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/* icache_model.c -- instruction 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 instruction

   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 "icache_model.h"

#include "abstract.h"

#include "stats.h"

#include "sim-config.h"

#include "spr_defs.h"

#include "sprs.h"

#include "sim-config.h"

extern struct dev_memarea *cur_area;

struct ic_set {

  struct {

    unsigned long line[MAX_IC_BLOCK_SIZE];

    unsigned long tagaddr;  /* tag address */

    int lru;    /* least recently used */

  } way[MAX_IC_WAYS];

} ic[MAX_IC_SETS];

void ic_info()

{

  if (!testsprbits(SPR_UPR, SPR_UPR_ICP)) {

    printf("ICache not implemented. Set UPR[ICP].\n");

    return;

  }

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

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

}

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

    - increment IC read hit stats,

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

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

    - read insn from the cache line

   and if not:

    - increment IC read miss stats

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

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

      ways unless they have reached 0

    - refill cache line

*/

unsigned long ic_simulate_fetch(unsigned long fetchaddr)

{

  int set, way = -1;

  int i;

  unsigned long tagaddr;

  extern int mem_cycles;

  /* ICache simulation enabled/disabled. */

  if ((!testsprbits(SPR_UPR, SPR_UPR_ICP)) || (!testsprbits(SPR_SR, SPR_SR_ICE)))

    return evalsim_mem32(fetchaddr);

  /* Which set to check out? */

  set = (fetchaddr / config.ic.blocksize) % config.ic.nsets;

  tagaddr = (fetchaddr / config.ic.blocksize) / config.ic.nsets;

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

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

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

      way = i;

  /* Did we find our cached instruction? */

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

    ic_stats.readhit++;

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

      if (ic[set].way[i].lru > ic[set].way[way].lru)

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

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

    mem_cycles += config.ic.hitdelay;

    return (ic[set].way[way].line[(fetchaddr & (config.ic.blocksize - 1)) >> 2]);

  }

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

    int minlru = config.ic.ustates - 1;

    int minway = 0;

    ic_stats.readmiss++;

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

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

        minway = i;

    for (i = 0; i < (config.ic.blocksize); i += 4) {

      ic[set].way[minway].line[((fetchaddr + i) & (config.ic.blocksize - 1)) >> 2] =

        evalsim_mem32((fetchaddr & ~(config.ic.blocksize - 1)) + ((fetchaddr + i) & (config.ic.blocksize - 1)));

      if(!cur_area)

        return 0;

    }

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

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

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

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

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

    mem_cycles += config.ic.missdelay;

    return (ic[set].way[minway].line[(fetchaddr & (config.ic.blocksize - 1)) >> 2]);

  }

}

/* 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 ic_inv(unsigned long dataaddr)

{

  int set, way = -1;

  int i;

  unsigned long tagaddr;

  if (!testsprbits(SPR_UPR, SPR_UPR_ICP))

    return;

  /* Which set to check out? */

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

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

  if (!testsprbits(SPR_SR, SPR_SR_ICE)) {

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

      ic[set].way[i].tagaddr = -1;

      ic[set].way[i].lru = 0;

    }

    return;

  }

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

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

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

      way = i;

  /* Did we find our cached data? */

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

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

    ic[set].way[way].lru = 0;

  }

}

inline void ic_clock()

{

  unsigned long addr;

  if (addr = mfspr(SPR_ICBPR)) {

    ic_simulate_fetch(addr);

    mtspr(SPR_ICBPR, 0);

  }

  if (addr = mfspr(SPR_ICBIR)) {

    ic_inv(addr);

    mtspr(SPR_ICBIR, 0);

  }

  if (addr = mfspr(SPR_ICBLR)) {

    mtspr(SPR_ICBLR, 0);

  }

}