source: branches/wt_ideal/lib/generic_cache_tsar/include/generic_cache.h @ 920

/* -*- c++ -*-
 *
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 *
 * This file is part of SoCLib, GNU LGPLv2.1.
 *
 * SoCLib is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation; version 2.1 of the License.
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 * SoCLib is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with SoCLib; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301 USA
 *
 * SOCLIB_LGPL_HEADER_END
 *
 * Copyright (c) UPMC, Lip6
 *         Alain Greiner <alain.greiner@lip6.fr> July 2008
 *
 * Maintainers: alain
 */

////////////////////////////////////////////////////////////////////////////////
// File         : generic_cache.h
// Date         : 07/01/2012
// Authors      : Alain Greiner
/////////////////////////////////////////////////////////////////////////////////
// This object is a generic, set associative, cache.
// Each slot can be in two states: VALID OR INVALID.
// Hit if ((matching tag) and (state == VALID).
// The replacement policy is pseudo-LRU. The victim selection process cannot
// fail.
/////////////////////////////////////////////////////////////////////////////////
// Implementation note
// The DATA part is implemented as an uint32_t array[nways*nsets*nwords].
// The DIRECTORY part is implemented as an uint32_t array[nways*nsets].
// All methods requiring a dual port RAM or cache modification using
// an associative search have been deprecated.
/////////////////////////////////////////////////////////////////////////////////
// Constructor parameters are :
// - std::string    &name
// - size_t         nways   : number of associativity levels 
// - size_t         nsets   : number of sets
// - size_t         nwords  : number of words in a cache line
// The nways, nsets, nwords parameters must be power of 2
// The nsets parameter cannot be larger than 1024
// The nways parameter cannot be larger than 16
// The nwords parameter cannot be larger than 64
/////////////////////////////////////////////////////////////////////////////////
// Template parameter is :
// - addr_t : address format to access the cache 
/////////////////////////////////////////////////////////////////////////////////

#ifndef SOCLIB_GENERIC_CACHE_H
#define SOCLIB_GENERIC_CACHE_H

#include <systemc>
#include <cassert>
#include "arithmetics.h"
#include "static_assert.h"
#include "mapping_table.h"
#include <cstring>

namespace soclib { 

enum cache_slot_state_e
{
    CACHE_SLOT_STATE_INVALID,
    CACHE_SLOT_STATE_VALID,
};

//////////////////////////
template<typename addr_t>
class GenericCache 
//////////////////////////
{
    typedef uint32_t data_t;
    typedef uint32_t be_t;

    data_t * r_data;
    addr_t * r_tag;
    int    * r_state;
    bool   * r_lru;

    size_t m_ways; 
    size_t m_sets; 
    size_t m_words;

    const soclib::common::AddressMaskingTable<addr_t> m_x;
    const soclib::common::AddressMaskingTable<addr_t> m_y;
    const soclib::common::AddressMaskingTable<addr_t> m_z;

    //////////////////////////////////////////////////////////////
    inline data_t &cache_data(size_t way, size_t set, size_t word)
    {
        return r_data[(way * m_sets * m_words) + (set * m_words) + word];
    }

    //////////////////////////////////////////////
    inline addr_t &cache_tag(size_t way, size_t set)
    {
        return r_tag[(way * m_sets) + set];
    }

    //////////////////////////////////////////////
    inline bool &cache_lru(size_t way, size_t set)
    {
        return r_lru[(way * m_sets) + set];
    }

    //////////////////////////////////////////////
    inline int &cache_state(size_t way, size_t set)
    {
        return r_state[(way * m_sets) + set];
    }

    /////////////////////////////////////////////////
    inline void cache_set_lru(size_t way, size_t set)
    {
        size_t way2;

        cache_lru(way, set) = true;

        for (way2 = 0; way2 < m_ways; way2++) 
        {
            if (cache_lru(way2, set) == false) return;
        }
        // all lines are new -> they all become old 
        for (way2 = 0; way2 < m_ways; way2++) 
        {
            cache_lru(way2, set) = false;
        }
    }

    ////////////////////////////////
    inline data_t be2mask(be_t be)
    {
        data_t mask = 0;
        if ((be & 0x1) == 0x1) mask = mask | 0x000000FF;
        if ((be & 0x2) == 0x2) mask = mask | 0x0000FF00;
        if ((be & 0x4) == 0x4) mask = mask | 0x00FF0000;
        if ((be & 0x8) == 0x8) mask = mask | 0xFF000000;
        return mask;
    }

    public:

    //////////////////////////////////////////
    GenericCache(const std::string &name,
            size_t nways, 
            size_t nsets, 
            size_t nwords)
        : m_ways(nways),
        m_sets(nsets),
        m_words(nwords),

#define l2 soclib::common::uint32_log2

        m_x( l2(nwords), l2(sizeof(data_t))),
        m_y( l2(nsets), l2(nwords) + l2(sizeof(data_t))),
        m_z( 8*sizeof(addr_t) - l2(nsets) - l2(nwords) - l2(sizeof(data_t)),
                l2(nsets) + l2(nwords) + l2(sizeof(data_t)))
#undef l2
        {
            assert(IS_POW_OF_2(nways));
            assert(IS_POW_OF_2(nsets));
            assert(IS_POW_OF_2(nwords));
            assert(nwords);
            assert(nsets);
            assert(nways);
            assert(nwords <= 64);
            assert(nsets <= 1024);
            assert(nways <= 16);

#ifdef GENERIC_CACHE_DEBUG
            std::cout << "constructing " << name << std::endl
                << "- nways  = " << nways << std::endl
                << "- nsets  = " << nsets << std::endl
                << "- nwords = " << nwords << std::endl
                << " m_x: " << m_x 
                << " m_y: " << m_y
                << " m_z: " << m_z
                << std::endl;
#endif

            r_data  = new data_t[nways * nsets * nwords];
            r_tag   = new addr_t[nways * nsets];
            r_state = new int[nways * nsets];
            r_lru   = new bool[nways * nsets];
        }

    ////////////////
    ~GenericCache()
    {
        delete [] r_data;
        delete [] r_tag;
        delete [] r_state;
        delete [] r_lru;
    }

    ////////////////////
    inline void reset( )
    {
        std::memset(r_data, 0, sizeof(*r_data) * m_ways * m_sets * m_words);
        std::memset(r_tag, 0, sizeof(*r_tag) * m_ways * m_sets);
        std::memset(r_state, CACHE_SLOT_STATE_INVALID, sizeof(*r_state) * m_ways * m_sets);
        std::memset(r_lru, 0, sizeof(*r_lru) * m_ways * m_sets);
    }

    /////////////////////////////////////////////////////////////////////
    // Read a single 32 bits word.
    // returns true if (matching tag) and (state == VALID) 
    // Both data & directory are accessed. 
    /////////////////////////////////////////////////////////////////////
    inline bool read(addr_t ad, 
                     data_t * dt)
    {
        const addr_t tag  = m_z[ad];
        const size_t set  = m_y[ad];
        const size_t word = m_x[ad];

        for (size_t way = 0; way < m_ways; way++)
        {
            if ((tag == cache_tag(way, set))  
                    && (cache_state(way, set) == CACHE_SLOT_STATE_VALID))
            {
                *dt = cache_data(way, set, word);
                cache_set_lru(way, set);
                return true;
            }
        }
        return false;
    }

    ////////////////////////////////////////////////////////////////////
    // Read a single 32 bits word.
    // returns true if (matching tag) and (state == VALID) 
    // Both data & directory are accessed. 
    // The selected way, set and word index are returned in case of hit.
    /////////////////////////////////////////////////////////////////////
    inline bool read(addr_t ad, 
            data_t * dt,
            size_t * selway,
            size_t * selset,
            size_t * selword) 
    {
        const addr_t tag  = m_z[ad];
        const size_t set  = m_y[ad];
        const size_t word = m_x[ad];

        for (size_t way = 0; way < m_ways; way++) 
        {
            if ((tag == cache_tag(way, set)) and (cache_state(way, set) == CACHE_SLOT_STATE_VALID))
            {
                *selway  = way;
                *selset  = set;
                *selword = word;
                *dt = cache_data(way, set, word);
                cache_set_lru(way, set);
                return true;
            }
        }
        return false;
    }

