From a4ea0b14840ef5946408a3893f3f1c92ed57ae80 Mon Sep 17 00:00:00 2001
From: Jake Mannens <jake72360@gmail.com>
Date: Wed, 20 Jun 2018 04:39:25 +1000
Subject: Added a very basic types.h header file that defines NULL, size_t and
 time_t. Moved the kernel's loading point down to address 0 in conventional
 memory and updated linker scripts accordingly. Began to experiment with
 loading a binary blob into extended memory (0x100000), switching to userspace
 mode, and executing it.

---
 kernel/usrbin/usrbin.s | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)
 create mode 100644 kernel/usrbin/usrbin.s

(limited to 'kernel/usrbin/usrbin.s')

diff --git a/kernel/usrbin/usrbin.s b/kernel/usrbin/usrbin.s
new file mode 100644
index 0000000..91dd94a
--- /dev/null
+++ b/kernel/usrbin/usrbin.s
@@ -0,0 +1,32 @@
+bits 32
+org 0x100000
+
+main:
+  push .msg
+  call puts
+  add esp, 4
+.loop:
+  ; loop forever
+  jmp .loop
+.msg: db "Hello World from Userspace!", 0
+
+puts:
+  push ebp
+  mov ebp, esp
+  push esi
+  push edi
+  mov esi, [ebp+8]
+  mov edi, 0xB8000
+.loop:
+  lodsb
+  cmp al, 0
+  je .end
+  mov [edi], al
+  mov byte [edi+1], 0x07
+  add edi, 2
+  jmp .loop
+.end:
+  pop edi
+  pop esi
+  pop ebp
+  ret
-- 
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