From 86771ec0f0631eaefb7be8e9dba75a18135df8cc Mon Sep 17 00:00:00 2001
From: Baptiste Wicht <baptiste.wicht@gmail.com>
Date: Wed, 29 Jan 2014 22:16:10 +0100
Subject: [PATCH] Prepare basic implementation of a sleep queue inside the
 keyboard driver

---
 kernel/include/keyboard.hpp    |  2 +-
 kernel/include/sleep_queue.hpp | 60 ++++++++++++++++++++++++++++++++++
 kernel/src/keyboard.cpp        | 37 ++++++++++++++++-----
 kernel/src/system_calls.cpp    |  7 +---
 4 files changed, 91 insertions(+), 15 deletions(-)
 create mode 100644 kernel/include/sleep_queue.hpp

diff --git a/kernel/include/keyboard.hpp b/kernel/include/keyboard.hpp
index 4902a872..14db4d98 100644
--- a/kernel/include/keyboard.hpp
+++ b/kernel/include/keyboard.hpp
@@ -24,7 +24,7 @@ char get_char();
 char key_to_ascii(uint8_t key);
 char shift_key_to_ascii(uint8_t key);
 
-char get_char_blocking();
+void get_char_blocking();
 
 }
 
diff --git a/kernel/include/sleep_queue.hpp b/kernel/include/sleep_queue.hpp
new file mode 100644
index 00000000..fcedfc8c
--- /dev/null
+++ b/kernel/include/sleep_queue.hpp
@@ -0,0 +1,60 @@
+//=======================================================================
+// Copyright Baptiste Wicht 2013-2014.
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at
+//  http://www.boost.org/LICENSE_1_0.txt)
+//=======================================================================
+
+#ifndef SLEEP_QUEUE_H
+#define SLEEP_QUEUE_H
+
+#include "stl/queue.hpp"
+#include "stl/lock_guard.hpp"
+
+#include "spinlock.hpp"
+#include "scheduler.hpp"
+
+struct sleep_queue {
+private:
+    mutable spinlock lock;
+
+    std::queue<scheduler::pid_t> queue;
+
+public:
+    bool empty() const {
+        std::lock_guard<spinlock> l(lock);
+
+        return queue.empty();
+    }
+
+    scheduler::pid_t wake_up(){
+        std::lock_guard<spinlock> l(lock);
+
+        //Get the first process
+        auto pid = queue.top();
+
+        //Indicate to the scheduler that this process will be able
+        //to run
+        scheduler::unblock_process(pid);
+
+        //Remove the process from the queue
+        queue.pop();
+
+        return pid;
+    }
+
+    void sleep(){
+        std::lock_guard<spinlock> l(lock);
+
+        //Get the current process information
+        auto pid = scheduler::get_pid();
+
+        //This process will sleep
+        scheduler::block_process(pid);
+
+        //Enqueue the process in the sleep queue
+        queue.push(pid);
+    }
+};
+
+#endif
diff --git a/kernel/src/keyboard.cpp b/kernel/src/keyboard.cpp
index d57ac77c..d9521ca5 100644
--- a/kernel/src/keyboard.cpp
+++ b/kernel/src/keyboard.cpp
@@ -10,6 +10,7 @@
 #include "kernel_utils.hpp"
 #include "semaphore.hpp"
 #include "spinlock.hpp"
+#include "sleep_queue.hpp"
 
 namespace {
 
@@ -93,22 +94,31 @@ char shifted_qwertz[128] = {
 
 const uint8_t BUFFER_SIZE = 64;
 
+//TODO Encapsulate the buffer
 char input_buffer[BUFFER_SIZE];
 volatile uint8_t start;
 volatile uint8_t count;
 
 spinlock lock;
-semaphore sem;
+sleep_queue queue;
 
 void keyboard_handler(const interrupt::syscall_regs&){
     auto key = static_cast<char>(in_byte(0x60));
 
+    std::lock_guard<spinlock> l(lock);
+
     if(count == BUFFER_SIZE){
         //The buffer is full, we loose the characters
     } else {
-        auto end = (start + count) % BUFFER_SIZE;
-        input_buffer[end] = key;
-        ++count;
+        if(queue.empty()){
+            auto end = (start + count) % BUFFER_SIZE;
+            input_buffer[end] = key;
+            ++count;
+        } else {
+            auto pid = queue.wake_up();
+
+            //TODO Give key to process pid
+        }
     }
 }
 
@@ -119,12 +129,23 @@ void keyboard::install_driver(){
 
     start = 0;
     count = 0;
-
-    sem.init(0);
 }
 
-char keyboard::get_char_blocking(){
-    //TODO
+void keyboard::get_char_blocking(){
+    std::lock_guard<spinlock> l(lock);
+
+    if(count > 0){
+        auto key = input_buffer[start];
+        start = (start + 1) % BUFFER_SIZE;
+        --count;
+
+        auto pid = scheduler::current_pid();
+
+        //TODO Give key to process pid
+    } else {
+        //Wait for a char
+        queue.sleep();
+    }
 }
 
 //TODO Once shell is user mode, can be removed
diff --git a/kernel/src/system_calls.cpp b/kernel/src/system_calls.cpp
index dff00313..bbeaf929 100644
--- a/kernel/src/system_calls.cpp
+++ b/kernel/src/system_calls.cpp
@@ -24,11 +24,6 @@ void sc_print_digit(const interrupt::syscall_regs& regs){
     k_print(regs.rbx);
 }
 
-void sc_get_char(const interrupt::syscall_regs& regs){
-    auto c = keyboard::get_char_blocking();
-    //TODO
-}
-
 } //End of anonymous namespace
 
 void system_call_entry(const interrupt::syscall_regs& regs){
@@ -48,7 +43,7 @@ void system_call_entry(const interrupt::syscall_regs& regs){
             break;
 
         case 3:
-            sc_get_char(regs);
+            keyboard::get_char_blocking();
             break;
 
         case 0x666: