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/* dcache_model.c -- data cache simulation

   Copyright (C) 1999 Damjan Lampret, lampret@opencores.org

This file is part of OpenRISC 1000 Architectural Simulator.

This program is free software; you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation; either version 2 of the License, or

(at your option) any later version.

This program 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 General Public License for more details.

You should have received a copy of the GNU General Public License

along with this program; if not, write to the Free Software

Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */

/* Cache functions.

   At the moment this functions only simulate functionality of data

   caches and do not influence on fetche/decode/execute stages and timings.

   They are here only to verify performance of various cache configurations.

 */

#include <stdio.h>

#include <string.h>

#include <errno.h>

#include <stdarg.h>

#include "dcache_model.h"

#include "abstract.h"

#include "stats.h"

#include "spr_defs.h"

#include "sprs.h"

#include "sim-config.h"

/* Data cache */

struct dc_set {

  struct {

    unsigned long tagaddr;  /* tag address */

    int lru;    /* least recently used */

  } way[MAX_DC_WAYS];

} dc[MAX_DC_SETS];

void dc_info()

{

  if (!testsprbits(SPR_UPR, SPR_UPR_DCP)) {

    printf("DCache not implemented. Set UPR[DCP].\n");

    return;

  }

  printf("Data cache %dKB: ", config.dc.nsets * config.dc.blocksize * config.dc.nways / 1024);

  printf("%d ways, %d sets, block size %d bytes\n", config.dc.nways, config.dc.nsets, config.dc.blocksize);

}

/* First check if data is already in the cache and if it is:

    - increment DC read hit stats,

    - set 'lru' at this way to config.dc.ustates - 1 and

      decrement 'lru' of other ways unless they have reached 0,

   and if not:

    - increment DC read miss stats

    - find lru way and entry and replace old tag with tag of the 'dataaddr'

    - set 'lru' with config.dc.ustates - 1 and decrement 'lru' of other

      ways unless they have reached 0

*/

void dc_simulate_read(unsigned long dataaddr)

{

  int set, way = -1;

  int i;

  unsigned long tagaddr;

  if ((!testsprbits(SPR_UPR, SPR_UPR_DCP)) || (!testsprbits(SPR_SR, SPR_SR_DCE)))

    return;

  /* Which set to check out? */

  set = (dataaddr / config.dc.blocksize) % config.dc.nsets;

  tagaddr = (dataaddr / config.dc.blocksize) / config.dc.nsets;

  /* Scan all ways and try to find a matching way. */

  for (i = 0; i < config.dc.nways; i++)

    if (dc[set].way[i].tagaddr == tagaddr)

      way = i;

  /* Did we find our cached data? */

  if (way >= 0) { /* Yes, we did. */

    dc_stats.readhit++;

    for (i = 0; i < config.dc.nways; i++)

      if (dc[set].way[i].lru)

        dc[set].way[i].lru--;

    dc[set].way[way].lru = config.dc.ustates - 1;

  }

  else {  /* No, we didn't. */

    int minlru = config.dc.ustates - 1;

    int minway = 0;

                dc_stats.readmiss++;

    for (i = 0; i < config.dc.nways; i++)

      if ((dc[set].way[i].lru < minlru) &&

          (getsprbits(SPR_DCCR, SPR_DCCR_EW) & (1 << i)))

        minway = i;

    dc[set].way[minway].tagaddr = tagaddr;

    for (i = 0; i < config.dc.nways; i++)

      if (dc[set].way[i].lru)

        dc[set].way[i].lru--;

    dc[set].way[minway].lru = config.dc.ustates - 1;

  }

}

/* First check if data is already in the cache and if it is:

    - increment DC write hit stats,

    - set 'lru' at this way to config.dc.ustates - 1 and

      decrement 'lru' of other ways unless they have reached 0,

   and if not:

    - increment DC write miss stats

    - find lru way and entry and replace old tag with tag of the 'dataaddr'

    - set 'lru' with config.dc.ustates - 1 and decrement 'lru' of other

      ways unless they have reached 0

*/

void dc_simulate_write(unsigned long dataaddr)

{

  int set, way = -1;

  int i;

  unsigned long tagaddr;

  if ((!testsprbits(SPR_UPR, SPR_UPR_DCP)) || (!testsprbits(SPR_SR, SPR_SR_DCE)))

    return;

  /* Which set to check out? */

  set = (dataaddr / config.dc.blocksize) % config.dc.nsets;

  tagaddr = (dataaddr / config.dc.blocksize) / config.dc.nsets;

  /* Scan all ways and try to find a matching way. */

  for (i = 0; i < config.dc.nways; i++)

    if (dc[set].way[i].tagaddr == tagaddr)

      way = i;

  /* Did we find our cached data? */

  if (way >= 0) { /* Yes, we did. */

    dc_stats.writehit++;

    for (i = 0; i < config.dc.nways; i++)

      if (dc[set].way[i].lru)

        dc[set].way[i].lru--;

    dc[set].way[way].lru = config.dc.ustates - 1;

  }

  else {  /* No, we didn't. */

    int minlru = config.dc.ustates - 1;

    int minway = 0;

                dc_stats.writemiss++;

    for (i = 0; i < config.dc.nways; i++)

      if ((dc[set].way[i].lru < minlru) &&

          (getsprbits(SPR_DCCR, SPR_DCCR_EW) & (1 << i)))

        minway = i;

    dc[set].way[minway].tagaddr = tagaddr;

    for (i = 0; i < config.dc.nways; i++)

      if (dc[set].way[i].lru)

        dc[set].way[i].lru--;

    dc[set].way[minway].lru = config.dc.ustates - 1;

  }

}

/* First check if data is already in the cache and if it is:

    - invalidate block if way isn't locked

   otherwise don't do anything.

*/

void dc_inv(unsigned long dataaddr)

{

  int set, way = -1;

  int i;

  unsigned long tagaddr;

  if (!testsprbits(SPR_UPR, SPR_UPR_DCP))

    return;

  /* Which set to check out? */

  set = (dataaddr / config.dc.blocksize) % config.dc.nsets;

  tagaddr = (dataaddr / config.dc.blocksize) / config.dc.nsets;

  /* Scan all ways and try to find a matching way. */

  for (i = 0; i < config.dc.nways; i++)

    if (dc[set].way[i].tagaddr == tagaddr)

      way = i;

  /* Did we find our cached data? */

  if ((way >= 0) && (getsprbits(SPR_DCCR, SPR_DCCR_EW) & (1 << way))) { /* Yes, we did. */

    dc[set].way[way].tagaddr = -1;

  }

}

inline void dc_clock()

{

  unsigned long addr;

  if (addr = mfspr(SPR_DCBPR)) {

    dc_simulate_read(addr);

    mtspr(SPR_DCBPR, 0);

  }

  if (addr = mfspr(SPR_DCBFR)) {

    dc_inv(addr);

    mtspr(SPR_DCBFR, 0);

  }

  if (addr = mfspr(SPR_DCBIR)) {

    dc_inv(addr);

    mtspr(SPR_DCBIR, 0);

  }

  if (addr = mfspr(SPR_DCBWR)) {

    mtspr(SPR_DCBWR, 0);

  }

  if (addr = mfspr(SPR_DCBLR)) {

    mtspr(SPR_DCBLR, 0);

  }

}