    ////////////////////////////////////////////////////////////////////
    // Read a single 32 bits word 
    // Both data and directory are accessed.
    // returns the access status in the state argument:
    // - VALID : (matching tag) and (state == VALID) 
    // - MISS  : no matching tag or INVALID state
    // If VALID, the data, the way, set and word index are 
    // returned in the other arguments.
    ////////////////////////////////////////////////////////////////////
    inline void read(addr_t ad,
            data_t * dt,
            size_t * selway,
            size_t * selset,
            size_t * selword,
            int * state) 
    {
        const addr_t tag  = m_z[ad];
        const size_t set  = m_y[ad];
        const size_t word = m_x[ad];

        // default return values 
        *state   = CACHE_SLOT_STATE_INVALID;
        *selway  = 0;
        *selset  = 0;
        *selword = 0;
        *dt      = 0;

        for (size_t way = 0; way < m_ways; way++) 
        {
            if (tag == cache_tag(way, set))  // matching tag
            {

                if (cache_state(way, set) == CACHE_SLOT_STATE_VALID)
                {
                    *state   = CACHE_SLOT_STATE_VALID;
                    *selway  = way;
                    *selset  = set;
                    *selword = word;
                    *dt      = cache_data(way, set, word);
                    cache_set_lru(way, set);
                }
            }
        }
    }

    ////////////////////////////////////////////////////////////////////
    // Read a single 32 bits word, without LRU update.
    // returns true if (matching tag) and (state == VALID) 
    // Both data & directory are accessed. 
    // The selected way, set and word index are returned in case of hit.
    /////////////////////////////////////////////////////////////////////
    inline bool read_neutral(addr_t ad, 
            data_t * dt,
            size_t * selway,
            size_t * selset,
            size_t * selword) 
    {
        const addr_t tag  = m_z[ad];
        const size_t set  = m_y[ad];
        const size_t word = m_x[ad];

        for (size_t way = 0; way < m_ways; way++) 
        {
            if ((tag == cache_tag(way, set)) && (cache_state(way, set) == CACHE_SLOT_STATE_VALID))
            {
                *selway  = way;
                *selset  = set;
                *selword = word;
                *dt = cache_data(way, set, word);
                return true;
            }
        }
        return false;
    }

    /////////////////////////////////////////////////////////////////////////////
    // Read one or two 32 bits word.
    // Both data & directory are accessed. 
    // Hit if (matching tag) and (valid == true) and (zombi == false) 
    // If the addressed word is not the last in the cache line,
    // two successive words are returned.
    // The selected way, set and first word index are returned in case of hit.
    // This function is used by the cc_vcache to get a 64 bits page table entry.
    /////////////////////////////////////////////////////////////////////////////
    inline bool read(addr_t ad, 
            data_t * dt, 
            data_t * dt_next,
            size_t * selway,
            size_t * selset,
            size_t * selword)
    {
        const addr_t tag  = m_z[ad];
        const size_t set  = m_y[ad];
        const size_t word = m_x[ad];

        for (size_t way = 0; way < m_ways; way++)
        {
            if ((tag == cache_tag(way, set))
                    && (cache_state(way, set) == CACHE_SLOT_STATE_VALID))
            {
                *dt = cache_data(way, set, word);
                if (word + 1 < m_words) 
                {
                    *dt_next = cache_data(way, set, word + 1);
                }
                *selway  = way;
                *selset  = set;
                *selword = word;
                cache_set_lru(way, set);
                return true;
            }
        }
        return false;
    }

    ////////////////////////////////////////////////////////////////////
    // Read one or two 32 bits word.
    // Both data and directory are accessed.
    // returns the access status in the state argument:
    // - VALID : (matching tag) and (state == VALID) 
    // - MISS  : no matching tag or INVALID state
    // If VALID, the data, the way, set and word index are 
    // returned in the other arguments.
    ////////////////////////////////////////////////////////////////////
    inline void read(addr_t ad,
            data_t * dt,
            data_t * dt_next,
            size_t * selway,
            size_t * selset,
            size_t * selword,
            int * state) 
    {
        const addr_t tag  = m_z[ad];
        const size_t set  = m_y[ad];
        const size_t word = m_x[ad];

