genode/repos/base-hw/include/base/ipc_msgbuf.h

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/*
* \brief IPC message buffers
* \author Martin Stein
* \author Stefan Kalkowski
* \date 2012-01-03
*/
/*
* Copyright (C) 2012-2015 Genode Labs GmbH
*
* This file is part of the Genode OS framework, which is distributed
* under the terms of the GNU General Public License version 2.
*/
#ifndef _INCLUDE__BASE__IPC_MSGBUF_H_
#define _INCLUDE__BASE__IPC_MSGBUF_H_
#include <base/native_capability.h>
#include <util/string.h>
namespace Genode
{
class Native_utcb;
/**
* IPC message buffer layout
*/
class Msgbuf_base;
/**
* Instance of IPC message buffer with specified buffer size
*
* 'Msgbuf_base' must be the last class this class inherits from.
*/
template <unsigned BUF_SIZE> class Msgbuf;
}
class Genode::Msgbuf_base
{
public:
enum { MAX_CAP_ARGS = 4 };
private:
friend class Native_utcb;
size_t _size; /* buffer size in bytes */
Native_capability _caps[MAX_CAP_ARGS]; /* capability buffer */
size_t _snd_cap_cnt = 0; /* capability counter */
size_t _rcv_cap_cnt = 0; /* capability counter */
public:
/*************************************************
** 'buf' must be the last member of this class **
*************************************************/
char buf[]; /* begin of actual message buffer */
Msgbuf_base(size_t size) : _size(size) { }
void const * base() const { return &buf; }
/**
* Return size of message buffer
*/
size_t size() const { return _size; }
/**
* Return pointer of message data payload
*/
void *data() { return &buf[0]; }
/**
* Reset capability buffer.
*/
void reset()
{
_snd_cap_cnt = 0;
_rcv_cap_cnt = 0;
}
/**
* Return how many capabilities are accepted by this message buffer
*/
size_t cap_rcv_window() { return _rcv_cap_cnt; }
/**
* Set how many capabilities are accepted by this message buffer
*/
void cap_rcv_window(size_t cnt) { _rcv_cap_cnt = cnt; }
/**
* Add capability to buffer
*/
void cap_add(Native_capability const &cap)
{
if (_snd_cap_cnt < MAX_CAP_ARGS)
_caps[_snd_cap_cnt++] = cap;
}
/**
* Return last capability from buffer.
*/
Native_capability cap_get()
{
return (_rcv_cap_cnt < _snd_cap_cnt)
? _caps[_rcv_cap_cnt++] : Native_capability();
}
};
template <unsigned BUF_SIZE>
class Genode::Msgbuf : public Genode::Msgbuf_base
{
public:
/**************************************************
** 'buf' must be the first member of this class **
**************************************************/
char buf[BUF_SIZE];
/**
* Constructor
*/
Msgbuf() : Msgbuf_base(BUF_SIZE) { }
};
#endif /* _INCLUDE__BASE__IPC_MSGBUF_H_ */