Remove SyncRequest from K::Object and create a new K::Session type

This is a first step at fixing the conceptual insanity that is our
handling of service and IPC calls. For now, interfaces still directly
derived from Session because we don't have the infrastructure to do it
properly. (That is, Processes and scheduling them.)

1 files changed, 58 insertions, 0 deletions

diff --git a/src/core/hle/kernel/session.h b/src/core/hle/kernel/session.h
new file mode 100644
index 00000000..06ae4bc3
--- /dev/null
+++ b/src/core/hle/kernel/session.h
@@ -0,0 +1,58 @@
+// Copyright 2014 Citra Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include "core/hle/kernel/kernel.h"
+
+namespace Kernel {
+
+static const int kCommandHeaderOffset = 0x80; ///< Offset into command buffer of header
+
+/**
+ * Returns a pointer to the command buffer in kernel memory
+ * @param offset Optional offset into command buffer
+ * @return Pointer to command buffer
+ */
+inline static u32* GetCommandBuffer(const int offset=0) {
+    return (u32*)Memory::GetPointer(Memory::KERNEL_MEMORY_VADDR + kCommandHeaderOffset + offset);
+}
+
+/**
+ * Kernel object representing the client endpoint of an IPC session. Sessions are the basic CTR-OS
+ * primitive for communication between different processes, and are used to implement service calls
+ * to the various system services.
+ *
+ * To make a service call, the client must write the command header and parameters to the buffer
+ * located at offset 0x80 of the TLS (Thread-Local Storage) area, then execute a SendSyncRequest
+ * SVC call with its Session handle. The kernel will read the command header, using it to marshall
+ * the parameters to the process at the server endpoint of the session. After the server replies to
+ * the request, the response is marshalled back to the caller's TLS buffer and control is
+ * transferred back to it.
+ *
+ * In Citra, only the client endpoint is currently implemented and only HLE calls, where the IPC
+ * request is answered by C++ code in the emulator, are supported. When SendSyncRequest is called
+ * with the session handle, this class's SyncRequest method is called, which should read the TLS
+ * buffer and emulate the call accordingly. Since the code can directly read the emulated memory,
+ * no parameter marshalling is done.
+ *
+ * In the long term, this should be turned into the full-fledged IPC mechanism implemented by
+ * CTR-OS so that IPC calls can be optionally handled by the real implementations of processes, as
+ * opposed to HLE simulations.
+ */
+class Session : public Object {
+public:
+    std::string GetTypeName() const override { return "Session"; }
+
+    static Kernel::HandleType GetStaticHandleType() { return Kernel::HandleType::Session; }
+    Kernel::HandleType GetHandleType() const override { return Kernel::HandleType::Session; }
+
+    /**
+     * Handles a synchronous call to this session using HLE emulation. Emulated <-> emulated calls
+     * aren't supported yet.
+     */
+    virtual ResultVal<bool> SyncRequest() = 0;
+};
+
+}