        // default return values 
        *state   = CACHE_SLOT_STATE_INVALID;
        *selway  = 0;
        *selset  = 0;
        *selword = 0;
        *dt      = 0;

        for (size_t way = 0; way < m_ways; way++) 
        {
            if (tag == cache_tag(way, set))  // matching tag
            {
                if (cache_state(way, set) == CACHE_SLOT_STATE_VALID)
                {
                    *state   = CACHE_SLOT_STATE_VALID;
                    *selway  = way;
                    *selset  = set;
                    *selword = word;
                    *dt      = cache_data(way, set, word);
                    if (word + 1 < m_words) 
                    {
                        *dt_next = cache_data(way, set, word + 1);
                    }
                    else {
                        assert(false && "can't request 2 words at end of line");
                    }
                    cache_set_lru(way, set);
                }
            }
        }
    }

    ///////////////////////////////////////////////////////////////////////////////
    // Checks the cache state for a given address.
    // Only the directory is accessed. 
    // returns true if (matching tag) and (state == VALID) 
    // The selected way, set and first word index are returned in case of hit.
    // This function can be used when we need to access the directory
    // while we write in the data part with a different address in the same cycle.
    ///////////////////////////////////////////////////////////////////////////////
    inline bool hit(addr_t ad, 
            size_t * selway,
            size_t * selset,
            size_t * selword)
    {
        const addr_t tag  = m_z[ad];
        const size_t set  = m_y[ad];
        const size_t word = m_x[ad];

        for (size_t way = 0; way < m_ways; way++) 
        {
            if ((tag == cache_tag(way, set)) 
                    && (cache_state(way, set) == CACHE_SLOT_STATE_VALID)) 
            {
                *selway  = way;
                *selset  = set;
                *selword = word;
                cache_set_lru(way, set);
                return true;
            }
        }
        return false;
    }

    ///////////////////////////////////////////////////////////////////////////////
    // Checks the cache state for a given address.
    // Only the directory is accessed. 
    // Returns the access status in the state argument:
    // - VALID if (matching tag) and (state == VALID) 
    // - INVALID if no match or (state == INVALID)
    // The selected way, set and first word index are returned if not empty.
    // This function can be used when we need to access the directory
    // while we write in the data part with a different address in the same cycle.
    ///////////////////////////////////////////////////////////////////////////////
    inline void read_dir(addr_t ad, 
            int * state,
            size_t * way,
            size_t * set,
            size_t * word)
    {
        const addr_t ad_tag  = m_z[ad];
        const size_t ad_set  = m_y[ad];
        const size_t ad_word = m_x[ad];

        for (size_t _way = 0; _way < m_ways; _way++) 
        {
            if ((ad_tag == cache_tag(_way, ad_set)) and 
                    (cache_state(_way, ad_set) != CACHE_SLOT_STATE_INVALID)) 
            {
                *state = cache_state(_way, ad_set);
                *way   = _way;
                *set   = ad_set;
                *word  = ad_word;
                return;
            }
        }

        // return value if not (VALID)
        *state = CACHE_SLOT_STATE_INVALID;
    }

    ///////////////////////////////////////////////////////////////////////////////
    // Checks the cache state for a slot (set,way)
    // Only the directory is accessed. 
    // Returns the access status and the tag value in the state and tag argument.
    ///////////////////////////////////////////////////////////////////////////////
    inline void read_dir(size_t way,
            size_t set,
            addr_t * tag,
            int * state)
    {
        *state = cache_state(way, set);
        *tag   = cache_tag(way, set);
    }

    ////////////////////////////////////////////
    inline addr_t get_tag(size_t way, size_t set)
    {
        return cache_tag(way, set);
    }

    ///////////////////////////////////////////////////////////////////
    // This function writes a complete 32 bits word
    // It does not use the directory and cannot miss.
    //////////////////////////////////////////////////////////////////
    inline void write(size_t  way, 
            size_t set, 
            size_t word, 
            data_t data)
    {
        cache_data(way, set, word) = data;
        cache_set_lru(way, set);
    }

