From c16b3e39cf8b0a6ea5e43812bc4187bf7867343d Mon Sep 17 00:00:00 2001
From: Baptiste Wicht <baptiste.wicht@gmail.com>
Date: Tue, 28 Jan 2014 20:48:31 +0100
Subject: [PATCH] Handle state of processes

---
 kernel/include/process.hpp |  9 +++++++++
 kernel/src/scheduler.cpp   | 22 +++++++++++++++++-----
 2 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/kernel/include/process.hpp b/kernel/include/process.hpp
index 945e8af0..a1d0d52d 100644
--- a/kernel/include/process.hpp
+++ b/kernel/include/process.hpp
@@ -16,6 +16,13 @@
 
 namespace scheduler {
 
+enum class process_state : char {
+    NEW = 0,
+    READY = 1,
+    RUNNING = 2,
+    BLOCKED = 3
+};
+
 struct segment_t {
     size_t physical;
     size_t size;
@@ -24,6 +31,8 @@ struct segment_t {
 struct process_t {
     size_t pid;
 
+    process_state state;
+
     bool system;
 
     size_t physical_cr3;
diff --git a/kernel/src/scheduler.cpp b/kernel/src/scheduler.cpp
index 4eb68983..10046c61 100644
--- a/kernel/src/scheduler.cpp
+++ b/kernel/src/scheduler.cpp
@@ -36,8 +36,7 @@ size_t idle_stack[64];
 size_t idle_kernel_stack[4096]; //TODO Perhaps not good
 
 void create_idle_task(){
-    scheduler::process_t idle_process;
-    idle_process.pid = next_pid++;
+    auto idle_process = scheduler::new_process();
     idle_process.system = true;
     idle_process.physical_cr3 = paging::get_physical_pml4t();
     idle_process.paging_size = 0;
@@ -53,8 +52,7 @@ void create_idle_task(){
     idle_process.regs.cs = gdt::LONG_SELECTOR;
     idle_process.regs.ds = gdt::DATA_SELECTOR;
 
-    processes.push_back(std::move(idle_process));
-    rounds.push_back(0);
+    queue_process(std::move(idle_process));
 }
 
 void switch_to_process(const interrupt::syscall_regs& regs, size_t index){
@@ -64,6 +62,8 @@ void switch_to_process(const interrupt::syscall_regs& regs, size_t index){
 
     auto& process = processes[current_index];
 
+    process.state = scheduler::process_state::RUNNING;
+
     gdt::tss.rsp0_low = process.kernel_rsp & 0xFFFFFFFF;
     gdt::tss.rsp0_high = process.kernel_rsp >> 32;
 
@@ -103,7 +103,13 @@ void switch_to_process(const interrupt::syscall_regs& regs, size_t index){
 }
 
 size_t select_next_process(){
-    return (current_index + 1) % processes.size();
+    auto next = (current_index + 1) % processes.size();
+
+    while(processes[next].state != scheduler::process_state::READY){
+        next = (next + 1) % processes.size();
+    }
+
+    return next;
 }
 
 void save_context(const interrupt::syscall_regs& regs){
@@ -126,6 +132,7 @@ void scheduler::start(){
 
     current_index = 0;
     rounds[current_index] = TURNOVER;
+    processes[current_index].state = process_state::RUNNING;
 
     //Wait for the next interrupt
     while(true){
@@ -157,6 +164,8 @@ void scheduler::reschedule(const interrupt::syscall_regs& regs){
     if(rounds[current_index] == TURNOVER){
         rounds[current_index] = 0;
 
+        processes[current_index].state = process_state::READY;
+
         auto index = select_next_process();
 
         //If it is the same, no need to go to the switching process
@@ -179,6 +188,7 @@ scheduler::process_t scheduler::new_process(){
 
     p.system = false;
     p.pid = next_pid++;
+    p.state = process_state::NEW;
 
     return std::move(p);
 }
@@ -186,4 +196,6 @@ scheduler::process_t scheduler::new_process(){
 void scheduler::queue_process(process_t&& p){
     processes.push_back(std::forward<scheduler::process_t>(p));
     rounds.push_back(0);
+
+    p.state = process_state::READY;
 }