gem5/src/mem/port_proxy.hh

/*
 * Copyright (c) 2011-2013 ARM Limited
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 *
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 * property including but not limited to intellectual property relating
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 * this software without specific prior written permission.
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 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 *
 * Authors: Andreas Hansson
 */

/**
 * @file
 * PortProxy Object Declaration.
 *
 * Port proxies are used when non-structural entities need access to
 * the memory system (or structural entities that want to peak into
 * the memory system without making a real memory access).
 *
 * Proxy objects replace the previous FunctionalPort, TranslatingPort
 * and VirtualPort objects, which provided the same functionality as
 * the proxies, but were instances of ports not corresponding to real
 * structural ports of the simulated system. Via the port proxies all
 * the accesses go through an actual port (either the system port,
 * e.g. for processes or initialisation, or a the data port of the
 * CPU, e.g. for threads) and thus are transparent to a potentially
 * distributed memory and automatically adhere to the memory map of
 * the system.
 */

#ifndef __MEM_PORT_PROXY_HH__
#define __MEM_PORT_PROXY_HH__

#include "config/the_isa.hh"
#if THE_ISA != NULL_ISA
    #include "arch/isa_traits.hh"
#endif

#include "mem/port.hh"
#include "sim/byteswap.hh"

/**
 * This object is a proxy for a structural port, to be used for debug
 * accesses.
 *
 * This proxy object is used when non structural entities
 * (e.g. thread contexts, object file loaders) need access to the
 * memory system. It calls the corresponding functions on the underlying
 * structural port, and provides templatized convenience access functions.
 *
 * The addresses are interpreted as physical addresses.
 *
 * @sa SETranslatingProxy
 * @sa FSTranslatingProxy
 */
class PortProxy
{
  private:

    /** The actual physical port used by this proxy. */
    MasterPort &_port;

    /** Granularity of any transactions issued through this proxy. */
    const unsigned int _cacheLineSize;

    void blobHelper(Addr addr, uint8_t *p, int size, MemCmd cmd) const;

  public:
    PortProxy(MasterPort &port, unsigned int cacheLineSize) :
        _port(port), _cacheLineSize(cacheLineSize) { }
    virtual ~PortProxy() { }

    /**
     * Read size bytes memory at address and store in p.
     */
    virtual void readBlob(Addr addr, uint8_t* p, int size) const
    { blobHelper(addr, p, size, MemCmd::ReadReq); }

    /**
     * Write size bytes from p to address.
     */
    virtual void writeBlob(Addr addr, uint8_t* p, int size) const
    { blobHelper(addr, p, size, MemCmd::WriteReq); }

    /**
     * Fill size bytes starting at addr with byte value val.
     */
    virtual void memsetBlob(Addr addr, uint8_t v, int size) const;

    /**
     * Read sizeof(T) bytes from address and return as object T.
     */
    template <typename T>
    T read(Addr address) const;

    /**
     * Write object T to address. Writes sizeof(T) bytes.
     */
    template <typename T>
    void write(Addr address, T data) const;

#if THE_ISA != NULL_ISA
    /**
     * Read sizeof(T) bytes from address and return as object T.
     * Performs Guest to Host endianness transform.
     */
    template <typename T>
    T readGtoH(Addr address) const;

    /**
     * Write object T to address. Writes sizeof(T) bytes.
     * Performs Host to Guest endianness transform.
     */
    template <typename T>
    void writeHtoG(Addr address, T data) const;
#endif
};


template <typename T>
T
PortProxy::read(Addr address) const
{
    T data;
    readBlob(address, (uint8_t*)&data, sizeof(T));
    return data;
}

template <typename T>
void
PortProxy::write(Addr address, T data) const
{
    writeBlob(address, (uint8_t*)&data, sizeof(T));
}

#if THE_ISA != NULL_ISA
template <typename T>
T
PortProxy::readGtoH(Addr address) const
{
    T data;
    readBlob(address, (uint8_t*)&data, sizeof(T));
    return TheISA::gtoh(data);
}

template <typename T>
void
PortProxy::writeHtoG(Addr address, T data) const
{
    data = TheISA::htog(data);
    writeBlob(address, (uint8_t*)&data, sizeof(T));
}
#endif

#endif // __MEM_PORT_PROXY_HH__