From d9d283e5ac12d2d298a9e556ec2445f59d7e4349 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Felix=20Quei=C3=9Fner?= <git@mq32.de>
Date: Fri, 6 May 2016 12:35:22 +0200
Subject: [PATCH] PMM::alloc now dies with a BSOD instead of returning an
 invalid value. Adds stub of scheduler driver.

---
 prototypes/base/include/driver/scheduler.hpp | 34 +++++++++++++
 prototypes/base/include/errors.hpp           |  1 +
 prototypes/base/include/pmm.hpp              |  4 +-
 prototypes/base/include/pointer.hpp          |  2 +-
 prototypes/base/init.cpp                     |  4 ++
 prototypes/base/src/pmm.cpp                  | 10 ++--
 prototypes/base/src/scheduler.cpp            | 50 ++++++++++++++++++++
 7 files changed, 96 insertions(+), 9 deletions(-)
 create mode 100644 prototypes/base/include/driver/scheduler.hpp
 create mode 100644 prototypes/base/src/scheduler.cpp

diff --git a/prototypes/base/include/driver/scheduler.hpp b/prototypes/base/include/driver/scheduler.hpp
new file mode 100644
index 0000000..84da410
--- /dev/null
+++ b/prototypes/base/include/driver/scheduler.hpp
@@ -0,0 +1,34 @@
+#pragma once
+
+#include "base.hpp"
+#include "cpustate.hpp"
+#include "pointer.hpp"
+
+namespace driver
+{
+	class Task
+	{
+	private:
+		physical_t stackBottom;
+		CpuState *cpu;
+	public:
+		Task();
+		Task(const Task &) = delete;
+		Task(Task &&) = delete;
+		~Task();
+	};
+
+	class Scheduler : 
+		public Driver
+	{
+	private:
+		static Scheduler *current;
+		static void dispatch(CpuState *cpu);
+		
+		void next(CpuState *cpu);
+	public:
+		Scheduler();
+		
+		void install() override;
+	};
+}
\ No newline at end of file
diff --git a/prototypes/base/include/errors.hpp b/prototypes/base/include/errors.hpp
index da59d7a..50c8db4 100644
--- a/prototypes/base/include/errors.hpp
+++ b/prototypes/base/include/errors.hpp
@@ -6,4 +6,5 @@ enum class Error
   OutOfMemory = 1,
   UnhandledException = 2,
 	UnhandledInterrupt = 3,
+	DriverAlreadyInstalled = 4,
 };
\ No newline at end of file
diff --git a/prototypes/base/include/pmm.hpp b/prototypes/base/include/pmm.hpp
index c31cd6b..e5aa39b 100644
--- a/prototypes/base/include/pmm.hpp
+++ b/prototypes/base/include/pmm.hpp
@@ -22,9 +22,9 @@ public:
 
   /**
    * Allocates a single page.
-   * @param success This boolean will contain true if the allocation was successful.
+   * @remarks This method will either return a valid value or die with a BSOD if out of memory.
    */
-  static physical_t alloc(bool &success);
+  static physical_t alloc();
 
   /**
    * Frees a given page by pointer.
diff --git a/prototypes/base/include/pointer.hpp b/prototypes/base/include/pointer.hpp
index 76c0356..8f93c00 100644
--- a/prototypes/base/include/pointer.hpp
+++ b/prototypes/base/include/pointer.hpp
@@ -72,7 +72,7 @@ public:
    * Allow explicit conversion to a raw pointer.
    */
   explicit operator void * () const {
-    return this->ptr;
+    return this->data();
   }
   
   /**
diff --git a/prototypes/base/init.cpp b/prototypes/base/init.cpp
index e088e8a..e17dd49 100644
--- a/prototypes/base/init.cpp
+++ b/prototypes/base/init.cpp
@@ -11,6 +11,7 @@
 #include "io.hpp"
 
 #include "driver/keyboard.hpp"
+#include "driver/scheduler.hpp"
 
 using namespace multiboot;
 using namespace console_tools;
@@ -22,6 +23,7 @@ extern dummy kernelStartMarker;
 extern dummy kernelEndMarker;
 
 driver::Keyboard keyboardDriver;
+driver::Scheduler scheduler;
 
 void timer(CpuState *cpu)
 {
@@ -94,7 +96,9 @@ extern "C" void init(Structure const & data)
 	IDT::initialize();
 	
 	IDT::interrupt(0x20) = Interrupt(timer);
+	
 	keyboardDriver.install();
+	scheduler.install();
 	
 	Console::main << "Interrupts set up.\n";
 	
diff --git a/prototypes/base/src/pmm.cpp b/prototypes/base/src/pmm.cpp
index 2e9dea2..ebe5e1e 100644
--- a/prototypes/base/src/pmm.cpp
+++ b/prototypes/base/src/pmm.cpp
@@ -1,6 +1,7 @@
 #include <inttypes.h>
 #include <stddef.h>
 #include "pmm.hpp"
+#include "bsod.hpp"
 
 /**
  * Number stored of pages in the bitmap
@@ -53,7 +54,7 @@ void PMM::markUsed(physical_t page)
   bitmap[idx] &= ~(1<<bit);
 }
 
-physical_t PMM::alloc(bool &success)
+physical_t PMM::alloc()
 {
   for(uint32_t idx = 0; idx < BitmapLength; idx++) {
     // fast skip when no bit is set
@@ -73,14 +74,11 @@ physical_t PMM::alloc(bool &success)
       uint32_t pageId = 32 * idx + bit;
       uint32_t ptr = 4096 * pageId;
       
-      success = true;
-      
       return physical_t(ptr);
     }
   }
-  // Do something here!
-  success = false;
-  return physical_t::invalid;
+  BSOD::die(Error::OutOfMemory, "Out of physical memory!");
+	return physical_t::invalid;
 }
 
 void PMM::free(physical_t page)
diff --git a/prototypes/base/src/scheduler.cpp b/prototypes/base/src/scheduler.cpp
new file mode 100644
index 0000000..8fcdbf9
--- /dev/null
+++ b/prototypes/base/src/scheduler.cpp
@@ -0,0 +1,50 @@
+#include "driver/scheduler.hpp"
+#include "bsod.hpp"
+#include "pmm.hpp"
+
+namespace driver
+{
+	Scheduler * Scheduler::current = nullptr;
+
+	Scheduler::Scheduler()
+	{
+		
+	}
+
+	void Scheduler::install()
+	{
+		if(Scheduler::current != nullptr) {
+			BSOD::die(Error::DriverAlreadyInstalled, "The scheduler is already installed.");
+		}
+		Scheduler::current = this;
+		
+		
+	}
+
+	void Scheduler::next(CpuState *cpu)
+	{
+	
+	}
+	
+	void Scheduler::dispatch(CpuState *cpu)
+	{
+		if(Scheduler::current != nullptr) {
+			Scheduler::current->next(cpu);
+		} else {
+			
+		}
+	}
+	
+	
+	
+	Task::Task() :
+		stackBottom(PMM::alloc()), cpu(nullptr)
+	{
+		
+	}
+	
+	Task::~Task()
+	{
+		PMM::free(this->stackBottom);
+	}
+}
\ No newline at end of file