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83 lines
2.1 KiB
C
83 lines
2.1 KiB
C
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/*
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* \brief NOVA-specific signal-source client interface
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* \author Norman Feske
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* \date 2010-02-03
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*
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* On NOVA, the signal source server does not provide a blocking
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* 'wait_for_signal' function because this kernel does no support
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* out-of-order IPC replies. Instead, we use a shared semaphore
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* to let the client block until a signal is present at the
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* server. The shared semaphore gets initialized with the first
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* call of 'wait_for_signal()'.
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*/
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/*
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* Copyright (C) 2010-2011 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU General Public License version 2.
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*/
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#ifndef _INCLUDE__SIGNAL_SESSION__SOURCE_CLIENT_H_
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#define _INCLUDE__SIGNAL_SESSION__SOURCE_CLIENT_H_
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#include <nova/syscalls.h>
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#include <base/rpc_client.h>
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#include <signal_session/nova_source.h>
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namespace Genode {
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class Signal_source_client : public Rpc_client<Nova_signal_source>
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{
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private:
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/**
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* Capability with 'pt_sel' referring to a NOVA semaphore
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*/
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Native_capability _sem;
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/**
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* Request NOVA semaphore from signal-source server
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*/
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void _init_sem()
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{
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/* initialize semaphore only once */
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if (_sem.valid()) return;
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/* request mapping of semaphore capability selector */
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_sem = call<Rpc_request_semaphore>();
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}
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public:
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/**
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* Constructor
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*/
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Signal_source_client(Signal_source_capability cap)
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: Rpc_client<Nova_signal_source>(static_cap_cast<Nova_signal_source>(cap)) { }
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/*****************************
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** Signal source interface **
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*****************************/
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Signal wait_for_signal()
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{
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/* make sure that we have aquired the semaphore from the server */
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_init_sem();
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/* block on semaphore, will be unblocked if signal is available */
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Nova::sm_ctrl(_sem.pt_sel(), Nova::SEMAPHORE_DOWN);
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/*
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* Now that the server has unblocked the semaphore, we are sure
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* that there is a signal pending. The following 'wait_for_signal'
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* request will be immediately answered.
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*/
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return call<Rpc_wait_for_signal>();
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}
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};
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}
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#endif /* _INCLUDE__SIGNAL_SESSION__SOURCE_CLIENT_H_ */
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