Changed to the based ASM syntax and implemented a rudementary GDT

1 files changed, 47 insertions, 109 deletions

diff --git a/src/header/boot.s b/src/header/boot.s
index 2276e3d..5eaa794 100644
--- a/src/header/boot.s
+++ b/src/header/boot.s
@@ -1,117 +1,55 @@
-/* multiboot header constants */
-.set ALIGN, 1<<0 /* Align loaded modules on page boundries */
-.set MEMINFO, 1<<1 /* Provide memory map*/
-.set FLAGS, ALIGN | MEMINFO /* Multiboot flag field*/
-.set MAGIC, 0x1BADB002 /*Lets bootloader find header*/
-.set CHECKSUM, -(MAGIC + FLAGS) /* Proves we are multiboot via checksum*/
-
-/*
- * Declare a multiboot header that marks the program as a kernel.
- * These are magic values that are docymented in the multiboot standard.
- * The bootloader will search fot this signature in the first 8KiB of
- * the kernel file, aligned at a 32-bit boundry.
- * The signature is in its own section so the header can be forced to be
- * within the first 8KiB of the kernel file.
- */
-.section .multiboot 
-.align 4
-.long MAGIC 
-.long FLAGS 
-.long CHECKSUM 
-
-/*
- * The multiboot standard doesn't define the value of the "stack pointer register,"
- * or esp, as it is up to the kernel to provide a stack.
- * This allocates room for a small stack through a few steps:
-    * 1. Create a symbol at the bottom of the stack
-    * 2. Allocate 16 KiB for the stack
-    * 3. Create a symbol at the top of the stack.
- * The stack grows DOWN on x86.
- * Since the stack is in its own section*, it can be marked "nobits"
- * which means the kernel file is smaller since it doesn't contain
- * an uninitialized stack.
- * On x86, the stack must be 16-byte aligned** according to System V ABI standard
- * and de-facto extentions.
- * The compiler assumes the stack is properly aligned, so failure to align will
- * result in UB.
- */
-.section bss 
-.align 16 
-.stack_bottom:
-.skip 16384 
-stack_top: 
-
-/*
- * Our linker script specifies _start as te entry point to the kernel.
- * The bootloader will jump here once the kernel is loaded.
- * We won't return, since the bootloader would be gone at that point
- */
-.section .text
-.global _start
-.type _start, @function
+MBALIGN   equ 1<<0  ; Align loaded modules on page boundries */
+MBMEMINFO equ 1<<1  ; Provide memory map*/
+MBFLAGS equ MBALIGN | MBMEMINFO ; Multiboot flag field*/
+MAGIC equ 0x1BADB002 ;Lets bootloader find header*/
+CHECKSUM equ -(MAGIC + MBFLAGS) ; Proves we are multiboot via checksum*/
+
+
+section .multiboot
+align 4
+  dd MAGIC
+  dd MBFLAGS
+  dd CHECKSUM
+
+section .bss
+align 16
+stack_bottom:
+resb 16384
+stack_top:
+
+section .text
+global _start:function (_start.end - _start)
 _start:
-  /*
-   * The bootloader loads us into 32-bit mode on x86 machines.
-   * Interrupts and paging are disabled.
-   * The multiboot standard defines our current processor state.
-   * The kernel has full control over the CPU
-   * The kernel can only use two things
-      * 1. hardware features
-      * 2. its own code
-   * No printing is available (Unless we make it).
-   * No security restrictions, safeguards, or debugging mechanisms.
-   * We only have what the kernel provides.
-   * ABSOLUTE POWER OVER THE MACHINE!!
-   */
+  mov esp, stack_top
 
-  /*
-   * To setup a stack, make the esp register point to the top of the stack.
-   * We have to do this in assembly since C wont even function without the stack.
-   */
-  mov $stack_top, %esp
+  extern get_gdtr
+  call get_gdtr
+  extern gdtr
+  mov [gdtr], eax
+  cli
+  lgdt	[gdtr]
 
-  /*
-   * This is a good point to initialize crucial processor state before our
-   * high level kernel is entered.
-   * It's best to minize early environment where crucial features are offline.
-   * The processor is not fully initialized yet, therefore
-   * features such as floating point instructions and instruction set extentions
-   * are ALSO not initialized.
-   * The GDT (global descriptor table) should be loaded here.
-   * Paging should be enabled here.
-   */
 
-  /*
-   * Enter our high level kernel.
-   * the ABI (?) requres the stack is 16-byte aligned at the time of
-   * the call instruction (which afterward will push the return pointer
-   * of size 4 bytes).
-   * The stack was 16-byte aligned above, and we have pushed a multiple of
-   * 16 bytes to the stack (we have pushed zero bytes so far), so 
-   * the alignment is preserved, and the call is well defined.
-   */
+  call reloadSegments ; this motherfucker is what is causing so many issues
+
+  [bits 32]
+  extern kernel_main
   call kernel_main
 
-  /*
-   * If the system has nothing else to do, we will infinitely loop.
-   * To do this, we must:
-      * 1. Disable interrupts with `cli` 
-      * (clear interrupt enable in eflags.)
-      * They are already disabled by the bootloader, so we can skip this.
-      * Keep in mind, we may have to do this later AND return from main 
-      * (for some nonsensical reason)
-      * 2. wait for the next interrupt to arrive with `hlt` (halt instruction)
-      * Since interrupts are disabled, this locks up the computer (yay!)
-      * 3. jump to the `hlt` instruction if it ever wakes up due to a
-      * non-maskable interrupt occuring or due to a system management mode.
-   */
-    cli
-1:  hlt
-    jmp 1
 
-/*
- * Set the size of _start to { current_location - (start of _start) }
- * This is useful for debugging or for call tracing later on.
- */
-.size _start, . - _start
+	cli
+.hang:	hlt
+	jmp .hang
+.end:
+
 
+ reloadSegments:
+    JMP   0x0008:.reload_CS ; should def define a CODESEG
+.reload_CS:
+   MOV   AX, 0x0010
+   MOV   DS, AX
+   MOV   ES, AX
+   MOV   FS, AX
+   MOV   GS, AX
+   MOV   SS, AX
+   RET