Adding a skeleton for the memory management code

Moved the PMM away from being object orientated as it is just plain annoying
renamed src folder to source
Set timeout to 5 seconds in the grub config

source/kernel/KernelLauncher/boot.s

@@ -0,0 +1,139 @@
+/*
+ * Multiboot 
+ */
+.set ALIGN,    1<<0             /* align loaded modules on page boundaries */
+.set MEMINFO,  1<<1             /* provide memory map */
+.set FLAGS,    ALIGN | MEMINFO  /* this is the Multiboot 'flag' field */
+.set MAGIC,    0x1BADB002       /* 'magic number' lets bootloader find the header */
+.set CHECKSUM, -(MAGIC + FLAGS) /* checksum of above, to prove we are multiboot */
+
+.section .multiboot.data, "aw"
+.align 4
+.long MAGIC
+.long FLAGS
+.long CHECKSUM
+ 
+/*
+*	Allocate initial stack
+*/
+.section .bootstrap_stack, "aw", @nobits
+stack_bottom:
+.skip 16384 # 16 KiB
+stack_top:
+
+/*
+* Preallocate a couple pages to get us bootstrapped 
+* Being carefull to not use any address the bootloader might 
+* be using for its multiboot structures
+*/
+.section .bss, "aw", @nobits
+	.align 4096
+.globl boot_page_directory
+boot_page_directory:
+	.skip 4096
+boot_page_table:
+	.skip 4096
+.globl multiboot_page_table
+multiboot_page_table:
+	.skip 4096
+# More page tables may be required
+
+# Entry point
+.section .multiboot.text, "a"
+.global _start
+.type _start, @function 
+_start:
+	# Get physical address of the boot_page_table
+	movl $(boot_page_table - 0xC0000000), %edi
+	# Map address 0
+	movl $0, %esi
+1:	
+	cmpl $(_kernel_end - 0xC0000000), %esi
+	jge 3f
+
+	# Map physical address as "present and writable"
+	movl %esi, %edx
+	orl $0x003, %edx
+	movl %edx, (%edi)
+
+2: # Size of page is 4096 bytes
+	addl $4096, %esi
+	# Size of entries in boot_page_table is 4 bytes
+	addl $4, %edi 
+	# Loop to the next entry if we haven't finished.
+	loop 1b
+
+3:	# Map VGA video memory to 0xC03FF00 as "present, writable"
+	movl $(0x000B8000 | 0x003), boot_page_table - 0xC0000000 + 1023 * 4
+
+
+	# IMPORTANT NOTE FROM WIKI.OSDEV.ORG/HIGHER_HALF_X86_BARE_BONES
+
+	# The page table is used at both page directory entry 0 (virtually from 0x0
+	# to 0x3FFFFF) (thus identity mapping the kernel) and page directory entry
+	# 768 (virtually from 0xC0000000 to 0xC03FFFFF) (thus mapping it in the
+	# higher half). The kernel is identity mapped because enabling paging does
+	# not change the next instruction, which continues to be physical. The CPU
+	# would instead page fault if there was no identity mapping.\
+	
+	# Map the page table to both virtual addresss 0x00000000 and 0xC0000000
+	movl $(boot_page_table - 0xC0000000 + 0x003), boot_page_directory - 0xC0000000 + 0
+	movl $(boot_page_table - 0xC0000000 + 0x003), boot_page_directory - 0xC0000000 + 768 * 4
+
+	# Set cr3 to the address of the boot_page_directory
+	movl $(boot_page_directory - 0xC0000000), %ecx
+	movl %ecx, %cr3
+
+	# Enable paging and the write-protect bit
+	movl %cr0, %ecx
+	orl $0x80010000, %ecx
+	movl %ecx, %cr0
+
+	# Jump to higher half with an absolute jump
+	lea 4f, %ecx
+	jmp *%ecx
+
+.section .text
+4:
+	# At this point, paging is fully set up and enabled
+isPaging:
+	# Unmap the identity mapping as it is now unnecessary  
+	movl $0, boot_page_directory + 0
+	
+	# Reload cr3 to force tlb flush 
+	movl %cr3, %ecx
+	movl %ecx, %cr3
+
+	/*Setup the stack pointer to point to the beginning of our stack */
+	/* I believe its a high address growing down to lower adress for the stack on x86*/
+	mov $stack_top, %esp
+
+	/*Reset EFLAGS*/
+	pushl $0 
+	popf 
+
+	/* push the pointer to the Multiboot information structure*/
+	pushl %ebx
+
+	/* push the magic value */
+	pushl %eax
+
+	call early_main
+
+
+
+
+
+	cli
+1:	hlt
+	jmp 1b
+
+
+.include "./src/kernel/Memory/GDT/gdt.s"
+.include "./src/kernel/irs_table.s"
+.include "./src/kernel/irq_table.s"
+.include "./src/kernel/Interrupts/idt/idt.s"
+.include "./src/kernel/Memory/paging.s"
+.include "./src/kernel/cpu.s"
+
+

