From d0c3c9ff6e8e3612cc696cc4f5f5df93a046c8e2 Mon Sep 17 00:00:00 2001
From: Stephen Marz <stephen.marz@utk.edu>
Date: Wed, 27 Nov 2019 17:02:07 -0500
Subject: [PATCH] Add Process structure and routines.

---
 risc_v/ch6/src/lib.rs     | 38 ++++++------------
 risc_v/ch6/src/process.rs | 83 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 95 insertions(+), 26 deletions(-)

diff --git a/risc_v/ch6/src/lib.rs b/risc_v/ch6/src/lib.rs
index 31142cd..986f69b 100755
--- a/risc_v/ch6/src/lib.rs
+++ b/risc_v/ch6/src/lib.rs
@@ -9,10 +9,10 @@
            alloc_prelude,
            const_raw_ptr_to_usize_cast)]
 
-#[macro_use]
+// #[macro_use]
 extern crate alloc;
 // This is experimental and requires alloc_prelude as a feature
-use alloc::prelude::v1::*;
+// use alloc::prelude::v1::*;
 
 // ///////////////////////////////////
 // / RUST MACROS
@@ -327,38 +327,24 @@ extern "C" fn kmain() {
 	// kmain() starts in supervisor mode. So, we should have the trap
 	// vector setup and the MMU turned on when we get here.
 
-	// Create a new scope so that we can test the global allocator and
-	// deallocator
-	{
-		// We have the global allocator, so let's see if that works!
-		let k = Box::<u32>::new(100);
-		println!("Boxed value = {}", *k);
-		// The following comes from the Rust documentation:
-		// some bytes, in a vector
-		let sparkle_heart = vec![240, 159, 146, 150];
-		// We know these bytes are valid, so we'll use `unwrap()`.
-		// This will MOVE the vector.
-		let sparkle_heart = String::from_utf8(sparkle_heart).unwrap();
-		println!("String = {}", sparkle_heart);
-		println!("\n\nAllocations of a box, vector, and string");
-		kmem::print_table();
-	}
-	println!("\n\nEverything should now be free:");
+	// Initialize the process list and anything else that needs to be done,
+	// here.
+	process::init();
 	kmem::print_table();
 
-	unsafe {
+	// unsafe {
 		// Set the next machine timer to fire.
-		let mtimecmp = 0x0200_4000 as *mut u64;
-		let mtime = 0x0200_bff8 as *const u64;
+		// let mtimecmp = 0x0200_4000 as *mut u64;
+		// let mtime = 0x0200_bff8 as *const u64;
 		// The frequency given by QEMU is 10_000_000 Hz, so this sets
 		// the next interrupt to fire one second from now.
-		mtimecmp.write_volatile(mtime.read_volatile() + 10_000_000);
+		// mtimecmp.write_volatile(mtime.read_volatile() + 10_000_000);
 
 		// Let's cause a page fault and see what happens. This should trap
 		// to m_trap under trap.rs
-		let v = 0x0 as *mut u64;
-		v.write_volatile(0);
-	}
+		// let v = 0x0 as *mut u64;
+		// v.write_volatile(0);
+	// }
 	// If we get here, the Box, vec, and String should all be freed since
 	// they go out of scope. This calls their "Drop" trait.
 
diff --git a/risc_v/ch6/src/process.rs b/risc_v/ch6/src/process.rs
index ce49afb..2ea1ba2 100644
--- a/risc_v/ch6/src/process.rs
+++ b/risc_v/ch6/src/process.rs
@@ -4,6 +4,45 @@
 // 27 Nov 2019
 
 use crate::cpu::TrapFrame;
+use crate::page::{alloc, dealloc};
+use alloc::collections::linked_list::LinkedList;
+
+// Here, we store a process list. It uses the global allocator
+// that we made before and its job is to store all processes.
+// We will have this list OWN the process. So, anytime we want
+// the process, we will consult the process list.
+static mut PROCESS_LIST: LinkedList<Process> = LinkedList::new();
+static mut CURRENT_0: u16 = 0;
+
+/// We will eventually move this function out of here, but its
+/// job is just to take a slot in the process list.
+fn init_process() {
+    loop {
+        unsafe {
+            asm!("wfi");
+        }
+    }
+}
+
+/// Add a process given a function address and then
+/// push it onto the LinkedList. Uses Process::new_default
+/// to create a new stack, etc.
+pub fn add_process_default(proc: fn()) {
+    unsafe {
+        let p = Process::new_default(proc);
+        PROCESS_LIST.push_back(p);
+    }
+}
+
+pub fn init() {
+    add_process_default(init_process);
+    unsafe {
+        let p = PROCESS_LIST.back();
+        if let Some(pd) = p {
+            CURRENT_0 = pd.pid;
+        }
+    }
+}
 
 // Let's represent this in C ABI. We do this
 // because we need to access some of the fields
@@ -14,7 +53,51 @@ use crate::cpu::TrapFrame;
 pub struct Process {
     frame: TrapFrame,
     stack: *mut u8,
+    program_counter: usize,
+    pid: u16,
+    data: ProcessData,
 }
 
+impl Process {
+    pub fn new_default(func: fn()) -> Self {
+        let pd;
+        unsafe {
+            let plb = PROCESS_LIST.back();
+            if let Some(p) = plb {
+                pd = p.pid + 1;
+            }
+            else {
+                pd = 1
+            }
+        } 
+        Process {
+            frame: TrapFrame::zero(),
+            stack: alloc(1),
+            program_counter: func as usize,
+            pid: pd,
+            data: ProcessData::zero()
+        }
+    }
+}
 
+impl Drop for Process {
+    fn drop(&mut self) {
+        dealloc(self.stack);
+    }
+}
+
+// The private data in a process contains information
+// that is relevant to where we are, including the path
+// and open file descriptors.
+pub struct ProcessData {
+    cwd_path: [u8; 128],
+}
+
+impl ProcessData {
+    pub fn zero() -> Self {
+        ProcessData {
+            cwd_path: [0; 128],
+        }
+    }
+}