From d093a8eea6bfb0ff7e621e9ba3307dae698322aa Mon Sep 17 00:00:00 2001
From: dzwdz
Date: Sat, 10 Jul 2021 16:37:45 +0200
Subject: separate the source code from object files; more modular Makefile

---
 src/platform/boot.s | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)
 create mode 100644 src/platform/boot.s

(limited to 'src/platform/boot.s')

diff --git a/src/platform/boot.s b/src/platform/boot.s
new file mode 100644
index 0000000..d5bfda5
--- /dev/null
+++ b/src/platform/boot.s
@@ -0,0 +1,47 @@
+.set MAGIC, 0x1BADB002
+.set FLAG_ALIGN,   1<<0 /* align modules on page boundaries */
+.set FLAG_MEMINFO, 1<<1 /* memory map */
+.set FLAGS,        FLAG_ALIGN | FLAG_MEMINFO
+.set CHECKSUM, -(MAGIC + FLAGS)
+
+.section .multiboot
+.align 4
+.long MAGIC
+.long FLAGS
+.long CHECKSUM
+
+/* a lil stack */
+.section .bss
+.global stack_top
+.type stack_top, @object
+.align 16
+stack_bottom:
+.skip 16384
+stack_top:
+
+
+.section .text
+.global _start
+.type _start, @function
+_start:
+	mov $stack_top, %esp
+	call kmain
+
+.global halt_cpu
+.type halt_cpu, @function
+halt_cpu:
+	cli
+1:	hlt
+	jmp 1b
+
+// temporary, will be moved to another file soon
+.global change_cs
+.type change_cs, @function
+change_cs:
+	/* retf pops off the return address and code segment off the stack.
+	 * it turns out that in the i386 cdecl calling convention they're in
+	 * the correct place already.
+	 */
+	retf
+
+.size _start, . - _start
-- 
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