    ////////////////////////////////////////////////////////////////////////////
    // this function writes up to 4 bytes, taking into account the byte enable.
    // It does not use the directory and cannot miss.
    ////////////////////////////////////////////////////////////////////////////
    inline void write(size_t way, 
            size_t set, 
            size_t word, 
            data_t data, 
            be_t   be)
    {
        data_t mask = be2mask(be);
        data_t prev = cache_data(way, set, word);
        cache_data(way, set, word) = (mask & data) | (~mask & prev);
        cache_set_lru(way, set);
    }

    //////////////////////////////////////////////////////////////////////////
    // This function invalidates a cache line identified by the set and way.
    // It returns true if the line was valid, and returns the line index.
    //////////////////////////////////////////////////////////////////////////
    inline bool inval(size_t way, 
            size_t set, 
            addr_t * nline)
    {
        if (cache_state(way,set) == CACHE_SLOT_STATE_VALID ) 
        {
            cache_state(way,set) = CACHE_SLOT_STATE_INVALID;
            *nline = (data_t)cache_tag(way,set) * m_sets + set;
            return true;
        }
        return false;
    }

    //////////////////////////////////////////////////////////////////////////////////
    // This function selects a victim slot in an associative set.
    // It cannot fail.
    // - we search first an INVALID slot 
    // - if no INVALID slot, we search an OLD slot, using lru
    // It returns the line index (Z + Y fields), the selected slot way and set, 
    // and a Boolean indicating that a cleanup is requested.
    //////////////////////////////////////////////////////////////////////////////////
    inline bool victim_select(addr_t ad, 
            addr_t * victim, 
            size_t * way, 
            size_t * set)
    {
        bool found   = false;
        bool cleanup = false;

        *set = m_y[ad];
        *way = 0;

        // Search first empty slot 
        for (size_t _way = 0; _way < m_ways && !found; _way++)
        {
            if (cache_state(_way, *set) != CACHE_SLOT_STATE_VALID)  // empty
            {
                found   = true;
                cleanup = false;
                *way    = _way;
            }
        }

        // If no empty slot, search first  old slot (lru == false) 
        if (!found)
        { 
            for (size_t _way = 0; _way < m_ways && !found; _way++)
            {
                if (not cache_lru(_way, *set))
                {
                    found   = true;
                    cleanup = true;
                    *way    = _way;
                }
            }
        }

        assert(found && "all ways can't be new at the same time");
        *victim = (addr_t) ((cache_tag(*way, *set) * m_sets) + *set);
        return cleanup;
    }

    //////////////////////////////////////////////////////////////////////////////////
    // This function selects a victim slot in an associative set.
    // - we search first an INVALID slot
    // - if not found we search a slot with the LRU bit unset
    // It returns the line index (Z + Y fields), the selected slot way and set, 
    // and two Boolean indicating success and a required cleanup.
    //////////////////////////////////////////////////////////////////////////////////
    inline void read_select(addr_t ad, 
            addr_t * victim, 
            size_t * way, 
            size_t * set,
            bool * found,
            bool * cleanup)
    {
        size_t _set = m_y[ad];

        *found = false;

        // Search first empty slot 
        for (size_t _way = 0; _way < m_ways && !(*found); _way++)
        {
            if (cache_state(_way, _set) == CACHE_SLOT_STATE_INVALID)
            {
                *found   = true;
                *cleanup = false;
                *way     = _way;
                *set     = m_y[ad];
                return;
            }
        }
        // all ways are valid, searching one with the LRU bit at 0
        for (size_t _way = 0; _way < m_ways && !(*found); _way++)
        {
            if (not cache_lru(_way, _set))
            {
                *found   = true;
                *cleanup = true;
                *way     = _way;
                *set     = m_y[ad];
                *victim  = cache_tag(*way, _set) * m_sets + _set;
                return;
            }
        }
        assert(false);
        // We should not be able to arrive here
        // returning way 0
        *found   = true;
        *cleanup = true;
        *way     = 0;
        *set     = m_y[ad];
        *victim  = cache_tag(*way, _set) * m_sets + _set;
        return;
    }

