133 lines
2.7 KiB
C++
133 lines
2.7 KiB
C++
/*
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* \brief IPC message buffers
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* \author Martin Stein
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* \author Stefan Kalkowski
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* \date 2012-01-03
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*/
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/*
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* Copyright (C) 2012-2015 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__BASE__IPC_MSGBUF_H_
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#define _INCLUDE__BASE__IPC_MSGBUF_H_
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#include <base/native_capability.h>
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#include <util/string.h>
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namespace Genode
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{
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class Native_utcb;
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/**
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* IPC message buffer layout
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*/
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class Msgbuf_base;
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/**
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* Instance of IPC message buffer with specified buffer size
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*
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* 'Msgbuf_base' must be the last class this class inherits from.
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*/
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template <unsigned BUF_SIZE> class Msgbuf;
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}
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class Genode::Msgbuf_base
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{
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public:
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enum { MAX_CAP_ARGS = 4 };
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private:
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friend class Native_utcb;
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size_t _size; /* buffer size in bytes */
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Native_capability _caps[MAX_CAP_ARGS]; /* capability buffer */
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size_t _snd_cap_cnt = 0; /* capability counter */
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size_t _rcv_cap_cnt = 0; /* capability counter */
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public:
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/*************************************************
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** 'buf' must be the last member of this class **
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*************************************************/
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char buf[]; /* begin of actual message buffer */
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Msgbuf_base(size_t size) : _size(size) { }
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void const * base() const { return &buf; }
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/**
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* Return size of message buffer
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*/
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size_t size() const { return _size; }
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/**
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* Return address of message buffer
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*/
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void *addr() { return &buf[0]; }
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/**
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* Reset capability buffer.
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*/
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void reset()
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{
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_snd_cap_cnt = 0;
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_rcv_cap_cnt = 0;
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}
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/**
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* Return how many capabilities are accepted by this message buffer
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*/
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size_t cap_rcv_window() { return _rcv_cap_cnt; }
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/**
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* Set how many capabilities are accepted by this message buffer
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*/
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void cap_rcv_window(size_t cnt) { _rcv_cap_cnt = cnt; }
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/**
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* Add capability to buffer
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*/
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void cap_add(Native_capability const &cap)
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{
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if (_snd_cap_cnt < MAX_CAP_ARGS)
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_caps[_snd_cap_cnt++] = cap;
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}
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/**
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* Return last capability from buffer.
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*/
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Native_capability cap_get()
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{
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return (_rcv_cap_cnt < _snd_cap_cnt)
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? _caps[_rcv_cap_cnt++] : Native_capability();
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}
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};
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template <unsigned BUF_SIZE>
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class Genode::Msgbuf : public Genode::Msgbuf_base
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{
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public:
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/**************************************************
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** 'buf' must be the first member of this class **
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**************************************************/
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char buf[BUF_SIZE];
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/**
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* Constructor
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*/
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Msgbuf() : Msgbuf_base(BUF_SIZE) { }
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};
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#endif /* _INCLUDE__BASE__IPC_MSGBUF_H_ */
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