From 5180348c39b5237c9afbc99d42320d1b7f6a4361 Mon Sep 17 00:00:00 2001
From: Eric-Paul Ickhorn <ericp.ickhorn@gmail.com>
Date: Sun, 16 Jun 2024 23:07:51 +0200
Subject: [PATCH] Add stage 2 loader entry point

This commit adds the entry point for the second stage of the loader.
It currently doesn't contain a lot of code, but it will have to expand
in the next bit of time.
---
 i386/bootsector/bootsector.asm |  2 +-
 i386/loader/src-asm/entry.asm  | 88 ++++++++++++++++++++++++++++++++++
 2 files changed, 89 insertions(+), 1 deletion(-)
 create mode 100755 i386/loader/src-asm/entry.asm

diff --git a/i386/bootsector/bootsector.asm b/i386/bootsector/bootsector.asm
index 1ca9116..45ce4fe 100644
--- a/i386/bootsector/bootsector.asm
+++ b/i386/bootsector/bootsector.asm
@@ -180,7 +180,7 @@ load_partition:
 
 
 jump_to_partition:
-    jmp 0x0000:0xa000
+    jmp 0x0a00:0x0000
     cli
     hlt
 
diff --git a/i386/loader/src-asm/entry.asm b/i386/loader/src-asm/entry.asm
new file mode 100755
index 0000000..3fde6c1
--- /dev/null
+++ b/i386/loader/src-asm/entry.asm
@@ -0,0 +1,88 @@
+; entry.asm: Entrypoint for the loader partition of the Nightloader.
+
+; WARNING: Never import at the top of this file!
+; If something has to be included, include it at the bottom!
+
+STACK_SIZE          equ 32768
+UPPER_STACK_POINTER equ 0x100000
+LOWER_STACK_POINTER equ (UPPER_STACK_POINTER - STACK_SIZE)
+
+bits 16
+org 0xa000
+entry:
+    mov ebx, LOWER_STACK_POINTER
+    mov ss, ebx
+    mov esp, STACK_SIZE
+    mov ebp, STACK_SIZE
+    push dx
+
+.check_a20:
+    push ebp
+    mov ebp, esp
+    call check_a20_wraparound
+    mov esp, ebp
+    pop ebp
+    cmp eax, 1
+    je .a20_is_enabled
+
+    cli
+    hlt
+
+.a20_is_enabled:
+    ; jmp .flat_gdt_loaded
+
+    ; Reset Display
+    mov ah, 0x00
+    mov al, 0x03
+    int 0x10
+
+    ; mov ah, 0x05
+    ; mov al, 0
+    ; int 0x10
+
+    mov ah, 0x0b
+    mov bh, 0x00
+    mov bl, 0
+    int 0x10
+
+    push ebp
+    mov ebp, esp
+    call setup_drivers
+    mov esp, ebp
+    pop ebp
+
+    mov edi, ebp
+    mov esi, esp
+    push ebp
+    mov ebp, esp
+    push .flat_gdt_loaded
+    call load_flat_gdt
+    mov esp, ebp
+    pop ebp
+.flat_gdt_loaded:
+    mov ebp, edi
+    mov esp, esi
+
+    mov ebx, some_text
+    push ebp
+    mov ebp, esp
+    push dword ebx
+    call dword write_text
+    mov esp, ebp
+    pop ebp
+
+    cli
+    hlt
+some_text:
+    db "This is some text.", 0x00
+
+; Utilities
+%include "utility/math.asm"
+%include "utility/memory.asm"
+
+; Memory Management
+%include "memory/a20.asm"
+%include "memory/gdt.asm"
+
+; Driver Manager
+; %include "drivers/manager.asm"