Import the "gerbert" kernel I worked on earlier this year.

It's a lot crappier than I remembered it. It's gonna need a lot of work.

Kernel/IPC.cpp

@@ -0,0 +1,104 @@
+#include "IPC.h"
+#include "Task.h"
+#include "i386.h"
+#include "StdLib.h"
+#include "VGA.h"
+#include "system.h"
+
+namespace IPC {
+
+Message receive(Handle src)
+{
+    for (;;) {
+        current->ipc.src = src;
+        block(Task::BlockedReceive);
+        if (src == Handle::Any && current->ipc.notifies) {
+            for (BYTE i = 0; i < 32; ++i) {
+                if (current->ipc.notifies & (1 << i)) {
+                    // FIXME: Source PID is `i' here. Do something with it?
+                    current->ipc.notifies &= ~(1 << i);
+                    break;
+                }
+            }
+            return Message(MSG_NOTIFY);
+        }
+
+        if (src == Handle::Any || src == current->ipc.msg.sender()) {
+            return move(current->ipc.msg);
+        }
+
+        // Why are we here?
+        ASSERT_NOT_REACHED();
+    }
+}
+
+void send(Handle dst, Message&& msg)
+{
+    Task* task;
+
+    // TODO: Block waiting for `dst' to spawn.
+    for (;;) {
+        task = Task::fromIPCHandle(dst);
+        if (task)
+            break;
+        yield();
+    }
+
+    // I'll fill this in myself thankyouverymuch.
+    msg.setSender(current->handle());
+
+    // Block until `dst' is ready to receive a message.
+    current->ipc.dst = dst;
+    block(Task::BlockedSend);
+
+    ASSERT(msg.isValid());
+    task->ipc.msg = move(msg);
+}
+
+void notify(Handle dst)
+{
+    Task* task = Task::fromIPCHandle(dst);
+
+    if (!task) {
+        // Can't really block here since we might be coming from
+        // an interrupt handler and that'd be devastating...
+        // XXX: Need to figure that one out.
+        kprintf("notify(): no such task %u\n", dst.data());
+        return;
+    }
+
+    if (current->pid() >= 32) {
+        kprintf( "notify(): PID must be < 32\n" );
+        return;
+    }
+
+    task->ipc.notifies |= 1 << current->pid();
+}
+
+Message::Message(Message&& other)
+    : m_data(move(other.m_data))
+    , m_type(other.m_type)
+    , m_sender(other.m_sender)
+    , m_isValid(other.m_isValid)
+{
+    other.m_type = 0;
+    other.m_sender = Handle();
+    other.m_isValid = false;
+}
+
+Message& Message::operator=(Message&& other)
+{
+    if (this == &other)
+        return *this;
+    m_data = move(other.m_data);
+    m_type = other.m_type;
+    m_sender = other.m_sender;
+    m_isValid = other.m_isValid;
+    other.m_type = 0;
+    other.m_sender = Handle();
+    other.m_isValid = false;
+    return *this;
+}
+
+
+}