue(list_t * list);
+
+void * list_peek_front(list_t * list);
+void * list_peek_back(list_t * list);
+
+void list_destroy(list_t * list);
+void listnode_destroy(listnode_t * node);
+
+int list_contain(list_t * list, void * val);
+
+listnode_t * list_get_node_by_index(list_t * list, int index);
+void * list_remove_by_index(list_t * list, int index);
+
+
+#endif

src/Include/math.h

@@ -0,0 +1,9 @@
+#ifndef __MATH_H
+#define __MATH_H
+
+#define abs(a) (((a) < 0)?-(a):(a))
+#define max(a,b) (((a) > (b)) ? (a) : (b))
+#define min(a,b) (((a) < (b)) ? (a) : (b))
+#define sign(x) ((x < 0) ? -1 :((x > 0) ? 1 : 0))
+
+#endif

src/Include/paging.h

@@ -0,0 +1,91 @@
+#ifndef __PAGING_H_
+#define __PAGING_H_
+
+#include "system.h"
+#include "isr.h"
+#include "pmm.h"
+#include "math.h"
+
+#define PAGE_SIZE 4096
+
+#define IS_ALIGN(addr) ((((uint32_t)(addr)) | 0xFFFFF000) == 0)
+#define PAGE_ALIGN(addr) ((((uint32_t)(addr)) & 0xFFFFF000) + 0x1000)
+
+#define PAGEDIR_INDEX(vaddr) (((uint32_t)vaddr) >> 22)
+#define PAGETBL_INDEX(vaddr) ((((uint32_t)vaddr) >>12) & 0x3ff)
+#define PAGEFRAME_INDEX(vaddr) (((uint32_t)vaddr) & 0xfff)
+
+#define SET_PGBIT(cr0) (cr0 = cr0 | 0x80000000)
+#define CLEAR_PSEBIT(cr4) (cr4 = cr4 & 0xffffffef)
+
+typedef struct page_dir_entry
+{
+    uint32_t present        :1;
+    uint32_t rw             :1;
+    uint32_t user           :1;
+    uint32_t write_through  :1;
+    uint32_t cache_disable  :1;
+    uint32_t accessed       :1;
+    uint32_t dirty          :1;
+    uint32_t page_size      :1;
+    uint32_t global         :1;
+    uint32_t avail          :3;
+    uint32_t frame          :20;
+}page_dir_entry_t;
+
+typedef struct page_table_entry
+{
+    uint32_t present        :1;
+    uint32_t rw             :1;
+    uint32_t user           :1;
+    uint32_t reserved       :2;
+    uint32_t accessed       :1;
+    uint32_t dirty          :1;
+    uint32_t reserved2      :2;
+    uint32_t avail          :3;
+    uint32_t frame          :20;
+}page_table_entry_t;
+
+typedef struct page_table
+{
+    page_table_entry_t pages[1024];
+}page_table_t;
+
+typedef struct page_directory
+{
+    page_dir_entry_t tables[1024];
+    page_table_t* ref_tables[1024];
+}page_directory_t;
+
+extern int paging_enabled;
+
+extern page_directory_t* TEMP_PAGE_DIR;
+
+extern uint8_t * pmm_bitmap;
+extern uint32_t  pmm_bitmap_size;
+
+extern page_directory_t* kernel_page_dir;
+
+void* virt2phys(page_directory_t* dir, void* vaddr);
+void* d_kmalloc(uint32_t size, int align);
+
+void alloc_region(page_directory_t * dir, uint32_t start_vaddr, uint32_t end_vaddr, int iden_map, int is_kernel, int is_writable);
+void free_region(page_directory_t * dir, uint32_t start_vaddr, uint32_t end_vaddr, int free);
+
+void alloc_page(page_directory_t * dir, uint32_t vaddr, uint32_t frame, int is_kernel, int is_writable);
+void free_page(page_directory_t * dir, uint32_t vaddr, int free);
+
+void init_paging();
+
+void switch_page_dir(page_directory_t* dir, uint32_t paddr);
+
+void enable_paging();
+
+void* ksbrk(uint32_t size);
+
+void copy_page_dir(page_directory_t* dest, page_directory_t* src);
+page_table_t* copy_page_table(page_directory_t * src_page_dir, page_directory_t * dst_page_dir, uint32_t page_dir_idx, page_table_t * src);
+
+void page_fault_handler(registers_t regs);
+
+#endif