From 88d4a8e6ffdbbe94e1db1f8fc5a2b5f7787adc50 Mon Sep 17 00:00:00 2001
From: Anthony Liguori <aliguori@us.ibm.com>
Date: Fri, 12 Nov 2010 08:08:36 -0600
Subject: [PATCH] Introduce the notion of a Plug

A plug stores a pointer to another device.  A plug can store a pointer to a
base class or it can store a pointer to a specific device type.  In the case
of the i8042, the controller only supports two types of devices and the devices
must occur on a specific port.

Besides providing for better marshalling support, a plug has NULL pointer
dereferencing checks built into it.  For the i8042, I need to update the code
to work properly with empty plugs.

Plugs need to be part of the factory interface.  So far we've been dealing with
non-optional devices that are constructed purely by composition.  Now that we
have optional devices, we need a generic way to instantiate the optional devices
and to attach them to the appropriate devices.
---
 include/i8042.hpp |  7 ++++---
 include/plug.hpp  | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 include/util.hpp  |  7 +++++++
 pc/i8042.cpp      | 24 ++++++++++-----------
 4 files changed, 84 insertions(+), 16 deletions(-)
 create mode 100644 include/plug.hpp

diff --git a/include/i8042.hpp b/include/i8042.hpp
index 240f936..c7a97b9 100644
--- a/include/i8042.hpp
+++ b/include/i8042.hpp
@@ -1,8 +1,9 @@
 #ifndef I8042_HPP
 #define I8042_HPP
 
-#include "ps2.hpp"
 #include "ps2_keyboard.hpp"
+#include "ps2_mouse.hpp"
+#include "plug.hpp"
 
 class I8042
 {
@@ -30,8 +31,8 @@ private:
     /* Bitmask of devices with data available.  */
     uint8_t pending;
 
-    PS2Keyboard *port0;
-    PS2Device *port1;
+    Plug<PS2Keyboard> kbd;
+    Plug<PS2Mouse> aux;
 
     OutputPin irq_kbd;
     OutputPin irq_mouse;
diff --git a/include/plug.hpp b/include/plug.hpp
new file mode 100644
index 0000000..2982e13
--- /dev/null
+++ b/include/plug.hpp
@@ -0,0 +1,62 @@
+#ifndef PLUG_HPP
+#define PLUG_HPP
+
+#include <exception>
+
+#include "marshal.hpp"
+
+class NullPointer : public std::exception
+{
+};
+
+template <typename T>
+class Plug
+{
+public:
+    void plug(T *ptr) {
+        this->ptr = ptr;
+    }
+
+    void unplug(void) {
+        this->ptr = NULL;
+    }
+
+    bool empty(void) const {
+        return (this->ptr == NULL);
+    }
+
+    T &operator*(void) const {
+        return *(this->get());
+    }
+
+    T *operator->(void) const {
+        return this->get();
+    }
+
+    T *get(void) const {
+        if (this->ptr == NULL) {
+            throw new NullPointer();
+        }
+        return this->ptr;
+    }
+
+private:
+    T *ptr;
+};
+
+template <typename T>
+void marshal(Marshaller *m, const char *name, Plug<T> *plug)
+{
+    bool empty;
+
+    m->start_struct(name, "Plug");
+    empty = plug->empty();
+    marshal(m, "empty", &empty);
+    if (!empty) {
+        marshal(m, NULL, plug->get());
+    }
+    m->end_struct();
+        
+}
+
+#endif
diff --git a/include/util.hpp b/include/util.hpp
index 4657431..7d40834 100644
--- a/include/util.hpp
+++ b/include/util.hpp
@@ -15,6 +15,13 @@ template <typename T, size_t N>
 class Array
 {
 public:
+    const T &at(size_t index) const {
+        if (index < 0 || index >= N) {
+            throw new OutOfBounds();
+        }
+        return this->data[index];
+    }
+
     T &at(size_t index) {
         if (index < 0 || index >= N) {
             throw new OutOfBounds();
diff --git a/pc/i8042.cpp b/pc/i8042.cpp
index 4544c9f..7a66b34 100644
--- a/pc/i8042.cpp
+++ b/pc/i8042.cpp
@@ -94,9 +94,9 @@ uint32_t I8042::read_status(uint32_t addr)
 void I8042::queue(int b, int aux)
 {
     if (aux) {
-        this->port1->queue(b);
+        this->aux->queue(b);
     } else {
-        this->port0->queue(b);
+        this->kbd->queue(b);
     }
 }
 
@@ -198,9 +198,9 @@ uint32_t I8042::read_data(uint32_t addr)
     uint32_t val;
 
     if (this->pending == KBD_PENDING_AUX)
-        val = this->port1->read();
+        val = this->aux->read();
     else
-        val = this->port0->read();
+        val = this->kbd->read();
 
     return val;
 }
@@ -209,11 +209,11 @@ void I8042::write_data(uint32_t addr, uint32_t val)
 {
     switch(this->write_cmd) {
     case 0:
-        this->port0->write(val);
+        this->kbd->write(val);
         break;
     case KBD_CCMD_WRITE_MODE:
         this->mode = val;
-        this->port0->set_translation((this->mode & KBD_MODE_KCC) != 0);
+        this->kbd->set_translation((this->mode & KBD_MODE_KCC) != 0);
         /* ??? */
         this->update_irq();
         break;
@@ -227,7 +227,7 @@ void I8042::write_data(uint32_t addr, uint32_t val)
         this->ioport92_write(0, val);
         break;
     case KBD_CCMD_WRITE_MOUSE:
-        this->port1->write(val);
+        this->aux->write(val);
         break;
     default:
         break;
@@ -240,8 +240,8 @@ void I8042::reset(void)
     this->mode = KBD_MODE_KBD_INT | KBD_MODE_MOUSE_INT;
     this->status = KBD_STAT_CMD | KBD_STAT_UNLOCKED;
     this->outport = KBD_OUT_RESET | KBD_OUT_A20;
-    this->port0->reset();
-    this->port1->reset();
+    this->kbd->reset();
+    this->aux->reset();
 }
 
 void I8042::pickle(Marshaller *m, const char *name)
@@ -252,10 +252,8 @@ void I8042::pickle(Marshaller *m, const char *name)
     marshal(m, "mode", &this->mode);
     marshal(m, "outport", &this->outport);
     marshal(m, "pending", &this->pending);
-    m->start_array("port");
-    marshal(m, NULL, this->port0);
-    marshal(m, NULL, this->port1);
-    m->end_array();
+    marshal(m, "kbd", &this->kbd);
+    marshal(m, "aux", &this->aux);
     marshal(m, "irq_kbd", &this->irq_kbd);
     marshal(m, "irq_mouse", &this->irq_mouse);
     marshal(m, "a20_line", &this->a20_line);
-- 
2.11.4.GIT