From a417a747310df36b7d13976ace1e8ae2e30be6b5 Mon Sep 17 00:00:00 2001
From: shockrah <alejandros714@protonmail.com>
Date: Mon, 14 Oct 2019 02:06:50 -0700
Subject: [PATCH] base working kernel with a gdt that doesn't restart
 emulator(no idea why this works yet)

---
 gdt.c     |  2 +-
 gdt.h     |  2 +-
 gdt_seg.s |  6 +++---
 kernel.c  | 15 +++++++++++++++
 kernel.h  |  4 ++++
 loader.s  | 12 ++++--------
 makefile  |  2 +-
 7 files changed, 29 insertions(+), 14 deletions(-)
 create mode 100644 kernel.c
 create mode 100644 kernel.h

diff --git a/gdt.c b/gdt.c
index 2c8785f..d3d35ef 100644
--- a/gdt.c
+++ b/gdt.c
@@ -39,5 +39,5 @@ void gdt_configure() {
 	gdt_configure_entry(4, 0, 0xffffffff, 0xf2, 0xcf);
 
 	// Load in the new changes to the gdt
-	load_gdt(&gdt_ptr);
+	load_gdt();
 }
diff --git a/gdt.h b/gdt.h
index 19858f5..6e151c3 100644
--- a/gdt.h
+++ b/gdt.h
@@ -22,7 +22,7 @@ struct GDT_Entry gdt_entries[NO_GDT_ENTRIES];
 struct GDT_PTR gdt_ptr;
 
 // this func is actually taken care of in gdt_seg.s
-extern void load_gdt(struct GDT_PTR* ptr);
+extern void load_gdt();
 
 void gdt_configure_entry(u32 entry, u32 base, u32 limit, u8 access, u8 gran);
 
diff --git a/gdt_seg.s b/gdt_seg.s
index 2767b45..338115a 100644
--- a/gdt_seg.s
+++ b/gdt_seg.s
@@ -2,16 +2,16 @@ global load_gdt
 extern gdt_ptr
 
 load_gdt:
-	lgdt [esp+4]
 	mov ax, 0x10 	; offset in the gdt to our data segment
 	mov ds, ax
 	mov es, ax
 	mov fs, ax
 	mov gs, ax
 	mov ss, ax
-	jmp 0x08:.flush_cs ; far jump to the code segment
+	jmp 0x08:flush_cs ; far jump to the code segment
 
-.flush_cs:
+flush_cs:
+	lgdt [gdt_ptr]
 	ret 
 
 
diff --git a/kernel.c b/kernel.c
new file mode 100644
index 0000000..48acec8
--- /dev/null
+++ b/kernel.c
@@ -0,0 +1,15 @@
+#include "types.h"
+#include "tests.h"
+#include "gdt.h"
+#include "kernel.h"
+
+void kinit() {
+	gdt_configure();
+	test_dispatcher();
+}
+
+
+void kmain() {
+	kinit();
+	for(;;); // the most amazing loop
+}
diff --git a/kernel.h b/kernel.h
new file mode 100644
index 0000000..0cf4dc0
--- /dev/null
+++ b/kernel.h
@@ -0,0 +1,4 @@
+#include "types.h"
+
+void kinit();
+void kmain();
diff --git a/loader.s b/loader.s
index 85ea6da..c40efca 100644
--- a/loader.s
+++ b/loader.s
@@ -1,16 +1,13 @@
 ; since we have no stack we have to create one for the OS
 
 global loader
-; this section is partly handled by nasm tolerating some minor bs
+
+; NOTE: these symbols are what we use to represent the "magic bytes" for the whole os
 MAGIC_NUMBER 	equ 0x1BADB002
 FLAGS 			equ 0x0
 CHECKSUM 		equ -MAGIC_NUMBER
-KERNEL_STACK_SIZE	equ 4096
 
-
-; size in bytes of stack 
-extern gdt_configure
-extern test_dispatcher
+extern kmain
 
 section .text
 ; align all instructions to 4 byte boundary by the x86 instruction set law
@@ -23,8 +20,7 @@ align 4
 ; sets up our gdt and segment selectors for later use
 	
 loader:
-	call gdt_configure
-	call test_dispatcher
+	call kmain
 
 .loop:
 	jmp .loop
diff --git a/makefile b/makefile
index c9a38b6..e4296c0 100644
--- a/makefile
+++ b/makefile
@@ -3,7 +3,7 @@ ASM=nasm
 LINK=ld
 ISO=genisoimage
 
-OBJECTS=gdt_seg.o gdt.o loader.o serial.o framebuffer.o ports.o stlio.o tests.o
+OBJECTS=kernel.o gdt_seg.o gdt.o loader.o serial.o framebuffer.o ports.o stlio.o tests.o
 AFLAGS=-f elf32
 CFLAGS=-m32 -nostdlib -nostdinc -fno-builtin -fno-stack-protector -nostartfiles \
 		-nodefaultlibs -Wall -Wextra -Werror -c