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!/* SPIM S20 MIPS Cycle Level simulator.
Definitions for the SPIM S20 Cycle Level Simulator (SPIM-CL).
Copyright (C) 1991-1992 by Anne Rogers (amr@cs.princeton.edu) and
Scott Rosenberg (scottr@cs.princeton.edu)
ALL RIGHTS RESERVED.
SPIM-CL is distributed under the following conditions:
You may make copies of SPIM-CL for your own use and modify those copies.
All copies of SPIM-CL must retain our names and copyright notice.
You may not sell SPIM-CL or distributed SPIM-CL in conjunction with a
commerical product or service without the expressed written consent of
Anne Rogers.
THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE.
*/
#include "spim.h"
#include "inst.h"
#include "reg.h"
#include "mem.h"
#include "mips-syscall.h"
#include "cl-mem.h"
#include "cl-tlb.h"
struct tlb_entry {
unsigned int upper, lower;
};
/* Exported Variables: */
int tlb_on; /* !0 -> tlb handling is on */
/* Local Functions: */
#ifdef __STDC__
unsigned int find_page (unsigned int vpn);
#else
unsigned int find_page ();
#endif
#define TLB_SIZE 64 /* tlb size */
#define PT_INCR 100 /* increment size for external page table */
#define tlb_VPN(i) (((TLB[i].upper) >> 12) & 0xfffff)
#define tlb_PID(i) (((TLB[i].upper) >> 6) & (0x3f))
#define tlb_PFN(i) (((TLB[i].lower) >> 12) & (0xfffff))
#define tlb_N(i) (((TLB[i].lower) >> 11) & 0x1)
#define tlb_D(i) (((TLB[i].lower) >> 10) & 0x1)
#define tlb_V(i) (((TLB[i].lower) >> 9) & 0x1)
#define tlb_G(i) (((TLB[i].lower) >> 8) & 0x1)
#define tlb_u_update(i, VPN, PID) \
{ TLB[i].upper = ((VPN << 12) | ((PID & 0x3f) << 6)); }
#define tlb_l_update(i, PFN, N, D, V, G) \
{ TLB[i].lower = ((PFN << 12) | (N << 11) | (D << 10) | (V << 9) | (G << 1)); }
#define tbl_update(i, VPN, PID, PFN, N, D, V, G) \
{ tlb_u_update(i, VPN, PID); \
tlb_l_update(i, PFN, N, D, V, G); \
}
/* local variables */
static struct tlb_entry TLB[TLB_SIZE]; /* tlb's register-based page table */
static struct tlb_entry *PT = NULL; /* external page table information */
static int pt_high;
static int pt_size;
#ifdef __STDC__
void
tlb_init (void)
#else
void
tlb_init ()
#endif
{
int i;
for (i=1; i < TLB_SIZE; i++) {
TLB[i].upper = 0;
TLB[i].lower = 0;
}
Random = 63 << 8;
free (PT);
PT = NULL;
pt_high = 0;
pt_size = 0;
}
/* Virtual Address Translation -- See Kane Ch. 4*/
/* VPN is in the low order 20 bits of the variable vpn */
/* PID is in the low order 6 bits of the variable pid */
#ifdef __STDC__
int
tlb_vat (mem_addr addr, unsigned int pid, int l_or_s, mem_addr *paddr)
#else
int
tlb_vat(addr, pid, l_or_s, paddr)
mem_addr addr, *paddr;
unsigned int pid;
int l_or_s;
#endif
{
int i, msb;
mem_addr temp_badvaddr;
unsigned int vpn;
if (!tlb_on) {
*paddr = addr;
return CACHEABLE;
}
vpn = addr >> 12;
temp_badvaddr = BadVAddr;
BadVAddr = addr & 0xfffff000;
