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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 "except.h"
#include "stats.h"
#include "spr_defs.h"
#include "sprs.h"
#include "sim-config.h"
 
/* Data cache */
 
struct dc_set {
  struct {
    unsigned long line[MAX_DC_BLOCK_SIZE];
    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
    - refill cache line
*/
 
unsigned long dc_simulate_read(unsigned long dataaddr, int width)
{
  int set, way = -1;
  int i;
  unsigned long tagaddr;
  unsigned long tmp;
 
  if ((!testsprbits(SPR_UPR, SPR_UPR_DCP)) || 
      (!testsprbits(SPR_SR, SPR_SR_DCE))   ||
      data_ci) {
    if (width == 4)
      tmp = evalsim_mem32(dataaddr);
    else if (width == 2)
      tmp = (unsigned long)evalsim_mem16(dataaddr);
    else if (width == 1)
      tmp = (unsigned long)evalsim_mem8(dataaddr);
 
    if(!cur_area) {
      if (width == 4)
        printf("EXCEPTION: read out of memory (32-bit access to %.8lx)\n", dataaddr);
      else if (width == 2)
        printf("EXCEPTION: read out of memory (16-bit access to %.8lx)\n", dataaddr);
      else if (width == 1)
        printf("EXCEPTION: read out of memory (8-bit access to %.8lx)\n", dataaddr);
      except_handle(EXCEPT_BUSERR, cur_vadd);
      return 0;
    }
 
    if (!pending.valid && cur_area->log)
      fprintf (cur_area->log, "[%08x] -> read %08x\n", dataaddr, tmp);
 
    return tmp;
  }
 
  /* 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[way].lru)
        dc[set].way[i].lru--;
    dc[set].way[way].lru = config.dc.ustates - 1;
    runtime.sim.mem_cycles += config.dc.load_hitdelay;
 
    tmp = dc[set].way[way].line[(dataaddr & (config.dc.blocksize - 1)) >> 2];
    if (width == 4)
      return tmp;
    else if (width == 2) {
      tmp = (unsigned long)((tmp >> ((dataaddr & 2) ? 0 : 16)) & 0xffff);
      return tmp;
    }
    else if (width == 1) {
      tmp = (unsigned long)((tmp  >> (8 * (3 - (dataaddr & 3)))) & 0xff);
      return tmp;
    }
  } 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) {
        minway = i;
        minlru = dc[set].way[i].lru;
      }
    }
 
    for (i = 0; i < (config.dc.blocksize); i += 4) {
      dc[set].way[minway].line[((dataaddr + i) & (config.dc.blocksize - 1)) >> 2] = 
        evalsim_mem32((dataaddr & ~(config.dc.blocksize - 1)) + (((dataaddr & ~3ul)+ i) & (config.dc.blocksize - 1)));
      if(!cur_area) {
        dc[set].way[minway].tagaddr = -1;
        dc[set].way[minway].lru = 0;
        printf("EXCEPTION: read out of memory (32-bit access to %.8lx)\n", dataaddr);
        except_handle(EXCEPT_BUSERR, cur_vadd);
        return 0;
      }
      if (!pending.valid && cur_area->log)
        fprintf (cur_area->log, "[%08x] -> read %08x\n", dataaddr, tmp);
    }
 
    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;
    runtime.sim.mem_cycles += config.dc.load_missdelay;
 
    tmp = dc[set].way[minway].line[(dataaddr & (config.dc.blocksize - 1)) >> 2];
    if (width == 4)
      return tmp;
    else if (width == 2) {
      tmp = (unsigned long)((tmp >> ((dataaddr & 2) ? 0 : 16)) & 0xffff);
      return tmp;
    }
    else if (width == 1) {
      tmp = (unsigned long)((tmp  >> (8 * (3 - (dataaddr & 3)))) & 0xff);
      return tmp;
    }
  }
}
 
/* 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, unsigned long data, int width)
{
  int set, way = -1;
  int i;
  unsigned long tagaddr;
  unsigned long tmp;
 
  if (width == 4)
    setsim_mem32(dataaddr, data);
  else if (width == 2)    
    setsim_mem16(dataaddr, (unsigned short)data);
  else if (width == 1)    
    setsim_mem8(dataaddr, (unsigned char)data);
 
  if ((!testsprbits(SPR_UPR, SPR_UPR_DCP)) || 
      (!testsprbits(SPR_SR, SPR_SR_DCE)) ||
      data_ci ||
      (!cur_area))
    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[way].lru)
        dc[set].way[i].lru--;
    dc[set].way[way].lru = config.dc.ustates - 1;
    runtime.sim.mem_cycles += config.dc.store_hitdelay;
 
    tmp = dc[set].way[way].line[(dataaddr & (config.dc.blocksize - 1)) >> 2];
    if (width == 4)
      tmp = data;
    else if (width == 2) {
      tmp &= 0xffff << ((dataaddr & 2) ? 16 : 0);
      tmp |= (unsigned long)(data & 0xffff) << ((dataaddr & 2) ? 0 : 16);
    }
    else if (width == 1) {
      tmp &= ~(0xff << (8 * (3 - (dataaddr & 3))));
      tmp |= (unsigned long)(data & 0xff) << (8 * (3 - (dataaddr & 3)));
    }
    dc[set].way[way].line[(dataaddr & (config.dc.blocksize - 1)) >> 2] = tmp;
  }
  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)
        minway = i;
 
    for (i = 0; i < (config.dc.blocksize); i += 4) {
      dc[set].way[minway].line[((dataaddr + i) & (config.dc.blocksize - 1)) >> 2] = 
        evalsim_mem32((dataaddr & ~(config.dc.blocksize - 1)) + (((dataaddr & ~3ul)+ i) & (config.dc.blocksize - 1)));
      if(!cur_area) {
        dc[set].way[minway].tagaddr = -1;
        dc[set].way[minway].lru = 0;
        return;
      }
    }
 
    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;
    runtime.sim.mem_cycles += config.dc.store_missdelay;
  }
}
 
/* 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;
 
  if (!testsprbits(SPR_SR, SPR_SR_DCE)) {
    for (i = 0; i < config.dc.nways; i++) {
      dc[set].way[i].tagaddr = -1;
      dc[set].way[i].lru = 0;
    }
    return;
  }
   /* 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[set].way[way].tagaddr = -1;
    dc[set].way[way].lru = 0;
  }
}
 
inline void dc_clock()
{
  unsigned long addr;
 
  if (addr = mfspr(SPR_DCBPR)) {
    dc_simulate_read(addr, 4);
    mtspr(SPR_DCBPR, 0);
  }
  if ((addr = mfspr(SPR_DCBFR)) != -1) {
    dc_inv(addr);
    mtspr(SPR_DCBFR, -1);
  }
  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);
  }
}