    //////////////////////////////////////////////////////////////////
    // This function update the directory part of a slot
    // identified by the way & set.
    //////////////////////////////////////////////////////////////////
    inline void victim_update_tag(addr_t ad, 
            size_t way, 
            size_t set)
    {
        addr_t tag = m_z[ad];

        cache_tag(way, set) = tag;
        cache_state(way, set) = CACHE_SLOT_STATE_VALID;
        cache_set_lru(way, set);
    }

    //////////////////////////////////////////////////////////////////
    // This function write the directory part of a slot
    // identified by the way & set
    //////////////////////////////////////////////////////////////////
    inline void write_dir( addr_t ad, 
            size_t way, 
            size_t set,
            int    state)
    {
        addr_t tag = m_z[ad];

        assert(((state == CACHE_SLOT_STATE_VALID) or 
                (state == CACHE_SLOT_STATE_INVALID)) and
                "illegal slot state argument in Generic Cache write_dir()");

        assert((way < m_ways) and "too large way index argument in Generic Cache write_dir()");
        assert((set < m_sets) and "too large set index argument in Generic Cache write_dir()");

        cache_tag(way, set) = tag;
        cache_state(way, set) = state;

        if (state == CACHE_SLOT_STATE_VALID) cache_set_lru(way, set);
    }

    //////////////////////////////////////////////////////////////////
    // This function change the state of a slot
    // identified by the way & set.
    // It does not affect the tag
    //////////////////////////////////////////////////////////////////
    inline void write_dir(size_t way, 
            size_t set,
            int    state)
    {
        assert(((state == CACHE_SLOT_STATE_VALID) or 
                (state == CACHE_SLOT_STATE_INVALID)) and
                "illegal slot state argument in Generic Cache write_dir()");

        assert((way < m_ways) and "too large way index argument in Generic Cache write_dir()");
        assert((set < m_sets) and "too large set index argument in Generic Cache write_dir()");

        cache_state(way, set) = state;

        if (state == CACHE_SLOT_STATE_VALID) cache_set_lru(way, set);
    }

    ///////////////////////////////////////////////////////////////////
    // This function writes a full cache line in one single cycle.
    // The target slot is identified by the way & set arguments.
    // Both DATA and DIRECTORY are written
    ///////////////////////////////////////////////////////////////////
    inline void update(addr_t ad, 
            size_t way, 
            size_t set, 
            data_t * buf)
    {
        addr_t tag = m_z[ad];

        cache_tag(way, set) = tag;
        cache_state(way, set) = CACHE_SLOT_STATE_VALID;
        cache_set_lru(way, set);
        for (size_t word = 0; word < m_words; word++) 
        {
            cache_data(way, set, word) = buf[word] ;
        }
    }

    ///////////////////////////
    void fileTrace(FILE * file)
    {
        for (size_t nway = 0; nway < m_ways; nway++) 
        {
            for (size_t nset = 0; nset < m_sets; nset++) 
            {
                fprintf(file, "%d / ", (int) cache_state(nway, nset));
                fprintf(file, "way %d / ", (int) nway);
                fprintf(file, "set %d / ", (int) nset);
                fprintf(file, "@ = %08zX / ", 
                        ((cache_tag(nway, nset) * m_sets+nset) * m_words * 4));
                for (size_t nword = m_words; nword > 0; nword--) 
                {
                    unsigned int data = cache_data(nway, nset, nword - 1);
                    fprintf(file, "%08X ", data );
                }
                fprintf(file, "\n");
            }
        }
    }

    ////////////////////////
    inline void printTrace()
    {
        for ( size_t way = 0; way < m_ways ; way++ ) 
        {
            for ( size_t set = 0 ; set < m_sets ; set++ )
            {
                addr_t addr = (((addr_t) cache_tag(way,set)) * m_words * m_sets + m_words * set) * 4;
                std::cout << std::dec << cache_state(way, set) 
                    << " | way " << way 
                    << " | set " << set 
                    << std::hex << " | @ " << addr;

                for ( size_t word = 0 ; word < m_words ; word++ )
                {
                    std::cout << " | " << cache_data(way,set,word) ;
                }
                std::cout << std::endl ;
            }
        }
    }

};

} // namespace soclib

#endif

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