source/kernel/KernelLauncher/bootcheck.h

@@ -0,0 +1,91 @@
+#pragma once 
+#include "../multiboot.h"
+#define CHECK_FLAG(flags, bit) ((flags) & (1 <<(bit)))
+#define __VERBOSE__
+#include "../Terminal/kterm.h"
+
+
+
+void CheckMBT ( multiboot_info_t*  mbt  ){
+      /* Set MBI to the addresss of the multiboot information structure*/
+        multiboot_info_t * mbi = (multiboot_info_t *) mbt;
+
+#ifdef __VERBOSE__
+        /* Print out the flags */
+        printf("flags = 0x%x\n", (unsigned) mbi->flags);
+#endif
+        /* Are mem_* valid? */
+        if ( CHECK_FLAG(mbi->flags,0)){
+                // Do nothing
+        }
+
+        /* is boot device valid ? */
+        if (CHECK_FLAG (mbi->flags, 1))
+        {
+#ifdef __VERBOSE__
+            printf("boot_device = 0x0%x\n", (unsigned) mbi->boot_device);
+#endif
+        }
+
+        /* is the command line passed? */
+        if (CHECK_FLAG ( mbi->flags,2))
+        {
+#ifdef  __VERBOSE__
+            printf("cmdline = %s\n", (char *) (mbi->cmdline + 0xC0000000));
+#endif
+        }
+
+        /* Are mods_* valid? */
+        if(CHECK_FLAG ( mbi->flags, 3)){
+            multiboot_module_t *mod;
+            uint32_t i;
+#ifdef __VERBOSE__
+            printf("mods count = %d, mods_addr = 0x%x\n", (int) mbi->mods_count, (int) mbi->mods_addr);
+
+            for(i = 0, mod = (multiboot_module_t *) mbi->mods_addr; i < mbi->mods_count; i++ , mod++){
+                printf(" mod start = 0x%x, mod_end = 0x%x, cmdline = %s\n", (unsigned) mod->mod_start, (unsigned) mod->mod_end, (char*) mod->cmdline);
+            }
+#endif
+        }
+
+        /* Bits 4 and 5 are mutually exclusive! */
+        if (CHECK_FLAG (mbi->flags, 4) && CHECK_FLAG(mbi->flags, 5))
+        {
+#ifdef __VERBOSE__
+            printf("Both bits 4 and 5 are set.\n");
+#endif 
+            return;
+        }
+
+        /* Is the symbol table of a.out valid? */
+        if (CHECK_FLAG(mbi->flags, 4)){
+            multiboot_aout_symbol_table_t *multiboot_aout_sym = &(mbi->u.aout_sym);
+#ifdef __VERBOSE__
+            printf( "multiboot_aout_symbol_table: tabsize = 0x%0x, strsize = 0x%x, addr = 0x%x\n", 
+            (unsigned) multiboot_aout_sym->tabsize,
+            (unsigned) multiboot_aout_sym->strsize,
+            (unsigned) multiboot_aout_sym->addr);
+#endif
+        }
+
+        /* Is the section header table of ELF valid? */
+        if (CHECK_FLAG(mbi->flags, 5)){
+            multiboot_elf_section_header_table_t *multiboot_elf_sec = &(mbi->u.elf_sec);
+#ifdef __VERBOSE__
+            printf("multiboot_elf_sec: num = %u, size = 0x%x, addr = 0x%x, shnd = 0x%x\n",
+            
+            (unsigned) multiboot_elf_sec->num, (unsigned) multiboot_elf_sec->size,
+            (unsigned) multiboot_elf_sec->addr, (unsigned)  multiboot_elf_sec->shndx);
+#endif
+            
+        }
+
+        /* Draw diagonal blue line */
+        if (CHECK_FLAG (mbt->flags, 12)){
+#ifdef __VERBOSE__
+            printf("Can draw!\n");
+#endif
+        } 
+
+
+}

source/kernel/KernelLauncher/crti.s

@@ -0,0 +1,14 @@
+.section .init
+.global _init
+.type _init, @function
+_init:
+	push %ebp
+	movl %esp, %ebp
+	/* gcc will nicely put the contents of crtbegin.o's .init section here. */
+
+.section .fini
+.global _fini
+.type _fini, @function
+_fini:
+	push %ebp
+	movl %esp, %ebp

source/kernel/KernelLauncher/crtn.s

@@ -0,0 +1,7 @@
+.section .init
+	popl %ebp
+	ret
+
+.section .fini
+	popl %ebp
+	ret

source/kernel/KernelLauncher/launcher.cpp

@@ -0,0 +1,28 @@
+#include <stdint.h>
+#include <stddef.h>
+
+void put_char(char ch, size_t x, size_t y ){
+    *((uint16_t*)0xb8000+(y * 80 + x)) = ch | ((7 | 0 << 4) << 8);
+}
+
+void write_ln(char* s, size_t length, size_t x , size_t y)
+{
+  // Because read only data is linked at a virtual address we'll need to convert
+  // the string adddres from virtual to phys.
+  s = s - 0xC0000000;
+  size_t column , row;
+  column = x;
+  row = y;
+  for(int i = 0; i < length ; i ++)
+  {
+    
+    put_char(s[i] , column,row );
+    column ++;
+
+  }
+  
+}
+
+extern "C" void testLauncher  () {
+  write_ln("hello", 5 ,0,0);
+}