msb = (vpn >> 19) & 0x1;
if (msb & (Status_Reg & 0x2))
return ((l_or_s) ? ADDRL_EXCPT : ADDRS_EXCPT);
for (i=0; i < TLB_SIZE; i++) {
if (tlb_VPN(i) == vpn)
break;
}
if (i >= TLB_SIZE) {
return ((l_or_s) ? TLBL_EXCPT : TLBS_EXCPT);
}
if ((!tlb_G(i)) && (tlb_PID(i) != pid))
return ((l_or_s) ? TLBL_EXCPT : TLBS_EXCPT);
if (!(tlb_V(i))) {
return ((l_or_s) ? TLBL_EXCPT : TLBS_EXCPT);
}
if (!(tlb_D(i)) && !(l_or_s)) {
return (MOD_EXCPT);
}
BadVAddr = temp_badvaddr;
*paddr = (tlb_PFN(i) << 12) | (addr & 0xfff);
return ((tlb_N(i)) ? CACHEABLE : NOT_CACHEABLE);
}
/* TLB Probe */
#ifdef __STDC__
void
tlbp (void)
#else
void
tlbp ()
#endif
{
int vpn, pid;
int i;
vpn = EntryHI >> 12;
pid = (EntryHI >> 6) & 0x3f;
for (i=0; i < TLB_SIZE; i++)
if (tlb_VPN(i) == vpn)
break;
if ((i == TLB_SIZE) || (tlb_PID(i) != pid))
/* no match found */
Index = (1 << 31);
else
Index = (i << 8);
}
/* TLB Read */
#ifdef __STDC__
void
tlbr (void)
#else
void
tlbr ()
#endif
{
int index;
index = (Index >> 8) & 0x3f;
EntryHI = TLB[index].upper;
EntryLO = TLB[index].lower;
}
/* TLB Write Indexed */
#ifdef __STDC__
void
tlbwi (void)
#else
void
tlbwi ()
#endif
{
int index;
index = (Index >> 8) & 0x3f;
TLB[index].upper = EntryHI;
TLB[index].lower = EntryLO;
}
/* TLB Write Random */
#ifdef __STDC__
void
tlbwr (void)
#else
void
tlbwr ()
#endif
{
int index;
index = (Random >> 8) & 0x3f;
TLB[index].upper = EntryHI;
TLB[index].lower = EntryLO;
}
/* Service a TLB miss */
#ifdef __STDC__
void
tlb_service (unsigned int pid, int l_or_s)
#else
void
tlb_service (pid, l_or_s)
unsigned int pid;
int l_or_s;
#endif
{
unsigned int vpn, pfn;
vpn = (BadVAddr >> 12) & 0xfffff;
pfn = find_page(vpn);
EntryHI = ((vpn << 12) | (pid << 6));
EntryLO = ((pfn << 12) | (1 << 11) | (!l_or_s << 10) | (1 << 9));
tlbp();
if (Index >> 31)
/* No match found */
tlbwr();
else
tlbwi();
}
#ifdef __STDC__
unsigned int
find_page (unsigned int vpn)
#else
unsigned int find_page (vpn)
unsigned int vpn;
#endif
{
int i;
for (i = 0; i < pt_high; i++)
if ((((PT[i].upper >> 12) & 0xfffff) == vpn) &&
((PT[i].lower >> 9) & 0x1))
{
return i;
}
if (pt_high >= pt_size) {
/* Initialization sets PT to NULL so must use malloc for the first time */
if (PT == NULL)
PT = (struct tlb_entry *) malloc(PT_INCR * sizeof(struct tlb_entry));
else
PT = (struct tlb_entry *)
realloc(PT, (pt_size + PT_INCR) * sizeof(struct tlb_entry));
if (PT == NULL) {
printf("malloc/realloc in find_page failed -- %d\n",
(pt_size+PT_INCR) * sizeof(struct tlb_entry));
exit(1);
}
/* Set pt_size to new boundary */
pt_size += PT_INCR;
/* initialize entries in new_space, that is, make them invalid. */
for (i=pt_high; i < pt_size; i++)
PT[i].lower = 0;
}
PT[pt_high].upper = vpn << 12;
PT[pt_high].lower = 1 << 9;
return pt_high++;
}
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