From d495a1745c83a8186bf1c6c531177887dd245436 Mon Sep 17 00:00:00 2001
From: Tianhao Wang <shrik3@mailbox.org>
Date: Thu, 6 Jun 2024 02:08:21 +0200
Subject: proc: basic infra for multithreading

including task and scheduler wrapper, context swap assembly, and some
notes... The lifetime of task is tricky, I'll fix it later

Signed-off-by: Tianhao Wang <shrik3@mailbox.org>
---
 src/proc/task.rs | 45 ++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 44 insertions(+), 1 deletion(-)

(limited to 'src/proc/task.rs')

diff --git a/src/proc/task.rs b/src/proc/task.rs
index 0ff2065..5cbe2f6 100644
--- a/src/proc/task.rs
+++ b/src/proc/task.rs
@@ -1,4 +1,7 @@
 use crate::arch::x86_64::arch_regs;
+use crate::defs::*;
+use crate::io::*;
+use core::arch::asm;
 
 /// currently only kernelSp and Context are important.
 /// the task struct will be placed on the starting addr (low addr) of the kernel stack.
@@ -6,8 +9,48 @@ use crate::arch::x86_64::arch_regs;
 #[repr(C)]
 #[repr(packed)]
 pub struct Task {
+	pub magic: u64,
 	pub task_id: u32,
 	pub kernel_stack: u64,
-	pub user_stack: u64,
+	// pub user_stack: u64,
 	pub context: arch_regs::Context64,
+	pub state: TaskState,
+}
+
+pub enum TaskState {
+	Run,
+	Block,
+	Dead,
+	Eating,
+	Purr,
+	Meow,
+	Angry,
+}
+
+#[no_mangle]
+pub extern "C" fn _task_entry() -> ! {
+	println!("I'm Mr.Meeseeks, look at me~");
+	unsafe { asm!("hlt") };
+	panic!("shoud not reach");
+}
+
+extern "C" {
+	fn context_swap(from_ctx: u64, to_ctx: u64);
+	fn context_swap_to(to_ctx: u64);
+}
+
+impl Task {
+	/// create new task. This is tricky because the task struct sits at the
+	/// bottom of the kernel stack, so that you can get the current task by
+	/// masking the stack pointer.
+	/// 1. allocate the kernel stack with predefined size and make sure the
+	///    address is properly aligned
+	/// 2. cast a task struct onto the stack
+	/// 3. set whatever fields necessary in the task struct, including a magic
+	/// 4. create a new stack frame, and update the stack pointer in the context,
+	///	   so that when first swapped to, the task will immediately "return to"
+	///	   the _func_ptr
+	pub fn new(_id: u32, _func_ptr: u64) -> Self {
+		todo!()
+	}
 }
-- 
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